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Join Date: Mar 2007
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turbo cutting out at 4000rpm

all stock '87, the engine wants to cut out @ 4000rpm, it does not happen all the time, when I punch it the turbo kick in and jerk with no power at around 4000rpm, can somebody please tell me what's wrong.

Thank you,
Yahow
Old 09-24-2007, 02:28 PM
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You are overboosting and hitting overboost swtich which cuts the fuel pump? It cuts the fuel around 1.1 bar.
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Old 09-25-2007, 05:44 AM
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Hi beepbeep, thanks for your reply, my turbo does not go over 1.1 bar, when it boots up to 0.4 bar then I feel the jerk and will not go any higher, there is no power and I also notice some black smoke come out when I was driving to work today when the car was jerking and the boots gauge was at 0.4 bar. All the seals from turbo to IC is new and I check the bottom everything seems bolted on tight there should be no leaks right? could something wrong with my turbo? The strange thing is sometimes I get full boots (0.8 bar) with no problem. Please help.

Yahow
Old 09-26-2007, 02:46 PM
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Check your spark plugs, if gap is too big the boost will extinguish the spark. Also, if car starts "sooting" prior to cutting out, you might be running very rich.

I don't think there is something wrong with the turbo as you can get it to boost 0.8 bar. I believe problem lies within ignition/fueling.

Start with grounding overboost switch, it might be malfunctioning. If it trips it cuts power for both fuel pumps with "dash in your face" syndrome.
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Old 09-27-2007, 12:51 AM
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Hi beepbeep, I like your "dash in your face" syndrome description, that is exactly what happen when it start cutting out, good one!

I will check them out and Thank you again for your help.

Yahow
Old 09-27-2007, 06:56 AM
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Hi, I unplugged the 02 sensor like someone suggested in this community and it works well, all the cutting out syndrome is gone and beepbeep you are right it is not the turbo problem when I step on it now it boots up smoothly to the top and I thank you again.

Now I want to learn more about this: (1) why it run so well when 02 sensor is unplugged, is this have to do with the fuel/air mixture? I didn't adjust anything before it just came on and ran terrible all the sudden. can the adjustment change on you without touching it? (2) If prolong leave the 02 sensor unplugged will that hurt the engine what is the good and the bad on this? (3) If I wish to plug the 02 sensor back on what do I have to do to make it run as good as when is unplugged? Can someone please explain that to me.

Thanks, Yahow
Old 10-11-2007, 10:37 AM
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Well your O2 sensor might be failing and is sending wrong signal to the box, whih leans/richens the fuel too much until engine starts missing.

O2 sensors are cheap, I suggest replacing it to begin with.

So your car is equipped with catalyst and O2 sensor? US modell or ROW?
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Old 10-11-2007, 11:18 PM
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Thanks beepbeep, my car is a US model and I will replace the 02 sensor, I know there is 02 sensor inserted into a pipe under the engine but I don't see the catalyst.

Thanks again, Yahow
Old 10-12-2007, 06:31 AM
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I thought on full wide open throttle the 02 sensor was bypassed for a richer mixture?
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Old 10-13-2007, 02:50 AM
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