Guys,have a 302 engine,which had a 2000rpm idle at start up,then after 30 seconds dropped to 1600rpm,after a few minutes down to 1100 and stayed there.After reading posts,removed and cleaned throttle body spotless,replaced throttle position sensor and the air idle control valve. Reset computer drove around and runs real good.
Restarted when cold,with little less idle speed. During a warm start will peak at 1900 and within 30 or 40 seconds will idle at about 1000 rpm.
Is this normal, first ford ever owned. Just seems too fast,what do you think? THANKS

 

Ok going to assume that it is an Automatic. What does it drop down to when you put it in drive?

Mike G

Visit my webpage @ http://www.geocities.com/mikevickig

 

Mike A. I don't have a tach so I don't know the rpm's but my truck also idles fast on start up and then drops down as it warms (about 20 - 30 secs.). I consider this normal.

1992 F150 Supercab SB 4x4 302 AOD 3.55 31x10.5 All Terrain on Ford 15x8 Ralleys

 

[font size="1" color="#FF0000"]LAST EDITED ON 29-Jan-01 AT 11:25 AM (EST)[/font][p] My '90 Bronco with 5.0 & automatic had a similar (if not exactly the same) problem. I checked everything I could sensor-wise, looked at accelerator cables and etc., etc., etc. Found out that the gasket that separates the upper and lower EFI manifolds had failed causing excessive oxygen in the mixture. The computer sensed the O2 and sent more fuel into cylinders to compansate for the lean condition causing a high idle 2000 rpm at start up and about 1200-1300 rpm when warmed up. I hope this helps out. Let me(us) know if this was the culprit.

Todd
BB79RANCH

 

Mike,when i put it in gear it will drop to about 800 rpm or little less. Seams ok in gear. I don,t kmow, maybe this is normal .

 

TODD,
Replaced that gasket after cleaning.Also,the air control valve gasket.
While i have your attention,tell me what you think of 134a freon
in this r12 system? Former owner had raditor work done and never had system recharged because of costs of r12.
Thanks for help.

 

I would change it over to 134a since you are going to have to do work and replace some components because of system contamination. It will be cheaper in the long run.
I hope this helps.

Todd
BB79RANCH

 

 

Can I ask how you reset the computer? Me and my dad have a 89 f150 and it sat for the summer. It's like it's not getting any gas, my dad wants to reset the computer... can someone please help me with this?

Thanks in advance,

Tom

 

mike a
As bb79 suggested, yours sounds like a vacuum leak. Pull each line off the big vacuum tee on your upper intake & block the port on the tee to see if it affects the idle. If not, reconnect them all and use a 3' section of garden hose to poke around the engine as a stethoscope & listen for hissing anywhere OTHER than near the air filter/fresh air duct.

Zero
Get a Haynes manual - it tells how to erase all the codes from the computer memory, but there's not really a "Reset". If it's not sputtering or trying to crank, your injectors are probably stuck shut. After you make sure the fuel pump will run (by checking for pressure at the Schrader valve on the fuel rail) and that the coil is firing (by checking for spark at the plug wires while cranking), turn the key on and ground the 2 tan wires going to the injectors. Some of them will have Tan w/Red stripe and the other half will have Tan/Org. Push a pin thru one tan wire and use another piece of wire to ground it, ONLY FOR ABOUT 1/2 SECOND at a time, but you can do it once per second. This will warm them up & unstick them. If you hear some clicking in addition to the small spark, then at least some of the injectors are opening. If not, keep tapping it to ground until you're sure all the injectors on that bank are opening. (Remember the key has to be on, which will supply a constant 12V to the red wire on all the injectors.) You can tell that a particular injector is opening by putting a finger on the widest part of the injector body & you'll feel the slight ticking. After you do half of the injectors (one bank), put the pin thru the other tan wire & do the second bank. Each tan wire goes to half the injectors, so you only need to do this twice for the whole engine. The engine I'm driving on now had sat for about 8 mo. after a wreck that shattered all the brackets, and that's how I unstuck the injectors. It's run great for about 200Kmi since then.

 

i had a similar problem also, i changed the gastket inbetween the upper an lower intakes, Idle air control valve, TPS and it ended up being the coolant temp sensor, but my truck only acted up when cold after i replaced the gasket(not too hard to do, the middle bolt on the pass side is a trick.)

 

Hey guys, I have been reading your posts and I have a 87 f150 4x4 manuel transmission that has a high idle problem now. I have changed the act sensor, the tps, and cleaned and changed the gasket on the intake. It still is running between 1100 and 1300 rpm. Please help. Thanks.

 

I have an 89 F-150, 302 4x4 with a 5 speed. The engine seems to cut-up at less than 2,000 rpms but once you reach that point its like someone hit it in the butt with a giant sledgehammer. its really the worst at 900 to 1100 rpms. I've replace the o2 ,iap and tps sensors also replaced the egr valve and fuel regulator.Checked the fuel pressure at the rail and the timing, it also advances like it is suppose to. I have tried every way I know how to check for vac leaks and have found none. Yet at time the engine will idle upduring gear change,and some times not come back down from 1800 to 1900 until after i stop and shut down the engine. I used to get code 33 but now i don't even get that.I can't pull the same hills as before without downshifting and my milage has gone to the dogs. hopefully there is a reasonable explanation,or has gas really gottn that bad.
I also ran seafoam through the gas tank and straight into the manifold through the vac line and used upper intake cleaner on the throttle body. I am at wits end an could use some help.