Need some tuning advice please

[DSM_23]

Ok Im having a little bit of a tuning issue, I just got my new block put in about 700 miles ago, Mods are in the profile. AFC settings are High= -7 across, any leaner I get more knock. Throttle points are 30, 65. I have 650 injectors so it seems a little rich but everything looks good plugs, piston tops are still pretty clean etc. Boost for this log was 20psi. And I know about the TPS not being fully at 100 as well. I am hitting fuel cut at the point of which knock hits 23 counts its very abrupt and I dont have an idea of whats causing it, base timing is at 5. Please anyone with advice share.

Timing O2V TPS Hz RPM Knock INJP
38.00º 0.00V 21.18% 119.51Hz 2687.50rpm 0 2.30ms
37.00º 0.00V 27.06% 201.28Hz 2625.00rpm 0 3.58ms
35.00º 0.64V 27.45% 226.44Hz 2656.25rpm 0 3.58ms
34.00º 0.04V 27.45% 239.02Hz 2718.75rpm 0 3.84ms
33.00º 0.78V 28.63% 251.60Hz 2750.00rpm 0 3.84ms
34.00º 0.33V 29.80% 270.47Hz 2781.25rpm 0 1.02ms
34.00º 0.70V 29.80% 289.34Hz 2843.75rpm 0 4.35ms
33.00º 0.72V 30.20% 301.92Hz 2875.00rpm 0 4.61ms
32.00º 0.68V 36.47% 358.53Hz 2937.50rpm 0 5.63ms
31.00º 0.80V 37.25% 415.14Hz 3000.00rpm 0 5.38ms
30.00º 0.21V 40.00% 459.17Hz 3093.75rpm 0 5.63ms
29.00º 0.08V 45.49% 522.07Hz 3187.50rpm 0 6.66ms
26.00º 0.84V 54.90% 666.74Hz 3312.50rpm 4 10.50ms
21.00º 0.86V 78.82% 893.18Hz 3437.50rpm 3 14.85ms
14.00º 0.84V 89.41% 1125.91Hz 3656.25rpm 3 15.62ms
15.00º 0.86V 89.41% 1138.49Hz 3875.00rpm 2 15.87ms
16.00º 0.86V 91.37% 1220.26Hz 4031.25rpm 3 15.87ms
17.00º 0.84V 92.55% 1339.77Hz 4281.25rpm 2 16.64ms
17.00º 0.84V 94.90% 1478.15Hz 4468.75rpm 6 18.43ms
16.00º 0.84V 93.33% 1566.21Hz 4656.25rpm 5 17.92ms
16.00º 0.84V 92.55% 1603.95Hz 4843.75rpm 5 18.43ms
16.00º 0.84V 95.29% 1603.95Hz 5062.50rpm 4 17.92ms
17.00º 0.84V 87.45% 1603.95Hz 5218.75rpm 4 19.20ms
20.00º 0.86V 94.90% 1603.95Hz 5375.00rpm 3 18.43ms
20.00º 0.86V 81.18% 1603.95Hz 5562.50rpm 3 18.43ms
21.00º 0.00V 92.94% 1465.57Hz 5625.00rpm 23 17.66ms

 

[Quasimondo]

Have you checked for any boost leaks? Fuel cut shouldn't be happening if you're using a 2G MAS. Even if you can't see any holes or leaks up and down your intake, that doesn't mean it's not there. Did you use new gaskets for the intake manifold, throttle body, and turbo outlet?

 

[DSM_23]

Yes new gaskets were used for that stuff, I have only gotten fuel cut since I rebuilt the block with the 8.3 compression ratio. Im not sure about the boost leaks yet, I havent gotten time to do that yet, but other than that what else could it be? Why would a boost leak instantly cause the fuel to cut at at set RPM? Thanks for the reply btw.

justin

 

[Quasimondo]

The MAS looks only at how much air is passing through it. When you have a leak in the intake system, the turbo must work harder to maintain the boost that is being lost. To the MAS, that's a lot of air that is passing through it, and that's what the ECU will see when it gets its Karmen readings. I can't remember what the threshold is, but when the ECU gets a reading that exceeds it, it shuts down the injectors to prevent engine damage.

Normally, this is a problem only for the 1G MAS. 2G sensors will give a lower reading compared to 1G sensors if the same amount of air is flowing through them, so you should have less of a chance for fuel cut. Usually when folks switch over to the 2G MAS, they have to richen it up for the ECU to see the signal properly, but since you're using 650's, your settings look to be right.

