MY97 Impreza - Power Loss

Sounds like the Air Flow Meter.

Or the coolant temp sensor.

Thanks for the input.

My mechanic determined that is was the ignition coil. It seemed reasonable, but the next day the car sputtered at a light and almost stalled. So far so good since then, I will give it a few more weeks for normal operation before I believe it's in normal working condition though.

I am waiting for a single digit morning to give it a real test to find out if the issue has been truly resolved. I'll keep you posted.

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Well after a few weeks of operation, here is and update:

After finally throwing a CEL, the MAF sensor was dead. I was able to get a USED MAF @ $75US. It ran fine (about 2 weeks) until today. When the power loss issue, reared it's head again, while driving on the highway. 2 to 3 hiccups (sudden loss of power).

I am assuming that since the MAF, threw the CEL and that the replacement MAF is used. I am thinking of getting an aftermarket MAF, any thoughts/ideas on if this is the reason for the power loss and should I replace it not fully knowing if this was the reason?

Also, does anyone have a site or something that details the logic behind the operation of the engine? Basically, what the ECU is doing/monitoring to regulate fuel/air, etc. and what it checks to determine the proper engine operation.

thanks for ideas.

-sc

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Don't rush out and buy a new MAF. It may be a loose connector or something. Inspect the MAF cable plug carefully, reseat it, and see if it starts working. You may want to reseat the connector on the computer as well. Another possiblility is that a frayed wire or bad computer is blowing out the MAF.

Get the CEL read (Autozone, etc). Are you using a K&N/reusable filter? CAI?

Good suggestions, also, reset the cpu to factory defaults with either a reader or disconnecting the battery for severla minutes. Also, on some MAFs, you can replace just the little wire/film sensor instead of the whole unit - maybe someone will know the part number. Do you use an aftermarket oiled filter? Some folks have ruined their MAFs with those.

just some thoughts

Carl

Jim Stewart wrote:

The repair shop said the CEL was a MAFs failure. They replaced the entire unit & reset the ECU. I have used a K&N in the past, but put a subaru filter in a while back since the K&N isn't the best fit and 'hums'.

I'll reseat the connectors and check the wires ASAP. So far no CEL has been thrown, but time will tell. I hope it's not the ECU causing the MAF to fail...... sounds expensive

I was talking to a VW owner and they had issues with power loss similar to mine and their Cat was clogged and was the culprit. Any chance of this being the issue and since it's borderline no CEL being thrown? The vehicle has 181k on it. Is there anyway to check to see if the Cat. converter is going? Sensor reading a high (almost out of tolerance) value, maybe?

thanks for all the ideas.

-SC

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On newer vehicles I think there are 2-3 oxy sensors and some shops can test cat flow by putting special sensors in the bungs for the oxy sensors. If the bad MAF or other problems ahve ever made your car run rich for a significant amount of time the cat could very well be bad.

Carl

SnatchCritic wrote: