Breaking up at rpm

[Alaskabuick]

My Turbo T has developed a miss at about 4600 rpm.. Almost like it hits the rev limiter.

Does not matter if it is under boost or just slowly rolling it up to 4600 it just starts breaking up.

It does not do it my just reving in Neutral.

I tested the Coil pack with on of the coil testers that take it up to RPM (think caspers made this), spark seems to look strong.

Car is you basic bolt on build, TT chip.

Dennis

 

[Bescurred]

Can't you test the wires with that coil tester too? I seem to remember using one with little plastic pieces that you could check the wires too...

 

[Alaskabuick]

Im not quite familiar with how I would test the wires with the tester?? Hum. let me look it over and see...

 

[gusszgs]

FWIW .....I had the exact same problem about 2 yrs ago. My T would pull great up to around 4500 or so and would start misfiring slightly. I changed out the spark plugs from the AC'c to some NGK's and she hasn't skipped a beat since.
I'm not saying this is your problem but it's possible and cheap maintenance.

 

[Hotrodbuick]

Had similar problem with mine, changed plugs and MAF, MAF made mine go away but plugs helped it idle smoother.


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[baby6]

Does it smoke at all at WOT?

 

[TurboTdr3.8]

Had similar problems like that it was the valve springs were bad

 

[MikeL.]

Mine did the same. Here's an easy test to rule out cam sensor. Start motor first, then unplug cam sensor while motor is running. This will put fueling in batch mode instead of sequential. Go make a pass.

If it pulls clean you need a new cap and/or rebuilt cam sensor. Plug cam sensor back in once you return.

Are the valve springs original?

 

[Alaskabuick]

Valve springs just installed 980 installed at 100# seat.
(Problem was there before the change as well).

I just swapped out the crank sensor and it appeared the original was showing wear.

Problem went away at 4600 but now seems to hit a wall and break up at 5k.
However maybe my cam is just done there (stock). This is a typical bolt on car (te44, 50lbs, 3"dp)

But to me it just sounds like it is still breaking up a bit at 500-5100 more than just running out of cam.

I will try the batch fire test.

Thanks Guys

 

[TurboTdr3.8]

What is your wb readings when it does that , have you did a leak down test on the engine ?

 

[Fast4Ward]

guys mine is doing the same and I was just about to post. it is also te44 50 #ers and 3" dp.
powerlogger show's nothing electrical.
I try to go wot and it stonewalls at 4200 rpm and feels like its bouncing off the rev limiter. easy into it and will just stick at 4200 same.


guess i'll start with the cam sensor and move to the plugs. already tried different plugs, coil and control module and no diff.

 

[Alaskabuick]

guys mine is doing the same and I was just about to post. it is also te44 50 #ers and 3" dp.
powerlogger show's nothing electrical.
I try to go wot and it stonewalls at 4200 rpm and feels like its bouncing off the rev limiter. easy into it and will just stick at 4200 same.


guess i'll start with the cam sensor and move to the plugs. already tried different plugs, coil and control module and no diff.

I replaced my Crank sensor that solved the issue at 4600 (at least seems to for now), I could clearly see wear on the old sensor. Maybe give that a shot. I still have a problem with it cutting out at 5000-5100, but maybe it is just running out of wind at that point...

 

[baby6]

My car has always been a pita, it was showing signs of valve float, when it was the turbo shooting oil through the intake at WOT, causing it to miss and sputter at high rpms. I checked and changed everything people have already stated. Had no clue until it wanted to finally retire and was burning oil like crazy.

 

[Alaskabuick]

My car has always been a pita, it was showing signs of valve float, when it was the turbo shooting oil through the intake at WOT, causing it to miss and sputter at high rpms. I checked and changed everything people have already stated. Had no clue until it wanted to finally retire and was burning oil like crazy.

Thats is a good point.. never thought of that one..

thanks,

Den

 

[1fastcobra]

Does ut get worse when hot?


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[Alaskabuick]

Does ut get worse when hot?


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It does not make any difference.

thanks..

 

[1fastcobra]

Did u ck your fuel pump. ?
I had the same thing happen
To me. Was my pump

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[baby6]

Check plugs to see what color they are after a few bursts and report back. Checked fuel pressure at WOT? Maf maxing out at 255? Any oil in intake piping. Check turbo for shaft play. Check alternator voltage. Check all vacuum lines. Put car into batch fire mode and do a run to see if it changes....these cars are finicky! PS- there are more things to check....start with those first.

 

[klmnla]

After 4 years of troubleshooting a similar problem, I found it was a wiped cam lobe. Replaced it with a comp cams 206 and all issues resolved. And of course I now have a collection of good spare parts.

 

[klmnla]

After 4 years of troubleshooting a similar problem, I found it was a wiped cam lobe. Replaced it with a comp cams 206 and all issues resolved. And of course I now have a collection of good spare parts.