Idle issues at startup

[shift1313]

because the egr unplug didnt work doesnt mean you can rule it out. It may be stuck open or sticking.

It really sounds like a sticky/slow iac to me. When you start the truck and it idles up like it should it seems fine, but then the iac starts to back itself off is when your issue starts like it can moderate itself, its off/on.

maybe yardape can answer this. If he starts the truck and it idles up and he unplugs the iac connector, will it return to the "off Position" or is it a stepper and will stay where its left?

 

[miesk5]

Idle or Stalling Problems & Troubleshooting; "...The IAC is usually a cylindrical unit attached to the upper intake manifold. This unit electrically controlled by the computer, and allows air to flow into the intake at idle, bypassing the throttle plate. The extra air is accompanied by extra fuel to bring the idle up to proper speed, and when cold, allows a high idle condition. These units may become dirty, and need cleaning. Many idle and stalling issues tend to be blamed on these units. Cleaning is achieved by removing the electrical connector, and two screws holding it on. Once off of the vehicle, clean with throttle body cleaner (or a good carburetor cleaner). Continue cleaning until unit is clean, like new; reinstall unit. This is also a good time to clean the intake, and EGR ports (if applicable). Testing may be achieved by bringing the engine to operating temperature, noting the idle speed (should be within spec). Unplug the unit

 

[shift1313]

i just thought about it. you mentioned your truck idles at 400rpms? and thats normal? is that really correct for your engine?

 

[Yardape]

because the egr unplug didnt work doesnt mean you can rule it out. It may be stuck open or sticking.
It really sounds like a sticky/slow iac to me. When you start the truck and it idles up like it should it seems fine, but then the iac starts to back itself off is when your issue starts like it can moderate itself, its off/on.

maybe yardape can answer this. If he starts the truck and it idles up and he unplugs the iac connector, will it return to the "off Position" or is it a stepper and will stay where its left?

I wish I could answer it, but unfortunately its Voodoo to me. I'm old school, thats why my truck is going carb. Haha.

 

[SirAltitude]

I'll try that "unplug" at normal operating temperature.

And ya, she idles' at 450normally, purrrrs like a kitten man, smooth, quiet, and consistant.

And no long crank times, i can just barely hit the key and she starts up most days, if'n it's not real cold out side, then it's two hits /emoticons/[email protected] 2x" width="20" height="20" />

 

[BroncoJoe19]

First thing I would do would give a serious look for vacuum leaks.

NExt thing is I would re-pull codes.

NExt get a vacuum guage (they are really inexpensive) and check for vacuum at each place that one should have vacuum. I think you should have about 18 inches of vacuum.

Follow the instructions for pulling codes and make sure that your coolent level is at the proper level. Yes you do have a coolent temperature sender, and it does send info for setting the timing.

How to scan FORD on board Diagnostic Trouble Codes (DTCs) in your driveway

Howto Pull Codes 1983-1995 Broncos, Mustang, F series Trucks, Econolines, 302, 351 and more

Checking for vacuum leaks.

Some of the sensors and some of the actuators either read the amount of vacuum, or use vacuum to move controls, therefore it is important to the proper functioning of the engine that your vacuum system is fully intact. Otherwise one may get codes falsely indicating that there is a problem with a controller/actuator, or a sensor when in reality it is caused by a lack of vacuum.

Look at your rubber vacuum hoses (they are about 1/4 - 3/8 inches in diameter, if they are dry rotted or cracked, replace them. IF they slip on/off of their connectors too easily, they may have stretched out a little bit, cut the ends off, and put them back on.

You may listen for a leak. Sometimes using a cut off piece of garden hose is a good aid to listen with. Sometimes a cardboard tube (like from gift wrapping paper) is helpful. Just remember that whenever you stick your head inside a running engine compartment, that you are not wearing any loose clothing or jewelry that can get caught.

Another suggestion is to use a spray can of carb cleaner and spray around the bottom of the intake manifold, and the base of the throttle body assembly. IF there is a leak, you should hear a change in your engine.

Keep a fire extinguisher handy, or use water instead of carb cleaner (it works, but not as well.) Be aware that if you use water and the wires get wet and it runs worse... your wires may be bad, and the water is allowing them to arc instead of jump the gap of the spark plug.

Another suggestion is: to take a propane torch, turn it on (but don't light it) and move it over the vacuum hoses and connections. The engine RPM's will increase if there is a leak and the propane gets sucked in.

Reember to check the PCV valve, hose and grommet

 

[BroncoJoe19]

Oh yeah... I think that mine idles at about 650 after it is warm. YOu may want to borrow a tach to see what your's is actually running at.

 

[BroncoJoe19]

I just re-read your first post, I thought that you said that you replaced the IAC. I see that you haven't, so certainly I agree with the others who mentioned a sticky IAC as suspect. Its relatively easy to pull and clean.

 

[miesk5]

yeah ... my 96's IAC was gunky, but the Throttle Body port (where IAC meets) was cruddy too. The IAC tested good, so I saved some $ on replacing it (but it''s on my List for repacement in spring)

Also, be prepared in better temps to clean EGR valve (I don't use solvents, just a Dollar Store brass brush) & ports and the "EGR passage under da throttle body...Throttle Body Passage Cleaning Depiction (EGR Groove)

Source: by Vincent C; next would be pulling upper intake manifold to complete cleaning + new PCV valve and vac hoses.

 

[bobstrat]

450 rpm idle seems kind of low, have you checked your initial timing?

