Hi guys:

It's my turn to be jinxed

'95 4.0L AWD with OBD-I

Car was working fine. Came home from work and car was fine. Went for an errand half an hour later and it will start and die right away, unless I keep the gas pedal down, and even then it's just limping enough to get it inside our garage. "Check Engine" light came on briefly. I pull the code and it says 157 & 158, which means MAF output is both too low and too high. I guess it was all over the place.

I checked the MAF and it was very clean, and the manual says a bad IAC could also cause these codes. Could a bad IAC really cause the PCM to throw a MAF code????? I don't want to replace the MAF only to find out it's not the culprit.

 

I wouldn't think a bad IAC would cause the situation as described but a faulty MAF would.

Can you swap the MAF with another to test? I have a spare, used one that you are welcome to test with. Of course, I don't know if it is operable.

 

I have something of the same going on with my 90 4.0, code pointed to the EGR, sense I do not have one, I was pointed to the ECT senser. I have yet to find it on the engine, so if anyone would point me in the right place I would very happy. Its the Wifes car, that's why I would be happy to fix it. lol

 

The ECT for the 4.0L is near the front of the engine, about the top of the timing cover. It has a two-wire connector. You should check the resistance before replacing it.

 

Dave, thank you for jolting my sleepy brain. I completely forgot that my brother has an Explorer with the same engine, and he's not driving it right now (expensive gas, I guess). I'll try to con him into lending me both his IAC and his MAF and I'll swap those one by one to see what the problem is.

 

Thanks, I will check it out.

 

OK, I swapped my brother's MAF in and the car starts right away, really smoothly. Put the old one back in and it dies again. Tried cleaning the old one, but that didn't help.

I'm waiting for the weekend to pull one from the junkyard. Can't seem to part with $100 for a rebuilt one from the parts store.

So, I know what's wrong with the car, but it's still not fixed. Cheap owner!

 

the heated elements do burn out....like a light bulb just no quite as hot...abt. 800d F....hot enough to leave scar burn marks

many of the later design MAF's(not Aero) use a super hot burn off cycle at engine turn off...good to clean but hard on the element

 

Copper,

The MAF have specific tunes for different years, engines, and options. So you should try to find one off of at least the same year engine.

Also, you realize that all you really need is that assembly with the two filaments and electrical connector that screws into the side of the MAF body? It might be cheaper at the salvage yard when you try to check out with a small sensor, vs a whole MAF body.

 

Hi xlt4wd90:

The part number for the old one I had is F07F-something-A2C for a '95 Aerostar 4.0L.

The one I have on right now comes from my brother's '93 4.0L Explorer and it has the same part number with the last part being -A2B.

It seems to work fine, with plenty of power.

In retrospect, the MAF must have been intermittently bad before, since I noticed that three things have gone away with the "new" MAF:

1) The slightly uneven idle while waiting at red lights. Not really rough, but the engine seemed to wander up and down at about 1 Hz, but ever so lightly I din't bother looking for the source.

2) The thunk when I step on (or let go) of the gas abruptly. I thought it might have been the U-joint and I was waiting until I have some time to look at it. It's gone now.

3) The occasional thunk when going at freeway speed, as if the ignition somehow missed for a beat or so and then picked up again. That, too, is gone.

The surprising thing is that the Check Engine Light never even came on, and no code was ever stored until the last moment when that MAF decided to quit, luckily on my driveway, I might add. Then it threw the 157 & 158 codes.

I feel like crap now for having ignored all these symptoms for so long. But what can I say, it was intermittent. All in all, I was extremely lucky it quit when it quit. Otherwise, I'd have had to limp home or pay for a tow truck.

Anyway, I'm too lazy to go to the junkyard, so I ordered one on E-bay. Same part number as my old one, and for $16 including shipping, I'll take my chances

 

congrads copper_ca,

another successful DIYer Aero repair....

 

Thanks Cliff. And yes, the two minutes spent reading the stored codes saved tons of time. I am impressed that our cars are finally getting smarter than us

 

our cars may be getting smarter than us, but they sure as hell don't know how to communicate to us....
¿Hablas inglés?, por favor?

glad you have your Aero running Tung and it didn't cost you the first born son at a dealer shop

 

I have the exact some model and had the same problems. I finally found a older model MAF sensor and mounted it to a larger 96 model housing. Made a cold air box. It is a very different ride now. Gas mileage might be better but can't stop flooring it to chirp tires and sounds good with the y-pipe dual exhaust system.