Log results - lots of knock! Eeeek!

[spyderturbo007]

Here you go guys,

According to this post, you can test the MAS with a meter:

http://www.dsmtuners.com/forums/showthread.php?t=9232&highlight=MAS+test

Wow, I guess I should have thought of the search button........

So Neal, I guess you have a plan for the weekend.

1) Check FP voltage
2) Buy Shop manual
3) Test MAS
4) Get Race Gas

Woo hoo......My weekend will consist of sitting around throwing back a couple of cold ones, thinking about all the hard work you are doing.

 

[Ultimatedsm]

The more I look at his log, the more I believe that his fuel pump is not pumping enough. I know the 550's should handle the 18 psi with out giving you issues with lean mixtures. Than again, you do have an EVOIII 16g and I have seen the 550's max out at 22 psi or so.

Your o2 voltage is low, with your -15%, it should be higher then .84 up top, it should be in the 0.90's at least (WOT of course). I still say turn down the boost and see what the threshold is before you start to knock.

 

[andymoraitis]

Woo hoo......My weekend will consist of sitting around throwing back a couple of cold ones, thinking about all the hard work you are doing.

Lazy bum. Gett off your ass and make some cookies dammit!

 

[Gromit]

Wow! I actually go do some work for a couple hours & come back to find a flood of replies! Seems my list of weekend tasks is getting longer & longer.

Let's see...I've got a factory service manual & planned to look at that to see if the MAS could be tested. Sounds like that's a plan.

As for the fuel pump, it's brand new. However, & Nathan will remember this issue, there was a fuel problem with a small hole in a piece of fuel line that was inside the tank. Basically, the car ran like ass but gave no indication fuel was "leaking" since it was spraying inside the tank. That issue has since been resolved & the car seems to run like normal. Wondering if this could be related to the suspected "fuel delivery" problem...I'll see what I can do about testing the voltage of the pump.

As for the knock sensor, I have not checked the torque specs. Out comes the trusty torque wrench...As for the black discharge - been there, done that, don't got none. Try to keep up, please. Just kidding!

Regarding the o2 voltage - it stays mostly at .88v until approaching the upper rpm's where all the knock occurs. I thought this was generally a "normal" value for a 1G & that the 2G's were typically in the .90's? Maybe I've got it backwards...

I'll hold off on the race gas for the moment, just because I've got nearly a full tank in there right now & plenty of other things to work with 1st.

Lots of different ideas/plans/suggestions here so I'll just try to knock them out 1 by 1 & see what happens. I'll post back when I have some useful info. Thanks, Andy, for your input on this as well.


P.S. I can't comment on Nathan's alleged "dorkiness". He's a chemist so perhaps it's to be expected. My degree is in physics so maybe I'm too dorky to recognize other dorks.

 

[kraka]

Just a quick test...

It doesnt look like adjusting the safc is doing anything...Possibly a bad connecton like stated earlier...

Heres a way to check, go to your idle/low throttle setting and for the 1k setting, lean it ALL the way out...- 50% ....If at -50% the car does not die out from being too lean, then its definitely not connected right....Just a thought...

Its not the knock sensor...Its not phantom knock...A wideband will solve the question on being too lean or not, but I can tell that the knock is real...My phantom knock is worse at partial throttle and its sparatic and annoying, the way this occurs seems like real knock...

 

[spyderturbo007]

Regarding the o2 voltage - it stays mostly at .88v until approaching the upper rpm's where all the knock occurs. I thought this was generally a "normal" value for a 1G & that the 2G's were typically in the .90's? Maybe I've got it backwards...

I really don't pay attention to O2 voltage. The narrowband sensor is basically worthless. To be honest, these days I don't normally log O2 when I'm making a pull. I would rather have an extra sample / second than see the O2 voltage.

 

[Gromit]

OK guys, here's the updated info. Had Friday evening to work on the car so I put in the new set of bpr7es plugs gapped to 0.028. I found the test procedure for the MAS in my factory service manual, got out my multi-meter & did that - tested good. I reset the base timing to roughly 2-3* BTDC. When I ungrounded the plug, the timing read 8* BTDC, which is per the manual. Also doubled-checked my fuel pressure - with vacuum hose off it's right at 37 psi which is where it should be. However, with the hose connected it's at 29 psi, as opposed to 27 psi. Also, I could not find anything on how to test the voltage to the fuel pump.

