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[Mk2] [Turbo] Rev3 turbo (swap), rev limit dropped to 6800rpm. - why?????

 
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Danbob
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Joined: 14 Nov 2011
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1993 Toyota MR2 Mk2 Turbo Rev2

PostPosted: Sun May 12, 2019 9:16 pm    Post subject: [Mk2] [Turbo] Rev3 turbo (swap), rev limit dropped to 6800rpm. - why????? Reply with quote Reply with quote including images

Hello, last year my car for some reason has stopped revving to 7200rpm normal rev3 redline and now will not rev past 6800rpm.

It definitely used to rev to 7200 I can confirm with Dyno graph, and I've double checked that the tacho is reading accurately.

Has anybody experienced this in the past?

Rogue motorsport suggested it could be the coil, but I've removed it and tested it and it meets Toyota spec (also only 2 years old).
A similar problem on a different car forum turned out to be tps related and another suggestion was a snapped valve spring.

Going to swap the coil anyway, got a sprint next week and don't want to drive the car to its limits without knowing what is wrong

Any other similar experiences you can share would be helpful!
Thanks
Dan


Car is a rev 2 turbo with rev 3 conversion running rev3 standard ECU
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steven63




Joined: 28 Nov 2014
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Location: preston
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PostPosted: Sun May 12, 2019 11:28 pm    Post subject: Reply with quote Reply with quote including images

if you are still running the rev2 ignitor that will be the problem, rev3 motors need a rev3 ignitor
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Danbob
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1993 Toyota MR2 Mk2 Turbo Rev2

PostPosted: Mon May 13, 2019 5:30 am    Post subject: Reply with quote Reply with quote including images

Yeah, sorry should have mentioned I'm running rev 3 ignitor.

And car had been running happily for two years with the rev3 swap with 7200 rev limit before this happened.

Has anyone experienced an ignitor failing? Maybe could be that..
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SonicSW20




Joined: 29 Nov 2010
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1997 Toyota MR2 Mk2 NA Rev4

PostPosted: Mon May 13, 2019 8:16 am    Post subject: Reply with quote Reply with quote including images

What exactly happens when you reach the 6800RPM limit? Is it a hard limit like a normal rev limiter, or does it just sort of "fizzle out" and just doesn't want to let the RPM go any higher?
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Danbob
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1993 Toyota MR2 Mk2 Turbo Rev2

PostPosted: Mon May 13, 2019 12:53 pm    Post subject: Reply with quote Reply with quote including images

It will bounce off of the 6800 rev limit like a factory limiter, it doesn't rise up and settle there, but it's also not a really harsh jerk like a fuel cut.

I confirmed that it's not just the tacho reading wrong by checking with an external tacho on the HT lead
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Danbob
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1993 Toyota MR2 Mk2 Turbo Rev2

PostPosted: Sun May 19, 2019 8:09 pm    Post subject: Reply with quote Reply with quote including images

UPDATE:
Swapped the coil pack for a new one, removed paint from Coil/Igniter bracket and made sure igniter has a really good earth, took it out to test and now won't rev past 6300!!
It's gotten worse by 500rpm since last test.

Engine and oil up to temp,. No fault codes, car otherwise behaves normally!
AFR shows its running rich (9.5) up to that point then looks like it's cutting fuel bouncing between 6300 and 6200, could still be cutting spark as the wideband would read the unburnt fuel as lean anyway,

Any new ideas?

Will swap ECU for a spare one next
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abovetherim




Joined: 16 Feb 2011
Posts: 587
Location: Leicester
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1991 Toyota MR2 Mk2 NA Rev1

PostPosted: Sun May 19, 2019 11:04 pm    Post subject: Reply with quote Reply with quote including images

I had a king lead making poor connection as the elbow end fitting was snapped inside the rubber end. Worth a look
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Danbob
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1993 Toyota MR2 Mk2 Turbo Rev2

PostPosted: Mon May 20, 2019 5:45 am    Post subject: Reply with quote Reply with quote including images

Did that cause similar symptoms?
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Danbob
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Location: Wellingborough
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1993 Toyota MR2 Mk2 Turbo Rev2

PostPosted: Tue Jun 11, 2019 9:27 pm    Post subject: Reply with quote Reply with quote including images

Just to close this off in case somebody is searching for a similar possible in the future.

The problem was caused because the cambelt had slipped two teeth on the crank gear backwards!

Hypothesis is it happened on a spin onto the infield where I didn't drop the clutch quick enough and the engine was stalled/shocked backwards.

Timing reset and car running great again! [thumleft]
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