Fuel problem?
Thread Starter
Member
Joined: May 2010
Posts: 54
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Fuel problem?
Hi
I have a problem with my truck that is not stopping me driving it,but is driving me crazy. When the engine starts (cold) rpm soars then comes down to normal rpm about 700 rpm and holds steady. So far so good. now when it warms up after about 2-3 minutes the idle starts going from about 675 to 800 rpm and back down to 675 continuously. this can also be heard and is noticeable.
I have changed the following and not necessary for this reason.
TPS,IAC ,O2 ETC and ACT sensors. New Cap and Rotor,spark plugs and wires. PCV,Throttle body. Manifold gaskets and electrical checked them all including the MAP. checked for vacuum leaks and EGR valve. Lowest compression is 86% of highest. pressure checked radiator . new old tested injectors. Fuel pressure good and holds. No codes KOEO or KOER
I noticed when i unplug the O2 sensor the engine goes to 800 rpm and holds rock steady, i presume i am putting it back to open loop. This is driving me crazy like an itch i can't scratch. Fuel problem?
Thanks
I have a problem with my truck that is not stopping me driving it,but is driving me crazy. When the engine starts (cold) rpm soars then comes down to normal rpm about 700 rpm and holds steady. So far so good. now when it warms up after about 2-3 minutes the idle starts going from about 675 to 800 rpm and back down to 675 continuously. this can also be heard and is noticeable.
I have changed the following and not necessary for this reason.
TPS,IAC ,O2 ETC and ACT sensors. New Cap and Rotor,spark plugs and wires. PCV,Throttle body. Manifold gaskets and electrical checked them all including the MAP. checked for vacuum leaks and EGR valve. Lowest compression is 86% of highest. pressure checked radiator . new old tested injectors. Fuel pressure good and holds. No codes KOEO or KOER
I noticed when i unplug the O2 sensor the engine goes to 800 rpm and holds rock steady, i presume i am putting it back to open loop. This is driving me crazy like an itch i can't scratch. Fuel problem?
Thanks
Senior Member
Joined: Nov 2012
Posts: 1,532
Likes: 62
From: Anchorage Alaska
What is the vac on the engine? Take the throttle cable off and see how it runs. If you goose the engine does the idle come down? Throwing parts at it don`t seem to be working for you. Do some reading on testing the egr,tps,iac,vac,fuel pressure,map, test,read ,test again and read some more.
Thread Starter
Member
Joined: May 2010
Posts: 54
Likes: 0
Hi
Vacuum is at 18 Hg at idle, i will try removing cable as suggested and also see what happens when i goose it, I have checked all the sensors, TPS,IAC EGR , but will test again.
Fordfuelinjection.com I am already living there. Great site.
Fuel pressure is 40psi KOEO and holds steady Both pumps, hmm I think this is below specs, removing the vacuum from the regulator the pressure goes up goes up by about 10 psi, Also the gauge rapidly fluctuates rapidly by about 10psi
when engine running, For some reason i thought 40psi was spec, but its too low. will investigate
Thanks
Vacuum is at 18 Hg at idle, i will try removing cable as suggested and also see what happens when i goose it, I have checked all the sensors, TPS,IAC EGR , but will test again.
Fordfuelinjection.com I am already living there. Great site.
Fuel pressure is 40psi KOEO and holds steady Both pumps, hmm I think this is below specs, removing the vacuum from the regulator the pressure goes up goes up by about 10 psi, Also the gauge rapidly fluctuates rapidly by about 10psi
when engine running, For some reason i thought 40psi was spec, but its too low. will investigate
Thanks