Set the HI Throttle settings to -15% across the board & did 2 pulls early Sunday AM while it was still relatively cool out. For the 1st log I included all those extra values ultimatedsm asked for. Then I did a 2nd pull with just the typical stuff so there'd be more samples. Here's the data:

Log #1

Timing FTRL FTRM FTRH O2 TPS MAFS RPM KNOCK INJP IDC AIRT
25° 104.5% 106.1% 114.7% 0.23V 34.9% 390.0Hz 2438 0 6.40ms 16 84.4°F
27° 104.5% 106.1% 114.7% 0.80V 83.1% 452.9Hz 2500 0 8.45ms 22 84.4°F
24° 104.5% 106.1% 114.7% 0.86V 97.6% 490.6Hz 2594 0 8.70ms 24 84.4°F
22° 104.5% 106.1% 114.7% 0.84V 98.4% 540.9Hz 2688 0 9.47ms 27 84.4°F
21° 104.5% 106.1% 114.7% 0.86V 98.8% 597.6Hz 2781 0 10.50ms 31 84.4°F
18° 104.5% 106.1% 114.7% 0.88V 99.2% 685.6Hz 2906 0 13.06ms 40 84.4°F
16° 104.5% 106.1% 114.7% 0.88V 99.6% 805.1Hz 3000 0 15.62ms 50 84.4°F
15° 104.5% 106.1% 114.7% 0.88V 99.6% 949.8Hz 3156 0 17.41ms 58 84.4°F
14° 104.5% 106.1% 114.7% 0.88V 99.6% 1107.0Hz 3281 0 18.69ms 65 84.4°F
15° 104.5% 106.1% 114.7% 0.88V 99.6% 1169.9Hz 3469 0 18.43ms 68 84.4°F
15° 104.5% 106.1% 114.7% 0.88V 99.6% 1169.9Hz 3625 0 17.66ms 68 85.2°F
16° 104.5% 106.1% 114.7% 0.88V 100.0% 1201.4Hz 3781 0 17.66ms 71 85.2°F
17° 104.5% 106.1% 114.7% 0.88V 100.0% 1276.9Hz 3938 0 18.18ms 76 86.0°F
18° 104.5% 106.1% 114.7% 0.88V 100.0% 1371.2Hz 4094 1 18.43ms 80 86.0°F
17° 104.5% 106.1% 114.7% 0.88V 100.0% 1440.4Hz 4219 1 19.20ms 86 86.9°F
17° 104.5% 106.1% 114.7% 0.88V 100.0% 1459.3Hz 4344 0 19.46ms 90 86.9°F
18° 104.5% 106.1% 114.7% 0.88V 100.0% 1471.9Hz 4500 0 19.20ms 92 86.9°F
18° 104.5% 106.1% 114.7% 0.88V 100.0% 1471.9Hz 4594 0 19.20ms 94 87.8°F
18° 104.5% 106.1% 114.7% 0.88V 100.0% 1465.6Hz 4688 0 18.18ms 91 87.8°F
19° 104.5% 106.1% 114.7% 0.88V 100.0% 1534.8Hz 4844 0 18.18ms 94 88.7°F
19° 104.5% 106.1% 114.7% 0.86V 100.0% 1503.3Hz 4969 0 18.18ms 96 88.7°F
19° 104.5% 106.1% 114.7% 0.88V 100.0% 1541.1Hz 5094 0 18.18ms 98 89.6°F
