92 explorer 4.0 overdrive problem.

[broncobuckinaround]

Going on a trip this weekend. And overdrive isn't working properly. No od @ 45 - 55. Then it engages but will shortly disengage. Some times it will engage on the high at 70 - 80 but also disengages. Need to know where to be begin. No codes.

Please help thx

 

[Big Jim M]

Oversize tires will cause this problem with an otherwise perfect tranny. The larger tires make the vehicle think it is going UPHILL at all times. So it don't like overdrive.
Also low fluid in there can be the culprit.
Then there is a partially stopped-up filter.
Big Jim

 

[broncobuckinaround]

Thx for posting. The tires are stock size.

 

[broncobuckinaround]

Update, found out the speed sensor wasn't outputting the correct readings. I'm just waiting for the computer to reset and ill be going on a test drive to see if that was the cause

 

[broncobuckinaround]

Update. It does go into overdrive now. But it takes a while. I had to run the father in law out to his house on a dirt road. This is weird, over drive engaged at 45 on dirt but not of pavement. Makes me think there's a connection issue. Still not sure tho. I'll do more digging tomorrow.

 

[Nhaz]

Odd question: does the floor get wet on the passenger side?

If so the 92 could rust a hole in the windshield rain drain area and drip water right down on the computer behind the passenger side kick panel. This I have seen in 2 92s to cause the overdrive to not function properly or at all.

In one case I was able to clean the computer out of the corrosion that had built up and in the second case I had to replace it.

 

[broncobuckinaround]

holy crap, that would suck. i never thought of that. i will check after work.

 

[broncobuckinaround]

just got back from my trip and well i wasnt as happy as i should have been. it did however engage overdrive from time to time. so im guessing the trans didnt over heat. i just kept it at 75 and watched for when od engaged. if it didnt id slow to 70 or lower til it would.

but anytime i let off the gas or use passing gear it would take for ever to engage again.

could the mass air flow sensor cause the od not to engage, say that its telling the pcm that there is more or less air going in that really is. more or less engine load. could a false reading cause the pcm not to engage od.

if so i need a way to check maf with a multimeter

 

[broncobuckinaround]

no corrsion. just really dusty.

 

[broncobuckinaround]

found a easy test for the maf. mine is reading at .65 volts and 1.96v at 4000rpm

is this good or bad. no jumps in voltage.