Hey all,
I'm having some uncertainty in diagnosing a fuel system issue, and I want to make sure I'm on the right track before I start spending actual money on parts that may or may not fix my problem.
My '98 TJ has an erratic idle, and stalls when cold (first half minute or so). Occasionally, at speed, it bucks (only once each time); otherwise, it runs great. The MIL is lit. I borrowed a friend's OBDII scanner and it reported code 0121. According to what I can find, this means that the TPS doesn't agree with the MAP sensor. If I disconnect the TPS, it behaves identically. If I disconnect the MAP sensor, I can't keep it running at all.
So I'm thinking that I need a TPS. However, since it doesn't say that the TPS has failed, only that it disagrees with the MAP sensor, I'm hesitating. It's a $50 part, and I want to be sure it's the right one to replace.
Are there any other tests I can do to nail it down? Has anyone else had this code, and what ended up being the root cause?
Thanks so much!
Hal