351w problems
Thread Starter
|
Senior User
Joined: Oct 2010
Posts: 126
Likes: 1
351w problems
88 f250 351w 4x4 5 speed. driving home the other day, the truck started missing very bad. so bad the motor and tranny were shaking side to side. this has turned out to be a whole lot worse than i thought. here is what i have done
new spark plugs
new spark plug wires
new distributo cap
new rotor button
new fuel filter
full compression test - good
timing gun - idle best at 29 btdc
soaked it in carb cleaner looking for vacuum leaks - none
check pcv setup
checked egr valve
after all that i did, the idle seems great. the second you touch the gas, it spits and sputters and shakes. the only other thing i think it could be is
low fuel pressure
bent pushrod
valves need adjusting.
some please help
new spark plugs
new spark plug wires
new distributo cap
new rotor button
new fuel filter
full compression test - good
timing gun - idle best at 29 btdc
soaked it in carb cleaner looking for vacuum leaks - none
check pcv setup
checked egr valve
after all that i did, the idle seems great. the second you touch the gas, it spits and sputters and shakes. the only other thing i think it could be is
low fuel pressure
bent pushrod
valves need adjusting.
some please help
FTE Legend
Joined: Jun 2006
Posts: 31,930
Likes: 1,499
From: Ottawa, Ontario
Check fuel pressure and pull the codes, if the motor idles smoothly it's unlikely there are any mechanical problems.
Then get out the timing light again and set the base timing correctly, because you didn't do it right the first time. To do that you get the motor idling, connect the light to #1 plug wire(passenger side front), pull the spout plug on the distributor wiring harness to disable computer advance, and rotate the distributor to achieve 10-12 deg BTDC.
Then get out the timing light again and set the base timing correctly, because you didn't do it right the first time. To do that you get the motor idling, connect the light to #1 plug wire(passenger side front), pull the spout plug on the distributor wiring harness to disable computer advance, and rotate the distributor to achieve 10-12 deg BTDC.
Thread Starter
|
Senior User
Joined: Oct 2010
Posts: 126
Likes: 1
I KNEW I WAS FORGETTING SOMETHING. i will check the timing again tonight and hopefully i will find my fuel pressure gauge so i can check it. can there still codes even though i do not have a CEL on?
Senior User
Joined: Oct 2010
Posts: 239
Likes: 0
From: Shawnee, OK
Also, Check the TPS as well. Mine was doing this a while back, idled fine, gave it gas, and it went to hell. Took a gamble and got a new TPS since my options were running out, and it turns out that was the problem. Good luck man
Thread Starter
|
Senior User
Joined: Oct 2010
Posts: 126
Likes: 1
frustrated
installed a new tps, new fuel filter and still the same problems. i reset timing by pulling the pin and setting on 12 btdc still no change. i pulled codes and i got 2 of the. 34 and 63. egr not detecting opiening and tp circut voltage low. i need some help really bad.
i unplug the iacv (think. . on the right of throttle body and the truck attempts to die. could that possible be it??
i unplug the iacv (think. . on the right of throttle body and the truck attempts to die. could that possible be it??
Senior User
Joined: Jan 2011
Posts: 185
Likes: 0
From: Gallitzin, Pa.
wont hurt doing the iac get used one 1st to try it. my iac stopped working and it kept floooding the vehicle i put new plugs in run for a bit then quit. put the iac on and no problems since.
Trending Topics
Thread Starter
|
Senior User
Joined: Oct 2010
Posts: 126
Likes: 1
i just talk with my dad, and he said eliminate the basic. . . fuel, spark, vacuum. so the spark and vacuum are both checked and are perfect. i havent checked any thing fuel pressure wise because i am an idiot. going to get gauge and check it. any one know what it should be?
FTE Stories
Ford Trucks for Ford Truck Enthusiasts
3 Best / 3 Worst Parts of Modern Ford Ownership
Brett Foote
10 Amazing Upgrades That Solve Common Ford Truck Owner Headaches
Pouria Savadkouei
Every 2026 Ford Engine Explained
Brett Foote
10 Ugly Ford Trucks That We Still Kinda Love
Joe Kucinski
10 Things Every Truck Owner NEEDS (2026 Edition)
Michael S. Palmer
Rezvani's Latest Post-Apocalyptic Monster Is a Ford F-150 Raptor Underneath
Verdad Gallardo
Top 10 Most Expensive Ford Trucks Ever Sold on Bring a Trailer
Joe Kucinski
2027 Ford Super Duty Buyer's Guide (Every Model, Engine, & Package)
Brett Foote
Top 10 Ford Truck Tragedies
Joe Kucinski
Posting Guru
Joined: Jun 2004
Posts: 2,433
Likes: 1
From: Apex, N.C.
If you are still getting the TPS circuit low, there is your problem. The engine is not going to run right regardless of how many parts you throw at it. Have you checked the voltage at it. Green and black wire with KOEO(key on engine off) with a digital volt meter. Voltage should be between .7 and 1 volt. If the voltage is too low/no signal, if it's too high the computer will ignore the signal also resulting in circuit low code and the engine running in limp mode. The voltage should gradually rise as you slowly open the throttle. A faulty TPS signal could also result in the EGR code that you are getting.
Did you get the TPS at a parts store or from the Ford dealer? I have found that the TPS's from the parts stores are a waste of money and my time. There is a reason that the Motorcraft TPS cost 4 times as much.
Also make sure that the cogs were properly placed when you installed the switch so that it turns as the butterflies open.
Has anyone messed with the set screw on the throttle body. That screw is not an idle screw. If it has been tampered the base Idle will have to be reset.
Unfortunately the basics fuel, spark, vacuum theory isn't enough to make these EFI engines run properly. Be patient, you'll figure it out.
Good Luck!
Did you get the TPS at a parts store or from the Ford dealer? I have found that the TPS's from the parts stores are a waste of money and my time. There is a reason that the Motorcraft TPS cost 4 times as much.
Also make sure that the cogs were properly placed when you installed the switch so that it turns as the butterflies open.
Has anyone messed with the set screw on the throttle body. That screw is not an idle screw. If it has been tampered the base Idle will have to be reset.
Unfortunately the basics fuel, spark, vacuum theory isn't enough to make these EFI engines run properly. Be patient, you'll figure it out.
Good Luck!
Thread Starter
|
Senior User
Joined: Oct 2010
Posts: 126
Likes: 1
the tps is from napa. the cogs are set correctly. i am in the process of putting in the fuel sending units with new fuel pumps into the tanks. the sending units were already bad and i figured that if i am there go ahead and put in the fuel pumps too. that is all new fuel setup minus the FDU. i will check the voltage at the tps probably in the morning. thanks for the help
Thread Starter
|
Senior User
Joined: Oct 2010
Posts: 126
Likes: 1
the set screw has not been touched. and as for the "basics", he just said it is the best place to start so that is what i have been doing. i did just test the voltage at the tps. koeo i got .17 and wot i got 1.7. any ideas?
Elder User
Joined: Aug 2003
Posts: 828
Likes: 0
From: Bellingham, WA
Check the routing of your spark plug cables, look for an induction crossfire. Basically, make sure that they aren't touching together or looping around each other. I had the same problems you are and was banging my head against the wall until another FTE guy suggested this. It's free too.
Thread Starter
|
Senior User
Joined: Oct 2010
Posts: 126
Likes: 1
i will take anything that is free right now. this truck is killing me. i have been reading some old post and some people have had the same voltage problem with the tps. the problem is that they never post what they did to fix it, just the steps that lead up to it 