Can any mechanics that work for ford dealerships clue us in on this?
I found a TSB on the mitchell on demand software for 92 thru 95 F-150
4.9L engines with hesitation, stalling, or rough idle and no codes built before 3/16/95. It states that there is a revised throttle body gasket. My question is what is different about this gasket and could it cure my problem of the truck falling on its face on acceleration? Also are there any precautions to take when installing this new gasket aside from anything obvious? Thanks in advance for any replies.

 

It basically says to replace the throttle body gasket with Ford Part No. F5TZ 9E936 BA . From what you describe Im not 100% sure it will solve the problem . I think what was going on was the original gasket was allowing unmetered air to enter the engine causing the problem . Have you checked your fuel pressure ? Has the fuel filter been replaced lately ? Does the engine die all the time ? Any diagnostic trouble codes ? Any details you provide will be helpful .

 

fuel filter is new, i installed it myself. engine doesn't die at all, no codes. what it does is, when you depress the gas pedal the rpms drop below idle(around 300 rpms) then rise up. if you depress the pedal really slow the rpms rise like normal. i replaced intake and exhaust manifold gaskets already(less than 5000 miles) new spark plugs also. the engine idles fine and it runs down the road fine, just have to watch the tach to make sure the rpms are going up instead of down when up shifting. i also found another tsb about the spout wire and pip circuit wire shorting against a drain wire in the main harness under the hood. i haven't unwrapped the wire harness to check them yet. i thought that might be another possibility. hasn't become a major problem yet, just real annoying when i go to take off and the thing falls on its face then goes. kind of embarassing, people who see it happen probably think i don't know how to drive a manual shift vehicle. hahaha. This problem has been the same since before i did any work to the truck so i know i didn't mess anything up yet. it actually runs better since i did the work i've done since i bought it. thanks for your help and for anymore advise you give.

 

What you describe sounds more like a Tps problem . They can test fine yet still be faulty . If you have repair manual with a test procedure for it run the test both when the engine is cold & at normal opertaing temp & see what you get .

 

Do a search on the 4.9L egr valve on this forum. I think you may find your answers. The blanking plate between the manifold and egr valve solved all my problems, no more hesitation @1800 rpm or so, better idle, a major difference

 

If it ain't broke.....change stuff till it is!


I had a similar problem. Pull the IAC(mounted to the right side of the throttle body) and clean it out. That might be clogging up. Then pull the throttle body off and clean the inside out. They are known to gum up. You may also want to check injectors and fuel filter. Ohm the injectors(should read between 11.5 and 12, but might want to check ford specs. to be sure). I still have a very minimal problem with varying rpm's at idle(fluctuates about 200 rpm's), but plan to fix that in auto class this week or next. I'll edit this if i think of anything else.

 

If you pull off the throttle body and clean it, make sure it doesn't have a special coating in it. Some of the newer ones do.

 

thanks for all the replies and advice. well i tried the restrictor plate thing. made it out of 1/16th inch thick stainless steel plate, 1/8" holes. i even stamped today's date into it and left a tab on the side of it and slots for the bolt holes so i don't have to take the bolts all the way out to remove it. god forbid they ever start doing a real smog inspection here in ny. made the plate at work and installed it before i came home. 22 miles i drove and come to the conclusion that: IT WORKS, WHAT A DIFFERENCE! however the rpms still drop before rising when you press the gas. but the hiccup when shifting is gone. and i don't have to press the gas pedal so far down to make it go anymore. no check engine light yet either. yet anyway. as for the tps sensor i'm still gonna look into that and test it like Paul suggested. iac motor i cleaned when i installed the new spark plugs. fuel pressure i haven't checked yet but i will when i test the tps. anyway just thought i'd let you guys know what i've done so far, and thanks again for the advice.

 

i know this topic is old now, but i broke down and bought the tps sensor. i haven't installed it yet., mostly because its been raining alot here and my problem has gone away. i'm betting on it coming back within the next three days on account of its suppose to warm up and be dry out. so i'm waiting for the weather to change and the problem to come back before i replace the tps sensor. i also plan on doing a few test before i replace it. just thought you guy's might like to know.

 

i replaced the tps and no change. problem still exists. i think i have problems in air injection system. think ther might be a check valve leaking. sounds like and exhaust leak on heavy acceleration but goes away on light acceleration. when i find the problem i'll let you all know what i came up with.