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When the engine runs under 2,000 RPMs it shudders like it has a misfire?

Tiny
TIMSDIAMANTE
  • MEMBER
  • 2000 MITSUBISHI DIAMANTE
  • 3.5L
  • V6
  • 2WD
  • AUTOMATIC
  • 100,000 MILES
My engine runs smoothly at 2000rpm and over but under that it shudders like it has a misfire. Have checked spark plugs, new leads and clean plugs. Checked fuel filter and pump and replaced fuel. Fitted a new Mass air flow sensor (though this itself could still potentially be an issue as I cannot source OEM).

It is almost stalling when you start to pull away almost like it is flooding or not getting fuel, not sure which. It will not accelerate smoothly until RPMs exceed 2,000 at which point it runs smoothly again.

Engine light is coming on, so I suspect a sensor somewhere.
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Friday, October 20th, 2023 AT 1:03 PM

12 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
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Hi,

If the check engine light is coming on while the engine is running, we need to scan the computer to see what codes are stored. That will point us in the right direction.

If you have a scan tool, could you let me know what codes are present? Also, if you don't have one, most parts stores will scan it free of charge. Is that something you could have done?

You mentioned it felt like it was getting too much or too little fuel. If it is flooding (too much) usually, there is a strong exhaust odor that is out of the ordinary. Additionally, there could be gray or dark gray smoke from the exhaust indicating a rich fuel mixture. See if you notice either of those things.

Let me know.

Joe
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Friday, October 20th, 2023 AT 10:01 PM
Tiny
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I will get it scanned next week. No smoke noticed yet. But when it happens, I am usually driving / starting to pull away from a stationary start or slow speed. Does not seem to happen as bad when cold- but very obvious when warm. Will reply again when I have codes.

Thank you
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Saturday, October 21st, 2023 AT 1:38 AM
Tiny
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I had it scanned and the codes don't seem to make sense to me.

One code was MFI - ID72 (TCL vent SV) Check code E6E7

And the other was TCL - ID72 and ID73 Vac Vent SOL check code 600D

Is there a way I can at least confirm whether the new Mass air flow sensor is working as it should or if I have purchasedd a piece of rubbish / faulty one?

Thank you for your time.
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Thursday, October 26th, 2023 AT 8:44 PM
Tiny
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Hi,

Where did you get the codes? None of them make sense to me either. The factory codes are two-digit numbers. The P codes will have the letter P followed by four digits. See pics below for examples. Note: I tried looking for a 72 and a 73. The list I have ends at 55.

Are these the only code numbers that were provided?

Let me know.

Joe

See pics below.
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Thursday, October 26th, 2023 AT 9:03 PM
Tiny
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These came off the reader that the neighborhood AA (I think it is the AAA overseas) used. It was quite a fancy unit. He also said they were very unusual codes that he had not seen before.I will look at taking it to the Mitsubishi dealer next week.

Primarily I have two possibilities- either the new Mass Air flow meter I just purchased is junk and that is still my problem, or the issue lies somewhere else.

Thank you.
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Friday, October 27th, 2023 AT 3:47 AM
Tiny
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Hi,

Yep, I never saw codes like that before. As far as the sensor, if you purchased it online at a low cost, there is a good chance that is the issue. I'm not sure where you are located, but often times a parts store will scan the computer for you.

Let me know how things turn out or if you get different information.

Take care,

Joe
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Friday, October 27th, 2023 AT 12:50 PM
Tiny
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Codes came back to the vacuum solenoids on the firewall for the emissions(?). The technician said there was no vacuum there or at the vacuum solenoid for the cruise control. He also told me the cruise control one may get (or not be getting) signal from the emissions one so to sort that one first and see if the cruise control one is faulty too or possibly not. I do have a part number for the solenoids in question. (MR450086 Valve assembly emission solenoid) Would you know if there is a work around that could avoid me needing these to start with? Or if it is the same part in the Mitsi Pajero 3.5l petrol which shares the same motor.

Again, Thank you for your time.
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Friday, November 3rd, 2023 AT 1:19 AM
Tiny
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Hi,

By any chance, did it determine where the vacuum is lost to the components? As far as the Pajero, I don't have that information.

Let me know.
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Friday, November 3rd, 2023 AT 8:47 PM
Tiny
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Not sure. I replaced the unit from the wreckers yard and it made a big improvement. Still there but nowhere near as bad.

I did notice an oil leak at the rear bank of cylinders onto the exhaust shield so will look to see where that is coming from. As for the Pajero, it was probably called something else there. It uses the 6G74 engine as well.
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Friday, November 3rd, 2023 AT 11:01 PM
Tiny
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Hi,

That is actually good news. By chance, have you checked to see if the same codes are still present? If not, clear the codes and see if the same ones reset.

As far as a 6G74 engine, nothing I have had that identification,

Let me know about the codes.

Joe
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Saturday, November 4th, 2023 AT 8:07 PM
Tiny
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I did not get much further with this, it is still doing it, but someone offered me cash for it, and I accepted. I did tell him of the issues etc, and he was aware of them and was still happy. It now has an SEP code (Someone Elses Problem) I think he thinks he knows how to fix it or is going to part it out.
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Sunday, December 3rd, 2023 AT 4:58 PM
Tiny
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Hi,

That is certainly one way to resolve the problem. I've done the same thing in the past. LOL

Regardless, thank you for the update. Please feel free to come back anytime in the future if you have questions.

Take care,

Joe
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Sunday, December 3rd, 2023 AT 9:53 PM

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