20° 104.5% 106.1% 114.7% 0.86V 100.0% 1604.0Hz 5219 1 17.92ms 99 89.6°F
20° 104.5% 106.1% 114.7% 0.86V 100.0% 1578.8Hz 5250 0 17.92ms 100 90.5°F
21° 104.5% 106.1% 114.7% 0.86V 100.0% 1604.0Hz 5406 0 17.15ms 99 90.5°F
22° 104.5% 106.1% 114.7% 0.86V 100.0% 1604.0Hz 5531 0 17.41ms 102 90.5°F
22° 104.5% 106.1% 114.7% 0.86V 100.0% 1585.1Hz 5688 0 16.90ms 102 91.4°F
23° 104.5% 106.1% 114.7% 0.86V 100.0% 1604.0Hz 5750 0 17.66ms 108 91.4°F
24° 104.5% 106.1% 114.7% 0.86V 100.0% 1604.0Hz 5875 0 11.78ms 73 91.4°F
21° 104.5% 106.1% 114.7% 0.84V 100.0% 1604.0Hz 5969 14 15.87ms 101 92.3°F
20° 104.5% 106.1% 114.7% 0.84V 100.0% 1604.0Hz 6094 21 15.62ms 101 92.3°F
18° 104.5% 106.1% 114.7% 0.80V 100.0% 1604.0Hz 6188 20 13.06ms 86 92.3°F
18° 104.5% 106.1% 114.7% 0.82V 99.6% 1604.0Hz 6313 20 14.85ms 100 93.2°F
19° 104.5% 106.1% 114.7% 0.82V 100.0% 1484.4Hz 6344 19 13.82ms 93 93.2°F
19° 104.5% 106.1% 114.7% 0.68V 100.0% 1604.0Hz 6500 23 15.36ms 106 94.1°F
20° 104.5% 106.1% 114.7% 0.04V 99.6% 1377.5Hz 6656 23 10.50ms 74 94.1°F
19° 104.5% 106.1% 114.7% 0.35V 100.0% 1371.2Hz 6563 30 7.17ms 50 95.0°F
23° 104.5% 106.1% 114.7% 0.68V 100.0% 1604.0Hz 6531 30 15.10ms 105 95.0°F
11° 104.5% 106.1% 114.7% 0.80V 100.0% 1409.0Hz 6844 29 11.52ms 84 95.0°F
14° 104.5% 106.1% 114.7% 0.76V 99.2% 1409.0Hz 7000 29 12.03ms 89 95.9°F
20° 104.5% 106.1% 114.7% 0.02V 98.4% 1604.0Hz 6844 28 11.26ms 82 95.9°F
15° 104.5% 106.1% 114.7% 0.02V 98.4% 1358.6Hz 6875 28 9.98ms 73 95.9°F
18° 104.5% 106.1% 114.7% 0.23V 98.4% 1604.0Hz 6781 28 14.08ms 102 96.8°F
12° 104.5% 106.1% 114.7% 0.74V 98.0% 1339.8Hz 6938 27 12.03ms 89 96.8°F
13° 104.5% 106.1% 114.7% 0.76V 98.0% 1409.0Hz 7094 27 10.50ms 79 96.8°F
14° 104.5% 106.1% 114.7% 0.72V 98.0% 1578.8Hz 7125 27 13.57ms 103 96.8°F
12° 104.5% 106.1% 114.7% 0.82V 11.0% 566.1Hz 6844 24 2.82ms 20 97.7°F
38° 104.5% 106.1% 114.7% 0.80V 11.0% 157.3Hz 7031 4 2.05ms 15 96.8°F
45° 104.5% 106.1% 114.7% 0.80V 11.0% 157.3Hz 6938 0 1.28ms 9 96.8°F


