well, as you may have read about my problem, i have been desperately seeking help/trying to fix my car. i have had NO PROGRESS on either goal. i type this new thread in hopes that SOMEONE will PLEASE help me with this problem. i know we have a LOT of very smart people on these boards and i KNOW someone out there can shed some light on this hairy situation.


first a little background on my IROC (this is gonna be a LOOOOONG thread, sorry ) Alyssa is a 1989 IROC with her original LB9/5-speed combo still intact. she is getting a little tired but still in fairly good shape. she needs a set of mains, i know, as oil pressure is a LITTLE bit lower then it should be and i can hear a VERY MILD tick when she is cold. the tranny is going FASTER and FASTER every day. i have plans to refurbish them in the near future, with new mains in the motor (to get me by until the 383 is done) and a basic rebuild kit in the T5 (again, to get me by until i can replace it). Alyssa was converted by my friend (previous owner of her) to speed density TPI about a year ago, and has had NO PROBLEMS until now. he only added two wires (for the speed sensor) and cut NOTHING. he studied up on the whole inner workings of BOTH systems for approximately 6 months before touching ANYTHING, just to make sure he got it right. she has a USED 730 ECM with a Hypertech thermo-chip inside(which is new), not sure where he got ithe ECM or it's actual age, which is why i have been asking ways to tell if it is good or bad. she has a "complex" and WILL NOT talk to scanners. they always come back with "vehicle not responding".

now for the problem. about 2 weeks ago, i was coming back from a friend of mine's house. i got a check engine light, ONE TIME. it came on, stayed on about 15 seconds, then IMMEDIATELY went off. it didn't come on again that night. i drove for about 40 more minutes. the next day i left to go to post and on the way there (about 10 mins into the trip) it came back on. this time it didn't go away and the car was weaker and "bucked" slightly. for about the next 3-5 days the car would decide what "mood" she was in. the light would come and go. so finally i REALLY begin digging into her to figure out the problem. i look for the ESC module since i had an extra. i couldn't find the module. i talk to my friend (who is vacationing in Michigan) and he tells me that there is NO ESC module on this car, for it is integrated into the ECM. ok, so i look at the knock sensor. i do the test where ya tap on the block near the sensor to trip it. NOTHING. so i figure the KS is bad. so i go buy another KS and try to install it. note that i said TRY. the old sensor just spun inside itself. so i wait and talk to my friend the next day and he tells me not to worry because there is another coolant plug in the other side of the block (i told him i didn't think it was a coolant plug, but elected to try it anyway) so i go and pull the plug (and of course NO COOLANT came out) and put the KS in that hole and route the wire over to it. this did NOTHING to fix my problem. so i wait and today im suppose to go to my friend's house as we are cleaning our Camaros (95 Z28, 87 IROC and mine) for a show tomorrow. we end up worknig on mine ALL day. to no avail. we found out that the KS wire has PERFECT continuity all the way to the ECM. and it is getting the proper voltage back from the ECM. we tried a few different things and nothing fixed the problem. finally we ended up (well, he did it ) unhooking the ECM. so we go to hook it up and decide to set the timing back down to stock (i had it at 12 adv.) and the car WOULD NOT idle. it would for a very short time, but then the ECM would start wigging out and it would die. it would idle with the ECM not in control (the brown/tan wire unhooked). so i went and drove it just in case the ECM needed to "re-learn" how to idle. it was DETONATING like mad!! this car has NEVER DETONATED AT ALL!!! but now it detonates all the time. and we can't make it stop. i have driven it for about a 35 mile trip (home) and it will not stay running by itself now and will not stop detonating! when i got home i checked to see if i had any NEW codes (i suspected i would with the new problems) and of course i did. now i not only have a code 43, but also a code 42.


well, now ya'll know the WHOLE story. sorry this post is so incredibly long, just needed to give EVERY detail to have the best chance of diagnosing it properly. i appreciate any input (besides "put a carb on it" ) and thank ya'll in advance for the help!!

Josh



P.S.- i tried to post this over on the DFI/ECM board (i know that is most likely where it belongs) but i got NO HELP. so, if you must move it, go ahead, but i would greatly appreciate it if ya'll would let it stay. thanks again!

 

I had that same code (43, ESC Module.) There is a ESC module. Its in the distributor. You see the two plugs that plug into your distributor? Thats it.

What it does, is the KC picks up on the knock, and the ESC retards the timing to compensate for it.

 

the ESC module is on the driver's side firewall near all of the relays. It's the farthest to the right in the little "cluster" of relays. You'll know it when you see it b/c it's the only thing that looks nothing like the others..... ....did that make any sense?

When you were setting the timing, did you disconnect the EST wire? If not, then your timing is WAY AHEAD and if it's too far ahead it won't idle, and it will definitely knock like hell.

 

Ahh sh*t. Now I gotta go research it.....

Seems what I was talking about was the "EST." (Code 42)

 

ESC= Electronic Spark Control ( knock module. recieves info. from knock sensor and reports to the ECM which adjusts the timing).

EST= Electronic Spark Timing. Disconnecting this wire bypasses the ECM advancing the spark. This takes the place of the vacuum line on an "old fashioned" vacuum advance distributor.

When setting the timing you need to disconnect the EST wire, make your adjusments, then re-connect the EST. If not, you will end up setting your timing to 8* with the computers +20* of advance which is actually way retarded.

 

newbie question: If you set your timing to 8* BTDC with the EST still reconnected, and the computer's 20* of advance, wouldn't you have 28* of advanced timing? Wouldn't that be way too advanced?

 

No. You will end up setting it to 8* WITH the computers +20* which would actually be -12* base timing. You want to set it between 6-8* advance with the EST disconnected. Then at idle the computer adds 20* and as load increases, the timing decreases.

 

well, thank you so much to everyone who replied, but i know what her problem is, and i could cry.


my baby has a rare condition known as Rodus Knockus...


guess i need that 383 sooner than i thought...


i could freakin cry...

Josh

 

ahhhh. also known as clankety-clank clank boom syndrome ( most likeyly caused by that excessive knock?). Sorry to hear about your loss, my deepest condolences go out to the family.