Bad Diveability Problem, Need Help! (kinda long)
 

Just did a head gasket job on a friend's 92 LX. I didn't take it apart, but got the job putting it back together.
Anyway, it's a generic 306, aluminum heads, Cobra intake, Vortech S trim car. After getting it all back together, it fired right up, and idled decent. After checking for leaks and stuff, I decided to take it around the block. The car didn't agree with that. Any throttle above an idle, the car will NOT take. In other words, it idles fine, but will not rev, in fact it is as if the accelerator cable is unhooked, totally non-responsive. While it was apart, I also added 42# injectors, and had meter re-cal'd by Pro-M. Fuel pressure was a bit high, I thought, at 58psi. Timing, I set at 8* because he doesn't want to add a fuel system just yet. I'm just trying to get him by while he prepares for the fuel system cash outlay. I did get a "Check Engine" light, which while doing a KOEO self test showed me a code 15 and a code 85. Code 15 says "Failure in Electronic Control Assembly (ECA)- problems with Keep Alive Memory", while Code 85 says either "Canister Purge (CANP) solenoid- circuit failure", OR "Electronic Control Assembly (ECA) status- adaptive "lean" limit reached in fuel control program."

Can't really figure why either code would make the car do what it is doing. I figure the Code 85 may be due to antifreeze fouled O2's??

Hitting a brick wall as far as the driveability problem goes...
It will "drive" only at about 1500 rpm's or less. Any more gas pedal, and car will nose dive like the gas pedal came unhooked...

Any ideas or suggestions are appreciated!

Thanks, BOB

Hi Bob,
Code 15 means there is a problem with either the ROM or the KAM. If it was a KOEO code, it's the ROM, and if it was in continuous, it's the KAM. The test is simple. Disconnect the 60 pin connector from the ECM, turn the key "on" (do not try to start it), and measure the voltage between pin 1 (pos. test lead) and either pin 40 or 60 (neg. test lead) in the ECM harness connector. If you have 10.5 vdc or more, the ECM is bad, and needs to be replaced. If you do not have 10.5 vdc, you need to trace the wires and find out why.

Code 85 means there is a problem with the solenoid that controls the flow from the charcoal canister. Check the wires.

The code 15 is likely being caused by an electrical short, which may have damaged the ECM, and is most likely creating your drivability problem.

Take care,
-Chris

Thanks for the reply!!!
 

Chris, I noticed today that if I unplug MAF meter, it will run, and at least enable it to be driven. I took it up the road a little ways, and then stopped and re-connected the MAF plug-in. It immediately started running rich and as soon as I disconnected it, and cleared it out(revved it up), it ran OK (not 100%, but just OK) again. I took it back home, and disconnected the battery for about an hour while I did some other things. I re-connected battery, and started the car back up. With 10 seconds, the CHECK ENGINE light was back on.:mad: I checked the KOER codes and got a CODE 98, which said it had a ECA problem and was in "limp" mode, basically...

Everything seems to be pointing towards the ECM (or ECA) right now. I will do the test you described tomorrow and see what happens. Thanks a lot, BOB

An S-trim blower, aftermarket heads, Intake, Pro-M, 42lb injectors set at 58psi AND NO HIPO FUEL PUMP? a recipe for disaster if I ever seen one, setting the timing to 8 degrees won't prevent anything. what does your friend think is going to feed those injectors?

I think I have your problem solved though, The computer isn't bad it's just not grounded? Look into that and see what happens.

My sentiments exactly...You can have 160# injectors, but if there's nothing to get the fuel to them, it means nothing.....He's popped a head gasket three separate times since I installed the S trim. FWIW, he did add a set of Aeromotive rails, and had me install a 255 Walbro intank to go with the T-Rex, a while back, but I have warned him several times that he needed "more". He has assured me that a sumped tank, and a much more able fuel system is next up on the agenda.:)

Is there a separate ground somewhere under the hood for the ECM?? If so, please share the location....

This whole ordeal is why I hate to follow up behind someone else's work. Everyone has a different "style"....

ecm ground
 

the ground for the ecm is in thepass. side kick panel,good luck

a buddy of mine and me both had that same problem when you unplug the mass air it runs fine but with it plugged in it will idle but act like it is running out of gas when you accelerate, it turned out to be our mass air sensors, both of them were bad, i had the same prob. on my 89lx, 95gt, and my buddies car is a 97gt, i would send that sensor back to pro-m, considering that both of the ones that i have had go bad have been pro-m's, HOPE THAT HELPS

Okay, disconnect the MAF, reset the ECM by disconnecting the battery (neg cable) and then turning on the headlight switch (to drain the capacitors) for 10 minutes. Reattach the battery cable, and run the KOEO self test with the MAF unplugged. You have short in the ECM harness that may have already damaged the ECM. It's possible that it could be in the MAF harness. Post the codes you get, and we'll go from there.

Take care,
-Chris

Well now you say he has a 255 in-tank and a T-Rex with big rails, FPReg, and 42's, Now to me that should be fine, problem must be with the Hitachi wire sensor on the Pro-M, it could be bad or calibrated wrong, I've known Bob Atwood owner of Pro-M since the early 80's ( he died recently) and they are a top notch company BUT mistakes happen, you could have accidentally gotten a hot wire for a 24lb set-up and so forth. Call them, tell them your problems, they will tell you the proper proceedures to test it.

There are 2 grounds for the ECM, 1 is under the kick panel as stated above, and that smaller wire on the negative battery cable is the other, i know this cuz when i did my battery in the back, i forgot to ground that and the car ran like crap, if at all.

quick put some 19 pound injectors in it and a stock mass air, set fuel to 38lbs, see if it will run right, don't boost it, just drive it normal and see.

Also, in my opinion, I think you are running way too much fuel pressure, with those 42's you should not need that much pressure, but, hey!, your there and I'm here. Good luck!

:) :)

OK, did that again Chris. Got a Code 15 and a Code 85 again.

I agree, I forgot to add, I did lower it to a much more reasonable 45 base...

I would try a different MAF and see if they botched the recalibration :p

If you disconnected the MAF, and still received those codes, then it's obviously not the MAF that's generating them anymore. The ECM may be damaged. Do what I said the first time. If there's good voltage, the ECM is bad, and if there's not, then you need to trace the harness and find out why not.

Take care,
-Chris

***UPDATE***
 

Just for curiosity's sake, I installed the meter off of my car on the problem car....

It idles, drives, revs, and runs excellent. No "Check Engine Light" either....

Pro-M just re-cal'd the meter omn the problem car a week and a half ago. :mad:

Thanks for the replies everyone.

Something doesn't wash here, but as long as you're happy, it's fine by me.

Take care,
-Chris