Help engine problems!
Thread Starter
Cruising
Joined: Sep 2011
Posts: 12
Likes: 0
From: Seymour Tn
no. if it is not setting a code, it SHOULD be fine, not sure how to check it and it is NOT easy to get to.
the IAC is simple with the haynes, that may cure the idle issue. I would verify all the ign parts if it was mine, wiring, plug wires, if it runs, the module and pickup coil are ok.
the IAC is simple with the haynes, that may cure the idle issue. I would verify all the ign parts if it was mine, wiring, plug wires, if it runs, the module and pickup coil are ok.
Race Director
Joined: Apr 2002
Posts: 10,036
Likes: 346
From: Anaheim CA
The ECM resets the IAC every time you shut off the car. No need to mess with it.
The vacuum fitting near the distributor goes to the cruise control and to the A/C and heater ducts inside the dashboard.
The symptoms (runs OK cold, bad when hot), suggest an O2 sensor problem. When you first start the car it runs in open loop mode and the ECM uses stored info to control the engine. After the engine warms up, the ECM switches to closed loop mode. The main difference is that the ECM looks at the O2 sensor and decides how much fuel to feed the engine based on what it sees. If the O2 sensor (and wiring, fuses, etc.) is bad then the ECM can't control the fuel mixture properly.
The vacuum fitting near the distributor goes to the cruise control and to the A/C and heater ducts inside the dashboard.
The symptoms (runs OK cold, bad when hot), suggest an O2 sensor problem. When you first start the car it runs in open loop mode and the ECM uses stored info to control the engine. After the engine warms up, the ECM switches to closed loop mode. The main difference is that the ECM looks at the O2 sensor and decides how much fuel to feed the engine based on what it sees. If the O2 sensor (and wiring, fuses, etc.) is bad then the ECM can't control the fuel mixture properly.
Thread Starter
Cruising
Joined: Sep 2011
Posts: 12
Likes: 0
From: Seymour Tn
The ECM resets the IAC every time you shut off the car. No need to mess with it.
The vacuum fitting near the distributor goes to the cruise control and to the A/C and heater ducts inside the dashboard.
The symptoms (runs OK cold, bad when hot), suggest an O2 sensor problem. When you first start the car it runs in open loop mode and the ECM uses stored info to control the engine. After the engine warms up, the ECM switches to closed loop mode. The main difference is that the ECM looks at the O2 sensor and decides how much fuel to feed the engine based on what it sees. If the O2 sensor (and wiring, fuses, etc.) is bad then the ECM can't control the fuel mixture properly.
The vacuum fitting near the distributor goes to the cruise control and to the A/C and heater ducts inside the dashboard.
The symptoms (runs OK cold, bad when hot), suggest an O2 sensor problem. When you first start the car it runs in open loop mode and the ECM uses stored info to control the engine. After the engine warms up, the ECM switches to closed loop mode. The main difference is that the ECM looks at the O2 sensor and decides how much fuel to feed the engine based on what it sees. If the O2 sensor (and wiring, fuses, etc.) is bad then the ECM can't control the fuel mixture properly.
Burning Brakes
Joined: May 2011
Posts: 838
Likes: 2
From: Louisville Ky
also, if tps is out of adj, you can unplug it and ecm will set a default for it. like the maf.
again, check simple stuff, wires, etc. possible that a sensor fails and does not set a code, have heard it many times, like the coolant sensor.
Race Director
Joined: Apr 2002
Posts: 10,036
Likes: 346
From: Anaheim CA
If the coolant temperature sensor is bad (or wiring), it will set a code 14 or 15.
The code does set a default value for TPS if it's bad (code 21 or 22). I guess the ECM would use the MAF air flow to run the engine in that case.
The code does set a default value for TPS if it's bad (code 21 or 22). I guess the ECM would use the MAF air flow to run the engine in that case.
Racer
Joined: Jun 2006
Posts: 361
Likes: 6
I had the same problem and no codes. Went through the FSM troubleshooting steps and everything pointed to the MAF. I unplugged the MAF and it ran better but not quite right. I bought a new MAF and it ran fine for about 15 minutes then started running rough again. Took the MAF back and exchanged it for another new one, the parts clerk had no idea what a MAF did so couldn't determine whether it was defective. Installed the second new MAF and it has been trouble free for 2 years now. I did the entire minimum idle procedure, pulled IAC and checked pintle length, adjusted TPS and checked the entire fuel system. Take your time and follow the procedures in the FSM. It's boring and tedious but you'll know how to better troubleshoot the systems the next time and you'll know the warnings your car gives you the next time a problem starts. 88 Coupe Auto by the way.
I'd toss the Haynes and get an FSM.
I'd toss the Haynes and get an FSM.
