my 1990 f150 W/ 5.0 /302 just recently it started to die after i start it . now it rough idles . and barely runs . any suggestions?

 

When was it's last major tune up? Once you get it moving does it do anything funny?

 

full tuneup!

First run the codes.

After that new plugs, wires, cap, rotor, PCV and filters. Check the timing, advance to 12*. Clean the ACT or replace it, clean the IAC motor and housing and the EGR valve.

 

last tune up was in august . has always ran great . the last few weeks gas mileage has gotten very poor . this happened all of a sudden as far as the other . once i get going like on the freeway it is ok but if i stop it wants to die . first day was ok as long as in gear now it hardly wants to run .

 

Sounds like the EGR is stuck open, or you have a vacuum leak.

Take care,
-Chris

 

thanx y'all for the input . will check it out this weekend and letcha know .

 

well chris you were right to an extent , ran the codes koeo came up the egr . i replaced the egr and then it came up the egr position sensor . replaced that too , now no codes are displayed koeo cept 11 as should be . only one problem . didnt help any . still runs the same . dies after starting , surging idle when it does run . checked for vacume leaks cant find any . koer test shows low idle/high idle and lean mixture . which i figure is a result of whatever the problem is , one note . on sept 11th 2001 i had the recall done on it for the ignition and the cross fuel flow recall . they replaced the fpr's , this has me wondering being as running shows lean mix if the fpr's are the problem?

 

If it was a pressure problem, it would be more evident at higher speeds, not at idle. Your description sounded pretty textbook for a sticky EGR, so I'm not surprised by the codes, but I am with the results. Have you tried removing and cleaning your IAB valve? If your EGR was sticking open, it probably has caked the IAB valve.

Take care,
-Chris

 

well a few months ago the air bypass hose on the lower end of the throttle body rusted off . i didnt have the money to replace the throttle body so i drilled it out and jb welded a piece of alum pipe in it and it has worked great . no leaks . i cleaned the entire throttle body then b4 reinstalling it but i didnt clean the iab valve . will do that tomorrow and get back with ya . thanx again for your help :-)

 

well today i installed a new iac valve . (air bypass) did full tune up and oil change . ran codes again koeo still nothing (code 11). koer still the same . code 12 , 13 (high idle/low idle ) and code 41 (lean mixture). runs a little better . not always wanting to die when i start it . still rough idle and seems like it is missing , does the same under a load and at high speeds . whats next? tps? makes me wonder even more about them fuel pressure regs they put on . plugs i put in last august still looked good . saved them , oil smelt a bit of gas , but had good texture given it's been over 5 months since i changed it ,some carbon build up in the plenium ,all in all it should be running tip top ,

 

Check and see what the TPS reads at idle, and then disconnect it, and attach a DMM, set to ohms, and rotate the throttle by hand. The DMM should change smoothly, and in the same direction, while opening the throttle.

let me know what you find.

Take care,
-Chris

 

well at idle the tps reads 4.16 volts , according to ciltons it should be 0.66 to 1.22 volts. connected dmm set to ohms . no readings at all . now it backfires through the intake when cold starting and when i try to give it gas the rpms go down , when i left off the gas they go up (cold engine). so i am assuming the tps is bad?