I,m working on my friends 87 Z, (305 TPI/auto, 119,000 miles), the car is all stock. The car is throwing code 14 (coolant sensor) and code 42( EST/ECM). I believe i know why it is throwing code 14, but i cannot figure out the code 42. So far i have replaced plugs/wires/cap/button/modul in distributor/fuel filter. I also sprayed wd-40 in all of the wire connectors i could reach. I also reset the ecm and it threw the codes right back at me as soon as i restarted the car. The car "usually" will start right up, but as soon as you touch the gas it "usually"falls on its face. If you baby it, you can rev it. But if you punch it, it backfires through the throttle body(not exhaust) and dies. What i need to know is: where is the ECM and what should the timing be set at (the sticker under the hood is missing). The timing is currently at 2* BTC with the plug above the heater box unplugged.

I,ve already done searches all over this site for code 42 and found out some good info, but still am looking for any other ideas before i replace the ecm(if i can find it).

BTW, the car ran fine before it started trowing code 42

Thanks...

 

I found ECM, now i just need to know what the stock timing is set at on an 87 Z 305TPI/Auto. I've read anywhere from 6* to 10*. If someone could take a sec and see what the sticker on their car says, i would appriciate it. Thanks.....

 

The timing is supposed to be set at 6*BTDC. When I unplug the EST bypass whatever the the wire is when I set my timing it runs like crap and throws a code 42 until I plug back in. If you have it unplugged the whole time it sounds to me that is your whole problem. Set the timing plug the wire together delete the codes and it should be fine. If thats not the problem then I can't help you.

 

The car was throwing 42 before i unplugged the plug. I'm gonna set the timing then reset ECM tonight.

 

This may sound stupid - even insulting - but are you sure you plugged the EST plug thingie (pass. side of engine bay, brown.black wire) back in??

 

Why did you spray WD-40 into all the wire connectors?

 

Yes i plugged it back in. I've always used wd-40 in wire connection/plugs, it cleans the connections, never had any trouble using it.

I set the timing today from where it was 2 btc to 6btc. The car runs great now but still randomly dies. The car will run good for 3 minutes then die or not idle (have to hold gas) for about 2 min. The ECM or? seems to try to over-correct itself during that 2 min, then it starts to run fine again.

Also the fans and a servo/relay/wire connection? at the vapor/charcoal box that clicks like mad during this 2 min.

The car is still trowing codes 14 and 42 even after resetting the ECM (again). I am out of ideas......

 

It sound like your CTS is messed up and maybe it is causing the engine to not be able to go into closed loop operation.

 

Im having the same problem but what is the CTS?

 

Coolant temperature sensor, it's on the passenger side head.

 

A loose prom in the computer has been known to cause a code 42.

 

89 IROC, thanks for the info, will change that out tomorrow. Yes, it seems like the car has 2 loops, kinda like when you run your A/C (when the a/c pump/clutch engages). The one loop it runs like there is nothing wrong with the car, and a couple min later it seems to go into another loop and you have to keep babying it to keep it running.

Does anyone know what the electric connection is that "clicks" on top of the charcoal canister. The thing clicks like crazy and the fan runs eratically in the "bad" loop.

Other ideas are still welcome, i hate to see my friend get rid of his Z...........

89 Iroc, do you think the CTS (code14) is causing the code 42 because of the loops? The codes come right back when the "bad" loop drops below 400 or 500 rpm.

Thanks again.....

 

Its hard to tell you anything since I dont have the car in front of me. TPI is still pretty new to me. I'm just trying to give you ideas of what could be wrong out of the experiences I've had with my car. My guess is that the code 14 means either you have a faulty CTS or a bad connection and that may not allow your car to go into closed loop operation. I can't really tell you anything about the code 42 because the only time I every got it was when I was setting my timing but after I was done I just deleted the code and it was fine. Check to see if your chip is loose like the other guy said.

 

I found a plug unplugged above(not in front) the starter selnoid. The pigtail plug connector was cracked. I need to know what >this plug< is, because a few minutes after plugging it in the car stayed running like it never had any problems. I have been told 3 different things, but here is what i can tell you, Before i plugged the plug in, the dash temp gauge worked and the fans worked eratically. Now everything seems to be working like it should. I drove the car for over an hour and had no problems . But i still need to know what this plug is (CTS?), fans(kinda worked), gauge(worked). Thanks again for your help....

The plug/sensor connection is single wire, looks like a mushroom, in fact it looks like my trucks' knock sensor.

 

Where was the plug? and where did it plug into?