Turbo Boost?

[rfoster]

This is only a drill. Information derived from this thread can save time and money if applied correctly:

What causes turbo boost or better yet what causes the loss of turbo boost?

There is no prize for the correct answer till you are on the road in the middle of the interstate - then you will appreciate the answer.

Find out tommorrow or the next day.

Answer Away

[Jon Wehrenberg]

Failed turbo boost sensor.

To check for turbo operation (especially on 8V92) make sure the exhaust system going into the turbo is leak free. Look for sooting.

If the exhaust to the turbo is tight, remove the air side or exhaust side, whichever is easiest to access and verify the turbo fan spins freely, and does not bind, have missing blades or wobble.

I had one sensor fail on my 8V92 and the bus couldn't hardly get past idle.

[hobobimmer]

Failed turbo boost sensor.

To check for turbo operation (especially on 8V92) make sure the exhaust system going into the turbo is leak free. Look for sooting.

If the exhaust to the turbo is tight, remove the air side or exhaust side, whichever is easiest to access and verify the turbo fan spins freely, and does not bind, have missing blades or wobble.

I had one sensor fail on my 8V92 and the bus couldn't hardly get past idle.

Word for word, that was going to be my answer, also. Jon just got to the keyboard before I did. Just kidding, Jon. I was going to guess leaky hub seals.

Eric Faires
Huntsville, TN

[JIM CHALOUPKA]

It's SHEEP, if you get SHEEP in the turbo the wool packs in and around the spool and binds it up. Simple as that, that's it for sure, NO!, maybe its BULL


JIM

[Mark3101]

This is only a drill. Information derived from this thread can save time and money if applied correctly:

What causes turbo boost or better yet what causes the loss of turbo boost?

There is no prize for the correct answer till you are on the road in the middle of the interstate - then you will appreciate the answer.

Find out tommorrow or the next day.

Answer Away

A loose or broken spring clamp on the intake tubing, usually between the turbo and the charge air cooler on a 60 series would do that. (this would apply on any engine, DD, Cat, Cummins etc.) Could also be a sensor, but those are more rare of a failure than clamps are....

[JIM KELLER]

Does altitude have an effect on Turbo Boost ? If it decreases boost is there a way to compensate.

[Kenneth Brewer]

Does altitude have an effect on Turbo Boost ? If it decreases boost is there a way to compensate.

Generally speaking, most turbo diesel truck engines have waste gates (internal or external to the turbo) to prevent excessive boost. I would not think you should be affected by altitude (less need for the wastegate to relieve) until you get to around 6 to 8 thousand feet. Our engine wasn't affected on our recent trip into the Rockies, but others may have a different story. Our Cat 3208 turbo started to fall off boost rather early and severely. Similarly, higher temperatures (lower air density) affect boost to an extent. But again, our series 60 doesn't seem to notice, which I attribute to excess capacity, but there seems to be slightly more boost pressure when it is colder. The BB was noticeably affected.

[Jon Wehrenberg]

If I remember Jack recently had a cracked intercooler on his Liberty that cost him boost and performance.

A failed turbo boost sensor is not uncommon, but is less common than broken turbo inlet pipes (on 8V92 engines).

[Gary & Peggy Stevens]

On my D60 I was having intermittent Turbo Boost Failure.

While driving I would notice the Turbo Boost Gauge would go to 0 and a light on the dash would come on. I took the bus to Stewart & Stevenson, and they determined I needed a New Style Barrometric Pressure Sensor. and ReProgram the ECM to the correct software level.

$700 later I haven't had any problems with the Turbo Boost.

Gary S.

[Jon Wehrenberg]

If my understanding is correct the turbo boost sensor works to determine how much charge air is available to the engine, and then DDEC via the injectors (which are solenoid controlled) introduces fuel in the proper ratio to air for combustion.

In the bad old days when stuff was mechanical you would see black clouds of exhaust from a diesel when the driver rapidly pressed the throttle or the engine was lugging under load. That was because the mechanical injectors introduced fuel relative to the position of the driver's foot on the pedal rather than how much air was available for combustion.

Since soot is on the EPA hit list, if the sensor fails in a manner in which it cannot measure boost or air pressure it only allows for the introduction of small amounts of fuel. If it fails in a manner in which it senses lots of boost pressure when there is none or very little there will be all kinds of black exhaust.

On 8V92 engines it is on the RH side, top of the engine looking forward. On the Series 60 it is on the RH side of the engine on the intake manifold, easily seen through the RH door looking over the batteries. It is a black plastic device about as big as a small cell phone.