97 explorer cold starting idle problems

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Apr 7, 2005 | 11:02 PM

97 stroker

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From: michigan

97 explorer cold starting idle problems

my daughter has a 1997 explorer 4.0 sohc 125,000 miles ,when its cold or sits all night when you start it ,it revs up to 1500/2000rpms then drops to 300/500rpms stalling sometimes if it dosen't stall it surges back up in to about 1500 rpms drops back ,have replaced the iac valve,cleaned everything esle ,checked by two different mechanics still can't figure it out,have two guys I work with have explorers with same problem there stumped too ,any help would be appreciated

Last edited by 97 stroker; Apr 7, 2005 at 11:07 PM. Reason: more detail

Apr 8, 2005 | 06:01 AM

bulldog3531

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From: Jacksonville, NC

check all of your vacumm lines, if they are good you intake manifold gaskets might be bad. good luck

Apr 8, 2005 | 01:07 PM

98xlt

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From: Las Vegas, NV

Was the M12 recall performed on this vehicle? Part of that recall included replacing some gaskets on the intake that are essential to smooth running. Cold weather really exacerbates that problem.

Apr 8, 2005 | 06:05 PM

97 stroker

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most all the gaskets on the upper end have been replaced within the last year and a half, last guy that worked on it smoked the motor. Its a difficult job took him most of a day to do it, he said it was a leaky intake gasket he dosen't tear in to the motors that much more of electical expert on cars.c hecked with mechanic who did timming chains, he said it was a leaky egr valve gasket he replaced it. still didnt make any difference still surges up and down

Apr 8, 2005 | 08:11 PM

98xlt

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From: Las Vegas, NV

are you getting any codes at all? MAF clean? (an oily KN filter can foul it) O2 sensors(these should code)? thermostat fairly new? PCV valve good? all vacuum hoses good? have you also disconnected the battery for 1/2 hour to clear computer? I'm grasping at straws like you.

Apr 9, 2005 | 10:37 PM

97 stroker

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From: michigan

only code comming up is 420,lean burn cat sensor ,I removed the cats they where rattling real bad so thats why the code 420 keeps comming,all sensors were replaced within the last year trying different things,tired of spending money on a dead horse

Apr 10, 2005 | 03:14 AM

CowboyBilly9Mile

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From: Eastern WA

I have to wonder if the EGR valve is opening too soon. And no, the problem will probably not be the valve itself, although I'd test it to make sure it is fully closed when no vacuum is applied. If it were mine I'd do a little test. I'd block the vacuum line leading to the EGR valve on a cold morning and give it a try. No problem and you have isolated the faulty system.

I also assume it's in good tune and that you have checked fuel pressure at the rail.