Cold start problems '98 Explorer (HELP!!)

[2000StreetRod]

keep your old IAC valve

When I first started having cold start problems I cleaned my IAC valve several times which resulted in very little improvement. Then I bought a new one and replaced the old one which only made a marginal improvement so now I have a spare. It wasn't until I replaced the manifold gaskets that there was a marked improvement. I suggest that you keep your old IAC valve until you know that it's really defective.

 

[tyri77]

Handsverd thanks for the link, I am going to try it tonight. In response to the last post I replaced my intake manifold gaskets- both upper and lower and it greatly improved my vehicle performance. I replaced them because I was having issues with rough idle after start up. After my 98 explorer with a 4.0 warmed up it would idle fine. I theorize that when cold there is a leak between the manifold and engine, and then as it warms up the gasket and engine expand just enough to seal the leak thus causing it to idle as it should. I now have a new problem in that when it is very cold and I start my explorer it will fire but will not stay running unless I keep my foot on the gas. It eventually idles on its own after it warms up. I am guessing as it warms up the valve loosens and becomes free allowin it to function properly. Anyways it is certainly worth a shot at cleaning it. I will post the outcome after cleaning it.

 

[Eagleisx]

Ect sensor

REPLACE THE ECT SENSOR,i had the same problem as you,after replacing the ECT Sensor the truck worked fine.

 

[hansvdweerd]

When I first started having cold start problems I cleaned my IAC valve several times which resulted in very little improvement. Then I bought a new one and replaced the old one which only made a marginal improvement so now I have a spare. It wasn't until I replaced the manifold gaskets that there was a marked improvement. I suggest that you keep your old IAC valve until you know that it's really defective.

Thanks for the advice. I will keep the old part. I also ordered new gaskets for the upper and lower air intake manifold, so when replacing the IAC-valve doesn't fix the problem, replacing the gaskets will be next.

I'll post the results!

 

[tyri77]

Okay so I went home last night and took my IAC off and cleaned it with brake cleaner. Initially it the valve was stuck as I could not get it to actuate. I took the the felt filter out from underneath the black cap and cleaned it as well. I let it dry over night and then installed it this a.m. It started right up first time without my foot on the pedal. Last night before I removed it from my vehicle I tried to start it and it wouldnt so it appears this has fixed my problem. Not bad I only spent $2.55 for some brake cleaner, and about 30 mins (cleaning time as well) in my own labor.

Another point to note- the gasket that everyone has eluded to is very hard to see, but it is there. I think a lot of people were expecting a paper type of gasket, but this is a black o-ring type of gasket, it stays sealed on the plenum and does not come off with the IAC valve. I also wanted to point out that my IAC valve never put out the hummm or moose call as others have been referring to. So dont rule out your IAC valve just because yours doesnt make any noise.

Hansvdweerd please post any questions you have should you attempt to replace the manifold gaskets.

 

[tyri77]

REPLACE THE ECT SENSOR,i had the same problem as you,after replacing the ECT Sensor the truck worked fine.

Eagleisx are you referring to my problem?

 

[hansvdweerd]

Okay so I went home last night and took my IAC off and cleaned it with brake cleaner. Initially it the valve was stuck as I could not get it to actuate. I took the the felt filter out from underneath the black cap and cleaned it as well. I let it dry over night and then installed it this a.m. It started right up first time without my foot on the pedal. Last night before I removed it from my vehicle I tried to start it and it wouldnt so it appears this has fixed my problem. Not bad I only spent $2.55 for some brake cleaner, and about 30 mins (cleaning time as well) in my own labor.

How did you try to actuate the valve itself when you first took the IAC off? And how much were you able to move the valve after you cleaned it? When functioning normally should the valve be easy to actuate?

When I cleaned the IAC-valve the valve itself was in the position that it stops the airflow (My technical English is not so great, this picture may be more instructive: http://autorepair.about.com/library/graphics//41933297.gif). There was hardly any movement (as far as I could move it), even after cleaning it with break cleaning fluid.

 

[2000StreetRod]

old style IAC valve

hansvdweerd, I didn't realize that you have the old style IAC valve with the integral air filter. Mine doesn't have the cap and air filter. Instead it gets filtered and metered air from the main intake tube. When the filter in yours gets dirty and clogged there is no way for throttle bypass air to get to the intake manifold for your idle. Except for leaks, air can only enter your intake manifold by the PCV path or by squeezing past the throttle plate.

 

[hansvdweerd]

Remove cap?

hansvdweerd, I didn't realize that you have the old style IAC valve with the integral air filter. Mine doesn't have the cap and air filter. Instead it gets filtered and metered air from the main intake tube. When the filter in yours gets dirty and clogged there is no way for throttle bypass air to get to the intake manifold for your idle. Except for leaks, air can only enter your intake manifold by the PCV path or by squeezing past the throttle plate.

