Hello everyone. I have a 99 Explorer with the 4.0 SOHC. I want to know if there is an easy way to determine if it's my IAC or Intake Gaskets that are causing my problems. Stalling and rough idle when I start it in the cold. The colder it is the worse it gets. At -10 degrees C it will stall, idle rough and surge (run rough then race to 2000 for a few seconds then back to rough idle). At -20 degrees C it is all I can do to keep it running by feathering the gas till it warms up a bit. My gas mileage has gone into the toilet (down 20%) and even after running on the highway for 20 minutes, when I get back into the city and stop at a light, the idle stays high (1000 - 1100) for a few moments till it will slowly drop back to normal. I have not had the check engine light come on at all and there is nowhere to get the codes pulled for free around me. I checked the IAC and cleaned it but the weather has warmed up a bit near me so the results are inconclusive (the problems are still there but it starts easier, but it's also on -5 out). Other than the spraying of carb cleaner around the intake, is there anything else I sould do or is there enough info in my post to determine which problem is mine? Any help would be appreciated. Thank you.

 

The easy was is to just plunk down the $80 for a new IAC. If it fixes it, great, if not, then it could be the gaskets. I think the IAC should be a "routine" replacement item anyway since they fail so regularly. Wouldnt hurt to stick a new one on anyway!

 

Have you had a chk engine light at all ?????
if not I would replace the Iac valve.

If you did or do I would get the vehicle scanned for codes an give us the codes we can help

You may have un meter air entering into your intake from a o-ring gasket .
The o-ring gaskets shrink when cold to alow air in and then expand once engine warms up.

Rich

 

Devil, I would just pop one on but the cheapest I can get around here is $130 tax included. Whereas the intake repair job is $350 tax included. I would rather pay only one of the bills because with my luck whichever one I do will be the wrong one and I'll end up paying $500. Before I started throwing money out the window I thought I would try to narrow it down better.

Fortyfords, as it says in the origional post I have not had a check engine light come on at all and I can't get the codes checked for free. Cheapest I have found is $35 (they call it a computer check test).

I'll probably do the carb cleaner spray test once it gets a little colder out (really looking forward to that <-- sarcasm). I am just hoping for some other way to diagnose the problem without spending money on guesswork.

Thanks for the help guys.

 

Sorry I missed your no chk eng light !
Does the chk eng light work ? when you first turn the key to on pos?
The bulb is not burnt out is it?

Where did you get that price on th IAC ?
Sounds high to me.

Was there alot of carbon build up in the passage ways when you cleaned the iac ?

sometimes without the right tools its hard to diagnos these new cars .

Rich

 

$130 Canadian....I meant $80 US. Same thing. I dont know your mileage but the gasket leak is free repair under 72K miles here in the US under an owner notification program.

 

Fortyfords, the check engine light does work and yes, there was some buildup in the IAC. Not alot but it did have a coating. I used carb cleaner on it.

Devil, yup, it's Canadin dollars with tax. The truck has 180,000kms on it but I have only owned it for a year so I have no idea what work was done on it before I owned it.

 

OK you would be out of the 72K mile (100K kilometer???) limit. If you want, talk to you dealer about Ford assistance on this manufacturing defect. Id still go ahead and buy an IAC and see if thats your problem. It would still save you money if its the problem.
.

 

To test for a leaky intake manifold gasket, you can spray carb cleaner or WD-40 (messier) on the seams around the intake/heads. Some people use starter fluid; it's a bit more dangerous though but also very effective. If they are leaking, there will be a change in idle speed. Also, why not try to retorque the bolts on the intake. O-rings can be a problem when cold; remember the space shuttle incident back in about 1986? Leaky O-rings.

On edit:

I didn't vote; I prefer to diagnose rather than go for it.

 

My 1998 4.0 SOHC (80K miles) had similar cold starting problems. The problems came on abruptly, like as soon as it got cold. Below (approx) 45 F it would idle very rough, surging up to 1500-2000, then back down, idle rough, nearly die, then surg again ~2000rpm. It would this (sometimes stalling) until it warmed up then it would behave pretty good.

I had already replaced my IAC and that did not fix it. It changed things and I suspect it was bad also but it did not fix it.

I cleaned the MAF and found no change.

I replaced the lower and upper manifold O-rings. The passenger side rear, lower intake manifold o-rings had visible evidence of an air leak. Essentially the mating serfaces were not clean. There was debris and gunk where there should have been a clean surface.

To retorque the torx screws that hold down the manifold would be a waste of time. By the time you remove enough of the upper manifold, etc to get to the screws you might as well pull the lower manifold and replace the o-rings.

In my opinion, if you can replace a water pump you could do this job. You will need a torque wrench, click type that is measured in INCH pounds or goes down to about 5 foot pounds. The manifold is plastic, I think a torque wrench is essential. You will also need torx tools/sockets/drivers whatever they are called.

The Hayes book made me think it was going to be a big pain in the a## job but it wasnt. However if its 35 F or worse (your in Canada) it could be a pain. Likewise the plastic manifold could crack. Perhaps you have a heated gargage?

My vote - its your o-rings. PS my check engine light never came on, I did not get any OBD-II codes.

Good luck.

 

Thanks Cowboy and twoexplorers, great info to have. As it stands it is way to cold here to even think of doing it myself. It was a high of -15C today and I don't have a garage I can use to do the job.

twoexplorers, your description exactely fits my problem, I have also cleaned the MAF (although I do this on a fairly regular basis and new it wasn't my problem). If you don't mind me asking what was the mileage on your explorer when this happened to you?

Thanks again.

 

I'll have to guestimate on my mileage but its around 80,000 give or take a couple of thousand. (Ijust did this last week) I'd go check but its raining outside and its about 45 and Im wearing shorts inside. Yes I know winter in Florida is tough but someone has to do it. My problem is so cold related I actually thought about just waiting it out till spring came. About 4 weeks here. Then I found this website and read all the posts and decided it was the o-rings. From reading other posts I dont think the problem is mileage related more like # of years? Im not sure but I got the impression (from this forum) that Ford knew about the o-rings but didnt want to recall them. Given that they might have made newer o-rings out of a better material.

 

Well everyone, I would like to thank everyone who offered advise on the subject. Thought I would let everyone know the truck is now fixed and the problem was ...


Drum roll please ...

IAC. I did the leak test of the intake manifold with carb cleaner and the idle didn't change. Dropped the cake down on an IAC and my problem is gone. My mileage is back to normal, startup and idle are now fine.

Thanks again everyone.

 

I got my replacement IAC from a wrecker when I had a similar issue.

Circuit tested and 4 month warranty (big deal) for $25.00CAD including the trottle body assembly.

It wasn't the problem. To bad you purchased one it seems I have a spare.

I can buy 4 more and still be under $130.00CAD.

Canadian Tire pricing - Brutal

Regards,

Gil in TO

 

Hey Gil, too bad you didn't post earlier. I could have used that iac, my only concern with a used on is that is could be faulty too. Not too much of a worry if it comes with a warrenty. Anyway I am just down the road in Hamilton. I paid the dealer price, Canadian Tire wanted over $200 for the thing, I laughed and hung up. Well thanks for the response.