My 2001 Isuzu Rodeo LS idles wildly at traffic stops and sometimes stalls altogether. Three different mechanics have told me three different causes of the problem: a faulty ac condenser, a faulty mass air flow meter, and a blown intake manifold gasket. How should I trust to fix my car?
You need a Tech trained in driveability. Any codes present? You can dismiss the condensor possibility,the intake gasket would be easy to verify,and a scan tool would give you data on the MAF, this problem could be as simple as low battery voltage,or a vacuum leak,EGR problems,the list is pretty long but not impossible to whittle down.
Well, normally I might suggest checking the ISC (Idle Speed Control), or vacuum hoses for leaks… however, it seems Isuzu put out a service bulletin (TSB SB03-01-S003) revising the torque specs for intake manifolds on '98-01 Rodeos. It’s not a recall mind you (though I suppose it might be covered if the car’s still under warranty), but it implies that your prob might very well be the IM gasket.
Unfortunately, there isn’t an Isuzu dealership around that would have a trained technician. As of this time, the “check engine” light has not lit up. I have already replaced the EGR valve and checked the battery terminals for corrosion. What else can I check before shelling out tons of money to parts stores or greedy mechanics?
Is there any way I can check the IM gasket theory before spending $700 on a replacement that may not even correct the problem? Friends tell me I should hear a ticking from the intake manifold if it’s the gasket, but I hear nothing like that.
The engine could be sucking in extra air through bad vacuum hoses. Don’t forget that the hose to the power brake booster (and, the cruise control) is a vacuum hose.
If the idle is runnig high all the time, disconnect all the vacuum loses from the intake manifold, and tape over the ports (holes). Run the engine. If the rpms are ok, reconnect each vacuum hose, one by one. If you get to one which causes the engine to race, you’ve found your culprit.
You can do a basic check for intake manifold leaks by taking a torch (like a basic propane or butane hand held torch) and feeding gas all around the intake with the engine running - i.e. turn the torch on but don’t light it. The engine will respond whenever you get it near a leak.
You should also do what hellokit suggested (below).
And I would check the wiring & plug for the mass air flow sensor (MAF) and idle air control (IAC). Pull the connections, clean them, inspect carefully. Then also pull both the MAF and IAC and clean those.
Then see where things stand.
I have noticed also that in warm weather, this problem is non-existent. Does that narrow down the possibilities?