Hi guys,

I recently had to replace the MAF sensor on my truck as it was causing a starting, driving and idle problem. The computer through the code for it maybe 2 times in a stretch of 2 years so I didn't suspect anything. The truck would take a coulpe turns to fire up and sometimes it would fire first time and starting to stumble a bit but would stay running. While driving it would buck slightly back and forth occasionally but no check engine light. I decided to change the intake manifold gasket, the cam synchronizer/sensor assembly(got the code for cam sensor often) and service the injectors. All done and fired the truck up and still had the funny idle and drove the same with the bucking, starting was quicker but after a day or 2 it started acting up with the starts again.

I was driving along one day and I got the check engine light come on, scanned it and it was for the MAF sensor.
I then opened the hood and unplugged this sensor and the idle smoothed right out, no more stumble and no more bucking. Also noticed with this unplugged the trans shifted better with no 3rd gear slip and went into 4th and OD properly with no hunting. I have replaced this sensor with the Genuine ford part and it starts up perfect, idles perfect and no bucking while driving but the 3rd gear slip is back and well as the 4th and OD back and forth. I know the trans is electronically controlled and operates properly when engine is functioning correctly so do you think the shift solenoids are in need of changing out now? It drags out the 3rd gear shift and rpms go up about 250-500 more while shifting (only 3rd gear) and 4th selects fine but when OD kicks in it jumps back to forth quite easily and goes back and forth if not just holding constant speed. With MAF unplugged all shifts go back to normal with no slip or gear hunting. And advise would be appreciated.

Thanks

 

With MAF unplugged the computer doesn't use regular shift parameters, it uses "safe mode" which should have direct shifting, not smooth, should be abrupt or often described as "harsh", lol.

MAF is a main sensor so computer runs engine and transmission differently, when it is unplugged

You have a 4R55E automatic in a 1996 4.0l Ranger, if it has alot of miles then changing out the Valve body and solenoids to the newer design wouldn't hurt and it can be done with just the pan removed.

The slipping is wearing out the clutches and bands(brakes) in the transmission, and they can only be replaced with transmission removed(rebuild), so the sooner the slipping is stopped the longer these parts will last.
And a new valve body should be done with full rebuild and it would already be there when that time comes so not a waste of money to do it now.

There are also "shift kits" that have good reviews, check those out as well

 

Thanks RonD,

I actually have a Transgo shift kit which I have had for some time now just haven't installed yet. (Transgo SK 44-55E) And I should add that when unplugged and shifting fine the shifts are not harsh or abrupt. I plan to service the trans fluid and filter very soon so might install the shift kit then.

Thanks again

 

Good

I would get the newer valve body, the original valve body used a separate gasket and that seemed to wear out and leak over time which caused the slipping.
All automatics run on ATF Fluid Pressure, the valve body routes that pressure to the clutches and bands, using the solenoids in 1995 and up Rangers.
So any leaks in the valve body passages reduces pressure, these leaks can be in the gasket or solenoid valves, no way to test which ones without visual inspection, and even then its not always clear/specific as to the problem.

The newer design valve body has gasket bonded to the valve body, eliminating 50% of possible leak points, lol

 

Thanks for the info, so I should get the new valve body and install the SK on that one then? Can you direct me to where I can get this newer valve body from and does it come with gaskets and ready to install?

Thanks

 

My mistake, the 5R were the ones that got the boded separator plate gaskets

 

No worries RonD, I will do the kit when I do the service and see how it goes.

Thanks again