Hey all,

so ive been chasing a problem for a while and am at wits end about it I will do my best to describe everything going on.

truck is a 98 f150 have been experiencing intermittent issues for about the last six months.first started with the truck one morning randomly being in limp mode or what I can only describe as limp mode (truck would start and idle fine)any kind of throttle movement would casue to studder almost die. But if the gas pedal was pushed slowly truck would fully rev up so first thing I thought was Tps sensor so replaced and the truck ran fine for about a week the. Started same issue no rhyme or reason hooked up a scanner to monitor love data I could see the sensor was matching rpm range(this may not be a conclusive test). So had to get to work out it off till that night go home truck started right up and was able to drive again for another two weeks . So fast forward two weeks truck starts doing same thing hook up scanner only this time I get no communication to scanner code with code present .scanner turns on indicates it's communicating with the computer by a little car icon when plugged in. So hit the link button and get a error tried three different scanner all giving same thing. Frustrated I pulled battery to try and clear codes it worked so hooked up scanner connected right away could monitor live data again everything checked out great . So drive it for another week leave it sit over the weekend go to start Monday morning and bam same thing clear the codes again by pulling battery hook up scanner this time i have a code for a vent control circuit valve . No big issue 35 bucks at autozone pulled off old valve and it was bad would not seal( tested it by applying current to valve heard it close the. Blew through it had blow by so I replaced. Truck ran great no issues for a couple weeks comes the weekend sits all weekend and Monday morning bam same symptoms as before throttle hesitant and can't link to the computer again pull battery this time codes won't clear and now can't read them at all at a loss here. Started to look at some different stuff on the truck looking into the fuel/air and trying to diag without being able to pull codes went through and replaced several of the sensors on the top end dpfe, Maf ,chts Egr control sensor and also the Egr valve also completely cleaned entire intake throttle body,elbow going into intake manifold all ports going to different sensors. Did all of that problem still persists still can't read codes nothing.

so now I'm to the point where I am going to try and replace the computer cam shaft position sensor I'm not sure I'm tired of throwing money at the thing

 

If you can't link to the PCM to read codes or live data no use in replacing parts on a guess and a hope.
The Evap system usually won't cause such an issue with running like you describe.
All you do is spend and get upset for the effort.

Look at the pins on the data link for being pushed back or bent.
If they are good, I would suspect the PCM of being faulty unless you can pin point some specific fault.
Check the PCM connector for being tight and all harness plugups.
Check the fuel pressure when its in a fault.
An engine that starts is getting enough fuel to idle and spark but needs more fuel to accelerate.
This involves the Mass Air meter, TPS, more fuel and of course the PCM to control these functions from software tables.
You not experiencing Limp mode under the circumstances you describe.
Limp mode is a running engine able to still power the vehicle to move but alters the running system just enough to prevent damage..
For example an over heating condition detected by the cylinder head temperature sensor alters cylinder fire order to cool the engine some..
Don't replace any more parts until you can connect to the PCM.
What can happen is you add more faults unknowingly, then real confusion sets in.
Good luck.

 

Hey bluegrass,

thank u for the reply first so looking into everything all pins look great and like I said when codes are not present it will connect fine read codes and can monitor live data as soon as this code spears which is a mystery code it all just confuses the hell out of me that's why I was thinking a computer replacement

 

If you read something, what is it?
It may be in Hexadecimal displayed by you device.
If yes convert it to Decimal.
Good luck.

 

Update: was able to pull some rather random codes from my truck p1509,p0113,p0118 were all stored then had p1298 pending and p0452. Due to sheer randomness of those codes I pulled computer out found out there was a jet power control module part #89813 so I'm wondering if I should remove that and try to run the truck could the chip be bad? When I u plug it I have nothing now to plug in there ? Also on the computer connection there was a lot of dust build up on some pins blew it all out going to try reinstalling see how it behaves

 

Remove the Jet module, put a piece of tape over the exposed hole on the ECU. Throw the Jet away.

 

Well there ya go, mystery solved but not the troubles.
This is why I told you not to go changing parts before you get a handle on the situation.
If you would look up the codes, you see what has been involved from the chip.
We always assume there has been no program mods done same as you.
Code 118 is missing CHT
113 is missing intake air temp sensor.
1298 is injector drive failure.
.
Think this is enough to give you your problems?
You may be in for replacing the PCM all because the last owner thought he could hop up the power and got into trouble, so now you have it.
And you may still have to repair those sensor circuits if they were butchered.
You got the answer now, that he did not.
Put the check in the mail. hi hi.
Good luck.

.

 

Awesome thanks for the help. Those jet modules are they not very good quality ? I've always had tunes done through open source so have 0 experience with these caned tunes. Reinstalled everything truck starts right up all codes have cleared only thing present now is a fuel tanks oressure sensor code which I will be replacing tmrw and goig for a drive to see how it has changed performance. Thanks again guys I no longer want to go drive my truck into a pole