Does that mean that removing the cap with the filter (when the filter is clogged and blocks air flow), and thus making airflow possible, would make a difference?

 

[2000StreetRod]

yes

The PCM and the IAC valve can't control the airflow if the breather is clogged preventing air from entering. Ford should have identified cleaning or replacement of the IAC valve air filter at some interval just like was done for the main air filter.

 

[hansvdweerd]

The PCM and the AIC valve can't control the airflow if the breather is clogged preventing air from entering. Ford should have identified cleaning or replacement of the IAC valve air filter at some interval just like was done for the main air filter.

When I'm back from work I'll remove the cap and see what happens. Thanks for the advise!

 

[tyri77]

Hans- I was able to move the valve with a q-tip after I cleaned it about. It moved probably about 5 mm afterwords. It doesnt sound like much but it was enough to make a difference. Looking at the diagram you posted it doesnt appear that it would move to much anyways.

Have you tried starting it after you initially cleaned it?

 

[hansvdweerd]

Hans- I was able to move the valve with a q-tip after I cleaned it about. It moved probably about 5 mm afterwords. It doesnt sound like much but it was enough to make a difference. Looking at the diagram you posted it doesnt appear that it would move to much anyways.

Have you tried starting it after you initially cleaned it?

Yes, I cleaned it as best as I could, allowing it to dry a few hours. Unfortunately it didn't do the trick for me! Maybe I'll take it off tonight again and try to put a little more efford in it . See if I can find a Q-tip.

I will take the cap (with the filter) off as well and try a cold start (thus eliminating a possibly blocked filter).

 

[tyri77]

It sounds like you might have had two issues, but still have one. If you had a seized up IAC valve, and now you can move it freely I am sure that was one problem. Mine both were bad at the same time so I am sure yours could be to. It is looking more and more like you are going to have to replace your intake manifold gaskets. I cant remember what your original problem was but if it idles rough "shakey" then it sounds like it was doing what mine was doing.

 

[hansvdweerd]

It sounds like you might have had two issues, but still have one. If you had a seized up IAC valve, and now you can move it freely I am sure that was one problem. Mine both were bad at the same time so I am sure yours could be to. It is looking more and more like you are going to have to replace your intake manifold gaskets. I cant remember what your original problem was but if it idles rough "shakey" then it sounds like it was doing what mine was doing.

Yes, it is shakey. But as soon as I shift the gear to Drive and use the gaspedal it seems like the IAC valve kicks in and gives 1000 to 1500 rpm. When I stop using the gaspedal it slowly goes back to about 1000 rpm (at the first traffic light). Eventually the idle is about 750 rpm.

But I ordered both the IAC-valve and the gaskets so it shouldn't be long until the problem's fixed!

I can't try the cold start without the filtercap on the IAC-valve today, because the misses took the Ex out for a spin on her day off while I was working

I'll be replacing the gaskets with the help of my mechanic so I trust that there will be no problems there.

 

[joe doe]

it is almost always the upper plenum to intake gaskets that needs replacing ,not the lower intake gasket itself .i see this problem is running rampant on the forum.

 

[hansvdweerd]

The PCM and the AIC valve can't control the airflow if the breather is clogged preventing air from entering. Ford should have identified cleaning or replacement of the IAC valve air filter at some interval just like was done for the main air filter.

Well, unfortunately removing the cap didn't make much difference. But the ordered parts are coming this week.

 

[tyri77]

mine is still idle just as it should, what a great feeling of accomplishment. Can wait for you to get yours fixed hans.

 

[hansvdweerd]

New IAC-valve

mine is still idle just as it should, what a great feeling of accomplishment. Can wait for you to get yours fixed hans.

Well, I replaced the old part with the new IAC-valve. When I crancked the engine I noticed that the startup flare was about 2000 rpm in stead of 2500/2600 rpm. It did however still have a shakey idle, but it didn't die.

I had already noticed (with the old part as well as with the new part) that when you first drive off you have to push the gaspedal till about 1500/1700 rpm and after that you can release the gaspedal and you will continue driving with about 1000 - 1400 rpm. At the first traffic light or stop (let's say 50 - 500 meters) the idle will drop to about 1000 rpm and then to about 750 rpm. The first time the idle reaches 750 rpm it will still be a bit shakey, but it doesn't die.

The outside temperature has been above freezing point (about 2 - 5 degrees celsius) the last week, so this probably plays a role as well.

Do these symptoms still match leaky air intake manifold gaskets?

Next week I'm scheduling an apointment for replacing them (upper and lower).

 

[Mirge]

My vote goes to intake manifold gaskets, upper & lower.

If you're paying a professional to do it, expect 2-3 hours labor. If they quote anything more than that... might wanna take it somewhere else.