Why would my 2000 Montero Sport run rough when warmed up and in gear?
What is your question?
I have a 2 wheel drive 3.0L with 185,000 miles. It starts quickly and idles fine at 1,200 rpm while cold. Once it warms up and idle drops to 800 it starts to have random hickups and RPM drops to 650-700 but quickly recovers. Sometimes only once every few seconds sometimes 2-3 times in a row every 3-4 seconds, completely random. It is worse when in gear with brake applied and idle drops to about 600. Really rough chug-a-lugging when trying to drive until you get up to 15-20mph then is runs smooth and has lots of power, but even worse and will hardly go at all if AC is on at the same time. I have replaced spark plugs, plug wires, all coils. Condition had gotten steadily worse over past month so I removed, tested and thoroughly cleaned all injectors and thoroughly cleaned intake manifold and throttle . All fired well out of vehicle. Cant reach injector plugs to test on vehicle. All vacuum lines are in place and in good shape. Idles smooth when cold and first started. What do I check next
What makes this problem better or worse?
It's worse when warmed up and in gear or AC is on.
How long has your 2000 Mitsubishi Montero Sport had this problem?
RepairPal Certified shops can diagnose and repair your 2000 Mitsubishi Montero Sport. They provide transparent pricing with a minimum 12-month or 12,000-mile warranty on repairs and services.
Hello, with respect: you haven't checked anything. You've replaced parts.
Have you employed the use of a diagnostic tool that is capable of monitoring all your engine performance related components to see what each component is doing, and what the proper specification is, and what might be out of range? Have you tested for any diagnostic trouble codes and followed any that were found down via pin pointed testing to find out what is causing any code to set?
You have an issue with spark, fuel, air, exhaust or any combination of those items. You could have an issue with engine timing. You could have emissions controls issues. You could have a wiring issue somewhere. You could even have a voltage / amperage output concern. Without proper testing and referencing shop manual information, it's all a massive guess (and so far, many guesses that appear to not affect operation.)
Seek professional guidance to perform actual testing, as it would have been cheaper to do that from the start rather than replacing all the components you have replaced (likely unnecessarily) already.
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