aftermarket intakes

[stockfornow]

that does make sense any idea where to go next then. there are no noticable vacum leaks. it is really fustrating because it got 16 city 20 highway when i got it a year ago

 

[skinner]

Well, considering everything you paid so far, it would not be a bad idea to see how much a local true diagnosis costs. Paying 75$ to KNOW the problem is cheaper than replacing everything on the truck.
Honestly my moneys going on a nasty vac leak though.
Good luck man.

 

[Dishtowel]

lol, I said loose performance, not stop running! but 'ya, we're on the same page.

IDK how to help you right now stockfornow, just have to go through the systems that you know and make sure they are all operating correctly. When's the last time you changed a fuel filter? (If you have the 'cup' style filter use some litium grease on the O-ring to keep it in place, it can be a PITA. (As opposed to the in'line filter))

I felt pretty stupid 2 months ago when I was *almost* out of patience with my 5.0L and I took one of my friends for a cruise and he said "seems like it's starving for fuel" sure enough, the fuel filter was CAKED with dirt. Such an easy fix, but I went through that entire EFI system looking for a problem. I know it reasonably well now because I tested EVERY sensor, found a bad TPS, bad air bypass valve, and a plugged injector, and failed fuel pressure regulator. I do NOT expect you to find more than two problems, the reason mine was in such "awesome" condition is because I got it from the wrecker, and the owner before me didn't know about 'maintenance'.

Start with the stuff you know, if that dosn't do it, then you have to learn enough about your system to tackle the rest of it. Good luck.


Edit: do you know how to check for vacuum leaks? Hint = WD40

 

[stockfornow]

thanks for all help. going to price out true diagnois later today. as far as parts go only have $400 in upgrades including rear bumper stock one was shot and $150 in brakes and o2 sensor. not bad considering truck was free from grandmother. changed fuel filter 2 weeks ago when diagonising front end noise that turn out to be a bad hub lockout

 

[Will]

Pull the vacuum line off of the fuel pressure regulator. If it's wet, it's bad. It's a common thing to fail. It's a diaphram with 20 years experience of holding back 35psi of fuel pressure.

 

[canyoncritter]

map sensor is possible

tps is possible

tfi is possible

FPR is possible

cloged up fuel filter is possibe

you need to find the specs to all you sensors and start testing them wiht a ohm meter.

have any exuast leaks above the 02 sensor?

this page may help you
http://fordfuelinjection.com/

 

[MAKG]

Something just everyone has left out is poor grounding to the PCM or any of the sensors.

All electrical devices require a reliable source of power and ground. Screw one up, and you can't know what it will do.

A big air leak is possible, but MY money is on a broken or missing ground.

 

[Shran]

Seriously consider replacing the coolant temp sensor. It made a world of difference for my '88, and I know that this fix has worked for several others here too.

 

[stockfornow]

Seriously consider replacing the coolant temp sensor. It made a world of difference for my '88, and I know that this fix has worked for several others here too.

planing on doing coolant temp sensor after i get paid