Log #2

Timing O2 MAFS RPM KNOCK
26° 0.66V 427.7Hz 2438 0
24° 0.86V 427.7Hz 2469 3
24° 0.86V 440.3Hz 2531 3
24° 0.86V 452.9Hz 2563 3
23° 0.84V 471.8Hz 2563 2
22° 0.84V 490.6Hz 2625 2
21° 0.84V 515.8Hz 2656 2
20° 0.84V 540.9Hz 2719 2
20° 0.84V 566.1Hz 2750 1
21° 0.84V 591.3Hz 2781 1
20° 0.86V 629.0Hz 2844 1
17° 0.86V 660.5Hz 2875 1
17° 0.86V 704.5Hz 2938 1
15° 0.88V 754.8Hz 2969 0
15° 0.88V 811.4Hz 3063 0
15° 0.90V 880.6Hz 3094 0
15° 0.90V 912.1Hz 3188 0
15° 0.88V 981.2Hz 3188 0
14° 0.88V 1037.9Hz 3281 0
15° 0.88V 1075.6Hz 3344 0
15° 0.88V 1132.2Hz 3375 0
15° 0.88V 1163.7Hz 3469 0
15° 0.88V 1169.9Hz 3563 0
15° 0.88V 1176.2Hz 3625 0
16° 0.88V 1176.2Hz 3656 0
16° 0.88V 1207.7Hz 3750 0
17° 0.88V 1239.1Hz 3813 0
17° 0.88V 1314.6Hz 3938 0
18° 0.88V 1333.5Hz 4000 1
17° 0.88V 1377.5Hz 4063 1
17° 0.88V 1396.4Hz 4125 1
17° 0.88V 1402.7Hz 4188 0
18° 0.88V 1427.8Hz 4250 0
18° 0.88V 1446.7Hz 4313 0
18° 0.88V 1484.4Hz 4375 0
18° 0.88V 1465.6Hz 4438 0
18° 0.88V 1484.4Hz 4469 0
18° 0.88V 1515.9Hz 4531 0
18° 0.88V 1509.6Hz 4625 0
18° 0.88V 1522.2Hz 4656 0
18° 0.88V 1515.9Hz 4688 0
19° 0.88V 1459.3Hz 4750 0
19° 0.88V 1484.4Hz 4813 0
19° 0.86V 1497.0Hz 4938 0
19° 0.86V 1528.5Hz 4969 0
19° 0.86V 1553.6Hz 5063 0
19° 0.86V 1566.2Hz 5063 2
19° 0.86V 1604.0Hz 5094 1
20° 0.88V 1534.8Hz 5188 1
20° 0.86V 1604.0Hz 5250 1
21° 0.86V 1604.0Hz 5344 1
21° 0.86V 1604.0Hz 5375 1
21° 0.86V 1604.0Hz 5406 0
22° 0.86V 1604.0Hz 5500 0
22° 0.86V 1604.0Hz 5500 0
22° 0.86V 1604.0Hz 5594 0
22° 0.86V 1604.0Hz 5656 0
23° 0.86V 1591.4Hz 5688 0
23° 0.84V 1534.8Hz 5719 0
25° 0.84V 1604.0Hz 5781 7
21° 0.84V 1604.0Hz 5875 7
21° 0.84V 1604.0Hz 5906 7
23° 0.84V 1585.1Hz 5938 7
23° 0.82V 1604.0Hz 6031 13
23° 0.82V 1559.9Hz 6094 14
23° 0.82V 1604.0Hz 6125 21
18° 0.82V 1604.0Hz 6156 21
17° 0.84V 1566.2Hz 6250 21
21° 0.80V 1547.3Hz 6313 25
19° 0.78V 1383.8Hz 6281 25
19° 0.20V 1251.7Hz 6375 25
20° 0.04V 1434.1Hz 6375 25
18° 0.62V 1553.6Hz 6469 25
20° 0.08V 1604.0Hz 6531 24
18° 0.70V 1503.3Hz 6563 24
18° 0.08V 1604.0Hz 6563 24
18° 0.74V 1446.7Hz 6531 26
20° 0.02V 1163.7Hz 6500 26
15° 0.12V 1585.1Hz 6719 25
15° 0.78V 1346.1Hz 6750 25
21° 0.02V 1239.1Hz 6719 25
15° 0.12V 1604.0Hz 6688 25
14° 0.78V 1604.0Hz 6719 25
16° 0.47V 1566.2Hz 6813 24
17° 0.25V 1478.2Hz 6844 24
18° 0.00V 1169.9Hz 6844 24
17° 0.02V 1553.6Hz 6969 24
14° 0.78V 1604.0Hz 6938 24
13° 0.76V 1541.1Hz 6969 23
16° 0.78V 1490.7Hz 6938 23
18° 0.14V 1333.5Hz 6844 23
15° 0.12V 1547.3Hz 6969 23
12° 0.80V 1346.1Hz 7031 23
20° 0.02V 1604.0Hz 7063 23
13° 0.84V 421.4Hz 6844 21
38° 0.82V 251.6Hz 7063 11
41° 0.78V 163.5Hz 6906 0
45° 0.82V 106.9Hz 6906 0



Knock is still hellacious, but lower in the 2nd pull despite no changes. The stuttering at approx. 6k rpm is still present. Everything else felt normal - pulls hard & smooth until the ECU starts yanking the timing due to all the knock. Fuel trims definitely indicate lean.

I'm a little under 1/2 tank of gas now so I could put in some race gas this weekend. If you have suggestions for changes & want me to make more pulls, I can do so if they're 2nd gear pulls - it's too congested where I live & during the workweek there's not a good place to be speeding along at 95 mph. A 2nd gear pull might be sufficient to see what effects any changes have.

Thoughts?

 

[andymoraitis]

The last few threads on this search should get you in the ballpark:

http://www.dsmtuners.com/forums/search.php?searchid=2053341

I still think you need to rule out anything related to fuel volume and fuel supply such as the pump, a failing FPR solenoid and a clogged filter.

