Too many add-ons = big headache
 

Hey everyone...I've got a 92 GT that I added a Accufab 65mm TB, ProM 73mm maf (calibrated for the 24lb injectors), Cobra intake, stock heads (ported with the bigger valves installed), Ford 1.6 rollers, B-cam (installed 2 degrees retarded) long-tube headers w/h-pipe, and a cold-air kit, and an MSD coil. Here's the problem: 1. Runs extremely rich 2. Surges almost constantly, no fun to drive. I know it sounds like a serious vacuum leak, I've checked all the hoses and they're tight. Any suggestions on where to start looking, or something I overlooked? Do I need to get a "hotter" chip for the computer now that nothing is stock on the car?

did the problem just pop up out of the blue or did it start when you changed something?

It may be your meter calibration, some companies have a hard time getting the calibration correct for 24lb'ers

Personally I'd ditch the 24's, and put the 19s back in. Mine is running great with just 19s

you said u checked all the hoses, but did u do it with your eyes or with a vacuum gauge? I would suggest getting a vacuum gague and rechecking the vacuum.

The car was running fine, just put 3.55's in it and an adjustable clutch w/ a Pro 5.0 shifter. One thing I just found when I was checking things was the TP sensor wasn't torqued down properly. Torqued it and the idle smoothed out quite a bit, but it still isn't right. Checked the timing and it's running at 10 degrees BTDC.

When you tightened down the TPS did you check the votage across it?

It needs to be about .96-.98 volts or so

What is your fuel pressure?

...I'd bump the timing up to 12-16 degrees, check the TPS voltage with the KOEO.... should be what fiveoh stated.

What plugs are you using, what are they gapped at? (just out of curiosity)

You torqued the TPS sensor down and it smoothed out???

With long tubes, the relocated O2's could be causing some problems... I never had any idle problems with my old combo which was similar to what you've listed, with the only difference being shorty headers and a different cam... I run longtubes now and have an idle that likes to surge occasionally... I rev it few times to clean it out and it smooths out for a bit, then goes right back to surging after idling for a while...

The TP sensor wasn't tightned down properly so I took it off, put in a new gasket, and bolted it back on...it helped. I didn't check the voltage across it, I'll do that though. I'm running Bosch plugs gapped at .050. They were gapped .035 in my stock engine, but I thought that since I added a stronger coil and am burning a bigger air/fuel mix I'd open them up for a larger spark. I'm thinking now thats too wide so I'm gonna get a fresh set of plugs and gap them to factory specs and see if that doesn't clear the air. And I'll bump up the timing after I do that. Stay tuned.

The TPS doesn't take a gasket bro... are you referring to the IAB valve mounted on the front of the throttle body? ... the TPS is on top of the t.b.

...and .045-.055 is good on the gap, .035 only if you're using nitrous or a supercharger

Good comments from ultraflo.

Also, someone mentioned the long-tube header/O2 sensor issue. I've seen this a few times and I think the surging idle comes from the fact that the O2's are too far down the pipes which causes them not to heat up enough and take proper readings? Just a guess.

I've got shorties so my O2's are right were they are supposed to be - no issues.

Definitely make sure that TPS is around .95-.97 or so - it will make a big difference w/idle.

E

The TPS was at .96, good to go. The timing was way off and the plugs were fouled like I suspected. New Motorcraft plugs gapped at .045, cleaned it up real nice. Idle's fine with 13 degrees and everything works now. Thanks for all the suggestions, ya'll are the best.

Glad you got everything worked out! ;)

E