Yet another high idle situation
Thread Starter
|
Senior User
Joined: Jul 2003
Posts: 107
Likes: 0
From: New Jersey
Yet another high idle situation
Here's one for ya'll...'90 F150 w/5.0 and 120K+ miles...up until a few days ago (after a road trip), idled perfectly...now idleing between 1500 and 2000 rpm. I have been reading all the threads on the idle problems ie. TPS, throttle stop screws, etc. Heres my thing...the only way i can get it down is to remove the vacuum hose from the MAP sensor...how about that? Disconnecting the IAC has no affect. I personally believe I have a vacuum leak somewhere, but what i want to know is, will plugged Cats screw with the O2 sensors and have the EEC stay open-looped?
Thanx
J.
Thanx
J.
Elder User
Joined: Jan 2003
Posts: 539
Likes: 0
Yet another high idle situation
Check your throttle cable for stretch and make sure your TB is fully closed when idling in park in your driveway. Other than that, look for a vacuum hose that has worked its way off.
Thread Starter
|
Senior User
Joined: Jul 2003
Posts: 107
Likes: 0
From: New Jersey
Yet another high idle situation
- fishin1976 - yeah, it apears as tho' the TB is closed...i need to find the leak. I was just curious about the Cat thing...I have VERY LITTLE exhaust coming out the tail pipes...
J.
J.
Posting Guru
Joined: Jan 2003
Posts: 1,061
Likes: 0
From: Still under the hood in O
Yet another high idle situation
Grab a screwdriver and with the handle, tap the converter lightly. If you hear a rattle, like loose sand, then it's toast, also check to see if the pipe has a red tint to it. A plugged converter will cause you to have no power.
Mine was so plugged that it blew the water pump gasket on the freeway. causing it to run out of water and overheat. Then when it was finally put all back together with new pump,cam,pushrods and lifters (a bent pushrod prompted me to do all this work), I completely blew the pump gasket again. Plus the valve cover gaskets (both of them) blew chunks due to the severe back pressure. I didn't think of it until after I had replaced the pump gasket 3 times. Cut the converter off and haven't had that problem since.
Up until the gasket failures there were no other symptoms of the clogged converter, it ran fine, under powered, but fine.
Mine was so plugged that it blew the water pump gasket on the freeway. causing it to run out of water and overheat. Then when it was finally put all back together with new pump,cam,pushrods and lifters (a bent pushrod prompted me to do all this work), I completely blew the pump gasket again. Plus the valve cover gaskets (both of them) blew chunks due to the severe back pressure. I didn't think of it until after I had replaced the pump gasket 3 times. Cut the converter off and haven't had that problem since.
Up until the gasket failures there were no other symptoms of the clogged converter, it ran fine, under powered, but fine.
Thread Starter
|
Senior User
Joined: Jul 2003
Posts: 107
Likes: 0
From: New Jersey
Yet another high idle situation
- 90f150moneypit - I think the only reason i haven't blown anything is because my left down pipe doesn't quite match up to the BBK shorty header and therfore i have an anoying leak there...I ordered the Bassani H-pipe w/cats last night, and also won an Ebay auction on a Pacesetter cat-back system. Should be good to go in about a week or two (exhaust-wise anyway)
J.
J.
Elder User
Joined: Apr 2001
Posts: 772
Likes: 0
From: Glen Burnie Maryland
Yet another high idle situation
Pull your IAC off and make sure it isn't stuck OPEN. If it's mechanically stuck, no amount of electrically cycling it will close it.
Clean it up and make sure the plunger is free. RE-install.
Larry
Clean it up and make sure the plunger is free. RE-install.
Larry
Fleet Mechanic
Joined: Aug 2001
Posts: 1,526
Likes: 0
From: Round Rock, TX
Yet another high idle situation
Plugging the vacuum line to the MAP sensor should drop the idle, if it doesn't cause the engine to die.
Take the air intake hoses off of the throttle body and block the throttle body ports with a block of wood. That should stall the engine unless you have a vacuum leak.
Take the air intake hoses off of the throttle body and block the throttle body ports with a block of wood. That should stall the engine unless you have a vacuum leak.
