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BAD ECM?

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Old Mar 26, 2007 | 01:06 AM
  #1  
Happinen Hank's Avatar
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From: Stockton, Ca
Car: 88 Iroc
Engine: supercharged 383
Transmission: 700R
Axle/Gears: 2.73
BAD ECM?

What's up everyone? Here is my story. Took my intake off to port everything. When I put the car back together and started it, it ran like crap back firing throught the intake, idle jumping all over the place, engine would even race to 3,000 RPM and just stay there and then stall. Double checked my firing order and so on. Checked for error codes and it was throwing a 42 code. Started to trouble shoot my ignition system and then my SES light went out and the car only farts for a few seconds and then dies. Checked the codes again and it is still throwing the 42 with nothing else. Correct me if I'm wrong, but I think my ECM took a big crap on me. Any input would be geatly appreciated. Would anyone be interested in trading a good 1227165 ECM for my hardly used Ostrich.


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Old Mar 27, 2007 | 01:13 PM
  #2  
Happinen Hank's Avatar
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Joined: Aug 2004
Posts: 29
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From: Stockton, Ca
Car: 88 Iroc
Engine: supercharged 383
Transmission: 700R
Axle/Gears: 2.73
Re: BAD ECM?

I just checked my voltage at my ECU and it read 14.6 volts so I checked my battery and it read 16.4 volts. So I started to check the ESC input at the ECU and it showed 14.2 volts. Everything I've read says it should be around 9.2 volts and that the ECU should really be at around 12-13 volts. Now I was wondering if anyone else has had this problem? Is it the reason why my ECU has taken a crap and if so, isn't the ECU protected against voltage overload?
Thinking maybe my voltage regulator has gone out and my alternator is simply overcharging my system but I hadn't even run the car for 4 months before I put it back together and it never even really ran after putting it back together. Hopefully someone will chime in here and give me some input.
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Old Mar 29, 2007 | 07:21 AM
  #3  
RBob's Avatar
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From: Chasing Electrons
Car: check
Engine: check
Transmission: check
Re: BAD ECM?

The code 42 is caused whenever the EST (bypass) connector is open. This is done to set the timing. A code 42 will also set if the wiring between the ECM & distributor is bad. This error indicates that the BYPASS and EST signals are not correct. A bad ignition module can also cause this error.

The revving up, holding, then stalling sounds like a vacuum leak.

The vehicle voltage of 13.8 to 14.4 volts is normal. I believe you are correct on the ESC line to the ECM. It shoud be in the 9 - 10 volt area. This is the signal to the ECM that knock is occurring. The ESC module may be bad as (again) I believe that the signal to the ECM is pulled up by the module.

If the module is unplugged the line to go to 0 volts (or so). And the ECM will report continuous knock counts.

RBob.
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