Engine/Transmission (1994 - 1998) Little to no boost on 12V

[weshope]

Allright, I´m a little confused on what has happened. I did an oil change on my truck and now I have little to no boost. the day before, it was normal. the only thing i did out of the ordinary was to drop the full oil filter when i was trying to pull it out. it came to rest on the frame upright. i checked the line going to the wastegate actuator and it appears to be on the nipple. i was short on time before i left town on a trip (not in the truck - it´s at home in the driveway). i have a banks stinger 2 plus kit installed. i´m not sure if the big head was part of this kit since it was installed when i purchased the truck 7 years ago, but i don´t think mine is stock. the kit was probably installed 9 to 10 years ago. the truck now has 189,000 on it and is still as strong as it ever was. i pulled the air intake and the turbo spins freely by hand and at idle. when i increase the rev´s, the turbo spins faster, but not like it should. i´m going to double check the line connection at the wastegate controller when i get home. in the test drive, i can only get about 4 to 6 psi boost at 2200 rpm under load when going through the gears. it´s flatter than fritter when starting in 2nd gear too. is it possible that the wastegate shaft has too much resistance all of the sudden to respond like it should? what does an oil change have to do with my turbo not working? just looking for some ideas when i get time to troubleshoot more. i hate to see my baby sick.

 

[hsmith]

Check the innercooler boot. Maybe when you dropped the filter it knocked it loose.

 

[edgeman]

I agree... . when i did my fuel plate the intercooler tube was not hooked up completely and I had no boost at all but smoked alot... is your truck smoking alot!

 

[GAmes]

I can't add anything for the lack of boost, but, if you pull the turbo intake tube off (two screw clamps) the filter is a lot easier to get to. Then slide a gallon zip-lock bag over the filter before you spin it off. It will drop into the bag and not create a mess or burn you with hot oil.

 

[Dave M]

My 97 had a torn boot that caused my boost to never exceed 6-7 psi. Replaced the boot and then got boost up to 28 psi. Check the boot that goes from the turbo along the passenger inside fender and connects to the bottom of the intercooler. Right there is a metal lip where the sheet metal for the fender and inner fender well meet. That boot can rub against the fender lip and cause the boot to leak.



They may have changed the clearance between the boot and fender on later models but mine was rubbing there. I had to remove the boot to see the 3 inch split in it. Can't hurt to examine all the boots and tighten the clamps.



Dave

 

[weshope]

Thanks for all the quick replies. I'll check the boot. It did not smoke when i drove it. I had to knock something loose when I dropped the filter. I'll keep you posted.

 

[Signal73]

you can make a boost leak detector out of a 4 to 3" fernco fitting, and some PVC parts with a fitting to hook up to a compressor. cheap easy way to find your problem:





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[weshope]

I have checked the couplings and they look good. I have a stupid question. Is the wastegate controlled via vacuum? If so, is it possible my big head controller is bad? Can I hook up a vacuum source to check it?

 

[MLee]

I have checked the couplings and they look good. I have a stupid question. Is the wastegate controlled via vacuum? If so, is it possible my big head controller is bad? Can I hook up a vacuum source to check it?

waste gate should be pressurized, not vac. see the tool that was used to test the system, also pressure. If it still is not working check out the connecting rubber tube that goes from the metal tube to the waste gate connector though Ex. manifold. mine disintrigated and no boast, and high EGT.



Ps;; we don't know what truck you have.

 

[kenny61]

If you have a leak in the line going to the AFC and wastegate I diont think the boost will build up because the leak will prevent it from fueling which will in turn prevent thr turbo from lighting

 

[weshope]

So it uses air pressure to make the wastegate controller close the wastegate. What produces the air pressure? It looks like the rubber line attaches to the rear part of the AFC. Is there some type of pump in this? I'm planning to T a direct pressure reading gauge into the line coming off the AFC to see what kind of pressure I'm getting. If the pressure changes with RPM increase, then the controller would be the next in line. I would think I can pull the line off of it and pressure using a mighty vac tester to see if it will hold pressure. If not, then the diaphram is ruptured.



On a side note, how do I update my profile to show what I have here as far as equipment?

