Knock issues + some other weird things, want a challenge then look inside..

[90 GSX]

Okay first off, I just want to say that for some reason, obtaining answers to questions on the dsmtuners forum has been a bit difficult for me. For some reason, my history is marked with unanswered questions and no feedback. This time it's not something I can figure out by myself, I need advice because I have exhausted everything except a couple of possibilities. Here are the symptoms, comments, and things I have already tried:

Symptoms:
-The car gets up to 30 counts of knock retard at 11 psi even at part-throttle and parts boost. The knock counts get higher as I push the car harder with more throttle/boost.
-At WOT I'm getting a maximum of about 13* of timing.
-The o2 voltage (under boost) on my bosch o2 sensor was .83-.85 at WOT. The o2 voltage on my denso sensor was .87-.89 as read on MMCD.
-The car has a random miss at idle which seems to become frequent when the car is very warm (after a long drive or something).
-The base timing is set at 5* btdc, but when I set the idle to 750, as soon as I remove the alligator clip grounding the timing adjustment plug by the firewall, the idle jumps up to between 950-1050 (no load from power steering, fans, headlights etc.) where it will happily idle with the occasional gurgle or pop when it misses with no major fluctuations.
-Spark plugs are white as a ghost, there a couple issues I did not have resolved that may have caused the plugs to become white, but they are definitely not changing their color. I'm not sure if plugs that have been ran under a lean conditon can still be used but I have replaced the plugs so many times, these are practically brand new. On the same note, my trims were between 110-120% until I swapped o2 sensors and reset them, now they are hovering around 100% give or take about 8%.

Things I have already tried:
-Swapping o2 sensors, in fact, I have tested, monitored, and/or swapped just about every single sensor in the car. I have tested and swapped the coolant temp sensor, maf, cas...
-FIAV, ISC, BISS, shaft seals, are all brand new (except the FIAV since it's built into the TB) but it works perfectly.
-The ECU is freshly rebuilt by motoguy's garage, it is a 91 EPROM with a chip for 550's and MAFT. Since my car is a 90, I did the full conversion to 91 ignition (wiring on ECU harness, gauge cluster, power transistor and coil pack). I have RC550 injectors to work with the EPROM. I am assuming that the MAFT has no effect and is similar to having a 1g MAF because my barometer, IAT, and maf readings all fluctuate normally.
-Car has absolutely negatively posolutely NO boost leaks. It seems like that is the first answer that everybody gives and I'm sick of hearing it (no offense intended). For each time I hear the word boost leak, I shall remove one of the violators toenails with a sharpened bamboo chute.
-

Comments:
-Could it be a weak fuel pump somehow? I highly doubt it, but I have not been able to check my fuel pressure yet due to the lack of a gauge. I did swap the FPR to no avail.
-Could it be false knock? Since I rebuilt my motor and removed the balance shafts, there is some vibration noise above ~4k rpm. I'm hoping most of it will be gone when I do my turbo back exhaust with no heat shields, but is there any way to see if is false knock or not? By the way, I do have the 3g "quiet" lifters and they really are quiet. The engine just purrs like a kitten.
-Could there be something in that EPROM that I don't know about that would make the fuel tables be off?? If the barometer and air temp were zeroed out would they still fluctuate on the logger?
-I believe that whatever is causing that random miss at idle is the source of my problem.

I have honestly racked my brain, stared at the engine fiddling with things for hours to see if something jumps out at me and there is nothing. I am not a newbie, I rebuild the entire motor from scratch, all the wiring, clutch and tranny, etc. etc. by myself and I just can't figure this out for the life of me. Anybody who helps me I would honestly be in your debt.

Thanks for reading the whole post, if there are any questions or clarification needed please mention it, you know that I will be monitoring this thread like a hawk.

TO ANYBODY IN THE SF BAY AREA THAT WOULD LIKE TO HELP, I WILL MAKE IT WORTH YOUR WHILE IF YOU COULD SPEND A COUPLE HOURS HELPING ME TROUBLESHOOT OR AT LEAST GET A FRESH MIND IN THE PICTURE.

 

[beatshack]

My fuel pump also operates at 9v on low throttle, but stomp the gas and the voltage shoots up to 12.5v.

 

[Zenja]

My car also has the same problems, but it idles at the right RPM perfectly. It knocks under boost at basically any RPM and misses at idle every once in a while. I'm almost sure that the problem is that the car is running lean. The question is why. I haven't tried replacing parts yet, but my main suspicions are the injectors, fuel pump, and fuel pressure regulator. That's really all it could be unless the ECU is telling them to squirt less fuel in than it should, and in that case, the problem would be something else like a MAS.

