hipposlapper

Hello everyone,

I have been trying to get the engine light to turn off on my 1987 442. The codes I get are 13, 21, and 44. I have replaced the O2 sensor and the TPS. I think that possibly the TPS I bought was defective, so I have ordered a new one which I have not received yet. I think that because when I try to adjust the voltage with that little screw, nothing happens. I have taken the car to a mechanic and he seems to have made the problem worse, my car now has trouble idling consistently, and will sometimes die when I step on the gas. I don't know much about cars and any insight would be helpful. Here is a link to the codes list if anyone needs it. http://www.seanster.com/scantool/ecm-codes.html#TOP

pogo69

Make sure your cat. converter is working properly also ...no bad smells for one,a bad converter wreaks havoc on other systems and it may not be your problem but keep it mind

hipposlapper

Okay, I will see if I can check that. It smells like it is burning rich to me, but I think the code says lean mixture so maybe it is the cat.

joe_padavano

If you plan to work on this car, you must get a factory Chassis Service Manual. The OBD I computers are extremely limited in what data they collect, so many failures that are not directly related to the code (and not controlled by or monitored by the computer) can set a code that leads you down the wrong path. You cannot successfully troubleshoot these cars if you expect to simply read the codes and replace parts.

Get a copy of a CSM (spend the $15 and buy a real paper copy on ebay), then read and understand the theory behind how the CCC system works. Follow the troubleshooting charts in the exact order specified. Do not cut corners.

I'll give you one example. My first CCC car ran rich but showed a code for lean. I tried replacing parts first, which didn't fix the problem. After carefully reading the manual, I figured out that the A.I.R. diverter valve had failed, causing the system to blow fresh air at the O2 sensor even after the system was in closed loop mode. The O2 sensor read this as a very lean exhaust and ran the carb full rich, which made for a lot of soot and poor running. This is a perfect example of how a part that is not monitored by the computer can trigger a false error code.

pogo69

I agree if you want to get to know your car you need a service manual and that will help you trouble shoot codes but be aware you still may end up just throwing parts at it on your own because you may not have the equipment to properly test some of the components so you may end with the " well it could be this or that" and its frustrating to take it to a so called "mechanic" and have it come back worse

hipposlapper

Yeah I agree, I have the chassis service manual, the problem is that I understand about 50% of it. So while I am figuring it out, I thought someone might be able to shed some light on it. I have basically narrowed it down to the TPS, the ECM might be faulty but I don't think so, or perhaps one of the wires is not connected properly. (Lots of packrats out here, like to chew on my wires.) I appreciate the help though, I didn't think of the catalytic converter or a AIR problem. I will let you know what I find out when I get the new TPS.

joe_padavano

First, the ECM is almost never the problem, despite the fact that it gets replaced a lot. That's a lot of money to waste. Second, how do you know the A.I.R. is not the problem? Did you run the tests as described in the CSM to verify it's operation? The part that can cause the problem is the switching valve. If it's bad, it will NOT set a code, yet it will fake the computer into setting other, misleading codes. This is where understanding the problem before throwing money at it is necessary.

hipposlapper

I don't know the AIR is not the problem, I just said I hadn't gotten far enough to think of that. I also said it is possible it is the ECM but I doubt it. I am picking up a voltmeter today to check the code 21 like it says in the manual I have. That will determine if it is the TPS or not. I assumed it was because my TPS went out last year and this one seems to have never worked right. But I will go step by step like you suggested and I will take a look at the AIR system as well.

hipposlapper

So I got the voltmeter and tested for code 21 like my manual told me. I am pretty sure I did it right, and I got a low reading on the voltage, meaning the problem is in the TPS or TPS connections. I have not had time yet to figure out the AIR system deal, but will get to that.

pogo69

Thats great sounds like your making some progress... Its a good feeling to beat that damn PCM or BCM or whatever hal system computer thats controlling your car

hipposlapper

So I got the new sensor and put it in, calibrated it with that little screw on the carb and the engine light is off! I feel very satisfied. Thanks for the suggestions guys.