idle surges

is the check engine light on? have you tried cleaning the throttle body?

yes the engine light is on but no i never have try that is that hard to do?

I have a 1997 ford f150 4.6 with 108,000mi. Great running truck until the heater core blew. I removed entire dash (lots of fun) and made the repair. I started the truck and let it warm up, heater blew hot and no leaks. I turned off the engine and while I was at it, replaced the air cleaner, fuel filter, and added some Lucas injector cleaner. Later, when I went for a drive, the truck ran normal except that when I came to a stop it would hesitate and die. It idles fine in all gears until it warms up, and then only in neutral and park. I am able to restart the truck immediately in park and neutral. No trouble codes, though I have replaced the IAC sensor to no avail. I guess the question is, what could I have done or not done to cause this problem? Thanks!

I would look for a vacuum leak or any other hoses that could of got unhooked. There cant be any leaks in the air intake system beyound the mass air flow sensor. The mass air flow sensor has to see all the air that enters the engine.

Try following the PCV line to where it hooks to the engine. The elbows tend to go soft and create a vacuum leak

hello i have a 97 f150 with a 5.4 liter engine usually i can diagnose and fix whats wrong but im stumped . one day it was running fine and then 5 minutes later it was crap . in order to keep the engine running i have to feed it gas it only idles at 500 rpm and then dies after a few secs the air in the cab will only blow throught the defrost and i have a problem stopping i know from these problems you would think vacum leak but i cant find it i have replace the pvc valve egr valve idle air control motor throttle body gasket and maf sensor along with a few vacum hoses that where dry rotted i have even cleared the computer but i still have no change in the way it runs plz help me figure this out sincerly brian in texas

first change the plugs and wires, also check distributor cap rotor, or coil packs/coils.

once you do that start it up and let it run a bit, then spray carb cleaner or starting fluid all over the vaccum lines and around the intake manifold base, if the idle goes up or down you have found your vaccum leak.

i have a 1995 5.0 f150 and i am having problems with the idle. i have already replaced the idle switch but that didnt seem to be the problem, do you possibly know what else the problem could be?

You may have a bad IAC ( idle air control) but try eliminating any vacuum leaks and cleaning the throttle body first. Remove the intake snorkel, have someone hold the throttle wide open for you and scrub the back side of the throttle plate and surrounding bore with an old tooth brush and some carb cleaner. Be sure to spray some into the small holes next to the throttle plate. That should help stabilize the idle. If it still has a problem, replace the IAC.

i have a 95 f150 4x4 5.0 when i start it when its cold outside itll start fine and accelerate high for about 10 seconds but then die down immediately almost stalling ive changed the iac valve but ill the same issue where should i go next ? i was thinking the coolant temp sensor

Check for vacuum leaks.

CAN THE COOLANT TEMP SENSOR TELL THE COMPUTER THE ENGINE IS WARMED UP BECAUSE THE CHECK ENGINE LIGHT WILL TURN ON RIGHT WHEN THE IDLE DROPS

Have you checked for trouble codes?

no i havent where can i get that done on a 95

95 should be an OBD2 system. Most parts stores will do it for free.

Thanks a lot ill see what I can do and let you know I appreciate your feedback

I remove the distributor to replace the stator. when I put it back together the timing is way off. I've done all the basics. Found tdc on compression stroke at number one. put in dist. and had rotor facing number one. removed the spout. I can't figure out why the timing is off. It starts but jerks go's up and down in rpms, I've turned the dist. 90 degrees in both directions and it only gets worse. I tried putting back in the spout and it just shut off. I don't know why the timing is so far off. before I removed the dist. the timing was spot on. Whay am I missing?. 96 150 4x4

This is an OBD1 system and you are going to need a professional scan tool for this one.

you need a pro type scanner to get it where it is supposed to be they can find the fewdegrees where it should be. try cleaning throttle plate on both sides with chokecleaner as well

I appreciate the reply, but if it was even close shouldn't i be able to get it close enough without a timing light so that it would at least be able to run somewhat decent? Also, when the timing does get set, do I put the spout bar back in? I'm no expert like you, but I am somewhat of a decent home mechanic, and I've been working on 302"s and 351"s for many years. Although it's been a few years since the last time I had a sever timing issue to deal with, the last time was a 302 on a 90"s model crown vic, and I was able to dial it in almost perfect by sight and ear. I just don't understand what could be making it be this far off.There has to be something simple i'm missing, but I just can't figure it out, and the timing was too good prior too this for it to seem logical that it's a timing chain issue. The reason I replaced the stator is because it woul

Thanks

sorry I screwed up you disconnect the spout connector prior to starting engine make sure it's run with ignition and nothing else, set at 10 btdc then rshut off engine and reconnect spout. then verify engine advances beyond initial setting. but your truck has to be over 8500lbs gvw and have eecIV if it's eecV then it's non adjustable. the only thing I can think of is the armature is on backwards and I dont' know how that could happen. I think that is what you call the stator

shold be apic with this as I didn't see it in last reply

I've done everything except put a light on it, but it's no where near close enough to even put a light on it. I got it running, but it jerks and increases speed very slowly. I actually took the dist. out and moved it slightly past the number one plug, and it still does the same thing. it runs almost as bad as it does if you forget to take out the spout. Any suggestions on how to get it close enough to time with a light?

timing with a light I covered in the previous answer directly from the manual. you may have to get this scanned. the dist teeth aren't worn down are they?

