PCM problems?
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PCM problems?
I have a '93 E-350, with 5.8L V8.
During the warmer months it gave me very little trouble. Now that its colder, the check engine light comes on and it will run rough, possibly even backfire although it can be hard to tell, and when it shifts, it will slam into the next gear. I'm beginning to suspect the PCM. I've wanted to check the codes, but I can't find the connector. The Haynes manual isn't helpful in that regard either. Everywhere it suggests, it doesn't appear to exist. So, I need to know where that connector is and if this is the PCM, or if there are multiple issues, or both? Have PCMs proven to be temp sensitive?
Thanks.
During the warmer months it gave me very little trouble. Now that its colder, the check engine light comes on and it will run rough, possibly even backfire although it can be hard to tell, and when it shifts, it will slam into the next gear. I'm beginning to suspect the PCM. I've wanted to check the codes, but I can't find the connector. The Haynes manual isn't helpful in that regard either. Everywhere it suggests, it doesn't appear to exist. So, I need to know where that connector is and if this is the PCM, or if there are multiple issues, or both? Have PCMs proven to be temp sensitive?
Thanks.
Lead Driver
Joined: Feb 2003
Posts: 8,140
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From: Oak Harbor, OH
On a '93 there is a D shaped connector with a black protector on the DRIVER'S side inner fender. It will be almost right beside the brake master cylinder. The PCM isn't the weak link here. You said it runs fine when it's warm out, but bad when cold. Maybe you just need a tune up with quality (not autozone, use napa or dealer parts, autozone sells motorcraft plugs. That is the only thing to buy there.) parts. You're ignition system is the make or break part of the engine.
Elder User
Joined: Feb 2004
Posts: 638
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From: Birmingham, AL
The connector is in the driver's side fender well by the battery. If it has stored both 3 digit and 2 digit codes it can be very hard to read by the blinking check engine light, but it won't hurt to try. You can go through them several times making hash marks as your Haynes manual suggest and then compare the several attempts to make sure you read them the same way each time.
Be sure to go through all of the test modes listed in your manual, KOEO KOER wiggle etc.
You can buy a digital code reader that will read out an actual number instead of flashes if you have trouble reading the flashes.
Gene
Be sure to go through all of the test modes listed in your manual, KOEO KOER wiggle etc.
You can buy a digital code reader that will read out an actual number instead of flashes if you have trouble reading the flashes.
Gene
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Ok, I found the connector. Just before you posted. I've been looking for weeks. Isn't that the way it goes. 
) Looking through my manual, I have several things that vary from it. Like sensor locations, etc. The engine is running right and is alternately racing and slowing down. It doesn't seem like a "tuneup" would be quite the answer as the behavior is sporadic. Not that it couldn't use one... I've got an Actron code reader, so I'll start with that and see what I can find and post back with results.
Thanks, for the posts.
) Looking through my manual, I have several things that vary from it. Like sensor locations, etc. The engine is running right and is alternately racing and slowing down. It doesn't seem like a "tuneup" would be quite the answer as the behavior is sporadic. Not that it couldn't use one... I've got an Actron code reader, so I'll start with that and see what I can find and post back with results.Thanks, for the posts.
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Well the KOEO and Continuous memory tests posted one error. Error 123. Haynes manual says the Throttle Position Sensor is above maximum voltage. Any ideas as to what this means? Also, would this affect how the vehicle shifts? I haven't done further testing yet. But will after lunch.
Lead Driver
Joined: Feb 2003
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From: Oak Harbor, OH
Actually yes, that's a good thing. Replace the TPS.. It's only about $35, and shouldn't take too long. It's mounted on the bottom of the throttle body. If it's bad it will indeed effect the transmission shifting. The transmission's shift points are controlled by the computer. It uses the TPS signal to tell where the go pedal is, and compares it with RPM. It then tries to figure out the best time to shift.
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Ok, that's very good to know. Can it be affected be external temps? It makes sense, though, as the RPMs were all over the place for awhile this am, too. Well I'll start with that and let you know how it goes.
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Just finished putting the van back together after swapping the rotor, distributor cap and Throttle Position Sensor (TPS). The van runs well now. The cap and rotor had wear on them, but they shouldn't have cause any problems. The TPS definitely made the difference. The engine runs smooth, no erratic idle, no check engine light and it shifts nicely. Thanks for the excellent advice. I couldn't have done it without you. Price was $46 at Checker and I had to replace the Throttle Body gasket as I had to remove the throttle body to replace the sensor. It was a bit of a job trying to access things and there were more hoses connected (some of which I replaced - they needed it) than Haynes let on, but at least I have a better clue as to what's all under there and how things work. Thanks again.
Hotshot
Joined: May 2003
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From: south louisiana
Originally Posted by pfogle
Actually yes, that's a good thing. Replace the TPS.. It's only about $35, and shouldn't take too long. It's mounted on the bottom of the throttle body. If it's bad it will indeed effect the transmission shifting. The transmission's shift points are controlled by the computer. It uses the TPS signal to tell where the go pedal is, and compares it with RPM. It then tries to figure out the best time to shift.