 

[fourreGsixty3]

Andy not sure if its me, but the link goes to a page that says "sorry no matchs."

Dustin

 

[Gromit]

Some more info:

I checked out the link Andy posted above & found some info on testing the fuel pump voltage (when I clicked the link I got the search results, but when I looked at it again later I got the same message fourreGsixty3 got ). Finally managed to find the test connector by the firewall - that little bugger is definitely tucked away in the harness & tape. Anyway, found the connector & stuck the multimeter on it with the car idling - voltage was 13.3v.

Also tested the Fuel Pressure Solenoid by disconnecting the vacuum hose on the FPR with the car idling - covered the hose with my thumb & felt plenty of vacuum. Tested the resistance of the connector - according to the factory service manual it should be 36-46 ohms at 68* F. It tested at 58 ohms with ambient temp at 80* F.

Lastly, I did what kraka suggested above - took the 1k Ne point in the LO Throttle setting of the SAFC & leaned it out while the car was idling. By -30% the car just about shut down, so I think we can rule out incorrect SAFC connection.

Things I have not done:

1. Checked the torque on the knock sensor - I can't get my torque wrench in there to do that. I have been assuming to this point that since the knock sensor has never been messed with it should not be over-tight.

2. Put in race gas - could do that this weekend.

3. Turned down the boost.

4. Turned up the fuel pressure.

Not sure where to go from here...

 

[spyderturbo007]

Wow, where did my post go. I was sure that I made a post on Friday to the effect of "Holy crap, you're out of injector". I wonder where the hell that thing went. Damnit Andy, were you deleting my posts again.

Neal, IDC's over 80 - 85% are never a good idea. It looks like you are out of injector and need to either invest in some 650's or drop the boost.

Anyone know what's going on with these data points?

19° 0.68V 1604.0Hz 6500 23 15.36ms 106%
20° 0.04V 1377.5Hz 6656 23 10.50ms 74%
19° 0.35V 1371.2Hz 6563 30 7.17ms 50%
23° 0.68V 1604.0Hz 6531 30 15.10ms 105%

Wow, during those 4 points, O2 voltage takes a dump, airflow drops by 300Hz, rpm bounces all over the place, IDC drops in half. WTF

Oh, and Neal, your car is starting to make my head hurt!

 

[andymoraitis]

If your head hurts, mine has already fallen off. Damn AFC's!

Anyway, even if the MAF tested good, I don't like the way it's dropping counts and that wierdness with the O2 brings up some concerns.

If we've eliminated fuel volume (to the rail) the only things I could consider are:

1. Faulty MAF
2. Bad O2 sensor
3. Solar Flares
4. Negative effects from Kevin Federline thinking he's a rapper.
5. Insufficient injector flow

IDC's really are out of whack and then you notice they drop like a brick along with the airflow. As much as I hate to say it, it may very well be the MAF since it controls almost everything relative to airflow.

Hell I don't know and I'm not all that bright anyway. If an MAF change doesn't fix it, I'd find that Federline prick and blame him for all of this...

 

[Gromit]

Wow, where did my post go. I was sure that I made a post on Friday to the effect of "Holy crap, you're out of injector". I wonder where the hell that thing went. Damnit Andy, were you deleting my posts again.

Neal, IDC's over 80 - 85% are never a good idea. It looks like you are out of injector and need to either invest in some 650's or drop the boost.

Anyone know what's going on with these data points?

19° 0.68V 1604.0Hz 6500 23 15.36ms 106%
20° 0.04V 1377.5Hz 6656 23 10.50ms 74%
19° 0.35V 1371.2Hz 6563 30 7.17ms 50%
23° 0.68V 1604.0Hz 6531 30 15.10ms 105%

Wow, during those 4 points, O2 voltage takes a dump, airflow drops by 300Hz, rpm bounces all over the place, IDC drops in half. WTF

Oh, and Neal, your car is starting to make my head hurt!

See, I told you before you were obviously getting old & forgetful!

Yeah, I saw the IDC's, too, & was not happy. I've got no problem switching to bigger injectors if that solves the problem, but I'm still perplexed why this set-up doesn't seem to work when there are gazillions of threads on this board recommending & running this combo.

