SR woes

[dpreuss]

Hey everyone. I have been having some driveablity problems with my SR since I upgraded to a 50 trim t3/t4 and did my rebuild. Here is my list of mods
- Power FC with datalogit software
- Innovate motorsports LC1 datalogger/wideband control kit
- Stock Fuel Rail with Nismo 740cc injectors
- Nismo adjustable FPR
- Stock Intake manifold
- z32 MAF
- Log Turbo Manifold
- Turbonetics t3/t4 50 trim
- Toda 264 cams
Whats happening is that i cannot have a steady stable idle, in fact it almost sounds like i have a misfire. This seems to happen until the I get load on the engine, then the car is nice and smooth again until i take load back off the engine. The car also seems to run extremly rich at idle. I am using Enthalpy's base maps, but I am waiting on a replacement wideband because i broke the other one removing it from my downpipe.
After spending a few hours doing a search I checked out the following
- MAF sensor reads around .48 v at KOEO, and around 1.28v at idle
- Set timing by matching timing reading on crank pully with reading on FC commander
-set base fuel pressure to 36 PSI by jumping fuel pump relay and setting pressure with engine off
- made sure my inj lag time was set to .66 ms and were at 50%
I still have to do a boost leak test (which im not exactly sure what the best way to do that is) and I also will find out my exact A/F ratio when I get my wideband. I'm just looking for some insight to see where I should start looking. I know my reading for my MAF is off, but i dont know if its off far enough for it to be bad. I was also wondering if my mechanical timing my be off a tooth. Anyway, I know its a lot of info but I'm getting tired of the car not running right. Thanks in advance to those who post. -Derek

[lazierhobo]

if you had a boost leak you would idle really high, like over 2000

when you mean rough idle, do you mean like jumps around between 800-1000?

[dpreuss]

Yeah, idle jumps around usually between 870-1000, but it almost sounds like a misfire (engine shakes pretty bad, sounds like a WRX, etc.). Then, it will stabalize, and the misfire will go away, but this only lasts for a few seconds, then it goes right back to the rough idle. It will also do the same if I rev the engine when its not under load, it will not clear up until the higher rpm. It's really pissing me off because i do not have access to a known good maf or CAS to see if one of those are my problems. The only other way to accuratly test these is if I could get ahold of an automotive scope, which is hard to do also. Please let me know if you have any more ideas. -Derek

[King 240]

I believe you have boost leak confused with a vac leak. The boost leak will make the car run completely like crap (meaning it will cough black smoke, run rich and stumble under throttle. A van leak will make the car idle high. You can test this by pulling the Vac line off the brake booster.)

So you've set timing
your CAS (crank angle sensor) is still good, I'm assuming you reused it
I'd check the gap on the plugs, timing again. Seems like you don't have enough spark then when you get into it, the spark is slightly stronger, thus why it seems to run fine.

[jrmiller84]

^^ I disagree with your vac line theory, I couldn't get my car to stay turned on when I first installed my SR because I didn't have the brake booster line connected. Look in my build thread, it's there.

It would start, stumble extremely bad for a few seconds and finally shut off. If the car's not getting the air it needs due to it escaping out of the brake booster line outlet, it doesn't make sense that it would idle high. Hell, it won't idle at all.

[dpreuss]

Thank you for your replies. Here is an update on the situation. I performed my boost leak check, and I found my BOV was leaking pretty bad. I fixed that, and also found a small leak near the IACV when the pressure went over 7psi. I could not pinpoint it, but I dont know if I should be worried about it if it only occurs over 7 psi. I also found that my FPR was leaking where the two pieces of it crimp together (nismo adjustable), and to get it to stop I needed to recrimp them with a pliers. I also entered in the correct injector lag time. That did help clear up some of the hesitation, but the car still does not idle worth a sh*t. I also rechecked my timing, and reset my fuel pressure to 50psi (jumped the fuel pump relay and set static pressure). I'm beginning to think I may have injector issue...either bad o-rings or even a problem with one of the injectors themselves. I bought my 740cc's off ebay "new", so that may be an issue. I did remove the fuel rail this spring and turned the key on with the injectors in, and found no leaks, but I was wondering if that was not a good test, since the fuel pressure is lower at KOEO then it would be at idle. I think I may just try my stock injectors to see if they help. If anyone has any other ideas on what could be the problem please let me know. Also, do you guys think that FRP is junk? Thanks again for your help. -Derek

[707coupe]

how is your throttle position sensor?