 

[kenny61]

ill tell u what to do when I get home in about30 minutes

 

[kenny61]

So it uses air pressure to make the wastegate controller close the wastegate. What produces the air pressure? It looks like the rubber line attaches to the rear part of the AFC. Is there some type of pump in this? I'm planning to T a direct pressure reading gauge into the line coming off the AFC to see what kind of pressure I'm getting. If the pressure changes with RPM increase, then the controller would be the next in line. I would think I can pull the line off of it and pressure using a mighty vac tester to see if it will hold pressure. If not, then the diaphram is ruptured.



On a side note, how do I update my profile to show what I have here as far as equipment?

It uses boost pressure to open the wastegate. Spring pressure holds it closed. The air pressure is actually boost pressure created by the turbo. the line goes from the manifold and splits off one to the afc one to the wastegate. To see boost the engine has to be under load, revving it in neutral will not produce any real boost. to check the wastegate diaphram you can either plug the line where it t's off to the afc or you can put pressure into it at the same location. if you have a compressor either using a regulator or shut it off at 30 psi and see if it holds the pressure mine was so bad it just blew right out the hole (wastegate)there was no missing it. the afc also has a diphram i dont know if you can hear it because it is inside the afc but you would be able to see the pressure dropping

 

[surfbeetle]

I have had my intercooler couplers get loose and the blue afc hose needed to be replaced at one point. You need to make the adapter pictured above and use a compressor to check for leaks. Worst case scenario is that you have a hole in the intercooler. Still you need to pressurize the system no more than 30 psi and look for leaks.



Also, get a boost gauge so that you can monitor your boost pressure as you drive.

 

[weshope]

I need another tool anyway. I'm on it. I have most of the pieces I need. Just need to make run to Lowes. I'll let you know what I find. Thanks for all the good info.

 

[weshope]

I made the tool, put the air to it and cannot get any pressure to build up in the system. I using a more simple version of the tool pictured above. I simply plumbed in male air chuck fitting and am using my differential compression tester. I can control the pressure input from 10 to 100psi. I only put 30 on it and the air is flowing, but I cannot find a leak. Is it possible that my wastegate is stuck in a partially open position? I also applied 30 psi directly to the wastegate controller and saw maybe 1/8" movement?? This does not seem right to me. The waste gate should be spring loaded in the closed position with no pressure to it. I also blocked off the pressure line that connects to the wastegate controller and drove it. No change. It is still flat off the line with basically the same boost on the gauge. I even T'd another pressure gauge into the line to check the pressure gauge. It followed the banks gauge mounted in the cluster. The most boost I can get is a very slow to come in 10psi with it matted in 2nd gear under load. This is not normal either. Any more ideas.

 

[kenny61]

the waste gate is on the exhaust side and would not effect your boost test. its possible the motoris in such a position where bioth the intake and exhausr valves are open during the overlap. I dont know how you are testing it.



1. plug the boot comin out of the cooler where it connects to the intake manifold apply pressure at the boot where in connects to the air filter. If you can not keep pressure there you have narrowed it down to those components



2. i am not sure abbout the valve overlap on a diesel so maybe someone else can chime in on test for boost leaks in the motor.



3. I i recall the wastegate actuator should move more than an eighth do you hear anything leaking when you put air to it?



4 plug the pressure sife of the line between the afc and wastegate and see if it runs anybetter. that will eliminate any guessing as to those parts of the system

 

[surfbeetle]

I too suggest disconnecting the pipe from the intercooler to the engine. Block off the exit from the intercooler and then repressurize. This will eliminate the possibility of leaks due to valve position. Then you can look for leaks.

 

[weshope]

I removed the wastegate controller so i could check the movement of the wastegate and do a leak test on the controller. When I removed the e-clip holding the rod end to the wastegate arm, the controller snapped, so the spring is working as it should. In fact I had to pry the rod end off the wastegate arm with a screwdriver due to the spring tension. I then put 30 psi directly to the controller. It moves maybe 1/2 inch give or take. The controller has a id tag that says 43 psi. It took about 60 psi to get it to move full travel so I could get it re-installed. To leak check it, I put a rubber hose on the nipple, applied 60 psi and used vice grips to pinch off hose to hold pressure. It held for 10 mins or better without moving. I can say with some certainty that it is not the controller. I will block off the engine side of the intercooler and see what I get. Thanks.

 

[kenny61]

there is also a diaphram in the afc that tears some times. I believe some people had an issue with the line going to the wastegate actuator leaking as well