SL jumping revs, and won't idle, seems like misfiring

414 Views 6 Replies 3 Participants Last post by white93gt, 12 d ago

nimrooz

Discussion Starter · 7 mo ago

1991 SL started early this year with jumping revs, and won't idle, seems like misfiring.
Have changed ptu, Cas, coils, plugs and plugwires (NGK).
Check engine light only comes on when it almost dies and goes out again when revving.
Sometimes it feels like it's only running on some cylinders.

Last year it also wouldn't stay on idle, at that point ecu was exchanged for a remanufactured one from rockauto and the iac was changed.

See video below, does anyone have a clue? -I'm starting to starve out of ideas.

3000gt jumping revs

youtube.com

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beegeezy

· #2 · 7 mo ago

Air, fuel, and spark! It sounds like you have spark covered. Have you checked your fuel pressure? When was the last time you changed the fuel filter?

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nimrooz

Discussion Starter · #3 · 7 mo ago

beegeezy said:
Air, fuel, and spark! It sounds like you have spark covered. Have you checked your fuel pressure? When was the last time you changed the fuel filter?

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Fuel filter was changed about 2 years ago, and it has been driven about 100 miles since, one round to the local grocery store and and one trip to the regularly government inspection.

Have yet to find the correct pressure regulator for the car, or else I would have exchanged that.
But I do not have checked my pressure.
I also put in new gasoline, just to be sure.

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beegeezy

· #4 · 7 mo ago

nimrooz said:
Fuel filter was changed about 2 years ago, and it has been driven about 100 miles since, one round to the local grocery store and and one trip to the regularly government inspection.

Have yet to find the correct pressure regulator for the car, or else I would have exchanged that.
But I do not have checked my pressure.
I also put in new gasoline, just to be sure.

I would get one of these https://www.3sx.com/fuel-pressure-gauge-adapter-kit

My guess is that your fuel pump is dying.

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nimrooz

Discussion Starter · #5 · 7 mo ago

beegeezy said:
I would get one of these https://www.3sx.com/fuel-pressure-gauge-adapter-kit

My guess is that your fuel pump is dying.

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Why have I missed the existence of this, thanks for the link.

Yes, fuel pump and injectors would be my best guess forward, but I'm not sure, and was thinking that others had experienced the same.

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nimrooz

Discussion Starter · #6 · 12 d ago

So, fuel pump changed, still the same.
Anyone have an idea?

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white93gt

· #7 · 12 d ago

Post deleted after rereading title and first post and realizing this original post was incorrect.

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