I have a stock '91 5.0 with EFI. When I accelerate slowly, it comes right up to 5K rpm no problem but when I step on it (as I normally do) it stumbles badly. I seem to lose one cylinder. So far I have replaced the TFI module (since at first I thought it got worse as it heated up) and the fuel filter. I have checked the plug wire resistance, the cap and rotor, the fuel pressure and all look good. I pulled #5 plug and it looked like new. Roger Stine did the wire diet and I have removed most of the polution stuff. I have some codes with engine off (67,84,85,34 and constant codes 29 & 34). Until now the thing has run great. I do have the EGR resistors but still get EGR codes. I have never had the transmission harness installed so I do not know why I am getting the VSS code. Fuel pressure key-on/engine off is 36 psi, at idle is 31 psi and it goes up to 40 psi when reved up, and I get 40 psi with vac hose off at idle. Is it possible that an injector is partially plugged? I am at a loss. Can anyone help me? Thanks...
On your wire diet, did you retain or delete the "salt-n-pepper" connectors at the firewall . . . these are a known issue with EFI cars if you don't rebuild them or delete them and wire directly.
HTH
Doc
__________________
little block, BIG BLOCK . . . HUMMMMMMM? FFR3712K (POPSDRM) in Lost Wages, NV. MKII, 5.0, GT40-EFI, E-303, T5, 17" 5-Lug Chrome Cobra "R's", 315's, PBR 4 wheel Disks, Full Tubular suspension, Flaming River, 3.73:1 3-Link, Drop Butt mod, Dash forward mod, Footbox Air vents, Custom Turn Signals, Custom 4-into-4 headers, Non-Donor build, Ford Royal Blue Pearl w/ Arctic White stripes.
Thanks for the replies. I still have the salt and pepper connectors and did not even think about them. The TPS I thought about but did not check yet but will....thanks again.....I will keep checking things until it is resolved. I am not used to feathering the throttle which kind of ruins the fun.....
Just another easy check, Make sure your MAF plug is tight. Mine was plugged together but I needed to push the wires tight into the plug from both sides.
__________________
Donor $2,500 -Kit $18,000 -Extra "needs stuff" $100's -$1,000's
300+hp tagged race car PRICELESS !! Best ET 12.898 @ 108.37 N/A
Completed: Passed PA Insp 3/19/12 Tagged 4/14/12
Mk III #5294 -Purchased 1/08,302 T5, 3-link, 3.55 posi, 13" Cobra brakes, SAI, twEECer R/T, BE & EEC Analyzer YouTube Videos: http://www.youtube.com/user/joeembery#p/u
My Pics: http://s207.photobucket.com/albums/b...cpZZ1QQtppZZ16
Make sure the hot wire in the MAF sensor is clean. The oil from the air filter will cause the hot wire to collect a layer of dirt that will send bad data to the computer. It will run lean. CRC makes a cleaner just for this use. While the engine is running use a water spritzer to squirt water on the plug wires and distributor. This will test the insulation of the wires and cap which is not the same as electrical resistance. If it's bad the car will start running poorly.
__________________
street roadster with under car exhaust, 3 link, coil overs,front and rear sway bars, and no roll bars
I have a stock '91 5.0 with EFI. When I accelerate slowly, it comes right up to 5K rpm no problem but when I step on it (as I normally do) it stumbles badly. I seem to lose one cylinder. So far I have replaced the TFI module (since at first I thought it got worse as it heated up) and the fuel filter. I have checked the plug wire resistance, the cap and rotor, the fuel pressure and all look good. I pulled #5 plug and it looked like new. Roger Stine did the wire diet and I have removed most of the polution stuff. I have some codes with engine off (67,84,85,34 and constant codes 29 & 34). Until now the thing has run great. I do have the EGR resistors but still get EGR codes. I have never had the transmission harness installed so I do not know why I am getting the VSS code. Fuel pressure key-on/engine off is 36 psi, at idle is 31 psi and it goes up to 40 psi when reved up, and I get 40 psi with vac hose off at idle. Is it possible that an injector is partially plugged? I am at a loss. Can anyone help me? Thanks...
Why did you pull #5 plug and confirm? Pull ALL the plugs and see if there is consistency. If all plugs are like, then go to dizzy cap and back to other ignition components. All stock EFI stuff?
__________________ work like a captain, play like a pirate
FFR2606 - 392
FFR2903 - 347
94 Yamaha GTS1000
76 Honda 750F1
Todd, yes it is stock EFI. The engine has about 60K miles on it. I sprayed the wires and cap with water yesterday and saw no change at all. I plan to run a container of Techron through it just to be sure the injectors are clean. I will pull all the plugs and check them. I just assumed that since one was good that all were OK.
Yeah I'd check the TPS voltage. Should be around .98 volts I believe. If it loosened up or got dirty even can mess up the response time.
Check that little hole in the throttle body isn't clogged with carbon too....
__________________ "You keep using that word. I do not think it means what you think it means." Inigo Montoya
Welcome to FFCars! The
representations expressed are the representations and opinions of
the FFCars.com forum members and do not necessarily reflect the
opinions and viewpoints of the site owners, moderators, Factory Five
Racing, Inc. or Ford Motor Company. This website
has been planned and developed by FFCars.com and its forum members
and should not be construed as being endorsed by Factory Five
Racing, Inc. or Ford Motor Company for any
purpose. "FFR", "Factory Five", "Factory Five Racing", and the
Factory Five Racing logo are registered trademarks of Factory Five
Racing, Inc. FFCars.com forum members agree not to
post any copyrighted material unless the copyrighted material is
owned by you. Although we do not and cannot review the messages
posted and are not responsible for the content of any of these
messages, we reserve the right to delete any message for any reason
whatsoever. You remain solely responsible for the content of your
messages, and you agree to indemnify and hold us harmless with
respect to any claim based upon transmission of your message(s).
Thank you for visiting the FFCars.com Forum dedicated to Factory
Five.
After 5 years and 8,000 miles my 5.0 is sick
? ? ?
Forum Roadster
Linear Mode
