Cold start problems '98 Explorer (HELP!!)

[gijoecam]

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.

Air is not drawn through that cap (and if it is, there's something else wrong). Air entering the system there would be both un-metered and un-filtered.

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

I wouldn't expect it to.

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).

That sounds like a vacuum leak, but it sounds like a more severe leak than just a gasket. I'd be looking for a vacuum hose leak somewhere in addition to the intake manifold gaskets that likely need to be replaced anyways.

 

[tyri77]

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).

Hans it sound more and more like the gaskets are the problem. let us know

 

[hansvdweerd]

That sounds like a vacuum leak, but it sounds like a more severe leak than just a gasket. I'd be looking for a vacuum hose leak somewhere in addition to the intake manifold gaskets that likely need to be replaced anyways.

Okay, all your reply's are extremely usefull! So the symptoms I presented indicate a vacuum leak (gaskets or otherwise). I'm trying to narrow the search as much as possible to avoid randomly replacing parts (which my mechanic doesn't like to do either, because he likes to keep me a content customer!)

I'll be asking him to double check the air hoses that go to the air intake manifold when he replaces the gaskets (both upper and lower).

I read earlier that the gaskets tend to seal up when the engine warms up. Does the same go for (severe) leaks in vacuum hoses? Otherwise it's a bit silly that it would run fine after a short drive.

And what's the best tactic for checking for leaks and when do you best check? Cold engine or warmed up engine?

Sorry for all the questions. I'm obviously a bit of a newbie when it comes to car maintenance and trouble shooting, but I'm eager to learn!

(To tell you the truth, this 'minor' flaw in the Ex is beginning to bug me )

 

[tyri77]

Hans I cant speak for everyone else, but my problem would go away as the engine warmed up. I felt like that was because the engine and intake expanded at different rates and sealed up as the engine warmed. I am not saying it cant be a vacuum leak but I would say at the least the gaskets are bad. I wouldnt think the vacuum leaks would go away as the engine warms up.

 

[hansvdweerd]

Hans I cant speak for everyone else, but my problem would go away as the engine warmed up. I felt like that was because the engine and intake expanded at different rates and sealed up as the engine warmed. I am not saying it cant be a vacuum leak but I would say at the least the gaskets are bad. I wouldnt think the vacuum leaks would go away as the engine warms up.

The O-rings were delivered today (upper and lower). Next week they will be replaced...

 

[hansvdweerd]

Gaskets replaced!

Today I replaced the upper and lower air intake manifold gaskets. My mechanic supervised at critical moments (and there were a few!) and I did all the work But doing that I saved considerably on labour costs.

I started at 0930 am and finished at about 0600 pm with about an hour lunch break. It appeared that the previous owner had replaced the upper gaskets (they were in pretty good shape), but not the lower. The lower gaskets had shrunk (they completely disappeared in the cut-out for the gasket), were hard and broke easily. My mechanic pointed out that there were at least two spots were outside, unmetered air could enter the lower air intake manifold.

I thoroughly cleaned the manifold and the top of the engine that connects to the lower part of the manifold. The cillinders itself didn't show any cracks. I also checked as good as I could all the air hoses, and found they were in good shape. I replaced the gaskets and added just a little film of liquid gasket.

I also applied the liquid gasket on the O-ring that seals the EGR-valve to the air intake manifold (the O-ring was in good shape and I didn't try to remove it, since I didn't have a replacement). Same for the throttle body gasket.

I checked the EGR-valve (it wasn't stuck open) and cleaned it. I also replaced the O-rings under the IAC-valve.

Tommorrow morning we'll see if all this worked! I'll be sure to let you know.

 

[Mirge]

Today I replaced the upper and lower air intake manifold gaskets. My mechanic supervised at critical moments (and there were a few!) and I did all the work But doing that I saved considerably on labour costs.

I started at 0930 am and finished at about 0600 pm with about an hour lunch break. It appeared that the previous owner had replaced the upper gaskets (they were in pretty good shape), but not the lower. The lower gaskets had shrunk (they completely disappeared in the cut-out for the gasket), were hard and broke easily. My mechanic pointed out that there were at least two spots were outside, unmetered air could enter the lower air intake manifold.

I thoroughly cleaned the manifold and the top of the engine that connects to the lower part of the manifold. The cillinders itself didn't show any cracks. I also checked as good as I could all the air hoses, and found they were in good shape. I replaced the gaskets and added just a little film of liquid gasket.

I also applied the liquid gasket on the O-ring that seals the EGR-valve to the air intake manifold (the O-ring was in good shape and I didn't try to remove it, since I didn't have a replacement). Same for the throttle body gasket.

