94bird

need ur input. i have a 90 f150 5.8. sometimes when i start it is will act like it has a really nasty cam in it. it'll spit and sputter. and sometimes if u bring the rpms up it will come out of it and idle real smooth. some ppl have told me that i may have a lifter sticking or burnt valve. i dont want to rebuild motor yet i need it all winter. some suspected parts i was thinking maybe a tps i put a new one on nothing happened put new distributor, cap, rotor plugs and wires nothing. i was thinking maybe ect, fuel filter, injectors. i know the motor is getting worn out it was a plow truck before. maybe a lifter but not sure. has anyone had this problem? truck does smoke alittle when started and idle like crap smokes blue so suspected oil problem. valve seals or oil ring. truck doesn't throw any codes just does this when it wants. help please?

H&HMarine

mine had the same problem but only mine did it when it was cold and i took it to a dealer they changed plugs and map sensor and charged me 525.00 and it actually ran worse when i got it back it turned out to be a capacitor on the ecm was burnt but your situation sounds a little different because like i said mine only did it when it was cold and it just idled high when it was warm on my 91 5.0

94bird

yea it'll do it even cold, or warm. i think my cheapest next thing to do it fuel filter. it wasn't real bad when i first bought the truck but gradually getting worse

dewman

Sometimes it is actually cheaper to have the problem diagnosed by a professional first. Then you can decide how best to attack the problem. You could spend a lot of time, and money, trying to replace parts until the problem goes away and never really solve the problem.

If you get the problem diagnosed, you can then decide if you want/can fix it yourself, or if you want the shop to do the work.

94bird

well i could do it at school cause i'm in auto mechanics we have a shops but we can hardly ever get our own vehicles in. we work on alot of customers were kinda turning into a dealership more ppl would rather brign there cars to our college than to them haha.

wde3477

If I understand this right, once you bring the RPMs up, it will go back down and idle normally???

Maybe consider that too much fuel is present at start - either through leaking injectors or fuel pressure that is too high? Just a WAG.

Valve stem seals could cause some of this I suppose, oil bleeds down into the cylinders while the engine is off. It's not that difficult of a job, as long as one doesn't drop the valve into the cylinder.

philipwk

Hi, Maybe clean the throttle body insides, be sure to check and clean the hole to side of the butterfly (idle) throughly.

94bird

today i went to start it it idled like crap and usaully i bring to rpms up to make it come out of it. well i didn't this time and it died. and was very hard to start afterward but i got it started and had to bring rpms up and then it come out of it. so to me it seems like its flooding its self out.

wde3477

'Philipwk' jogged a memory - agree with the throttle body crud suggestion, perhaps go ahead to remove and inspect the Idle Air Control (IAC) solenoid.

These have a known tendency to crud up and stick on our model years, causing all sorts of idle problems. This solenoid is easy to remove and clean thoroughly with carb cleaner. Make sure the plunger rod can move freely.

H&HMarine

it got colder here and once again mine started doing the same thing as yours again so if you get it figured out let me know but i replaced my IAC and EGR and it never even phased it so i'm out of ideas