Hi --

I've got a 2002 MONTERO LIMITED, would LOVE some help from the experts, please!

-- Four days ago, got a "Service Engine Soon" light -- first time! -- but figured I can wait for my next oil change in four weeks to address;
-- BUT the very next day, while on the freeway, I noticed very low RPM (1200), had no acceleration, so I got off freeway to head back;
-- On way back, at every stop sign/light, it would shake at idle, with very low RPM, but upon acceleration, shaking would stop, but RPM was still abnormal;
-- Took it to O'Reilly, plugged in their machine to find a P0300 error code (no details, just "random misfire"); one of their techs fooled around with the engine coils to test, said one or two must be bad;
-- Took it to my secondary mechanic, he switched out a "bad" ignition coil, which cleared the code, BUT RPM was still at 400-500, VERY LOW, and rattled at idle when in gear;
-- He couldn't figure out why, and felt it didn't know enough;
-- So I took it to another very reputable mechanic (it's in their garage now), and they usually deal with Honda/Toyota/Acura;
-- This new mechanic played around, said it looks to him that all the coils are good, and so are the cables;
-- As of now (car is in their garage till tomorrow), he thinks the cable that goes from the coil to the computer is "reading oddly" between two of the coils.
-- He doesn't think it's related to 02 sensor, says the spark plugs look good (they were also changed 15,000 miles ago).
-- Thoughts?!

— NOTE: At 95,000, and with recent new rebuilt tran, no other recent work, FYI.

ALSO, is it safe for the car to drive? as I may need to find a dealer or specialist.


He said, it could be a computer issue -- and "if that's the case, you might need to bring to a Mitsu dealership or an expert, because" he may not know what to do.

I guess I'm just asking to see if what this sounds like, maybe I can throw a few suggestions to help him along -- he's OG, very good, so I'm not gonna take him to a forum ... But I'm just frustrated, a bit scared this is gonna be $$$, and also -- I would like fix this issue. WTF?!
They all griped about how Mitsu codes are so vague.

Please help, thanks!

=

 

The P0300 error code indicates that a car's computer has detected a random or multiple cylinder misfire.
When was the timing belt serviced last? Check timing before anything else! If you rig is still running, it could have a jumped timing issue. Possibly a failed timing belt tensioner. You have an Interference engine so stop driving it before you do more damage! Check your timing belt now!

 

I am having the same problem. I have a 2002 Montero limited. I am having a multiple random misfire. Ehen I first crank it up when engine is cold runs fine. When it warms up is when I can tell its misfiring. Not as bad when in park but when i am in drive is when you can tell. Shaking bad and jerking at a stop sign.

I have had the timing belt and tensioner replaced about 2k miles ago.

I have replaced the plugs and wires
I have replaced the MAF
Cleaned the Throttle body

I'm completely lost at what to do.

Montero has 190k miles

 

I had the exact same problem and fought it for months, finally traced down to this part (ignition power transistor (Mitsubishi p/n MD349207) I pulled one from another montero, took about 15 minutes to change and the problem was resolved. Runs like it was 2001 again

 

Random musfire code P0300 is NOT a Mitsubishi code, but a OBD2 generic engine management code. That is why it is so vague. Many things can cause random misfires, including bad readings on many sensors, fuel delivery issue, incorrect fuel/air mixture and ignition problems. When they read the code at O'Reileys, by any chance did the tech look at the Freeze Frame data? Knowing that might help to narrow down which pathway to go. It may also help to figure out why it is still acting up