[dpreuss]

well, its hard to do a sweep just by looking at voltage, but it seems to working fine. I do wish i had access to a scope, because in my grand prix (daily driver) There was a blip in the wave form around 20-30% open, causing my trans to shift funny and stuff. However, the car still seems to be running rich (I should have my wideband within the next day). It also cranks a long time before it starts. Its really starting to p*ss me off.

[dpreuss]

Thanks everyone for your replies. I found a major problem when i ran a new set of tests. I pulled the fuel rail, jumped the fuel pump relay, and found that fuel was gushing past my #4 injector at static pressure. I changed the orings and reinstalled the injector and restested...all leaks were gone. I then started the car expecting a tremendous improvement. However when i started the car, it had improved (did not have to crank it forever to start it as i did before) but it still does not idle for SH*T. The powerband is much smoother, and it is still much smoother @ low rpm, but when it isnt under load it still seems to be misfiring. I had to raise the idle up to 1400 RPM to get it to idle halfway decent. It still seems on the rich side also at idle. The next thing im going to do tomorrow is install me wideband to get AFR's and also install a tach signal converter (its a 90' hatch) so my tach works. I figure there may be a remote chance that since the tach is still hooked up and needs an analog signal instead of a digital signal it may be backfeeding voltage....and I am tired of not having a tach. One more thing I forgot to ask is how to know if the IACV is broken? Let me know what you guys think. Thanks again. -Derek

[dpreuss]

Well, yet another find that is leaving me clueless. I installed my wideband today, only to find that my AFR's at idle were actually LEAN......around 19:1 to 21:1. I added some fuel to my injector map and the car idles a little bit smoother, with AFR's now 15:1-16:1ish. The rest of my map looks real good from the couple of 4th gear pulls i did tonight....around 12.8:1-13.5:1 through the power band all the way up near redline. Although I'm pleased with how the car runs under load, I still cannot think of anything that would make it run the way it does when its not under load. I think i may pull the fuel rail again (im gonna put new injector seals on all of them for a saftey measure) and pull the CAS and spin it and watch to see how the injectors are firing. I am also going to replace my cold pipe with one that doesnt have a bov to see if it idles better...I heard that an atmospheric BOV can cause a shitload of problems on pull through setups. Anyway, if anyone else has anything to add please do. I will keep you posted. Thanks again. -Derek

[driftage240]

have u checked maybe a bad injector...mine was doin similar stuffed to what ur sr is doin.. bad injector...

[SexPanda]

When you replace you injector o-rings, cover them in vasoline. Vasoline because it dissolves with gas (petrollium based) so it doest hurt anything. Trust me, your day will go alot quicker if you do.

And yeah, same thing with my KA. One of the injectors wasnt getting much power. It ran Ok under load, like you said yours did, but idle was shitty. You could have a minor short with the injector's wires like I had.

[dpreuss]

I noticed I had a typo in my last post . My AFR at WOT is around 10-11.8.......pretty good I think. It is at partial throttle that im reading 12.8-13.5.....I dont know why I got the two confused when I typed the last post, late night i guess. Anyway.....I bought a noid light and tested my injectors....all seem to be okay. I also checked the resistance of each injector and they were the same across all of them. I seriously think that it is a bad AAC valve, because nothing happens when it is unplugged, and adjusting the air screw (with the tps unplugged of course) does nothing. So, on another note, does anyone have a known good AAC valve lying around? Also, I am going to wire my wideband into my datalogit box, so I should have datalog maps that include afrs soon. Thanks again for your posts...and as always, keep the ideas coming! -Derek