Engine/Transmission (1998.5 - 2002) Over Boost / Boost elbow question

[Walt-L]

Not long ago I put a boost gauge on and noticed I can regularly hit 24-25 lbs of boost when I first get deep into the throttle. From the post's I see it should be about 20 stock. So I checked for codes and sure enough there were 2 over boost codes set. Iv seen pictures of those boost elbows and thought may be the previous owner might have put one on. So I was hoping some one can tell me just where on the block does this boost elbow go! The truck does run rather flat (defueling?) when you get in the juice petal. Is there a sensor for boost that may have gone bad if there is no boost mod? I have a set of bosio RV275's that still need to be installed. Am I right in thinking even with the 275s, it will still defuel at 25lbs of boost? Will it run better with the 275s and stock 20lbs of boost since there will be no call from the ecm to defuel? I can't go for the MAD right now (byin Passat TDI wagon), so i need a opinion on get it back to OEM boost or leave it alone once the 275s'are in?

Thanks a bunch for the help

Just got back from a test drive to make sure I didn't monkey somthing up and still have a solid 25LBS boost WOT up the hill. AND I got the 2 overboost codes again. Could a week actuator let the boost slip to 25? Could it be out of adjustment?

 

[DwayneKelch]

Walt-L,



The boost elbow screws into a port on the compressor housing of your turbo. The boost elbow is connected to a diaphram that actuates the wastegate in the turbine housing of your turbo. The boost elbow will either be hard-piped or have a rubber hose that connects to the diaphram. Does your truck have an automatic or manual transmission?



Since you're not the original owner, it's quite possible there used to be a fueling box on the truck. If so, there's going to be a restricter fitting in the boost line/elbow to the diaphram. Too, it's possible that the wastegate is hung up/defective. Either way, this will allow you to build more boost before the wastegate is actuated or opened at all. However without some sort of boost fooling capability the boost felt at the MAP sensor will send the appropriate signal/voltage needed to cause the ECM to decrease fuel, thereby bringing boost back down.



Even with the RV275s, you'll need some sort of boost fooling capability (EZ, TTPM, MAD ECM, etc) and the modified boost elbow/line. Remember, the more fuel you add to the cylinders, the more combusted gases you get, in turn, the turbine spins faster, the faster the turbine spins, the compressor builds more boost. It's a viscious cycle that's controlled by the MAP, wastegate, and ECM to prevent the turbo from grenading.



Dwayne

 

[Walt-L]

Dwayne, Thanks for the tips, I have a Auto Trans. The boost acuator has a solid pipe that comes off the back of it ,turns, and goes directly into a port in the turbo housing. I tryed to remove it and got as far as haveing the actuator pipe out of the grommeted port and that was as far as you could pry it without the possibility of bending the rod to it or denting the diafram body. So it seems the wast gate has one hell of a return spring on it somewhere internaly that keeps the actuator planted even tho you have the nuts loose and pipe out! The Wast gate rod arm has zero lateral movement so you can't just slide the acuator off the turbo bracket. Is there a "procedure" to take the D*** thing off ? I thought the wast gate could be checked by hand for hang ups once the actuator was off. Then How do you know you have the correct adjustment in the threaded actuator rod? I would guess you would turn the actuator around and around untill you have no more slop in the adjustment? Does the diafram suck in or push out to work the wastgate? My aim is to get the over boosting fixed so I can see what the thing is supposed to run like stock before I move on with the rv275's and then the MAD ecm down the road. I can't thank you enough for the free education!!

 

[DwayneKelch]

Walt-L,



If I'm reading your post correctly, you have removed the two nuts from the back side of the wastegate actuator (diaphram) and have tried to pry the actuator away from the compressor housing!?



After the nuts are removed, spring tension will hold the wastegate actuator in place. Therefore, the actuator must be pryed off its seat (bracket), horizontally, to remove the boost tube from the compressor port.



Once removed, apply 20-25 psi to the boost tube to see if the control rod moves the wastegate. The travel isn't much, around 1/4". If it doesn't move, try to move the control rod by hand to exercise the wastegate. If it moves by hand and not by air pressure through the actuator then you've got a bad actuator. If it doesn't move at all then the wastegate is hung up.



Also, take a look at the end of the boost tube (end that goes into compressor port) to see if there's a restrictor fitting pressed into it. It's much smaller than the tube diameter and will have a whole drilled in one side of the tube. If there is, you'll have to apply 30-35 pounds of air to the boost tube to get the actuator to move the wastegate.



Let me know what you find.





Dwayne

 

[DieselMinded]

with my Comp (BOOST FOOLER) removed from the truck and the Turn Buckle Removed from the waste gate I was continuely getting the over boost code my self ... not sure if its the pusher pump Mod or the BHAF or the added load via TC upgrades but I was over boosting with everything else stock... I just cleared the codes and put my Comp back on and all is well.



