constant CE, no codes, wiring problem?

[iangoround]

Sorry for the long post.

So I'm having a bit of trouble figuring this one out. My car has a constant CE light on whenever it is running, and it won't throw me any codes, not even 12 or 55. I've burned a stock 87 T2 cal to it, running a 2 bar MAP and I've got my 52lb injectors dialed back to mimic 33-ish lb injectors. It starts right up, but idles like crap for a while until it warms up some, kind of like the LM has lost its memory and is relearning the car.

The constant 12v feed to the LM is good. The switched 12v feed to the LM is good, as are most of the grounds (except below). So I'm not sure why it is losing its memory, if that's what it is doing.

There are a few oddities though. For example, N6 -7.5v supply from the PM to the LM is more like 12v and N5 signal ground to sensors is showing me 8v with the key off and connector unplugged. The N5 circuit is kind of confusing me. I would think that it shouldn't read anything at all.

I'm going to start by running a new line from the LM to the PM for the N6 feed in case the existing wire is cracked somewhere and contacting a 12v line, but I bet that voltage regulator is now toast. Does anyone know how much current the LM draws down that line? I was thinking about putting a 7.5v zener diode on it to see if it fixes anything. As for the N5 signal ground, maybe I have something wired backwards? I guess I'll investigate that and possibly run a new N5 circuit.

[black86glhs]

First thing I would do is verify all the terminals in the LM connector are in the right locations, then go from there.

[iangoround]

I think I got through about half of them and hadn't found any mistakes yet. The N6 circuit is in the right pin on both ends. I tested the voltage on both ends of it and got 12v both times. I'll get through the rest of the wires at the LM tomorrow I think.

[black86glhs]

Could have a bad LM. I had 2 of them that came with my car. Have you tried another chip in the LM to make sure the chip isn't at fault?

[Force Fed Mopar]

You unhook any of the solenoids under the hood?

[shackwrrr]

Did you test the n6 with the PM wires hooked up or disconnected? With the wire disconnected the output can float up to 12 volts.

[iangoround]

Could have a bad LM. I had 2 of them that came with my car. Have you tried another chip in the LM to make sure the chip isn't at fault?

I've got two chips I've been trying. I have another LM, but it needs a socket. I'm hoping the local hobby shop has at least a machine pin socket or something I can try out.


You unhook any of the solenoids under the hood?

Nope.


Did you test the n6 with the PM wires hooked up or disconnected? With the wire disconnected the output can float up to 12 volts.

That's good to know. I testing it with things unplugged. I'll recheck with everything hooked up properly when I get home from work.

[iangoround]

OK, here is what I did today:

Doublechecked pin-out of both connectors -found nothing wrong
Retested the N6 circuit while hooked up to the LM --found it at 8.3v
Spliced MAP signal ground to the N5 circuit instead of going straight to ground --no change
Socketed and tried new logic module - no change

I'm going to try buying some new chips and flashing those in case I have two funky ones. Other than that, I'm stumped.

The CE light comes on with key on for the lamp check, then goes off. It turns back on again as soon as I start the car. If the car is idling stupid low for some reason...say 500rpms, the CE light goes out. I still can't get it to give me any codes at all, which I find highly suspicious.

[Force Fed Mopar]

What cal template are you using? Using D-Cal or MPTuner? Are you sure you have the wiring correct? (I am assuming you have converted from '86 electronics to '87, or are you trying to run a GLHS cal?)

[iangoround]

At the moment, I'm running a stock cal 87 T2 MTX cal out of the stock cal repository.

I'm sure I have the wiring correct. I converted to 87 wiring. I checked both plugs twice with my 86 wiring diagrams and the 87 pinouts, and metered any lines I was unsure of.

Once the car starts up, it will run quite happily on the stock cal, 2 bar, and 52lb injectors dialed back but the CE stays on. I'm tempted to rip the entire wiring harness out and rebuild it.

[Force Fed Mopar]

At the moment, I'm running a stock cal 87 T2 MTX cal out of the stock cal repository.

I'm sure I have the wiring correct. I converted to 87 wiring. I checked both plugs twice with my 86 wiring diagrams and the 87 pinouts, and metered any lines I was unsure of.

Once the car starts up, it will run quite happily on the stock cal, 2 bar, and 52lb injectors dialed back but the CE stays on. I'm tempted to rip the entire wiring harness out and rebuild it.

I would check the wiring for the CEL, I suppose it could be possible that it is getting grounded or shorted somewhere, making it come on even though the computer isn't telling it to. Do you have the CEL Flash mod turned on? I have had a bad knock sensor randomly cause it to come on.

[iangoround]

I would check the wiring for the CEL, I suppose it could be possible that it is getting grounded or shorted somewhere, making it come on even though the computer isn't telling it to. Do you have the CEL Flash mod turned on? I have had a bad knock sensor randomly cause it to come on.

I'll double check that. It comes on normally with key on as the lamp check and goes out, but pops back up with the engine running.

There are no mods to this cal. It is 100% stock straight from Ma Mopar. I was running a turbonator cal at first and thought maybe it was the CE flash mod acting up because my wiseco pistons are pretty noisy at startup, but it never shuts off AND I turned the CE mod off.

Most of my sensors are brand new, I bought them when I assembled the motor 282 miles ago.

[Force Fed Mopar]

Hmm, maybe something up with the PM?

[black86glhs]

Good idea. Try another PM and see what happens.

[iangoround]

I'll try the other PM I have, but it has a bad voltage regulator. Worth a shot though, I suppose.