94 GT Running problems..help!

[lees gt]

I'm Hoping one of you Mustang Gurus in the U.S Can help! I'm running a totally stock 94 GT 5.0 ( import) When i purchased it,it had melted cats on left cylinder bank,sorted that out and replaced 02 sensors but the car still runs bad. Checked everything plugs,leads,cap,rotor,fuel filter etc.No vacuum leaks,replaced MAF,Ignition module,set TPS,IAC is OK,Fuel pressure ok,injectors ok.Did a leak down test,results fine.Plugs look very lean to me and i have slight detonation at standard timing,idle is poor and and pops and misses from left tail pipe.Runs great when i first start it but once in closed loop runs rough.If i disconnect MAF car idles great but MAF checks out fine! Any ideas,computer maybe? Also shift points seem wrong,goes into overdrive at 40mph....Reward for whoever helps me sort this..or go back to Chevys!

Lee

 

[99FiveOh]

I suspect the MAF is dirty or going bad. When you say it checked out fine, how did you come to that conclusion.

 

[KamiKaziDK]

+1, when my maf went out my cats were orange they were so hot

 

[lees gt]

Hi Mark,i cleaned the maf first although it wasn't really dirty car has low miles ,so i replaced it with another one, problem was the same.Can't remember voltages off hand but it did change as per the manual. I agree though it does sound like a MAF fault..i wondered if the ECU is not using the Maf values correctly? CEL is not coming either...

 

[99FiveOh]

the ECU is usually the last thing on the list of possible faults. Is this car an AODE or 5 speed?

 

[lees gt]

Its an AODE box Mark, cars running really lean too, don't get any deposits on plugs at all..doesn't seem to have much power either..Had an old Alfa Romeo 3.0 V6 that would blow the socks off this thing! One thing i've noticed is the right tailpipe i get normal steam/condensation on a cold day at idle left pipe nothing,pull the MAF connector and i get the same condensation from both pipes and idle smooths out.
Your help is much appreciated!

 

[RIO5.0]

Have you pulled any codes out if it???

 

[lees gt]

I did run the test on it but it came up with something different each time,seemed to get half way through the engine running test and stopped doing anything..not getting any CEL light when i'm driving either.

 

[99FiveOh]

Reason I asked about the trans was because my buddy's 94 GT AODE was acting like you describe and it was caused by the torque converter locking up at idle or something like that. Was putting some kind of load on the engine and made it run like crap when idling and driving.

The only thing that could cause the different banks to act differently is the 02's, but I see you replaced them. I thought when you pulled the MAF the car goes into limp home mode and stop reading from the MAF and O2's. Maybe swap the O2's from one side to the other on the H pipe and see if the "condensation" follows.

 

[HISSIN50]

Shifting into OD at 40 is normal or better than normal.

Are you sure there's no exhaust restriction still? Did you check your vac readings at 3K RPM while for a little while? It's as good of a quick test as I know.

Did you check the wiring near the cat that overheated? An exhaust restriction and glowing cat can cause a LOT of damage to wiring and plastic items. The AODE trans harness is a real snake.

Also check the EGR. An exhaust restriction can cause an EGR to fail. This leads to poor idling, poor performance and detonation.

The first thing I would do however is see why you cannot retrieve a full batch of codes. Once this is remedied, go from there. Otherwise you might be chasing issues that are downstream of bad EEC wiring or a bad EEC (though as Mark noted, they very seldom fail).

Good luck. And where are you from?

 

[lees gt]

Thanks for the info guys, i'll take a look over the weekend..Wife permitting i'll let you know how i get on. I'm from Northamptonshire in England by the way Hissin.

Thanks again Lee

 

[95_cobra123]

Long shot but timing might be the dampener had that prob. before good luck

 

[tderrick]

just something simple, maybe...

You have disconnected the Battery so the computer can reset haven't you?

Let it idle til hot

 

[lees gt]

Guys problem solved!!!!!!!!!!! Re checked everything but at the computer end this time, guess what..bad return voltage on left bank 02. The plug behind/below the power steering pump all crudded up inside..now running sweet as a nut!!
Thanks guys for all your help