Other conditions for fuel cut is setting the AFC too rich, but if your settings are at -7, that's not a problem. Running too much boost can cause it too, but with that air sensor and that turbo, it shouldn't happen. I can't think of anything else other than a leak somewhere.

 

[DSM_23]

hey, alrite I did a boost leak test tonite, and found a fairly big leak so Im like great good deal. Well its about 40 degrees out tonite so I went out and did a few pulls, 20psi, same afc settings No boost leaks now, and boom fuel cut at almost exactly 5500-6000rpm everytime I dont get it, its never had fuel cut since this block was redone... What else could it be?

 

[Quasimondo]

Where was the leak found? What did you do to fix it?

 

[andymoraitis]

I agree with Armando about the boost leak being a likely cluprit, but also wanted to talk about your knock counts. The motor obviously pulls well into the middle RPM ranges, but I'm not liking the knock counts as you get higher up in the RPM's. While not excessive, you may be dealing with a bit of a fuel volume issue to the rail or simply an increase in knock sensitivity due to a change in compression ratio.

As an example, when someone changes the bottom end comp ratio to run closer to 2G levels, there's a need to reduce max timing to avoid knock. Richening the AFC will only bring about fuel cut sooner and run you more into a power-robbing rich condition. I'd strongly recommend looking into an EPROM ECU with a custom A/F tune and capped 2G maps. For reference the 2G map peaks at 16 degrees of advance above 2.1 g/rev and is therefore more tolerant of higher levels of boost on pump gas with an increased compression ratio.

Another thing I'd like you to do is check your 190 pump's voltage to be sure that you're getting proper fuel volume to the rail. While some tuners can run into the 11's on their 190's the moment I added cams to the old 2.0 I had insufficient volume to the rail and needed to switch to a 255 HP. If you haven't re-wired the pump, I'd also look into that as insufficient pump voltage can create similar issues and fuel starvation as it struggles to keep up.

Sorry if this rambles, but I'm still getting that first cup of coffee down.

Andy

 

[DSM_23]

Where was the leak found? What did you do to fix it?

There was a pretty large leak on the coupler right before the throttle body and a small leak below the J pipe. I sprayed soapy water and repositioned the clamps to solve the leak.
Also, my injector duty cycles are around 70-75ish I believe if that helps, It seems as if I should be running rich with such a low correction deficate, but the motor does breath very well so I suppose thats where all the needed fuel is coming from. Could I adjust my base timing or would that just throw everything off.

 

[DSM_23]

?? Anybody

 

[TimG]

Raise the fuel pressure and lean it out even more. That way your MAF sees a lot mess airflow and the ECU won't cut your engine out. A cheap way to raise the fuel pressure is to use a n/t FPR. And yes it rises with boost.

 

[DSM_23]

Raise the fuel pressure and lean it out even more. That way your MAF sees a lot mess airflow and the ECU won't cut your engine out. A cheap way to raise the fuel pressure is to use a n/t FPR. And yes it rises with boost.

I can use one off of any N/t year? Also how much fp does it increase it by? Is there any other people that have done this with good result?. Thanks for replies.

justin

 

[spyderturbo007]

Fuel cut is airflow related, but without being able to "see" airflow on a 1g, we can't tell if you are actually reaching the ECU's limit. I don't like the fact that your TPS is bouncing around. Normally it will hold steady all the way through WOT. I would look into that before you go too far.

Also, how about plug gap? Base timing? Check your knock sensor lately? ECU for leaking caps? I'm going to go out on a limb here and say that your knock at leaner AFR's is correctable, but it's the reason that your having to add so much fuel back with the SAFC. This, in turn, is causing the ECU too see way too much air and introduce you to the wonderful world of fuel cut.

There are some other options we can explore after you look into everything listed above I wouldn't go throwing parts at it just yet.

 

[DSM_23]

Fuel cut is airflow related, but without being able to "see" airflow on a 1g, we can't tell if you are actually reaching the ECU's limit. I don't like the fact that your TPS is bouncing around. Normally it will hold steady all the way through WOT. I would look into that before you go too far.

Also, how about plug gap? Base timing? Check your knock sensor lately? ECU for leaking caps? I'm going to go out on a limb here and say that your knock at leaner AFR's is correctable, but it's the reason that your having to add so much fuel back with the SAFC. This, in turn, is causing the ECU too see way too much air and introduce you to the wonderful world of fuel cut.

