QuestionQUESTION: I have a 1994 2.5l jeep wrangler I was driving the other day and I have very little power the engine will not go above 3000rpms, and my check engine light came on I did the whole diagnostics test with the on off on off on key bit, and I got a code 12, 33, and 51 the code 13 is for a battery and the 33 is for some ac relay, the only thing is, is I don't have ac? so I have no Idea what to do with the code 33 the 51 went away after disconnecting the battery but I still have no power and the 33 persists, where should I look?
ANSWER: Question:
Did the loss of power happen suddenly or gradually?
A/C cutoff and PS cutoff circuits may be the same as far as that computer is concerned. If this switch goes bad in the 'WOT' range it is possible for it to cause a loss-of-power condition but not typical.
My advice would be to hard reset that ECM (disconnect the battery with the key ON, NOT RUNNING! for 15 minutes) and see what codes it has after you restart it.
Thanks for the question, I hope this information is helpful to you.
Kb
---------- FOLLOW-UP ----------
QUESTION: The power loss was some what sudden, we tried the hard disconnect and it runs fine while in open loop but as soon as closed loop starts I loose all power. Also with the code 51 it was a fuel lean so it's causing a rich mixture? any further ideas
AnswerHi Jimmy,
This is a difficult problem to diagnose in-absentia and I don't want to lead you on a wild goose chase but I would start by testing sensors. Start with the o2 sensor(s), TPS, and MAP. In open loop the only sensor the computer 'listens' to is the coolant temp sensor. Once this sensor states the engine has reached NOT, the computer reads the rest of the sensors and adjusts the timing and fuel ratio to accommodate a warmed-up engine. I could argue that it is possible that the IAC valve is faulty but that may only cause the engine to stall when warm but I wouldn't totally rule it out. If all the sensors check out fine then check the fuel pressure regulator (TPI? check the pattern of fuel spray as well. with the engine running, attach a strobe-timing light to the coil wire if possible and view the injector spray pattern, it should look like an upside-down funnel and consistent) and any vacuum ports that open once the engine is warm such as PCV and EGR. In fact, I'd make sure to do a thorough 'wiggle' test on the engine wire harness as well as the vacuum hoses. Got a hand-held propane torch? while the engine is idling with low-power, feed the propane into the TBI and see if it smooths out the idle. If it does, that indicates a fuel-system or vacuum problem. OH, vacuum, DUH! Get a vacuum gage like back in the old days, attach it to the engine and see what it reads. Most Chilton manuals still have vacuum diagnostics in them. If not, submit a follow-up and I'll do what I can.
Thanks for the question. I hope this information is helpful to you.
Kb