Our goal for this car is to have something with decent power (300 awhp, or so), handles well (a little stiffer & more aggressive than a daily driver, but not auto-x level), & most importantly runs smooth & solid. I'm not out looking to street race every teenager in town, but I wanna have fun on the weekends where I can. If bigger injectors are the final piece to the equation then great - that's easy.

I've no clue what to make of those data points you referenced. That is the rpm point at which there is the stuttering - usually somewhere around 6k - 6.5k.

As far as your aching head goes, that's not due to my car - that's just the effect of shrinking brain mass due to aging!

 

[Gromit]

If your head hurts, mine has already fallen off. Damn AFC's!

Anyway, even if the MAF tested good, I don't like the way it's dropping counts and that wierdness with the O2 brings up some concerns.

If we've eliminated fuel volume (to the rail) the only things I could consider are:

1. Faulty MAF
2. Bad O2 sensor
3. Solar Flares
4. Negative effects from Kevin Federline thinking he's a rapper.
5. Insufficient injector flow

IDC's really are out of whack and then you notice they drop like a brick along with the airflow. As much as I hate to say it, it may very well be the MAF since it controls almost everything relative to airflow.

Hell I don't know and I'm not all that bright anyway. If an MAF change doesn't fix it, I'd find that Federline prick and blame him for all of this...

Whoops! Missed this while I was typing up my reply.

So we've got 1 aching head, 1 missing head, & I'm about to get out my 45 & take it to either my head or the car (I'm not thinkin' the wife will let me shoot the car, though, since it's technically hers - this does not bode well for me ).

Let's see...Andy, your suggestions are:

1. Faulty MAF - Could be. I can't rule it out, even though the test seems to indicate it's OK. The test process only tested the resistance as it changed relative to temperature change. Did I miss something there?

2. Bad o2 sensor - Less likely. It's a brand new Bosch unit & only seems to give erratic readings at a particular point. While just cruising around or at idle or through most of the wot pull it reads just fine.

3. Solar flares - Well, since we're currently at the lowpoint of the 11 year cycle the flare activity is below the minimum threshhold for low-level electromagnetic interference & fuel-flow pooching. So I don't think that's it.

4. Negative effects from K-Fed asshat - Thank God I missed his vomit-inducing debut. However, I am considering contacting my attorney to file suit against him for future pain, suffering, & mental anguish. I might as well add causing fuel flow problems to the suit.

5. Insufficient injector flow - OK, back to that we are.

So either spend money on a MAF or on injectors. If I have to buy a MAF, what about a 2G version? Pros & cons?

And what about a custom chip for the ECU? This would make tuning with the SAFC much easier (especially if I had to go with bigger injectors) & more accurate & allow for finer adjustments, right?

Thanks again for all the input!

 

[andymoraitis]

Neal,

If we replace the AFC with a custom tuned EPROM ECU, the benefit is that we can cap the air/fuel and timing maps so that you can run solid boost on pump gas without running into airflow subtraction and timing issues from using larger injectors. You could run 950's and not know the difference.

But, and this is a heavy but, an EPROM ECU won't solve the current issues relative to your airflow counts being dropped like they are. I wonder if you're not hitting MAF overrun and in that regard, I'd look into a 2G MAF since it will allow for higher airflow before overrun. There's some special wiring that needs to be done and you can find some more information on it here:

http://www.vfaq.com/mods/2GMAF-1G.html

I think that Nathan was on to something when he identified dropped counts a while back. If you have no issues with latent changes in the adiabatic lapse rate of Jupiter, I'd give this a shot.

 

[weith1111]

Why not convert to a GM MAS? Eliminate the MAF as the problem and upgrade as a bonus.

 

[andymoraitis]

Why not convert to a GM MAS? Eliminate the MAF as the problem and upgrade as a bonus.

Good idea Andy. I never think of stuff like that...

 

[spyderturbo007]

I guess it could be a problem with the ECU instead of the MAS??? I know that I had Neal pull the ECU and he said that everything looked fine, but I wonder if there could be something that he is unable to see. I'm also not happy that we can't get the actual airflow and I don't know that there is a correlation between Hz and lbs/min. It would be nice to be able to do the calculation and verify that he is indeed overrunning the injectors. That would give us a lot more information.

I really hate to tell you to go out and buy injectors and a MAS, but I'm stumped. Well, I don't feel too bad not being able to help you fix the problem since everyone else is stumped. I was hoping that it wouldn't be something stupid that I missed, although that would be much easier on Neal.

