Transmission Lag and Slip

Tiny
RMOORE09
  • MEMBER
  • 1999 FORD EXPLORER
  • 212,000 MILES
Hey, my explorer will rev up between 1st and 2nd gears and not accelerate. After it revs up it will accelerate just fine. When I stop, something will unstick underneath the floorboard. I could really use help on this, this has been going on for months and I cannot find the issue. There are no codes at all. The transmission fluid is perfect. It will not lag all the time. It can drive for two to three days and not do it. It does like to do it more often with the AC running. Earlier I was terrified, because when taking off from a stoplight, it would not go(the whole suv shook while it wouldnt go.) And then all of a sudden it jumped. Im so glad a car was not in front of me. Any ideas? I was told I could have a bad MAF but how can it be a sensor if my check engine light is off?
Also could it actually be a bad Valve Body Gasket? Thats what I think it is?
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Wednesday, March 28th, 2012 AT 10:32 PM

9 Replies

Tiny
HMAC300
  • EXPERT
Try cleaning the throttleplate with choke cleaner on both sides as well as the iac hole. It may be sticking. If that doesn't cure it then take to a trans guy so he can scan for codes as alot of times those don't show on the auto part scanners.

If the problem is electrical, there would usually have trouble codes and since none is present, it would be mechanical or hydraulically related.

Slipping can be due pressure leaks in the system.

It could be a failing seal, which explains the intermittent condition.

You would need to perform pressure test to check if anything is wrong.
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Thursday, March 29th, 2012 AT 1:16 PM
Tiny
RMOORE09
  • MEMBER
Went there and there were no transmission codes.
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Friday, March 30th, 2012 AT 7:12 AM
Tiny
HMAC300
  • EXPERT
Check your fuel pressure as well and check for a vacuum leak. Also check the hoses going to the valve covers for holes.
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Friday, March 30th, 2012 AT 1:30 PM
Tiny
RMOORE09
  • MEMBER
I do for a fact have a bad fuel pressure regulator for sure which causes it to kinda rough start sometimes. There are no vacuum leaks and all hoses good.
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Saturday, March 31st, 2012 AT 4:29 AM
Tiny
HMAC300
  • EXPERT
Then fix the regulator first if you know it's bad.
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Saturday, March 31st, 2012 AT 1:40 PM
Tiny
RMOORE09
  • MEMBER
For my model its replacing the fuel pump, but how would that cause the transmission to slip?
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Saturday, March 31st, 2012 AT 8:33 PM
Tiny
HMAC300
  • EXPERT
Because you are leaning the engine out and if the engine doesn't run right then neither will the trans work right. Ask any trans guy and they will tell you the same thing.
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Saturday, March 31st, 2012 AT 8:36 PM
Tiny
RMOORE09
  • MEMBER
If I were leaning it wouldnt it show lean codes like Bank 1 or 2 too lean?
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Saturday, March 31st, 2012 AT 8:42 PM
Tiny
HMAC300
  • EXPERT
Maybe maybe not
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Saturday, March 31st, 2012 AT 8:59 PM

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