MAP sensor repair?

Is it possible to take the MAP sensor apart and repair it successfully?

Not that I know of - I've not seen "MAP Sensor Parts Kits..."

Since a good seal in the sensor housing is so important anyhow, I'd be loath to try it.

Why for do you ask?

5-90

they should be pretty cheap

XgeekstarX said:

they should be pretty cheap

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You haven't had to replace one yet, have you? At least for a 96+ they are ~$100.

5-90 said:

Not that I know of - I've not seen "MAP Sensor Parts Kits..."

Since a good seal in the sensor housing is so important anyhow, I'd be loath to try it.

Why for do you ask?

5-90

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This is why--
The entire engine was under water for 10-15 seconds, and about two-thirds of it was under for about 5-6 minutes. On the way home (2.5 hrs.), I was getting 8-9 mpg. I usually get 18-20 on the highway. Immediately after the baptism, I pulled a P0171 code with my cheapy code reader. Too rich, bank 1. I checked all injectors but the one that's obscured by stuff (can't remember which "stuff," though). All were exactly 13.4 ohms. Fine. Disconnected the cruise servo because the engine started to redline. Took care of that. Disconnecting the battery got the code to go away and got the gas mileage back to normal for a bit.
The problem is that if I just drive on normal streets, the mileage is normal, whereas if I get on the freeway (and have to get into the gas to merge), it starts running too rich again and the mileage takes a dump. Again. Also, when slowing down, the RPMs get down to 450-500. I researched the situation, and it would seem to be MAP sensor related. I suppose it could be an O2 sensor, however. Oh, yes. I also changed the plugs last Sat. which seemed to help a bit.

Sounds like OBD-II, so you're 1997-up, right? You didn't say.

"Too rich" sounds like a HEGO sensor fault- which makes more sense than a MAP sensor, since HEGO sensors are hot and might not like being immersed. I don't recall the code offhand, but I can check - hold on...

OK, OBD-II Code P0171 (DTC 51) is "Fuel System Lean, indicated by a 'Rich' AFR correction factor." Yep - sounds like a HEGO fault - they tend to wear out faster than the MAP sensor will, and they're subject to a good deal of heat (which both wears them out quicker, and would cause them to not like bathing...)

At least, that's my initial thinking...

5-90

Yes, sorry. It's a '99. I'd seriously considered that it might be the downstream O2 sensor. I guess I'll test it and go from there. I'm sure it didn't like being cooled off so quickly after running trails for an hour.

Here's a question for the sensor gurus: do you know whether the later MAP sensor is electronically compatible with the older one? I noticed when cleaning my throttle body the other day that despite its location, the later one is still connected to the TB by a little tube. It just occurred to me to wonder if you could mount an earlier one remotely.

CartsXJ said:

You haven't had to replace one yet, have you? At least for a 96+ they are ~$100.

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used to work at a parts store and i wanna say around 30 bucks for my 92

The "downstream" HEGO doesn't have anything to do with fuel metering - just a check on cat function. You'd be more interested in the "upstream" HEGO - the one in the exhaust manifold.

Matt - I've been wondering something like that myself, mainly for my own information. It's on my "list of things to check out one of these days" - but let me know if you happen to come up with anything...

5-90

5-90 said:

The "downstream" HEGO doesn't have anything to do with fuel metering - just a check on cat function. You'd be more interested in the "upstream" HEGO - the one in the exhaust manifold.

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Thanks and will do.

Dump question but did you change the air filter, a wet/dirty filter will give those readings and many swell when wet and restrict air flow, vacuum would be way high and cause all the symptoms you have.

Totally dry (except for the requisite oil) K&N flat panel filter. I have a MadXJ cowl snorkel and a "sealed" airbox. It did end up with about an 1/8" of water in the bottom of the 'box. I think it entered through the snorkel when the water came up onto the windshield. That's the second or third thing I checked after getting extracted.

Try it without the filter just to be sure.