Lost boost
03-29-2002, 08:55 PM
#3
Senior Member
Join Date: Jul 2001
Posts: 428
I'll help you if you still need it. You have a boost gauge so you need to do a 40-70 run in 3rd gear. Cruise steady at 35 mph floor it have someone watch the boost and note the boost pattern.
You should get:
rpm psi
3,000 10
4,500 8 (as 2d turbo comes on)
4,500+ 10 (recovers almost immediately)
6,000+ 8 (and holds to redline)
Let me know what your numbers are.
You should get:
rpm psi
3,000 10
4,500 8 (as 2d turbo comes on)
4,500+ 10 (recovers almost immediately)
6,000+ 8 (and holds to redline)
Let me know what your numbers are.
03-31-2002, 09:57 PM
#4
Junior Member
Thread Starter
Join Date: Mar 2002
Posts: 2
Originally Posted by 7sins' date='Mar. 29 2002,18:55
I'll help you if you still need it. You have a boost gauge so you need to do a 40-70 run in 3rd gear. Cruise steady at 35 mph floor it have someone watch the boost and note the boost pattern.
You should get:
rpm psi
3,000 10
4,500 8 (as 2d turbo comes on)
4,500+ 10 (recovers almost immediately)
6,000+ 8 (and holds to redline)
Let me know what your numbers are.
You should get:
rpm psi
3,000 10
4,500 8 (as 2d turbo comes on)
4,500+ 10 (recovers almost immediately)
6,000+ 8 (and holds to redline)
Let me know what your numbers are.
03-31-2002, 10:27 PM
#5
Senior Member
Join Date: Jul 2001
Posts: 428
Sounds like it could be a boost leak. Hope that it is just that. To really get things going I need a full report at least as detailed as what I outlined. I do not want come across as a jerk, but turbo troubleshooting requires precision.
You may have multiple issues.
1. Give a FULL report on your boost behavior based on the "chart" above. How it builds, drops... everything.
2. Do you have a vacuum/pressure test gauge? If not see if you can find one to borrow. Yhey cost less than $20, but hey thats still $20. We will use this later.
3. We need to get the primary working. The Secondary Turbocharger requires the Primary Turbocharger to generate more than 8 psi to operate actuators that control the Secondary Turbocharger. So we will need to get the primary boost where it needs to be.
These are the easy ones to check:
Y-Pipe connector hose, (coupling)
* This is a very common failure part. This short hose, (coupling) will split and vent boosted air in copious amounts. The trick with this one is that when just looking at the part on the car it will look just fine. You need to remove the 90 degree plastic duct on top and completely remove the rubber coupling, then examine the rubber coupling by gently stretching it to see if there are any splits. Typically costs about $47 at dealer.
Check ~1" diameter hoses for leakage
* If you can rotate these hoses while attached, then the clamps are too loose. Get properly sized screw-clamps if the stock ones are not up to the job. New hoses will also help, but usually tightening the hose clamps is enough. A sign that there is air leakage is the presence of oily dirt on the aluminum casting around the hoses. New hose-clamps will set you back about $10 maximum for good ones. Note, clean up the oily dirt around the aluminum so that you will be able to see if these hoses start to leak again, (carburetor-cleaner works great).
Primary Turbo Inlet
* Typically collapses under high volume air through air cleaner into Primary Turbocharger. When the engine bay is hot the rubber is more prone to collapsing. Typical symptoms are having good boost at lower RPMs and then a loss of boost at higher RPMs, this is aggravated when engine warms-up softening the rubber allowing for easier and more complete collapse of the hose. Typically costs about $90 at dealer.
To/From Intercooler
* Same symptoms as the Y-Pipe coupler. When under boost, the hose-clamps prevent the hose from expanding due to the air pressure inside the hose. Do not under-estimate the force of 10 psi or more on 3" diameter hoses, what looks OK with engine not running may not work under boost conditions.
Giving me the full results requested above should help narrow the problems down. If it is a loud whoosh coming from the passenger side it cloud be a cracked Y-pipe.
You may have multiple issues.
1. Give a FULL report on your boost behavior based on the "chart" above. How it builds, drops... everything.
2. Do you have a vacuum/pressure test gauge? If not see if you can find one to borrow. Yhey cost less than $20, but hey thats still $20. We will use this later.
3. We need to get the primary working. The Secondary Turbocharger requires the Primary Turbocharger to generate more than 8 psi to operate actuators that control the Secondary Turbocharger. So we will need to get the primary boost where it needs to be.
These are the easy ones to check:
Y-Pipe connector hose, (coupling)
* This is a very common failure part. This short hose, (coupling) will split and vent boosted air in copious amounts. The trick with this one is that when just looking at the part on the car it will look just fine. You need to remove the 90 degree plastic duct on top and completely remove the rubber coupling, then examine the rubber coupling by gently stretching it to see if there are any splits. Typically costs about $47 at dealer.
Check ~1" diameter hoses for leakage
* If you can rotate these hoses while attached, then the clamps are too loose. Get properly sized screw-clamps if the stock ones are not up to the job. New hoses will also help, but usually tightening the hose clamps is enough. A sign that there is air leakage is the presence of oily dirt on the aluminum casting around the hoses. New hose-clamps will set you back about $10 maximum for good ones. Note, clean up the oily dirt around the aluminum so that you will be able to see if these hoses start to leak again, (carburetor-cleaner works great).
Primary Turbo Inlet
* Typically collapses under high volume air through air cleaner into Primary Turbocharger. When the engine bay is hot the rubber is more prone to collapsing. Typical symptoms are having good boost at lower RPMs and then a loss of boost at higher RPMs, this is aggravated when engine warms-up softening the rubber allowing for easier and more complete collapse of the hose. Typically costs about $90 at dealer.
To/From Intercooler
* Same symptoms as the Y-Pipe coupler. When under boost, the hose-clamps prevent the hose from expanding due to the air pressure inside the hose. Do not under-estimate the force of 10 psi or more on 3" diameter hoses, what looks OK with engine not running may not work under boost conditions.
Giving me the full results requested above should help narrow the problems down. If it is a loud whoosh coming from the passenger side it cloud be a cracked Y-pipe.
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