fresh rebuild, car running like crap

[dewdew]

Just rebuilt the engine, pistons, rods, valves, cams, the works..... my car is running very poorly.. engine cuts out around 5000rpm full throttle, misses, almost sounds like rev limiter. If I give it partial throttle it will have a smooth powerband. my pocket logger readings are saying i'm running too lean going off of the o2 readings. needs to be 0.92 of correct, but when i try to correct it runs worse. I think it is running too rich but am afraid to lean it out. i do have all supporting mods. fuel pump, 660cc inj, fpr, fuel rail, fmic, 3" exh., on 14b. any ideas?

 

[burldude]

How about log for fuel trims ?

 

[sweet97]

That's a lot of fuel for a 14B. What are you using to tune with, I missed that? 660's would support a 50 trim!Mark

 

[dewdew]

I am working on the whole turbo thing alright. As of now fuel press is set to stock. I have an S-AFC and a MAF-T to tune with, dont know about fuel trims, what kind of numbers should i be looking for?

 

[Kevin Jewer]

Having an unwanted rev limiter is almost always a too rich situation. On a 1g, you want 100 for all the trims. If its this rich, you should be able to tell right at idle. I believe the numbers will be lower suggesting the ECU is trying to lean it out. Why would it be too rich after an engine rebuild though? And the last thing you want when trying to seat rings is too much fuel.

 

[sweet97]

Gom to: www.fullthrottletech.com and check out the assistance forum for the translator. Turn the safc off for now. you must be RICH! Set the base at 8 and the auxiliarly to 1.
i would setthe MID and WOT both at "A". You might want to switch the last 2 to "9 or "B". fter driving it. 9 would be leaner and "B" richer. The lasr knob is WOT and easy to set. The mid takes some practice. Mark

 

[dewdew]

but how come my o2 readings on the pocket logger aren't right. when i tune it to 0.92 it runs like complete ass.

 

[1fast97gsx]

because .92 is rich on a 1g .. you are probably just running way too rich

 

[Kevin Jewer]

I say it is because front O2s are useless 10:1 to 14:1 is .98 volts on my stock O2 sensor. The sensor works great for what it is designed to do, keeping my AFR correct while in closed loop and getting good emisions and gas mileage. Thats about it though. Perhaps .92 is know to work on your car? Thats fine. But there shouldnt be anyone else jumping in and saying .9134386 would be better. Getting back to the last question in my previous post, why is it rich. Start with the usual things. Is the AFC still setup properly. Is the MAFt the way is was before all this work. Is the fuel pressure still correct. Are there any boost leaks. Is an injector sticking open. And why did the work you did make this change. What could have been disturbed when you were doing that work. Is it even really rich in the first place? Etc. Have to start the process of elimination somewhere. Good luck.

 

[dewdew]

alright, i tuned and it is better. was running way too rich. i will tune further, but what should fuel press, base timing be at

 

[awddsm95]

check ur timing

 

[Kevin Jewer]

Base pressure hose off should be ~38 on a 1g and ~43 on a 2g. With the hose on it should be base pressure minus half of your vacuum in "/hg (2"hg = 1psi). Base timing is typically 5 degrees, but some poeple change that. Run 5* until you get it running right anyway.

 

[dewdew]

My idle fuel pressuer is 62psi, 68psi unplugged with about 90in/hg at idle so your calculations are correct. why is my fuel pressure so high. could this be causing a lot of my problems. I have a B&M Commando Flo FPR which is supposed to run between stock FP and higher, but it is turned all the way down.

 

[sweet97]

WOW! Fuel pressure is astronomically high! You must need to turn that B&M the other way or replace it and you don't have 90" of vacuum, maybe 9". You found your problem!! Mark

 

[uberstrafe]

get rid of that B&M pos, youre running a walbro 255 lph on the stock fpr still which is overrunning it. I did the same thing, car ran rich as hell. Spend the money for an aeromotive fpr and adjust it to stock 1g fuel pressure and go from there (37psi w/o vaccum). After you do that Im sure your car will run fine.

 

[Spoolin4Ever]

Let us know how it goes.

 

[dewdew]

Aeromotive FPR on the way, i'll let you know how it goes. Also, I did mean 9in of vacuum

 

[sweet97]

Looking forward to hearing your motor running well. Also wouldn't hurt to change the oil as it could be contaminated with gas--not good! mark

 

[bullettdsm]

Aeromotive FPR on the way, i'll let you know how it goes. Also, I did mean 9in of vacuum

I suspect that you've solved your problem (62, WOW!). You might want to save some time and figure out where you want to install it. There are a couple threads on this. I know it sounds pretty straight forward but I did not do it and I spent around an extra hour with my thumb up my a$$ lookin' like a dork while I tried to decide where I thought it looked and fit best. What a woman! Next thing you know, I'll buy more than 1 pair of shoes. Good luck and keep us posted.
MB

 

[Maglin]

Also do a boost leak check. They create tons of problems if you are running your GM MAF in pull through ie. before the turbo. Will run lean under vacuum and rich under boost. My buddies 1G is having simular problems. Doing the free running engine settings for the SAFC and 660's we only had like 9-12% of negitive correction. He didn't have a boost leak tester and under WOT it would just act like the ignition was cutting out. We are sure it's a boost leak. My tester is a 4" for my turbo and he is running a 18G TDO5. So yeah. Even though you think you don't have a leak chances are you do. Also 660's are big. You could turn the fuel pressue down to like 35-32PSI with vac off and set your MAFT base to like 600ish injectors. You wouldn't have so much timing advance under WOT and as long as you kept your IDC under 95% you should be just fine. Currently I'm only hitting 690% IDC with my 1000cc injectors with my hugh turbo. Which is basicly what maxing out 690cc injectors would be doing. so I'm sure you can turn them down to 600ish and be just fine.

 

[sweet97]

Maglin setting the base pressure may help however the MAF-Translator suggestion I believe is reversed. Setting the base for a smaller injector will RICHEN the mixture across the RPM range. Mark

 

[oldman]

Also do a boost leak check.

Definitely do this, your vacuum is way low during idle, it should be around 18-20 hg.

 

[dewdew]

Well, I installed the FPR, but not much change other than it idles better. I figured out that my gauge was broken and reading like 20psi high. I was high on pressure, but not as high as I thought so it didn't help much. Also, I have cams (264/272) would this be the reason my vacuum is low. I do have around 15in of vacuum at 1000 rpms, but at idle around 700 it drops to around 9in.

 

[dewdew]

I had the exhaust manifold off today and I noticed the valve stems were wet. Could this be oil from a bad seal?

 

[dewdew]

Fuel Pressure at 34psi, timing 5deg BTDC, i cant get my o2s above 0.90. Usually aroung 0.88 no matter how much fuel i give it. help me. Should I try a differnt spark plug? What else can I adjust or check?