Turbo Over Boost When Cold

SargeIndustries · **Posted:** Mon Jan 31, 2011 9:26 pm

Has anyone with a boost gauge noticed a tendency of overboost when engine isn't up to temperature and mixture leaned out? With a scan gauge I noticed that the max MAP reading is 37.4. With my boost gauge I can get it to read 30 and then I have to add one atmospere on top of that. This occurs only when the engine is cold. Turbo also makes a warbling noise when boosting too much...

warp2diesel · **Posted:** Mon Jan 31, 2011 9:33 pm

Once mine shot up to 25PSI in the manifold when it was sub zero. If you measure the boost right out of the turbo it is higher. Since I want to know what boost the engine is getting, I tapped into the manifold and only get up to 20PSI when I drive.
Might just be due to the vines being a little sluggish to move and limit boost until the exhaust heats it up.

SargeIndustries · **Posted:** Mon Jan 31, 2011 9:51 pm

The noise still bothers me. I even rebuilt the turbo and still it makes the same warbling noise. I wish I knew how to post pics on this forum. I will send you pics to your email if you would like. 70,000 of homebrew bio tends to cause build up on the turbine...

warp2diesel · **Posted:** Mon Jan 31, 2011 11:37 pm

SargeIndustries wrote:

The noise still bothers me. I even rebuilt the turbo and still it makes the same warbling noise. I wish I knew how to post pics on this forum. I will send you pics to your email if you would like. 70,000 of homebrew bio tends to cause build up on the turbine...

There are several ways to post pics, I use Photobucket by Google (free). Sign up, upload the pics, copy the IMG code and paste the image code into reply page.

The noise may be just a harmonic in your custom exhaust system that comes to life in the cold. Use a video cam with sound and post on Photobucket or you tube.

SargeIndustries · **Posted:** Tue Feb 01, 2011 1:21 am

Turbo pics

Joe Romas · **Posted:** Tue Feb 01, 2011 9:20 am

Sarge.

In photobucket there's 4 choices. Use the last one, "IMG imiage", to link a photo. You can test your work have two explorer windows open and use the "preview" on LOST to make sure you have the correct one. It will automatically appear.
The correct one will start with [img] then the link to photobucket :SOMBRERO:

Hope this helps

As for build up on the turbo vanes. TDI's get a build up on the exhaust side variable vanes that cause them to stick too so it may not be your bio alone

Could what your seeing cold possibly be the vacuum that controls the turbo is weak when cold :?:

nursecosmo · **Posted:** Tue Feb 01, 2011 9:54 am

I can see where the turbine might be dirty if you are running sub-spec Bio, but why does the compressor look like that?

SargeIndustries · **Posted:** Tue Feb 01, 2011 12:17 pm

That is the exhaust side of the turbo. I replaced the boost solenoid but that made no difference. The vacuum canister maintains vacuum fine. When I pull the hose off, if bleeds off vacuum.

nursecosmo · **Posted:** Tue Feb 01, 2011 6:10 pm

Oh. I thought you were showing both wheels. There is a boost solenoid and a vacuum solenoid. Did you replace both? Have you compared the MAP signal going to the ECU to your boost gauge?

SargeIndustries · **Posted:** Tue Feb 01, 2011 8:07 pm

I did not replace vacuum solenoid. It appears to be a shut off for the whole vacuum system attached to the canister so it does not loose vacuum when engine is off. I am not certain of that. All I know is that there is no shortage of vacuum when it is cold. I have compared the boost pressure to the MAP sensor reading and it is of course one atmosphere higher of a number. Today I noticed that the EGT was 1140F the RPM was 1800 on flat road with my foot barely on the pedal. I was going about 53 MPH. The boost gauge read 19 PSI at the turbo. Normally when I am pulling a 6% grade the EGT only goes to about 950F with the vehicle warm. It sure seems like an excess of fuel is being squirted in when the vehicle is not up to full operating temperature. I can understand a little extra when cold, just seems like too much to me...

I am going to pull the turbo apart again and clean the fin area with a caustic solution so I know that out of balance will not be an issue. I only cleaned the back side because I was afraid I would damage the fins. Since then I have learned that I can boil the unit in a caustic solution instead of scrubbing and picking...

nursecosmo · **Posted:** Wed Feb 02, 2011 9:51 am

Solve the overfueling problem first. Once that's done, the turbine should take care of itself. 1140F will burn off all deposits in a short time as long as you are not adding new by overfueling.

Turbo Over Boost When Cold

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