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Hello all. I’m working on a 91 Mitsubishi 3000GT with under 115k on the clock. At intown speeds and highway speed the car stutters. It would also idle at 300rpm. From a dead stop it would accurate okay but wouldn’t drop down to a low gear for good passing power (automatic), stutters at 3000-4000 rpm and then run strong to 6000 rpm. I cleaned the ISC (idle speed control) which was packed with carbon. I also “seafoamed” the car. It now idles at 900 and drops down to a passing gear but still feels low and power and still hesitates and stutters at highway speeds / 1400-1800 rpm.
Please advise
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Sounds like a weak spot in the ignition system..could be a bad spark plug,plug wire (boot)or weak coil(s). Not sure on your engine configuration to advise correctly.
So I had the car diagnosed (OBD1) and they didn’t find any codes in the ECU, Transmission, etc.
Wysetch- The engine setup: 6G72 3.0 V6 24V DOHC
Should I try a tune up before throwing parts at it? E.G. ECU, EGR, throttle body, fuel injectors, MAF?
I did notice something else.
When I begin to drive, the needle on the speedo doesnt move for a couple of seconds. The tach is going and i’m doing 8 to 10 MPH but the speedo is at 0 then jumps to 20MPH. Do you guys think that it could be linked to this issue? The cruise control works fine. I had an Honda once and the two were tied together is why i mentioned that.
So, I changed the plugs and cleaned out the engine intake, egr and the throttle body. The car now has a lot more power BUT still sutters. Could the timing belt cause this?
The O2 sensor I would not put that before, plugs wires, etc. I vote tune up first. Then take it from there. Check for vacuum leaks, and clean the MAF sensor. while you are at it. http://youtu.be/rsGTeWayqIU.
I would think O2 sensors would throw a code if they were bad. I’d replace the fuel filter first. I’ve had similar symptoms on my truck before and I found it to be a partially clogged filter and it’s a good start as they’re usually only $10-$20
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