Engine/Transmission (1998.5 - 2002) Question on turbo wastegates

[TomGolden]

Hi all,



I have isolated my truck's mysterious power loss to my turbo. I had been calling it a de-fueling, since I thought it was a sudden loss of fuel, but I have since found the problem is somewhere in my turbo.



In short, at WOT maximum acceleration, at about 2000 RPM, after a few seconds of hard pulling, suddenly the engine felt like it just quit. Then, after maybe 3 - 5 seconds, with the pedal kept on the floor, the engine just picked right back up and accelerated as expected again. I tried a new Comp box, switched to a new fuel filter, tried a new MAP sensor, cleaned my IAT sensor. All did nothing. Someone suggested it may be a turbo problem, since when everything cut out, all of a sudden my boost gauge showed a vacuum (like -10 PSI), maybe the wastegate was opening waaaaaaay to soon. Bone stock HX40 set to 43 PSI.



So, I got out my allen wrenches and adjusted the set screw in my adjustable boost elbow to the fully closed position. I figured this would basically cause the wastegate to never open. Well, another WOT run down the freeway, the power cut out didn't occur until around 2700 RPM, and it lasted only about 1 second, instead of 3 - 5 seconds.



This seemed promising, so I pulled the boost elbow, and checked it to see if in fact it was sealing solidly. I blew into the end of the elbow, and it was still allowing a tiny amount of air to get through the elbow, so I replaced it with a solid plug in the turbo so there was absolutely ZERO air going to the wastegate actuator. After several more WOT freeway runs, I now have absolutely no power cutting out. I am able to make 39 PSI on the boost gauge with the Comp on 2x3 in all gears, so it appears I have finally solved this nasty problem.



My question is - It seems that the problem is in fact with the wastegate mechanism. If I get the turbo off, is there anything in the wastegate mechanism that can be adjusted, or is it such that the wastegate is toast and now I have the excuse to upgrade to a B1



Thanks,

Tom

 

[Whitmore]

Tom

I would just leave the plug in and call it good, its fixed, I think you are safe up to 40 for sure... ... ... ... ... Kevin

 

[GeneralMachine]

Waist Gate?

Hi Tom Im haveing a simular problem with one of out service truck's, around 70 mile and hour it will cut back like you are explaining and then will just pick back up and go somemore with no problem's, this truck is stock and has good fuel press. it is a 2001 3500 i think you might be on to something with the turbo. for we have been trying to figure out what's going on with this truck for awhile. Sorry but im not sure if there is any adjustment it look's all preset on this stock one to me. Harv

 

[Steve Campbell]

What this sounds like to me....

... . is the "elbow" should have a very small hole drilled "downstream" (wastegate actuator side) of that set screw you were tightening down. If the air that gets by the set screw can not escape the short line to the actuator fast enough, it would be holding your wastegate open until the boost pressure in that line finally does escape.

 

[fj40charles]

I'm having the same problem Tom is describing. However, I can get 30 PSI max boost (adjustable eblow) with DD2's and Comp on 1x3. I'll hit max of 30 PSI with comp on 5x5.



This would lead me to believe it might be related to a wastegate and/or boost elbow. I've got 3 adjustable boost eblows I've been experimenting with and they all seem to work differently. The latest one seems to have the largest bleed hole on the waste gate (where the hose connects) side which should delay opening of the wastgate since it will be

"bleeding" more air and not allowing pressure to build up as quickly.



Using a plug has yielded the highest PSI (36 max) with comp on 5x5 unloaded on the highway. I'm sure I could get more boost if I had a trailer behind me.



Anyone know if there is a way to see if the waste gate is completely closed on the turbo without having to remove it?



Charles

 

[fj40charles]

TTT

 

[LSMITH]

Charles, grab the wastegate actuator rod and shove it toward the front of the truck. If it moves it was not shut all the way. They can be stuck or sticky from soot buildup.



Steve, all of the elbows I have seen with the setscrew in them have a small bleedhole drilled into the setscrew. I have not gotten ANY effect from them by turning the screw.