When it is cold out my trucks idle goes up and down and almost dies.

does the problem go away when it gets warmed up after running?

No the teeth are in good condition. Do you think the scanner at auto zone would work, or do you think I need to break down and take it into a shop? I really hate to do that, other than having a trans rebuilt when I was laid up with back surgery a few years ago, I haven't had to go to a garage since I was in high school.

[quote:6f98227e79="blackop555"]does the problem go away when it gets warmed up after running?[/quote:6f98227e79] yes

it needs a pro type scanner as I mentioned in the previous answer as they can read by degrees. auto zone scanners only read and erase codes nothing more. Besides the code they give may only be a code and not the actual problem that is wrong with the vehicle.what was the original code? if it was a misfire did you bother to check fuel pressure as low fp will give a misfire or lean condition code.scanning and check fuel pressure should always be done prior to just changing parts, even if it is a n autozone type scanner.

yes the problem goes away when it has been running

sounds to me like a bad IAC or a throttle body full of build up!. clean the THrottle body, and if you can post back a picture of the IAC i can tell you if it is able to be cleaned or not. the pintle in it should be free moving and the housing of the IAC should not be scored nor should the IAC.

also check the Coolant temp sensor.

1992 F150 W/5.0L engine, 165,000 miles. Upon starting the truck there is no high idle. When left to idle it surges and sometimes dies. Sometimes have to hold accelerator to the floor to get it to restart. I drove it five miles and it died when I pulled into parking lot, but it starts right back up. Scanned it, but no codes. Changed fuel filter and I added Lucas fuel additive, heat and filled both tanks. I've only driven 10 miles since adding, so it probably hasn't had a chance to take affect yet. I sprayed for vacuum leaks, but may try that again. Any help would be greatly appreciated. Thanks guys!

I would check the EGR valve. It can cause some of the problems that you are experiencing. You need to ensure that the valve opens and closes and is not stuck. This rascal should be located on the intake manifold.

I have been fighting a idle speed problem for a long time. I can cold start the truck and it will idle at 1100 rpm until it warms up and the idle will go down to 750 rpm. It will idle at this rpm for a few minutes and then will go to 3000 rpm and I haven't touched the truck. The upper plenum body was leaking air and I replaced the gasket. I have replaced the throttle position sensor, the air bypass control valve twice and the map sensor. I have replaced the plugs, wires, cap and rotor. This is a new crate engine with 6000 mil;es. Could this be the o2 sensor? I thought about changing the computer but I couldn't find it under the dash. Please help

Hello
Thanks for the donation.

The erratic idling is a symptom of a faulty idle air control valve. You say you already replaced this? It may also be a vacuum leak somewhere in the engine compartment. It is a new crate engine with 6k miles so I am guessing it was recently installed into your vehicle? If so then whoever installed the engine may have missed a vacuum hose somewhere.

Are there any engine codes popping up? If so, scan and post codes. . I do not believe the culprit is an O2 sensor, but if the problem does lie within the O2 sensor then the engine light would illuminate.

Hope this helps..
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Thanks for the response. I have replaced the idle air control valve twice. If it was a vacuum leak wouldn't it do it all the time? I disconnected the battery negative cable to reset the computer and restarted the engine. It will idle normally for a few minutes but seems to be running rough and then it's like the computer tells the air bypass valve to open and the idle goes to 3000 RPM to try and correct a bad fuel mixture or something. I don't have a device to check for codes but it seems like I going to need one. What do you recommend. Thanks for the help.

Since you DO have codes on, the first thing to do is to get those codes. You can have your vehicle scanned for free at most local part stores such as AutoZone, O'Reilly Auto Parts and Advance Auto Parts. Since the issue is only itermittent then it does seem like it would be more on the electrical side then mechanical , ruling out the vacuum leak. Post the codes you receive and I will follow up.



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I went to advance to check the codes and was told they couldn't check any vehicle before 1996. I tried to purchase a code reader that was reliable and the only model they had that could read my 1991 truck was a model CP9015. I did a check and the codes were 53 which indicates a problem with thethrottle position sensor and 67 which I'm not sure about. I've already replaced the throttle position sensor could it be installed incorrectly??
Thanks,
Van

idle is fluctuating at idle or in gear IAC motor, MAP sensor, O2 sensor all tested bad changed them. Cleaned TBI. PCV valve was plugged changed it. Wonder if it could be upper plunem gasket blown between ports?

Great. Thanks for that info.
First off, the code 67 is - Neutral Drive Switch Circuit Open. This probably is indicating that the neutral drive safety switch is faulty and needs replaced. The purpose of the switch is to prevent activation of the starter (by creating an open circuit) when the transmission is in any gear other than P (park) or N (neutral).


Possible causes for the code 53 are the TPS is not seated properly, faulty TPS sensor (not likely since your sensor is new), faulty ECA , or VREF circuit shorted in vehicle harness. Double check the wiring and installation of the TPS and post your results. If you need some installation instructions for this component just let me know and I will post for you.


Hope this helps..
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