Maybe we should shoot a PM to Steve and see if all ECU problems are visually noticable. (I think he's the offical ECU repair guy? )

 

[andymoraitis]

I'll shoot him a PM and see if he'll jump in on the thread.

 

[Stanford]

Why have you not turned down the boost and done a log? To me that seems so simple. I may have missed it but read most of this thread and didn't see any mention of logging at lower boost. Try a log at 13psi and see what it says. Then increase 1psi at a time and log each run. Then you can see exactly when the knock will take place and it will start out small. Instead of doing repeated runs where your knock gets OUT OF CONTROL. 30 counts of knock is no good man and quite frankly not healthy for the internals ar all. If it were me I would have turned down the boost long ago and slowly started going up. Instead of starting at what should be MAX pump gas boost and trying to figure out why it's knocking to death.

Have you ever pulled the injectors and had them checked? One may be slightly clogged and limiting your flow to that cylinder. I'd send them out to be cleaned and flowed to eliminate that as a possibility. www.cruzinperformance.com is who I would suggest.

 

[steve]

You guys said you checked the ECU but what did you check it for?
Does it have original caps?

I don't have logs from one breaking up at high RPMs but it could look like this where the airflow, IPW, and RPM break up. It's hard trying to tell which parameter is the cause and which are the result. I'm not sure that the knock isn't the result of the airflow signal breaking up.

Yes, he running out of injector. That could be from yet unfound boost leaks.

So, I'd check the ECU again replacing the caps if they are original, swap in another ECU just to be sure and same for the MAF. If you upgrade MAFs think about going to a 3G/EVO MAF so you don't have to deal with the oval piping. It can flow even more than the 2G MAF.

Steve

 

[Gromit]

Why have you not turned down the boost and done a log? To me that seems so simple. I may have missed it but read most of this thread and didn't see any mention of logging at lower boost. Try a log at 13psi and see what it says. Then increase 1psi at a time and log each run. Then you can see exactly when the knock will take place and it will start out small. Instead of doing repeated runs where your knock gets OUT OF CONTROL. 30 counts of knock is no good man and quite frankly not healthy for the internals ar all. If it were me I would have turned down the boost long ago and slowly started going up. Instead of starting at what should be MAX pump gas boost and trying to figure out why it's knocking to death.

Have you ever pulled the injectors and had them checked? One may be slightly clogged and limiting your flow to that cylinder. I'd send them out to be cleaned and flowed to eliminate that as a possibility. www.cruzinperformance.com is who I would suggest.

I am aware that all this knock is not healthy for the internals - in 3 months I have only done 5-6 total WOT pulls. And I do not want to keep making minor adjustments & doing more pulls without knowing what the source of the problem is. If I lower the boost & eliminate the knock, then raise it a bit at a time to see where it starts, what info does that give me? I could understand doing that if I were trying to run the highest boost level possible for this turbo, but 17-18 psi is more than reasonable with all the supporting mods I have, even with pump gas. Maybe I'm missing something here, but I think something else is going on, as mentioned in the more recent threads. I don't plan on doing any more WOT pulls at this point & when driving around normally I rarely even exceed 4k rpm.

I noticed in the 2 most recent logs from this past Sunday that the knock values vary quite a bit between the 2 runs, even though nothing was changed. I'm wondering if this is related to temperature differences & if that also points to the MAF being the culprit. I'm going to do some more reading of old threads about MAF overrun - some of what I've read so far sounds a lot like what's going on here.

As for the injectors, they are brand spankin' new with less than 300 miles on them so I can't see spending money to have them cleaned.

 

[spyderturbo007]

You guys said you checked the ECU but what did you check it for?
Does it have original caps?

I had him check for obvious damage caused by the leaking caps, but I don't think either of us are electronics experts, so he may have missed something, or I could have told him the wrong thing. I also told him to give it a good "smell" because I had remembered you saying about a rotten egg smell.

Steve, are you the person that everyone sends their ECU to for repair, inspection and cap replacement? If so Neal, you may want to send Steve your ECU had have the caps replaced, because eventually I think all 1g's leak. That would rule one thing out and is problably cheaper than getting a new MAS.

 

[Stanford]

While your new injectors may be clean they may not all flow the same. Aftermarket injectors can often have quite the flow variance. It's just a suggestion, but look at it like this. If some are on the low side and some on the high side you will forever have a poor tune. It's worth knowing the peace of mind to have them flow tested to know they are equal, like I said totally up to you though.

