2nd Generation Specific (1986-1992) 1986-1992 Discussion including performance modifications and technical support sections.

Detonation in front rotor?

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Old Jun 26, 2004 | 09:46 PM
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Detonation in front rotor?

I was wondering which rotor turboII's usually detonate in. I always hear about the rear rotor losing compression most often, and it sounding like a metalic ping upon detonation.

ON my car its different, it sounds more like a creak and its coming from the front rotor. How do i know? Well late one night a i *cough* put on the plug wires backwards *cough* so that the leading wire was on the trailing wire. And it was making this creaking sound under boost. It makes this same sound when under a heavy load in 5th gear, so im assuming its the front rotor.

How can i correct this and is it unusall for this to be hapening in the front rotor?
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Old Jun 26, 2004 | 09:48 PM
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Oh yea, when i switched up the plug wires it was only on the front rotor
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Old Jun 27, 2004 | 01:51 AM
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at some point everyone got the wires mixed up..I have...not because I did not know what goes where but just cause...and my car still runs today...unless you drove a few thousand miles under heavy load, then that was not your problem....
Next...front rotor detontion can happen....did to me...Intercooler hose popped off and BAM!!! front rotor gone....too much air went in, not enough gas and there you have it...detonation!
As far as your creak....no way to tell over the forum..is it a creak like a wooden floor, creak when metal bends..too many creaks(or was that too many freaks) to pin point that...guesses will range from water pump, air pump. alternator to xxxx, at what rpm, etc....does your car run fine? Boost ok, idle ok? Is the car the same as before the mix(sans creak) up then it is something up front near the front rotor...good luck with that creak
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Old Jun 27, 2004 | 02:14 AM
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Originally posted by Travelintrevor
at some point everyone got the wires mixed up..I have...not because I did not know what goes where but just cause...and my car still runs today...unless you drove a few thousand miles under heavy load, then that was not your problem....
Next...front rotor detontion can happen....did to me...Intercooler hose popped off and BAM!!! front rotor gone....too much air went in, not enough gas and there you have it...detonation!
As far as your creak....no way to tell over the forum..is it a creak like a wooden floor, creak when metal bends..too many creaks(or was that too many freaks) to pin point that...guesses will range from water pump, air pump. alternator to xxxx, at what rpm, etc....does your car run fine? Boost ok, idle ok? Is the car the same as before the mix(sans creak) up then it is something up front near the front rotor...good luck with that creak
when the intercooler pipe pops out you get richnes....
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Old Jun 27, 2004 | 03:23 AM
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Yea, damn 1 in the morning engine mount fixes... i just trew the wires on without paying attention and i messed the front ones up. I drove it only down the block like this, and when the turbo started to boost i would hear this detonation creak in the front rotor. Came home and fixed the problem right away.

Regardless of this problem i have always had a detonation problem under a heavy load in 5th gear WOT. When i go to WOT as soon as the turbo boosts all the way i will hear this same creak. So im thinking its front rotor detonation...

I am going to slightly retard my ignition timing tomorow to hopefully get rid of any detonation probs. It sounds like a creak when you snap a twig slowly... i almost certain its detonation. The motor still runs fine, i am going to check compression just to be sure though.

The only thing i can tell thats different since the mix up of the plug wires is that my car now idles intermitantly from 1500-2000 rpm's. Sometimes it will do this, sometimes it will idle normal. This has only started to happen after the mix up....
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Old Jun 27, 2004 | 04:23 AM
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Originally posted by MARTIN
when the intercooler pipe pops out you get richnes....
...uh..no you dont....you get a surge of air(remember that the car is SUCKING in air at the time the hose pops off) with the same amount of fuel...too much air and not enough fuel is lean
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Old Jun 27, 2004 | 04:33 AM
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The engine isn't going to suck in more air then the turbo was feeding it. Thats the point of forced induction. If your hose carrying air which is pressurized to 1.4 bar, and it pops off, the pressurized air is going to the atmosphere and the engine is sucking in non-compressed air (from what ever opening is not attached to the regular intake)which is at atmospheric pressure, or 1.0 bar. So by the hose popping off but maintaining the same amount of fuel, you would get a rich condition.
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Old Jun 27, 2004 | 09:58 AM
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The knock sensor is in the front housing for a reason.
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Old Jun 27, 2004 | 10:09 AM
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if your car has been detonating as you say it has, it should have blown by now. detonation sounds like a bunch of metal ball bearings being dropped into an empty folgers coffee can.
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Old Jun 27, 2004 | 10:06 PM
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From: Miami
Originally posted by Travelintrevor
...uh..no you dont....you get a surge of air(remember that the car is SUCKING in air at the time the hose pops off) with the same amount of fuel...too much air and not enough fuel is lean
look if you are gunna reply, atleast say something smart... when an intercooler hose pops off, you donnot get a surge of air into your engine.... if what you are saying were true, then we wouldnt need turbos.... so please check what you are saying.....and yes you do go rich if you were underboost and a hose pops out of place....
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