I'd say make sure that the fuel pressure under boost is right, that those injectors aren't bad, and that the fuel pump isn't half-dead. It really should be one of those things. If you find a solution, please post it because this problem is very annoying to me too. I can fix most problems but not if I don't know what's causing a crippling problem like this.

 

[NOMIEZVR4]

Maybe I can help...

These are all excerpts from my original thread on DSMtalk..here is the direct link if needed

http://www.dsmtalk.com/forums/showthread.php?t=139464

Hey guys I got some news for everyone. Here is what happened, last night I had the opportunity to seafoam the car. The car let out HUGE clouds of *thick* white smoke. I have a picture or two of that scenario that I will shortly put up.
Shortly thereafter, I wanted to install my new spark plugs and then go out for some race gas. Well, I did get a chance to get some race gas but I did not get a chance to throw in my new spark plugs.

I did however log the car. The results are good With the gas light on, I went to the nearest gas station and filled up with 2.X gallons of 100 octane. It was a cool night out, maybe in the lower 50's. I went to the nearest strip and put the car in 2nd gear rolling at 30-35mph, then I hit it. WOW, even at the same boost setting the car just rocketed through 2nd gear. Usually with my crappy 90 exhaust cam, the car stops pulling at 5.5-6k rpms BUT....

Last night, it zipped to redline anyways, I shift to third and the action does not stop. I get a quick glance at the logger and the knock count is pretty much flat. Maybe a quick count of 5-7 was evident at the most. The race gas REALLY woke the car up. The reason being because I usally get 12 degress of timing at the top of third. Last night with the race gas, I was seeing 20 degrees, tapering off to 17 near redline. The best part is, im still on crappy autolite spark plugs..

So, where do I go from here? What does this mean? I know one thing is for sure, the knock that I was seeing is definitely real knock not being caused by loud lifters or anything of that sort.

Exactly, you know it is "real" knock. That is a big help. Now you have to find a way to get that same effect (0-5 knock) from normal piss-91. It really can only come from a few things.
1 too much heat (get an intake air temp sensor to verify)
a turbo out of range: not 14psi on a 14b
b boost leak: your turbo is pushing much more cfm and makeing extra heat: get rid of the boost leaks.
c inefficent IC: maybe, try that Supra SMIC

2. too little fuel (use wideband to verify)
a fuel pressure incorrect: check fpr, fuel pump, etc.
b injectors overrun: not likely at 14psi/14b; check with logger

3. too much fuel (use wideband to verify)
a fuel pressure incorrect: check fpr, fuel pump, return line, etc
b boost leaks again: engine thinks more air is going in than really is so it adds more fuel.

4. hot spots in combustion chamber (use flash light to look in chamber from spark plug hole)
a carbon is causing hot spots: use MCCC
b spark plug is causing hot spots: use a different temp plug.

Are you still on the stock fuel pump? I recently found out from personal experience that fuel pumps wear out over time, and yours isn't the youngest DSM out there. It might be time to get a Denso 150 or a Walbro 190 in your car.

OK. Here's what was happening with my Laser; I was running 107% duty cycle on 660 injectors with a EVO 16G at 16 psi and my O2 volts were dropping down to .76 at WOT, plus I had plenty of knock. I changed the FPR and did some logging- no change. Installed a new fuel filter and logged it- no change. I checked the pump wiring, fuses, and replaced the relay- no change. I ran some numbers and found out the pump I was running (a 4 year old Denso 150) would run out of flow with 660's at 100%. So I took a chance and ordered a Walbro 255hp. Now I'm at 19psi and 75% duty cycle.

Or maybe the electrical system isn't running at max voltage. Log battery volts when you do some pulls and see if it stays above 13v. Again, a '90 isn't the youngest DSM. With my '90 Laser I went through all the major electrical connections and cleaned off the oxidation with some steel wool. I saw running volts go up about 0.3v, but my car lives in sunny California, YMMV. Do they salt the roads in Chicago? I'd recomend taking a look at the alternator terminals, battery terminals and wire ends, and grounds. It couldn't hurt, and it's free!

The most common causes for phantom knock are:
Noisy lifters (may not actually be audible). Fix with 3rd gen lifters.
Ticking timing belt tensioner. Fix with new tensioner.
Bad knock sensor. Fix with new sensor.
Bad timing belt idler pulley or tensioner pulley. Fix with new pulley(s).
Bad balance belt pulley if you still have your balance shafts.
Low oil level

HOpe this helps..if you have any more questions, my email address is [email protected]

Im still chasing my problem, but progress has slowed down because is so freaking cold in chicago..im proabably going to finish it up in spring.