I checked the EGR-valve (it wasn't stuck open) and cleaned it. I also replaced the O-rings under the IAC-valve.

Tommorrow morning we'll see if all this worked! I'll be sure to let you know.

I'm confident your cold start troubles are a thing of the past.

 

[hansvdweerd]

Succes at last!

Last night the temperature was about 25 F so the circumstances were perfect for a cold start this morning.

The startup flare was considerably reduced to about 1300-1400 RPM (before it was 2500 - 3000 RPM) and immediately dropped to about 1000 RPM and about a minute later to about 750 RPM.

It didn't stall and I could drive off very smoothly without having to use both pedals to keep it running. After about 3/4 mile the engine switched smoothly from petrol to LPG. No hesitations or irregular idle.

Sounds great, doesn't it!

Thanks to all of you for your input!

 

[2000StreetRod]

Congratulations!

I'm glad to hear that your Explorer is now running correctly and that you fixed it yourself! Thanks for posting the update.

 

[Mirge]

Last night the temperature was about 25 F so the circumstances were perfect for a cold start this morning.

The startup flare was considerably reduced to about 1300-1400 RPM (before it was 2500 - 3000 RPM) and immediately dropped to about 1000 RPM and about a minute later to about 750 RPM.

It didn't stall and I could drive off very smoothly without having to use both pedals to keep it running. After about 3/4 mile the engine switched smoothly from petrol to LPG. No hesitations or irregular idle.

Sounds great, doesn't it!

Thanks to all of you for your input!

1300-1400 is well within the "normal" range I would say. Glad she's all fixed up

 

[tyri77]

Great to hear that all is well, I am sorry you had to go through all of that, but at least you went through all that and came out with a perfect running explorer. Congrats for fixing it yourself. Weren't those rear gasket bolts fun?

 

[hansvdweerd]

Great to hear that all is well, I am sorry you had to go through all of that, but at least you went through all that and came out with a perfect running explorer. Congrats for fixing it yourself. Weren't those rear gasket bolts fun?

It was arduous task that might have given me my first grey hair! At times I thought it was designed that way to discourage DIY-maintenance

 

[tyri77]

You are right on the money there...nice working with you.

 

[bikrboyr6]

I have a 97 4.0 SOHC and I HAD the same problem. I live in Wisconsin and winters get pretty cold. When temps dropped this winter I noticed the stalling and sputtering as well. It was extremely annoying when all i wanted to do was start it so it could warm up. I too had a hole in my muffler but I dont believe this affected this issue. I looked for many of problems with all the valves and what not. I also did the vaccuum test by spraying around the intake and hoses. In the end i decided just to change the intake plenum gaskets. The kit was like 20 bucks at autozone, and included an upper and lower set. I did it myself and it took me about 2.5 hours. Immediatley i noticed a difference and the next morning...Ran like brand new. I was very happy to have solved this issue. keep in mind my xplorer has 192,x.. miles on it. All these parts need the tlc and replacements. Glad you solved the problem!

 

[Machinegunrat]

Believe it or not I had the same problem. The throttle cable was stretched and allowed it idle to low I set the idle up higher as a fix until I can replace the cable and it stopped.

 

[gijoecam]

Believe it or not I had the same problem. The throttle cable was stretched and allowed it idle to low I set the idle up higher as a fix until I can replace the cable and it stopped.

Except the throttle cable doesn't establish the idle, and cranking the adjusting screw simply masks the problem rather than fixing it...

 

[Machinegunrat]

Except the throttle cable doesn't establish the idle, and cranking the adjusting screw simply masks the problem rather than fixing it...

It does with mine ran fine for 2 years with the idle screw all the way out then one day wouldn't idle I didn't mean it as a perminate fix but as a way to keep it running until you can like the zip tie fix for a stretched cable

 

[gijoecam]

It does with mine ran fine for 2 years with the idle screw all the way out then one day wouldn't idle I didn't mean it as a perminate fix but as a way to keep it running until you can like the zip tie fix for a stretched cable

Again, because the screw on the throttle body (which is NOT called an idle screw) does not fix the problem, adjusting it simply masks the underlying cause, which is usually either a vacuum leak (which can be caused by leaking lower intake manifold gaskets among other things) or a stuck/sticking Idle Air Control valve. Adjusting the screw to move the throttle body is no different than pressing on the accelerator pedal, it just does it all the time for you. The ecu still learns the new RATCH voltage from the tps, and adjusts the parameters accordingly, but again, it doesn't fix the underlying problem (which is NOT a stretched cable either).

 

[Hoppy]

I concur. Throttle cable will not change anything.