4.9 ltr Problems

Flames · 10-04-2009, 10:48 PM

Hello all,
New here, and have a problem with my truck that I cant seem to hammer out. Its a 92 F150 short box with 3 inch lift and 35's. Has 200K km on it. It is a very odd problem. Here we go, when acellerating it seems to miss and hesitate if I only give it throttle from 0-1/2 but if I give it more then that it has no prob. Another symptom is if I take my foot off the throttle and let it coast down hill in gear then when I put my foot back into it, it will jump and hesitate unless I floor it.
It isn't throwing any codes at me and I have replaced cap, rotor, plugs, fuel filter, air filter, TPS sensor and recently did the timing gears in it. However I did have the problem before the timing gears went, and its still there. I have no idea what it is and any help at all would be greatly appriciated! Thanks all!

BroncoJoe19 · 10-05-2009, 05:10 AM

For $20 I'd replace the VSS/RABS sensor in the rear, one bolt replacement and no adjustment needed. With 35's on there you won't even have to jack up the truck

BroncoJoe19 · 10-05-2009, 05:10 AM

Nice truck BTW

Flames · 10-06-2009, 09:31 PM

Thanks, I have had a few pple say that I should replace the vss. Its a little bit more then 20bucks up here though more like 50 lol. I'll give it a whirl and letcha know what happens. Thanks for the help.

BroncoJoe19 · 10-07-2009, 03:18 AM

hmmm at $50 you might want to pull codes first, or maybe pull the connector to it, and reinsert it. could be a poor connection to it, and sometimes disconnecting and reconnecting it is enough to clean it.

Here is how to pull codes with a 4 inch piece of wire and counting flashes of the CEL on the dash.

Pull Diagnostic Trouble Codes (DTCs) From your onboard computer.
Your engine and transmission are computer controlled.
The computer uses sensors to tell it a number of different things and it controls actuators that push or pull mechanical levers (kinda). If one or more sensors aren't working properly, the computer goes "blind" and doesn't know what to do. If the computer can "see" but one of the actuators is broken and therefore can't follow the commands of the computer; the engine won't run correctly. The computer is preprogrammed with set values for each of its sensors, and each of its actuators. It will run a self check of all systems, like the space shuttle; it will compare its set value(s) to the value(s) it recieves from its sensors, and actuators. If any sensor or acutator is out of the "normal" range the computer will generate a "code." It will generate some codes on the fly, and others will be stored while you are driving. There is a simple method to "pull codes" out of the computer for one to use for diagnostic purposes.

Earlier versions of On Board Diagnostics OBD 1983-1995 can flash the error code to the dash board and can be pulled in one's driveway without any special tools.
Later versions of On Board Diagnostics OBDII some 1995, and pretty much all 1996 and newer, require one to use a code reader or scanner tool.

Some auto parts stores will scan your engine codes for FREE, you may want to call around. Some will scan OBDII but not the older (prior to 1996) OBD systems.

SO here you go...
How to scan FORD on board Diagnostic Trouble Codes (DTCs) in your driveway
Howto Pull Codes 1983-1995 Broncos, Mustang, F series Trucks, Econolines, 302, 351 and more

Flames · 10-08-2009, 08:51 PM

yea I pulled codes its giving me 111 which means all good. Still has the problem. Changed the VSS, no diff. I did however unplug the MAP which did make it run better. So I changed it out aswell but when I plugged the new one in it still does the same thing.... I'm stumped