Nomie

 

[90 GSX]

Thank you. That helped a lot. Unfortunately, I already checked most of those things. Except the wideband A/F ratio of course... I get 14v at idle, not sure about under load.

I am thinking about rewiring my pump without installing my walbro because I don't have an AFPR yet. When you do the rewire, is it preferable to change the ground all the way to the terminal on the sending unit or just how it shows it in the VFAQ???

 

[NOMIEZVR4]

i followed the instructions via vfaq.

Nomie

 

[femmeDSM]

I am thinking about rewiring my pump without installing my walbro because I don't have an AFPR yet. When you do the rewire, is it preferable to change the ground all the way to the terminal on the sending unit or just how it shows it in the VFAQ???

Maybe I missed this, but do you have a 190 or 255? If you've got a 190, I would go ahead and install it w/o the AFPR -- it should be safe (unless someone has info that I don't). There are plenty of people running 190's w/o AFPRs (at least temporarily) and I haven't heard of anyone having a problem.

As far as rewire, are you referring to drilling out that black/rubber cap on the bracket plate and running another wire directly to the fuel pump? If that's what you're asking about....No. You do not have to do that. My wires were all kinds of gross (thanks, previous owner! ) and when I rewired/installed my walbro 190, I did not drill out the housing plate, although I will need to do that eventually whenever I want my gauge to work, since that wire was disconnected from its housing underneath the plate ( )

Hope this helps a little. I have become the fuel pump rewiring master (), so if you need any additional advice or help, let me know.

Good luck

 

[90 GSX]

Thanks for the response. The pump I have unfortunately is a 255 Hi Pressure... At the time I bought the pump, I knew less than I know now. I don't plan for my car to be extreme enough to have a pump that size. I'd be willing to trade for a 190 if I had the opportunity. So you think I'll be okay without drilling the housing plate... interesting, I wonder what kind of voltage difference it will make at the pump. Maybe I'll set up an experiment when I do the rewire...

 

[femmeDSM]

Thanks for the response. The pump I have unfortunately is a 255 Hi Pressure... At the time I bought the pump, I knew less than I know now. I don't plan for my car to be extreme enough to have a pump that size. I'd be willing to trade for a 190 if I had the opportunity. So you think I'll be okay without drilling the housing plate... interesting, I wonder what kind of voltage difference it will make at the pump. Maybe I'll set up an experiment when I do the rewire...

I'd be interested in seeing your results on that, if you end up doing the 'experiment'. When I take my pump back out to drill out the holes for the new Fuel Gauge wiring, I will probably go ahead and drill out the rest of them to make a "complete" re-wire as well (since I am anal like that), so let me know if you have any luck w/ it.
I don't think you'll have any problem finding a new home for that 255HP. Put it up in the classifieds and someone will take it off your hands. I would, but my mods don't require that kind of fuel delivery yet
Or you could just get the AFPR -- they're always good to have anyway

 

[green_bread]

Ok, so a little background, here:

I just completely rebuilt my 6 bolt in my 92 AWD. With the rebuild, i replaced the knock sensor and bolted on a buscher fmic with short route piping, a big 16g, and 550s(not everything but what i feel is relavent for this discussion). So, I already had an SAFC and a logger and i wanted to make sure everything was looking good for the break in period.

when i went out and logged while i was just cruising around, i was getting a lot of knock above like 2800 rpm. i thought this was awfully strange since i am running boost off the wastegate and only making like 6lbs. and with the AFC zeroed out in the low settings, and 550s, i should be pretty rich, right?(engine runs real smooth at idle and smells like it is pretty damn rich)

i have a walbro 190 that i havent installed yet but the stock pump has been rewired. i highly doubt that the pump is the problem at all. my fuel trims are all pegged out too rich at 81.2 but i cant get those set because of what i believe to be a bad o2 sensor. i am running a 1g but i have a 2g mas to go with the 550s.. i thought they should pretty much even each other out, right?

anyone have any ideas as to what might be giving me the knock?

thanks for any help!
ADAM

 

[donmagicjuan]

It almost sounds like mechanical knock, if you're seeing it at part throttle. The fact that you just replaced the knock sensor makes this possibility even more likely. The knock sensors will pick up the tiniest vibrations if they are overtorqued. The spec on them is 14-18 ft-lbs.

 

[green_bread]

i have also removed the blanace shafts and the rear motor mount is solid. these could also be contributing factors with the added engine vibration and all. i will remove it and retorqe it just to make sure.

thanks for the suggestion!

ADAM

 

[JayRolla]

Yep its PK if its happening when your not boosting, check the knock sensor, most likely to tight or may even be real lose and vibrating.