Trending Topics
Tuned
Joined: Jun 2003
Posts: 489
Likes: 1
Yet another high idle situation
you can test if you have an exhaust leak by putting a vacuum guage on the plenum and driving around (putting under load and not just reving in park). If you notice the vacuum drop significantly while driving and not building up again quickly, you know you have an exhaust restriction. It usually doesn't completely plug, but restricts more--it will increase your engine backpressure too, could blow out some seals it is gets too bad. Mileage would be really bad too. good luck.
FTE Stories
Ford Trucks for Ford Truck Enthusiasts
10 Things Every Truck Owner NEEDS (2026 Edition)
Michael S. Palmer
Rezvani's Latest Post-Apocalyptic Monster Is a Ford F-150 Raptor Underneath
Verdad Gallardo
Top 10 Most Expensive Ford Trucks Ever Sold on Bring a Trailer
Joe Kucinski
2027 Ford Super Duty Buyer's Guide (Every Model, Engine, & Package)
Brett Foote
Top 10 Ford Truck Tragedies
Joe Kucinski
AEV FXL Super Duty - the Super Duty Raptor Ford Doesn't Make
Brett Foote
Lobo Vs Lobo: Proof the F-150 Lobo Should Be Even Lower!
Michael S. Palmer
Ford's 2001 Explorer Sportsman Concept Looks For a New Home
Verdad Gallardo
10 Best Ford Truck Engines We Miss the Most!
Joe Kucinski
Posting Guru
Joined: Jan 2003
Posts: 1,061
Likes: 0
From: Still under the hood in O
Yet another high idle situation
jbrdrummer
Where did you order it from? I'm having a hard time finding dealers. When I get my BBK's I just may go with the H pipe assembly myself.
Where did you order it from? I'm having a hard time finding dealers. When I get my BBK's I just may go with the H pipe assembly myself.
Thread Starter
|
Senior User
Joined: Jul 2003
Posts: 107
Likes: 0
From: New Jersey
Yet another high idle situation
- Moneypit - I actually "stole" the BBK's off of Ebay...brand new in the box for $99.00...BEWARE, the drivers side down pipe will not align properly. The bassani system is coming from the compay that the "exhaust" link points to.
- Larry - I did as you suggested, cleaned/inspected the IAC...no help. I found a small leak and plugged it, but still runs with the throttle inlets closed off...the ONLY way I can get the idle down is to remove the vacuum line off of the MAP...that in turn makes the 'puter go full rich (my cat was glowing after test drive)...I am going to do the 'ol vaccum cleaner hose-to-the-ear trick...i swear i hear a massive leak, but can't tell if it is that or the alternator...arrrggg!
- Larry - I did as you suggested, cleaned/inspected the IAC...no help. I found a small leak and plugged it, but still runs with the throttle inlets closed off...the ONLY way I can get the idle down is to remove the vacuum line off of the MAP...that in turn makes the 'puter go full rich (my cat was glowing after test drive)...I am going to do the 'ol vaccum cleaner hose-to-the-ear trick...i swear i hear a massive leak, but can't tell if it is that or the alternator...arrrggg!
Posting Guru
Joined: Jan 2003
Posts: 1,061
Likes: 0
From: Still under the hood in O
Yet another high idle situation
Unfortunately this site automatically adds their own link to words like down pipe and exhaust. Thanks anyway lol
Try spraying starting fluid around the manifold and vacuum hoses.
Try spraying starting fluid around the manifold and vacuum hoses.
Thread Starter
|
Senior User
Joined: Jul 2003
Posts: 107
Likes: 0
From: New Jersey
Yet another high idle situation
- Moneypit - Yeah, i know...i just ordered from the link...no wait, that points to flowmaster...hang on a sec.....................her ya go: www.proficientperformance.com
J.
J.
Thread Starter
|
Senior User
Joined: Jul 2003
Posts: 107
Likes: 0
From: New Jersey
Yet another high idle situation
To every one in the FTE...This site rocks!!! My high idle problem is fixed, thanks in no small part to this forum...After reading evrything on here about idle problems, I was able to narrow it down to a vacuum leak, sure enough, my upper intake manifold (plenum) gasket was blown in about four places...swapped it out for a new one, and she idles beautifully. Thanks to every one who submitted ideas to my question(s) and to everybody else on this forum...ya'll definatly got yourselves a worthwhile venue for the do-it-yourselfer, and I for one am proud to be a part of this site.
J. Hilliard
J. Hilliard