A few problems showed up at once on my 92 5.0 w/ E4OD tranny. First idle was stuck high around 2000, it was shifting hard, stalling. Took it to mechanic, he replaced MAF sensor. He said test drive was fine. Next day idle was at normal speed but it continued to stall and it was shifting hard and early. Threw a code 122,so I replaced Throttle Position Sensor and cleaned the connector pins. Also cleaned throttle body and replaced gasket. I checked all vacuum lines, no leaks. Checked all fuses, all lights working. This cleared up the stalling, but the idle is lower than usual, especially when cold.

Still getting hard shifts, check engine light and code 122. Any ideas?

 

Have you disconnected the battery for 5-10min?

 

Haven't disconnected battery, but I cleared the codes with scanner. I'll also disconnect the battery if necessary.

 

OK, unhooked battery and turned on lights for 20 minutes, hooked back up , same problem. Check light on about 10 seconds after start, idle a little low. I'm sure it still has code 122.

 

A '92 doesn't have a MAF. Codes don't mean to change parts - they tell you where to BEGIN diagnosis. Did you test the old TPS? Did you keep it? Did you test the new TPS? Read these captions:

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What is the idle speed? It might have simply been too high before, and now it might be normal.

 

I didn't test old or new TPS, just mounted new one and plugged it in. I also tossed the old one cause it had 230K miles on it. I've had good success using this R&R method before but looks like this time it will be a lot tougher to fix.

 

My truck's TPS has over 450Kmi and still works fine. They don't wear out with miles or age - they just go bad sometimes. So you always have to test; even the new ones. That applies to all sensors & actuators, and most other parts.

 

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