About to install a new TPS on an '85 with the 4.9 six and the feedback carb. I'm getting a code 23 saying the signal voltage from the throttle position sensor is out of spec. It has an eradic idle and often stalls when you stop or slow down. The Haynes manual says on the 4.9 you just install the tps and don't need to adjust the position for a base voltage like on the V8's. Does anyone agree with this? I've got the battery disconnected to clear the codes before the install and also went ahead and put a new O2 sensor in too. I haven't been able to find any bad hoses or vacuum leaks, so I'm hoping just the tps is the problem. Just want to be sure I install it right from the get go.

 

If the holes on the tps are not slotted, then you do not have any adjustment. I haven't ever installed one on one of these carbs before though.

 

Ok that makes sense. I checked and one hole is round and just over 3/16". The other is slottled, maybe 1/8" x 1/4", but it's horizontal to the other hole and the main hole where throttle shaft goes through. So strange as that sounds, it doesn't appear you could rotate the position?

 

Best I can remember there isn't any adjustment for the TPS on the 4.9, at least don't remember any when I replaced my carb.

 

No adjustment is possible on these, just bolt it on.

 

Installed the new TPS (that part was easy) along with a new O2 sensor (that was tough...had to get an offset socket) and some new belts (this parts was the worse). Breaking the O2 sensor free and loosening up everything to put the belts on was really tough. Thank god for acetylene and Kroil. But even with that, the head of the tensioning bolt to the power steering frame twisted off. Even heat, Kroil, and left handed drills wouldn't get out the broken bolt. Ended up drilling it out and taping it for a new bolt and it's fine now Anyway it's purring again like an old kitty with a steady idle. Still have to take it out for a test drive and run some scans on it again to be sure all is well. Not sure how many miles I need to put on before I should run the scans? Anyone know? Now to pass the emissions test.

 

You won't need to put any miles on it to see if it still has the code, although the code might be in the continuous memory. Don't worry about it and do the scan, friend.

 

I should have mentioned I did disconnected the battery through all this, so I assumed the codes are all gone.