As for your logic of 18psi should be more than resonable, well lots of things are reasonable. It doesn't mean it wouldn't hurt to try a lower boost log. I don't see whats so hard about it. What would it tell you? Everything thats what. If you do a run at 13psi and get no knock obviously you have learned something. That 18psi is to much for your setup for some reason. Then go to 14psi and do again, if no knock still keep going up. There are to many variables for you to assume 18psi should be ok so you will start there. It's like saying oh I have 1600cc injectors, FP3575, and All supporting mods. I will start out at 35psi and go from there. No you start as low and possible and work up, or at least thats my thought.

Your pistons are old and have many years worth of carbon and build up on them. One may have a tiny hot spot causing the knock.

Your stock fuel pump wiring may be badly corroded and limiting voltage to it up high which leans out the car.

The pump may not be seated well into the housing and it's leaking at high pressure causing a fuel pressure drop up high which leans it out and knocks.

There are MANY reasons it could be knocking. It's great you don't get on it all the time because as it is I wouldn't. It's knocking like a Girl Scout selling cookies.

Lower the boost and try again. 550's aren't that big so 18psi may be to much, all cars are different. The AFC is increasing timing when you pull fuel. Sure you lowered the BASE a little but still. Your not doing yourself any favors by trying to tune the MAX output at first. Crawl>Walk.

Edit- I see no MAF listed in your Mods. So I guess you are still on a bone stock 1g MAF. If so yes you are probably overrunning it. Also reading the log remember the MAF reading will be skewed by the AFC. Lower the boost and try again, it will pull a lot less air through the MAF and probably not over run it. As it is, that could be the case. Get out a Dremel and hack it or upgrade to a 2g MAF since you have injectors. They are somewhat of a close match so you wouldn't have to pull NEAR as much fuel with the AFC and the timing wouldn't be near as affected.

 

[Gromit]

Aaaack! More replies!

OK, let me back up a bit...

Andy - thanks for the info on the custom tuned EPROM ECU. I realize it won't solve the current problem but wanted to consider how it fits into the situation. It was something we had considered for a future upgrade anyway. And as far as the latent changes in the adiabatic lapse rate of Jupiter, it's not a factor. As part of my Master's thesis I developed an orbital propagator & space tracker for use with the Hubble telescope. So I verified the position of Jupiter & it's not in the house of Orion so it's more likely to impact your sexual performance than automotive performance.

Weith111 - yeah, I've heard of the GM MAS & will look into that vs. the 2G MAS & the 3G/EVO MAS that Steve suggested. Been reading more on the MAS overrun & I think this is the area I should focus on. Just have to decide which solution would be easiest & most likely to solve the problem.

Nathan & Steve - as far as the ECU goes, I can't rule out a problem that wasn't visible & no, I'm not an electronics expert. But I do have experience with computer boards & upgrades & have seen overheated or burned out chips. I can tell you that this board looked pristine - like it had just come from the factory. There was no oozing green gunk, no nasty dead fish smell, no burn marks, no dust, no nuthin'. So at this point I'm not inclined to think that's the problem. Instead, since we might go with the upgraded ECU down the line, I'm going to leave it for now.

Stanford - thanks for the clarification. Just as a piece of background info, I didn't just start to tune at 18 psi. The car was originally tuned at a dyno shop & gradually raised to that boost level. I did some more work on the car & then wanted to fine tune it & possibly raise the boost another 1-2 psi. Once I saw all the knock, I enlisted Nathan to help me sort it all out. You are correct - I'm got a bone stock 1G MAS. I think this is the area I should focus on for now.

Basically, seems like there's 2 lines of thought here - either there's a faulty part or we've exceeded the capacity of some piece of the system. Based on all the testing I've been doing over the last 2 months & the fact that I know the car's entire history, I'm leaning toward the idea that we've exceeded the capacity of something like the MAS or the injectors, or both.

I appreciate all the suggestions/insights/thoughts! Definitely given me some new areas to look at. I think my plan is to read more about the MAS & pick an upgrade there. I may still be maxxing out the injectors, but I don't want to get new ones until I know what the ECU plan is (if I go with the custom tuned chip I might as well get big ass injectors & not have to worry whether the SAFC can handle it). At least I've sort of got a starting point now...