Check Engine Light! 94 Mustang

[andr3w51]

ok i'll try to cut to the point. i have a 94 5.0 that is not running right. This started after i got the exhaust put on (longtubes, xpipe no cats, flow muffs). The car idles rough, like the idle comes up and down and sometimes dips so low it almost stalls the car, but sometimes idles fine. And after driving it for a while the CEL comes on. So i ran the code, and got 314, 311, and that cylinder 6 was failing when i did cylinder balance test. So i checked out the exhaust work and everything seemed to be pretty much back in place where it was on the stock exhaust, except the cats, and the plumbing coming from the smog pump going to the hard pipe between the heads. So i tracked down those parts (hoses and two diverter valves) and put them on last night. When I was test driving car after about 15 minutes the CEL came on again. now i'm going to run the codes when i get home from work but i was wondering if anyone could point me in the right direction. i'm fairly new to working on my stang so any help is greatly appreciated.

also, in the meantime while i was trying to get car right (after the exhaust was put on) i installed bbk 70mm TB and MAF. dont know if this may have anything to do with it

 

[desertcox05]

Did you put the headers on or did someone else?
Either way one of the spark plugs could have been damaged in the process.

 

[HISSIN50]

AIR codes should not cause a performance issue like you're having.

How many times did you run the CBT?

 

[andr3w51]

let me clarify. the idle only comes up and down when i first start the car. and after it warms up it seems to idle just fine. i ran codes tonight, here's what i got

KOER Test: 314, 311 (Thermactor air system/fault during engine run self-test)

Cylinder Balance Test: 90 (PASS)

Any ideas as to where to start troubleshooting? Other than replacing the smog system (which i allready did) i dont know what else to do to try to fix this problem. Thanks again

 

[HISSIN50]

What KOEO codes were stored?

It sounds like you might have a vac leak.

The other issue could be that with the LT's, the O2's can be affected. The EEC uses O2's as part of the feedback loop when checking the AIR component function. The AIR system can function fine but the O2's allow an AIR code due to hysteresis or diminished performance because they cool below their operating threshold. The O2's location itself could be the issue as well.

 

[andr3w51]

the KOEO code i drew was 332 (Insufficient EGR flow detected). but i'd like to run the test again tomorrow to make sure because i only did it once. i like to double check. the o2 sensors are hooked up with extenders to the bottom of the longtube headers. is there anything else i should look for?

 

[ProKiller]

i think hissin is right with the location of the o2s being some if not most of your problem with the start up. takes a min for the o2s to heat up and read properly.

the long tubes you got, we're they for 94-95 or foxbody? how did you hook up the EGR tube as most times you need an extender.

 

[Jmellone7]

Well it def is some type of leak if you are idling rough. I would check your EGR valve to make sure there are no leaks there. Exact same thing happened to me when my car was idling poorly, and I also had a header leak.

 

[andr3w51]

Well it def is some type of leak if you are idling rough. I would check your EGR valve to make sure there are no leaks there.

how do i check the egr for leaks (sorry newbie)? I disconnected the battery last night to try to clear any codes, then ran the tests again today.

KOEO: 1st pass: 116, 512
2nd pass: 116, 111

KOER: 314, 311 still

I visually checked egr components and everything "looks" ok except just above where the hard pipe is bunged into my header there is a slight kink in the hard pipe, like when the guy installed the header he had to bend the pipe a little or somethin. Could this be the cause? Would pictures help?

 

[HISSIN50]

Was the engine up to temp when you pulled codes? If it was, your ECT circuit might be out of calibration, which can screw with the AF trim.

 

[andr3w51]

this last time it actually wasnt, i believe thats why i got the 116 code, but every other time i tested it i did let the engine warm up, i had to or else the idle would dip too much and maybe stall once or twice making it very hard to perform the KOER test

 

[andr3w51]

ok i think i found the leak. on the egr tube between the valve and the header there is a kink. i felt around to the back of the kink and it actually feels lie the pipe may have cracked a little. so it seems that all i would need to do would be replace that egr tube. would this kink/leak cause the problems i'm having (CEL, pinging in 5th gear cruising, rough idle at startup)? i want want to order the egr tube to get this problem fixed once and for all. would this be the part i want to get or is there something else that would work better? Mustang 94-95 Egr To Header Tube, 5.0L by Ford at LRS - Same Day Shipping!