 

[Roninseattle]

I'm having the same problem *** is up with this problem! I'm gonna change the fuel filter and PCV valve and see if that's the problem for me! /emoticons/[email protected] 2x" width="20" height="20" />

 

[BroncoJoe19]

Ron,

Idle issues are often vaccum leaks or a sticky IAC.

 

[SirAltitude]

I've not had a decent oppurtunity to clean/replace($$$) IAC yet, I've also not driven the truck for a few days.

I've had the door apart replacing these little round thingys in the window motor, which was quite fun.

Had to drill a couple holes for access to the mounting screws/bolts and work it out of the door.

There are'nt any large holes for my arms to get into the door and grab it, so I had to finger it around to get it to where i could remove it.

I had read a post in here somewhere about replacing those rubber round thingys w/ 1/4 nuts.

The cost is close to similar when you price 'em.

I spent two bucks for replacement rubber thingys.

The trick was getting them in the original position, but it works like a charm, I'm gonna go back and buy three more to do the passenger window.

Does'nt need'em yet, but, might as well.

It's gonna be warmer the next couple days. I plan on pulling the IAC and giving it a good cleaning. I'm also gonna use the 'ole tube listening trick to find a vacuum leak along w/ some propane? Butane? which would be more determining? I have both...

*note to self: buy brass brush, carb cleaner, and wool socks....

 

[shift1313]

of all things i went out to start my truck this morning and it ran like crap! high idle fine but was only running on 3 cyls. i pulled the back 3 plug wires off and nothing changed. Of course it was 8 degrees outside today Somehow my plugs were fouled like crazy. swapped in a new set and she purrs. wish your problem was that simple

 

[bobstrat]

I've not had a decent oppurtunity to clean/replace($$$) IAC yet, I've also not driven the truck for a few days.
I've had the door apart replacing these little round thingys in the window motor, which was quite fun.

Had to drill a couple holes for access to the mounting screws/bolts and work it out of the door.

There are'nt any large holes for my arms to get into the door and grab it, so I had to finger it around to get it to where i could remove it.

I had read a post in here somewhere about replacing those rubber round thingys w/ 1/4 nuts.

The cost is close to similar when you price 'em.

I spent two bucks for replacement rubber thingys.

i used the 1/4 inch nuts on my back window and that ***** can trim tree branches now. the only problem with the OE replacement is you're gonna have to do it again.

 

[bobstrat]

It's gonna be warmer the next couple days. I plan on pulling the IAC and giving it a good cleaning. I'm also gonna use the 'ole tube listening trick to find a vacuum leak along w/ some propane? Butane? which would be more determining? I have both...

carb cleaner works well.

if you have the bucks, i would suggest picking up a mighty vac. comes in handy testing vacuum operated devices, can also be used for bleeding brakes easily by yourself. handy little device.

 

[stangyog]

1994 351 Eddie Bauer... I have the same problem, I checked my timing, cleared the check engine light codes, fixxed a couple vacuum line issues, and still no better. Then I had an idea... I got a 1/2" inch wrench and beat on the soleniod on the AIC a couple times and it started right up and purred like a kitten! No problem for 2 days now. I know this is a tempoary fix for me but it might work for you too.

Good luck!!! /emoticons/[email protected] 2x" width="20" height="20" /> /emoticons/[email protected] 2x" width="20" height="20" /> /emoticons/[email protected] 2x" width="20" height="20" />

 

[SirAltitude]

****!! I've got a BFH in the box made for jobs just like that!! But i'm gonna do the cleaning first!!

I really dont have the cabbage to spend on "extras" right now. I'm doing good to get by. I will put that on my list of "tools to buy".

And as far as the OE rubber thingies in the window, well, your right. I will prolly have to buy more later, but it makes me sleep better knowing there's not metal being ground into the actuator motor, instead it'll be an easier clean later than 1/4 nuts that could potentially grind out the innards of that thing /emoticons/[email protected] 2x" width="20" height="20" />

 

[Roninseattle]

My wife forget We had a log in and made her own account ErikatheRed and posted out of thread.

But we are having the same problem, here is what she wrote:

I have a 1994 XLT. I'm at 115,000 miles and the last time it was serviced aside from oil changes was a few years ago for its 90,000 mile check-up. At that time they moved the idle a little lower. Since then when I start up the car it usually will idle quite high for a while; I give it some gas; then, the RPMs drop down. This has been the norm since my maintenance. Recently I've had problems with my truck stalling out right after it starts. The RPMs go immediately higher than I would expect and after a few seconds it stalls. When it begins to stall the check engine light comes on and stays on.

Battery seems fine

Belts are moving

Starter motor is obviously moving

Hoses all seem fine

These symptoms are intermittent. The weather is unseasonable chilly.

Since I have fuel injection I'm sure this is just coincidence, but after trying to turn it over several times I gave it a little gas and it started. Could that be related?

After reading other people problems I think it's probably has something to do with fuel regulation. I plan to replace the fuel filter tomorrow along with the PCV valve and the air filter (it's fairly old and dirty). If the symptoms persist what should I do next?

I appreciate any info you can give me. This is a great forum. Long live the Ford Bronco!!!

So as it turns out theirs 2 of us with this problem.

 

[SirAltitude]

I plan on cleaning up the IAC today. I'm headed out the door to the parts shop to get some carb cleaner and a brass brush.

I'll let ya know if that makes a difference...