Chevy Camaro Engine Questions

[brlarl]

I've got a question or two for anyone who may know!!  This is not about a C10 but is about a 1985 CHEVY IROC-Z with TPI and VIN code "F"!  The car was given to me and once I got it I tore down the engine as far as the taking the heads off and having them checked.  They checked out fine no problems.  I proceeded to replace the head gaskets setting them to torque specs and correct order, set the valves to proper setting by using the two revolution method first on #1 cylinder then one complete revolution to #6.  I reinstalled the manifold using the correct torque and order of tightening the bolts.  Distributor was stabbed right on the money with number one piston up in compression stroke.  After getting it all back together I fired it up and after adjusting everything had the car running like a top!!!  No misses no noises nothing what so ever, the car ran great!!!!  After letting the car sit over night I went out the next morning to start the car and it ran like crap and still does!!.  It idles real bad.  The check engine light came on and set a "42" code.  I pulled all the plugs and replaced them, replaced the ignition module, ignition coil, cleaned up all wires inside the distributor and checked for cracks.  The only thing I did not change in the distributor was the pick up coil.  I then proceeded to follow the steps in Alldata Pro listed for code "42".  I checked the Resistance on wire 423 on the 4-wire connector of the distributor and it showed 800+ohms which shows to be an opened circuit on 423.  Resistance should be 500ohms or less.  I then checked all the wires as mentioned above and the reading went down to 498ohms but the car still runs the same.  The car is missing, I also checked the routing of the plug wires, checked the fuel pressure (40-45 lbs key on), checked the engine compression ( highest being 165lbs-lowest being 150lbs).  The problem has to be something simple but I can not figure it out.  There were no other codes set just code "42".  Help from anyone is greatly appreciated.

[DnStClr]

Brlarl, it sounds like trouble with the pickup coil or magnets. Does this copy of the codes help?
http://www.iroczone.com/specs/TroubleCodes.htm

[brlarl]

Thanks for the info.  I found the same info in all data.  I may replace the pick up coil since everything else is new.  Thanks again.

[VileZambonie]

It's not the pick up coil. When you checked the resistance in ckt 423 to ground did you disconnect the ECM connectors and have the ignition switched on? Did you leave the EST connector in bypass when you originally set the timing? Did you set the timing?

[VileZambonie]

Also make sure you reconnected those ground wires at the back of the cylinder head!

[DnStClr]

Yeah. Loose grounds are the cause of a lot of the elect. problems we see on here. Loose connectors too.

[brlarl]

When I checked ckt 423 I did have the ignition on but did not disconnect the ECM.  I did set the timing to 6 degrees BTDC.  I did disconnect the bypass when doing so.  I've checked and the vacuum hoses and made sure the grounds behind the drivers side head were reconnected tight.  I'm stumped.  If the ECM is bad what kind of problems would I have with the engine while it is running or would it even run at all?  Thanks in advance!

[VileZambonie]

Well if you didn't perform the steps in the diagnostic procedure correctly your results are invalid. You need to recheck it correctly.

[brlarl]

What is the chance that the ECM is bad?  I have not redone the test procedures for code "42" but lastnight I started the car and it ran fine!!!  I ran as if I did not have any problems.  How can the EMC be checked to see if indeed it is faulty?  Thanks in advance.

[VileZambonie]

Recheck all of your connections especially those I mentioned above. The only thing you can really do if it's a faulty ECM is lightly tap on it and see if anything happens. (do not beat it) I think you have a poor negative connection somewhere.

[brlarl]

I checked all the grounds that I know of.  Can you tell me where they are so that I can make sure that I'm looking in the right location. Or if there is a schematic I can look at please let me know.  Thanks

[DnStClr]

If the car starts  and runs ok it's got to have a good computer. I think the only way to make sure it's good is to r&r with another unit. Did you run the car long enough for a good warmup to make sure something wasn't breaking down when it warmed up?
BTW is the engine a 305 or 350?

[brlarl]

Today after returning from work I went out to start the car and today it runs like .........well you know!!!  I did not touch anything from yesterday as it was running great!!!  Yes the car was at operating temp!!  The car must have Gremlins??

[brlarl]

Well I think I have the problem figured out but can someone tell me what the purpose of the  Burn Off Module "MAS" is?  I've been able to Isolate the problem to this module.  I got good deal on a reman. ECM with a Lifetime Warranty so I changed it out but there is this module attached to the ecm that has a small relay inside that if the contacts are opened the car dies out.  I figure this is the problem since the car was running like crap after installing the new ECM and I tapped on the Smaller module and the car idled right??  Any suggestions from anyone?  Thanks in advance.

[VileZambonie]

Wha ju talkin bout willis?



Post pix please because I have no idea what you're talking about