There are some other options we can explore after you look into everything listed above I wouldn't go throwing parts at it just yet.

Ok, the tps was me basically because I figured if it just slammed the gas I'd hit fuel cut instantly but, now that I drive it more its only happening about 5500-6000rpm. Plugs were checked 2 days ago gapped at .28, look great, not lean not to rich. Base timing was done couple weeks ago to 5 degrees. Knock sensor is brand new. Ecu has caps replaced, so everything you listed is it top shape. Whats your next suggestion?

 

[XxrusianxX]

Hey are you using just the afc to tune those 650 injectors, because from what I can remember the afc is only good for 500 injectors. Try running race gas to see where your knock will go to. This will do a couple of things. If knock goes down then you know the knock sensor is good. Also if you get no fuel cut then you know it is knock related.

 

[DSM_23]

Hey are you using just the afc to tune those 650 injectors, because from what I can remember the afc is only good for 500 injectors. Try running race gas to see where your knock will go to. This will do a couple of things. If knock goes down then you know the knock sensor is good. Also if you get no fuel cut then you know it is knock related.

I know this, My timing seems a bit high, at 5800 rpms it was peaking at 24 degrees and thats when fuel cut happens, wtf is up with that, is something wrong here or what?

 

[iiiwildfireiii]

I'm curious as to why your airflow is peaking at 4843.75rpm and keeping @ 1603.95 hz until 5600 rpm when you hit your fuel cut. I know my MAF reads higher than 1600. Problems with wiring of the MAF? Is there a spare one to try or borrow? Also, is your TPS reading 0% when you're off the throttle?

 

[DSM_23]

I'm curious as to why your airflow is peaking at 4843.75rpm and keeping @ 1603.95 hz until 5600 rpm when you hit your fuel cut. I know my MAF reads higher than 1600. Problems with wiring of the MAF? Is there a spare one to try or borrow? Also, is your TPS reading 0% when you're off the throttle?

Mas wiring is fine this all started after the block was reinstalled, TPS does read 0% as well.

 

[NitrousBob]

Do you have a wideband or just using an autometer nb sensor? I would add fuel to those spots and see what happens. I am suspect of your tps, it needs to read correctly. 100% at WOT. Have you tried lowering the boost a little and see what happens.

 

[compression]

I'm curious as to why your airflow is peaking at 4843.75rpm and keeping @ 1603.95 hz until 5600 rpm when you hit your fuel cut. I know my MAF reads higher than 1600. Problems with wiring of the MAF? Is there a spare one to try or borrow? Also, is your TPS reading 0% when you're off the throttle?

The logger will only read 1600 hertz thats as much as will come out of the diagnostic port, when you get a keydiver chip he will cut the hertz in half and then with most logging software will have an option to double the airflow so you can read higher then 1600 hertz.

 

[compression]

Do you have a wideband or just using an autometer nb sensor? I would add fuel to those spots and see what happens. I am suspect of your tps, it needs to read correctly. 100% at WOT. Have you tried lowering the boost a little and see what happens.

and adding fuel via afc , maft or any other piggy back fuel controller will only induce more fuel cut, i suggest upping the fuel pressure and leaning it out via afc, i honestly dont know why you would be fuel cutting at only 70-80% indc somethings up if you ask me.

 

[DSM_23]

Something is up and I know it, I havent had to deal with fuel cut since I ran a 14b , and now all of a sudden its back, ill try any suggestions you think could help. Oh and I have lowered the boost to 16psi and it still cuts fuel at same rpm. I'll try and post a new log with full throttle and see if the tps is 100% on tmw or the next day.

 

[compression]

did your engine rebuild come with those hks 272's? maybe your just flowing alot more air now because your engine is breathing a hell of a lot better, and just hitting some high airflow numbers, thus making your ecu fuel cut, you need a chip or dsmlink or something with fuel cut elimination, thats the only thing i can think of. what kind of airflow does your afc read? check that also and let me know.

 

[spyderturbo007]

Whats your next suggestion?

You are definately on the ball with your research. I guess I'm going to have to think about this one.....

Where did you start your tune? I would almost bet my paycheck that with a 16g and showing the ECU all but 7% of the airflow puts you over the 2.55g/rev limit.

