Boost Issues

[ercaduceus]

Hello, I am hoping you guys can help me with some issues I've been having with my truck. I have been using the search function on this site but I am stuck. If this has been covered, I apologise.
For awhile I had been having issues with low boost. After checking the vacuum system I discovered a faulty solenoid. I replaced the part and the truck ran fine for a few months. Then things got a whole lot worse. No boost, no power, tons of smoke. The computer gave me the PO236 and high EGR codes. As a last ditch I cut off my Catalytic converter (couldn't get it apart otherwise due to rust) and ran around with just the down pipe (I know, I know I'll keep the windows open :o), waiting on a new exhaust. The cat was packed. I cannot believe the truck even ran at all. What a difference in power. I can hear the turbo. I get boost and peak at about 12 pounds until the computer kills the boost at high RPM.
Now my issue is that about 1/3 of the time I give the truck throttle and the truck seems to fall on its face. It makes a little boost (1-3 pounds), it blows smoke, and doesn't want to rev. The boost and RPMs will often slowly go up. This is significantly more than typical turbo lag. This seems to occur in the mid rpm range. Also, the computer is giving the code for low EGR flow. I assume because there is no back pressure. Does that have anything to do with my power issues.

Thanks for help and wisdom

[More Power]

Sounds like you're seeing more issues related to the EGR. Could be due to faulty EGR solenoids or the EGR valve itself, or due to low vacuum (vacuum pump or a leaking vacuum line).

Begin troubleshooting by ensuring the vacuum pump is generating 18-22" of vaccum with the engine idling.

If there are no vacuum pump problems or vacuum leaks, I'd probably replace the EGR solenoids on the bracket where you found the turbo boost solenoid. Be careful to re-install the vacuum hoses in exactly the same orientation as they were originally.

If still no change, I'd look at the EGR valve. In addition, if it hasn't been done in a while, the inside of the intake plenum may need a good cleaning to remove the build-up of soot.

Jim

[ercaduceus]

Thanks for the reply. I have 18" of vacuum. I'll check the EGR related stuff. I doubt the intake has ever been clean due to the fact that the truck tas sat in a barn for most of the last 10 years. Is there a way to delete the EGR? I had planned to put a non-EGR intake on the truck in the near future when I change the injectors, glow lugs Etc. I have heard from some people that I can just disconnect the vacuum line to the EGR and put a screw in it. However others have told me that the '98 and never trucks cannot be modified in that way. The vehicle is emissions exempt.

Thanks for reading

[More Power]

In the OBD I trucks, you can just unplug the EGR valve. Can't in the OBD II trucks.... I've heard some have installed an HD PCM, which doesn't look at the EGR stuff. Kennedy would know....

Jim

[ercaduceus]

I plan on upgrading to a perfomance ECU anyway. I'm having a hard time deciding who to buy through. I have heard alot about Heath recently. How does the Kennedy unit compare. I spoke with another company a while ago who would not sell me a non-egr performance ECU for a truck originally equiped with an EGR because of emissions. He said it was illegal for him to do so. I guess i should contact one of the other companies.