Engine/Transmission (1994 - 1998) Testing Boost/ waste gate (I have no gauge)

[PWeber]

My truck has been dead on power since I got it. Someone suspects I don't have boost. Where is a good place to tap in to check boost with a temporary gauge? Also, does someone have a link that explains the functional operation of the waist gate and what operates it on a 1996? (vacuum, pressure, etc. I understand what it does but want to understand what actuates/ regulates it) Also, can I grab the lever on the waste gate "servo" down there and expect it to move by hand and will that hurt anything with or without it running? (I have a 1996 5 spd)

 

[illflem]

You'll have a hard time moving the wastegate actuator by hand but it won't hurt anything. Here's a good link on the wastegate.



Another for trouble shooting http://www.dieselpage.com/tips.htm



Connect a temp boost gage to the same place you do if it's perminate, on the manifold behind the injection pump remove the 1/8" plug and tap in there. You will have to plumb the gauge with hose to your windshield and tape it there as you will have no boost unless you are moving.

 

[PWeber]

From what I read I assume with low or no boost I would have major black smoke during "flat foot". I do not at all. Does that make sense?

 

[Todd T]

yes, it probably means you have no fuel then!



check the fuel filter, and pre filter screen. in fact if you dont know when it was changed just change your filter and mark that off your list.



your afc feed line could be cracked too. that would hold off your fuel.



check that your fuel shutoff is pulling all the way up.

 

[johnjackson]

It takes fuel to spool up the turbo. A boost guage is a must to know what is going on with engine. If your going to the trouble to hook up a temp, go a little farther and make it permanent. I really like my windshield post boost and pyro guage pod set up.



John

 

[PWeber]

I changed the fuel filter and checked the screen last week. No diff. Also, I hear the turbo very load and clear through the K&N filter. If the waste gate is dumping it will I still hear it the same, (or even louder?) My concern with hooking the gauge to the tap point on the pump is it does not really confirm I have a positive preasure situation out of the turbo, through the intercooler up to the intake. I checked all of the boot/ tubes on the intercooler and turbo. They are fine. Is there a good way to confirm boost intake preasure?

 

[Steve Roseman]

Before I purchased my guage set, I used a water pressure guage temporarily. I just used the plastic line and fittings that came with an oil pressure guage.

Having permanent guages is really nice, well worth the money.

If your afc isn't turned forward, it would be hard to tell if it's a boost or fuel problem by watching the exhaust.

A quick check to see if you're loosing boost and power because of your wastegate would be to pinch the line going from the turbo to the wastegate with some small vice grips. If you do that and nothing changes, the problem isn't with the wastegate. A guage would make things easier, you're working blind without one.

 

[johnjackson]

Tap boost guage right into intake manifold,not turbo. There is an 1\8" pipe plug in the side of manifold just waiting for you . Take out plug and install 1\8" pipe to plastic speghatti line fitting. Speghatti line goes to back of boost guage. Now you know what pressure you have right at engine.



John



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[PWeber]

OK, I was thinking this tap location was on the side of the pump actally sensing presure to the waste gate servo. My mistake as a new cat. I agree, I need to get a boost gauge. I will get one and try it next.

 

[PWeber]

OK, I talked to a guy today at the local "diesel expert" shop. He suspects the tube running from the pump to the waste gate has rubbed a hole where it passes by the axhaust manifold and said it operates off pressure. He said this is a common problem. Can anyone advise a troubleshooting process to check this tube?

 

[Todd T]

Originally posted by Todd T

your afc feed line could be cracked too. that would hold off your fuel.

i should have been a little clearer



you can take the line loose at the AFC housing that is the little bump out on top of the injection pump. blow or suck through it. if you can move any air, it's cracked and should be replaced.





be careful when you take it loose. dont bend it real far or twist it.



this line senses boost from the turbo and moves the AFC lever forward to allow the fuel stop lever to ride up the plate. if it doesnt move or is slow to move you get no fuel. no fuel, no boost and worst of all NO SMOKE!

 

[cowboy up]

Also check your hoses that connect to the intercooler and intake. when you hook up your boost guage it should be at 23 to 25 lbs of boost,atleast thats what my 96 5spd is at

 

[johnjackson]

PWeber,I was in the same place with my CA truck when it was new. Wondered if the turbo was working or if the waste gate was stuck partialy open. I ordered guages and they were on the way but I was impatient. Sooo, I unhooked the rubber waste gate line from the AFC housing at the back of the injection pump, took out the fitting and installed a 1\8" pipe plug in the hole. Just left the waste gate line laying there. The truck ran so strong it was sort of scary. This sugested a waste gate problem. I also thought I better install the guages right away before having so much fun turned into something else. With guages in and waste gate line still unhooked the 30# boost guage was being instantly peged ! No dought the turbo was doing it's job. I hooked up the waste gate line and could barely make 15# boost. I adjusted the waste gate rod by using 28# of air from a regulated compressor applied to the rubber line that conects to AFC housing. It took three adjustments to get the truck to go to 28# easily. It still pegs the guage if I keep my foot in it but does't act like the head might come through the hood any second like it did with no waste gate. Hope that helps.



John

 

[PWeber]

johnjackson,



Please check your PM. I just sent you a request.