no catalytic converter/turbo probs

[farmerpatrick]

Hey guys,
I get an intermittent SES light and am pulling a PO236 code (turbo boost sensor A). I just bought this truck and I want everything to be right before I go and start fooling around with it. I made an appt with the dealer service department, but since then I discovered that there is no catalytic converter or muffler on this truck. I thought it just had a loud muffler when I bought it. Is there possibly not enough exhaust backpressure to properly run the turbo. Note: I don't hear any turbo whine in the cab when pulling and there is a moderate amount of black smoke when accelerating. I don't think the black smoke is excessive by any means, but I get it all the time whether pulling or not. I've never driven another 6.5 but I did expect a little bit more power. Truck has 116K miles. 3.73 rear end. 8600lb GVW. 4wd. 98 model. Any help would be appreciated.
Should I go ahead with the dealer appt?
Should I install a catalytic converter for backperessure?
Anybody know of any top-notch diesel shops in the Florida Panhandle? I'm near Pensacola.
Thanks,
Patrick

[MTTwister]

Patrick - to get the ball rolling until more knowledgeable folks join in -
1. You don't need / want back pressure on the turbo charged engine. Ideal is to eliminate back pressure.

2. black smoke - turbo is probably not pumping enough air - black smoke = "too rich'.

With the engine idling, you should not be able to push the wastegate acutator rod ( on the turbo) down, it should be suck up by the vacuum.
on the drivers side there is a wastegate solenoid that contrls vacuum form the vacuum pump. you should see about 20" vacuum coming from the vacuum pump, and about 15" going out of the solednoid. These have been known to fail, either internally, or the wiring harness to it. There could also be breaks in the vacuum lines that impede the performance of the wastegate actuator on the turbo ( ie screws things up).

For futher information on this, do various searches on the forum related to wastegae, wastegate solenoid, vacuum, etc and there is a wealth of discussion. Chances are you might be able to find the problem without paying the dealer a chunk of change.

Good Luck!

[Andy Chesek]

See this thread: Code 236 (http://forum.thedieselpage.com/cgi-bin/ultimatebb.cgi?ubb=get_topic;f=1;t=006329#000001)

If you like to at least tinker with your vehicles, you can fix this yourself without a trip to the dealer. Saving money and improving the reliability/power of your truck is what this site is about.

Many members, myself included, run without the catalytic convertor. In a turbo application, you want less backpressure.

[Cowracer]

Originally posted by farmerpatrick:

Should I install a catalytic converter for backperessure?
The whole "turbo needs 'backpressure' to function" thing is a myth. Turbos will never be more efficient that when the run with their outlets open to atmosphere. (well actually, that's not entirely true, if you can have one exhausting into a perfect vacuum, well, that would be more efficient)

Any pipes or anything attached downstream of the turbo reduces exhaust gas flow and reduces turbo efficiency.

Tim

[farmerpatrick]

turns out vacuum pump and wastegate solenoid are both shot.

[20050627|3|008327|000043|65.183.99.20]

Then I'd look at pulling them both and using a TurboMaster
Heath (http://www.heathdiesel.com/T/Chevy-GM/Chevy-9601/Turbocharger-Boost-Controllers/)

But a 96 may have different issues then my 94. My stock setup is working but if it ever gives me trouble, off it will come.

[rjwest]

If you have to go to the dealer for each little problem that occurs with your 6.5l diesel

SELL SELL SELLL It Now, Or you will soon be in the poor house....