4 signs of bad turbos that I've personally witnessed...maybe it'll kill some paranoia, or make
04-24-2002, 05:50 AM
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4 signs of bad turbos that I've personally witnessed...maybe it'll kill some paranoia, or make
life even worse for ya 
..note: in every case, the overall power of the car remained about the same as it built up proper boost pressure at some point throughout the revs. In cases 1 or 2, it is very noticeable while chipped and can result in the turbo(s) dying even earlier. But regardless, they'd be destroyed anyway under the stock chip. The first two cases have been due to the impeller shaft warpage.
1. Higher pitch than normal turbo spooling sound. Almost sounds similar to a high pitch dentist drill. Witnessed this on the passenger side turbo.
2. An in-and-out wailing type sound of the turbos spooling. Very noticeable while chipped. Witnessed this on the passenger side turbo.
3. Major amounts of oil leaking into the intake side. Witnessed this on the driver's side turbo in two cases.
4. A very inconsistent dyno plot. Power and torque are built later in the rpm range(typically around 500 rpm+), and then they both die off earlier and much more rapidly as the revs max out (typically around 5k rpm).
One of the best ways to diagnose this has been to plot boost pressure versus rpm for the particular engine computer and then compare it to a healthy car. I looked into checking actual versus requested boost, but this has not shown anything. My friend and I were talking last night, and you'd think that the ECU would recognize that the boost is not building according to when it was desired and you'd want to set a fault code. Oh well...didn't/doesn't happen.
hope the descriptions helped a bit...here's a typical case...green is good (notice how the boost comes in earlier) while blue is bad (boost comes in late)
<img src="http://pictureposter.audiworld.com/21977/map_vs_rpm_green_good_and_blue_bad.jpg">
..note: in every case, the overall power of the car remained about the same as it built up proper boost pressure at some point throughout the revs. In cases 1 or 2, it is very noticeable while chipped and can result in the turbo(s) dying even earlier. But regardless, they'd be destroyed anyway under the stock chip. The first two cases have been due to the impeller shaft warpage. 1. Higher pitch than normal turbo spooling sound. Almost sounds similar to a high pitch dentist drill. Witnessed this on the passenger side turbo.
2. An in-and-out wailing type sound of the turbos spooling. Very noticeable while chipped. Witnessed this on the passenger side turbo.
3. Major amounts of oil leaking into the intake side. Witnessed this on the driver's side turbo in two cases.
4. A very inconsistent dyno plot. Power and torque are built later in the rpm range(typically around 500 rpm+), and then they both die off earlier and much more rapidly as the revs max out (typically around 5k rpm).
One of the best ways to diagnose this has been to plot boost pressure versus rpm for the particular engine computer and then compare it to a healthy car. I looked into checking actual versus requested boost, but this has not shown anything. My friend and I were talking last night, and you'd think that the ECU would recognize that the boost is not building according to when it was desired and you'd want to set a fault code. Oh well...didn't/doesn't happen.
hope the descriptions helped a bit...here's a typical case...green is good (notice how the boost comes in earlier) while blue is bad (boost comes in late)
<img src="http://pictureposter.audiworld.com/21977/map_vs_rpm_green_good_and_blue_bad.jpg">
04-24-2002, 05:54 AM
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welcome back.
btw PAWHN STAH ins't sure about his yet...do you think blow by/back could be the cause of oil in the TBB area? that was brought up a couple times...think donp has it too.
04-24-2002, 05:56 AM
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I always tell people, in regards to the sounds, if you have any doubt, its not blown...
You know the real siren sound when you hear it, and you absolutely know the high pitched whine of a dead turbo.
Its not an absolute rule, but it stops a lot of panic when people realize that most of the sounds they hear are normal.
Its not an absolute rule, but it stops a lot of panic when people realize that most of the sounds they hear are normal.
04-24-2002, 05:59 AM
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thanks...the blow by is different...in Ant's case, we couldn't trace the
oil from the two lines tapped into the intake on or near the y-pipe. Has he pulled the lower turbo air outlet line yet (right before the IC inlet)? Pull that and I bet it's nasty.
AS far as the oil lines to the turbos themselves leaking, this has been a problem before.
I haven't seen any coolant problems yet.
AS far as the oil lines to the turbos themselves leaking, this has been a problem before.
I haven't seen any coolant problems yet.
04-24-2002, 06:09 AM
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question for you - do you have the miltek turbo back exhaust?
I seem to remember that you posted about a CE light with this system. I have the miltek and am getting the catalyst inefficency CE pretty consistently now - where I never experienced this last year. How did you fix this or are you going to live with it?
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04-24-2002, 06:15 AM
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yep...but, that code you are seeing is not terrible. You shouldn't be seeing a check engine
light with that code...(please correct me if I'm wrong)...it's been a while since I've seen that. That code can be set if you really push the car hard....(i believe that's how I set it before)
The DTC's I've been getting was for an O2 sensor correction factor. THis is due to either bad cats or bad O2 sensors or both. It is set when the ECU doesn't see a proper secondary O2 sensor voltage after the inline cats.
The DTC's I've been getting was for an O2 sensor correction factor. THis is due to either bad cats or bad O2 sensors or both. It is set when the ECU doesn't see a proper secondary O2 sensor voltage after the inline cats.