DM

 

[Walt-L]

Thanks for the rep. I can tell you that there is no device in the tube to the actuator or in the grommeted hole. So its a factory set up. I was useing a 16" screw driver to pry the actuator off the bracket to the right and was only able to get the tube out of its seat. From the looks of it the acuator does not slide off to the right of the bracket. I probed the tube and houseing port and found them empty. Im thinking now that maybe the op. rod unscrews from its female counter part to alow for removal. And since there is no lock nut on the threaded op rod, the rod may have over time backed out alowing the wast gate to not open as far as it should to dump the extra boost. Does any one know if the threaded operating rod that comes out of the acuator spin freely of the diafram inside the acuator body? IF IT DOES, I will guess that is where the over boost could be coming from. If Im right, I will need to remove it by unscrewing the op rod from the female end that is riveted to the wastgate fly, Put a lock nut on it, then reassemble and keep test driveing it untill I get the rod turned in to the piont I only get 20lbs boost, THEN lock the setting in with the added lock nut. Please comment if this sounds right.

 

[DwayneKelch]

Walt-L,



I know the earlier model turbos (1998 12v and earlier) used an adjustable control rod (AKA turnbuckle) to set the amount of boost at which the actuator would open the wastegate. There was a clevis that fastened to the wastegate lever via a nut. The clevis could be removed from the wastegate lever and the length of the rod adjusted by turning the rod in or out of the clevis. Once properly adjusted, the jamb nut is tightened to prevent the rod from turning inside the clevis.



It appears, although I haven't personally done it, that our turbos have an adjustable control rod too, although no jamb nut. If you look closely at the end of the pin that goes through the clevis you'll see a retaining clip. If you remove the clip you can slide the clevis off the pin (wastegate lever). This will allow you to turn the clevis to shorten or lengthen the control rod. I'm not sure if spinning the control rod within the actuator will damage the actuator, so I'd be careful when turning the clevis.



Before I attempted any adjustments, I'd apply air pressure to the actuator to see if it moves the control rod/wastegate lever. Have you tried this? Start at 20 pounds and gradually increase until you see the rod move. I wouldn't exceed 30 pounds of pressure.



When excessive boost is felt at the actuator, the control rod moves toward the back of the engine compartment to open wastegate valve. You should be able to push the rod backwards and watch the clevis (connected to wastegate lever) move slightly.



Not much room to work with the turbo inside the engine compartment. Have you thought about removing the turbo and adjusting on the bench? Also, it would allow you to inspect everything a little easier/better.



Hope I've been able to help some. I wished I had a shop manual and parts breakdown I could refer to for detailed info.



Let me know what you find. Thanks.





Dwayne

 

[Walt-L]

Dwayne, Now I think I know what I have to "TRY" to do. The female end of the actuator rod siimply has a flat end on it that I thought was riveted to the wastgate operating lever. You say that there is infact a E clip or spaner clip that holds the op rod in place there. Well, if there is, and I think I felt something there that could be this clip, it would be a royal PITA to get at to push off LET ALONE pinch back on! Beleive me when I tell you, there is absolutly NO slop on this clip/clevice pivot. Im not going to fart around with this actuator with over 100K on it. In the morning Im going to order a new actuator, beat,grind, pinch, twist the clip off while I lavish this hidden assembly with a wealth of abusive verbage!! Will the pivot pin come off once I manage to get the clip off? Hope fully it does at which piont I will make up a new pin that will have a double nut arraingment on it or something similar to EASE reassembly. I tryed to take the turbo off once to drill the manifold for the pyro sender and just flat out could not get the forth nut loose with out knowing I could not get the leverage to get it retightened again. So I did the grease and magnet trick.

Once again my hat is off to you for not blowin this off !!

I will certainly give this post an update on how I got the overboost fixed with out the ECM up grade. THANKS!

Walt

 

[DwayneKelch]

Walt,



Best I can tell, the pin is part of the wastgate lever. Once you remove the e-clip, the clevis just slips off the wastegate lever/pin. Not sure any modification would be possible, especially with the turbo still attached to the engine. After the clevis is free from the wastegate lever, removing the wastegate actuator would be simple. Once the actuator is removed, apply compressed air to the actuator to see if the control rod moves.



Also, after the control rod/clevis is disconnected from the wastegate lever, see if you can actuate the wastegate valve by hand. Hopefully you can.



Hurry up and get this problem fixed, then install those RV275s. Oh yeah, don't forget some sort of boost fooling component. Good luck!





Dwayne

 

[Walt-L]

Well folks, just found out that Dodge can only sell the wastgate actuator WITH the turbo assembly! I guess they are loosin too much money just to stock that meaningless little (made in mexico?) part. The guy did say try a Cummins dealer, they MIGHT have a individual PN for it. I can remember when you could... ... ... ... ... . , Oh, whats the use

 

[Walt-L]

Id like to close this post with the big bucks cure. Marco's CaTCHER. It is actualy worth it!! The truck is running great now and I imagine with the 275's going in next week I will have all the power I personaly would ever want. With just the Catcher alone I max out at 29 lbs boost now. Thanks again to those who have helped with this post.