need a bit of help 1996 wrx
 

hello iv just got myself a impreza wrx 1996. im having a problem with the engine missing under hard acceleration and when at very low revs it seems to be bogging down and i need to used a lot of revs for low speed parking ect. I'm getting a error code 31. so i tested the Throttle position sensor (i have 4pin)and i am getting 5.0v at idle and seems to go down to about 0.7v wide open. according to guides iv read else ware thats the way to test them and mine is fine. is this the case or do i need to fine a replacement? any help would be greatly appreciated :)

you can adjust the tps by twisting it once the screws are loose and that will either raise or lower revs depending on which way you twist. i adjusted mine so when warmed up it revs at idle 900 rpm. i kept getting 42 before i done this and that was the idle switch which is part of the tps.

Thanks I'll give that ago in the morning ! Also I have now taken it out of diagnostic mode and it's now flashing on intermittently while driving. So it could be a intermittent thing. I don't wanna go buying a tps for It to not solve the problem. Are the diagnostics pretty accurate ? Iv never owned a car with obd1 before

Flashing CEL is an indication of knock being detected I believe. Be careful!

I will do thanks for the warning :-) I'm hoping its something simple I really can't be bothered to change the engine in the cold. Do you think it will be the tps causing the issue or something else causing the problem

Honestly I don't know, it could even be the knock sensor itself. Mine was cracked and was throwing up faults all the time. Having said that, the CEL stayed on and didn't flash!

Check vacuum pipes etc. I had issues with my car cutting out when warm just after I bought it. It was dead and misfiring as well. I found a hose off and some more cracked and brittle ones. Once I repaired them all (plus the knock sensor), I reset the ECU and the car has never looked back. Going 100%.

Thanks I'll have a good inspection and see if I can sort it out. Where abouts is the knock sensor ?

It's right below where the intercooler is, my car has a FMIC so it's easy enough to see. It has a white connector with one single wire coming from it. The sensor itself is a round black job with a bolt going through the middle of it.

Today I have taken the ecu cover off and probed pin 37 and 38 on the 12 pin plug and it is reading 4.7v all the time! Are there the correct pins. Just need to know before I go trying to rewire it !