Lets say that you are flowing 35lbs/min, 20psi @ 5500rpm. With your mods, this should be a resonable number. That means that you are showing the ECU almost 34lbs/min. The ECU is going to see about 2.8g/rev and cut your fuel.

Even at 32lbs/min, you are still showing the ECU 2.56g/rev. I know you have to be hitting 32lbs/min, if I can hit 33lbs/min, 20psi @ 6400rpm and that's on the stock exhaust.

We need to figure out why you have to be so rich to offset the knock. I'm confident that if you lean everything out, the FC will go away, but the knock may go through the roof. Or you could be so rich that you are knocking. Do you have access to race gas?

 

[DSM_23]

You are definately on the ball with your research. I guess I'm going to have to think about this one.....

Where did you start your tune? I would almost bet my paycheck that with a 16g and showing the ECU all but 7% of the airflow puts you over the 2.55g/rev limit.

Lets say that you are flowing 35lbs/min, 20psi @ 5500rpm. With your mods, this should be a resonable number. That means that you are showing the ECU almost 34lbs/min. The ECU is going to see about 2.8g/rev and cut your fuel.

Even at 32lbs/min, you are still showing the ECU 2.56g/rev. I know you have to be hitting 32lbs/min, if I can hit 33lbs/min, 20psi @ 6400rpm and that's on the stock exhaust.

We need to figure out why you have to be so rich to offset the knock. I'm confident that if you lean everything out, the FC will go away, but the knock may go through the roof. Or you could be so rich that you are knocking. Do you have access to race gas?

Lol of course, Im trying my own things just wanting others opinions as well, I dont have access to race gas . Anyways here are some new logs I have 2 They were both at full throttle and the current boost for these was 17psi, Fuel cut occured this time at 6500 and I did lean it out a tad .Throttle positions are 30/60. NE points are as follows:
2600 3k 3600 4k 4600 5k 5400 5800 6400 7k
-8 -9 -10 -10 -10 -11 -12 -11 -11 -11

Heres the most current log I did Duty cycles peaked at 87.5% at 6100 then dropped to 82%. Also Im not sure whats up with the tps, Afc reads 100% logger reads this....

TIMA O2-R TPS RPM KNCK INJP
30.00 0.74 50.98 2718.75 0.00 5.38
30.00 0.82 61.57 2812.50 0.00 6.91
28.00 0.84 68.63 2906.25 0.00 7.42
27.00 0.84 85.10 3000.00 0.00 8.19
25.00 0.86 87.45 3156.25 0.00 9.73
23.00 0.82 92.94 3281.25 0.00 12.03
20.00 0.86 92.55 3437.50 0.00 12.29
21.00 0.86 90.20 3625.00 3.00 12.54
21.00 0.86 94.90 3781.25 3.00 12.80
21.00 0.82 91.37 3937.50 2.00 13.57
20.00 0.82 90.20 4125.00 2.00 13.82
20.00 0.84 94.90 4312.50 1.00 14.08
21.00 0.82 94.90 4500.00 1.00 15.36
20.00 0.82 94.12 4625.00 0.00 14.85
18.00 0.86 91.37 4843.75 0.00 15.10
21.00 0.82 90.20 5000.00 0.00 15.62
20.00 0.86 92.16 5187.50 0.00 16.38
20.00 0.86 94.90 5375.00 0.00 16.64
21.00 0.86 92.94 5437.50 0.00 16.38
22.00 0.82 92.55 5531.25 0.00 16.64
23.00 0.82 94.12 5687.50 0.00 16.64
24.00 0.82 94.90 5843.75 0.00 16.13
24.00 0.82 92.94 5843.75 5.00 16.38
23.00 0.94 92.94 6062.50 4.00 17.41
20.00 0.82 86.67 6125.00 4.00 17.15
21.00 0.86 90.20 6250.00 4.00 16.90
21.00 0.80 94.12 6406.25 3.00 15.62
20.00 0.94 94.51 6562.50 3.00 15.36
19.00 0.23 85.88 6343.75 10.00 3.33

 

[DSM_23]

did your engine rebuild come with those hks 272's? maybe your just flowing alot more air now because your engine is breathing a hell of a lot better, and just hitting some high airflow numbers, thus making your ecu fuel cut, you need a chip or dsmlink or something with fuel cut elimination, thats the only thing i can think of. what kind of airflow does your afc read? check that also and let me know.

272s were done last year, the car does flow pretty well im not sure what my afc Hz readings are though.