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Topic
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2003 Montero Limited 113,000 miles
I’ve only had it a few months, daily driver, 2-5hr highway trips on the weekends
No CELs or pending codesIssue: starting to hear a rattling-type pinging sound when on highway. Onlywhen in OD and I push the accelerator under load. This transmission does tend to want to stay in 5th when I would prefer it kick down to 4th sooner. The pinging may happen no matter if it actually does kick down to 4th or if it stays in 5th when gassed.
Idle is a little rough. Otherwise runs smoothly (feels underpowered, but I think that’s probably because it is). Has the common 2200rpm Montero engine vibration, but it’s fairly mild.
Compression test results:
RIGHT 185, 190, 185
LEFT 210, 240, 180 (rechecked)
Long term fuel trims average about + 9-10 for the left (drivers) bank and + 3-4 for the right bank. The drop to near zero when on the highway.I am using 93 octane. I have run techron and seafoam through a couple half tanks of gas.
New plugs, coils, wires, valve cover gaskets, timing belt, water pump
Vacuum leak test didn’t find anything
Manifold vacuum test rock steady at 21 or 22 hg at idleQuestion: What’s up with the high compression in those two left cylinders? Is the timing off a tooth (was done by dealer but who knows)? Carbon buildup?
I assume the pinging is related to the high compression. Please let me know what you think. I think the next step is probably to stick a scope in the high cylinders and look to confirm carbon, but I don’t really know. That seems easier than checking the cam timing (I don’t have much space or shelter to do much work on the vehicle now).Thanks!
Matt
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Replies
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I may be wrong but,
I believe the 3.0L and 3.5L engines recommend Regular (87) octane.
The 3.8L is the only variant that requires Premium (93) octane.
So if your vehicle is equipped with other than the 3.8L that may be the cause of your pinging.
Another possible cause:
Mitsubishi recommends timing belt replacement on most of the models 60,000 miles.
Do you know when the last time it was replaced?
A worn timing belt could throw off the engine timing.Question: What’s up with the high compression in those two left cylinders? Is the timing off a tooth (was done by dealer but who knows)? Carbon buildup?
Easy enough to check for carbon build up with a inexpensive bore scope.
If the timing is off high compression would not be the result.
I assume the pinging is related to the high compression
Assuming things can be costly.
Better to pin point the cause.
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