Engine/Transmission (1998.5 - 2002) Boost

[Alexdring]

What would be the normal maximum boost on a stock truck WOT towing about 6. 5k? My truck will only reach 19 psi. Seems like there should be more boost. It takes forever for it to climb there too. Not exaggerating, it must take 30 seconds of WOT for it to reach 19 psi going up a hill.

 

[WOT]

Seems like 20 PSI is about right for a 2002 however it should get there pretty quick. What are your EGTs like during the period? If they are low then I'd say you are lacking fuel, if they get pretty high then i'd say you might have a leak somewhere that is bleeding boost off. There might also be something wrong with the wastegate.

 

[telliott]

yeah i think max boost on a stocker is right around 21, but like "WOT" said you should be able to get there very quickly at WOT.

 

[Alexdring]

Well the EGT's get up to 1000 easy and very quickly, towing or empty. It never has gone past 1000 WOT. It will pop to 1000 driving empty as soon as I hit sixth gear. To get it that high in any other gear I have to mash it and it will climb slowly, EGT that is. But in sixth it seems to almost automatically climb to 800 and then to 900-1000 as I apply fuel.

 

[WOT]

With low boost and not seeing over 1000 EGT I'm wondering if it is a fueling issue. I would think if you have fuel but low boost you would likely have some pretty high EGTs and some smoke. Do you have any error codes?

 

[WOT]

Give us some EGT and BOOST examples at:

cruising, flat ground, at 60 MPH (and what RPM)
up grade, foot on floorboard, max boost and max EGTs at that boost
cruising, flat ground, at 60 MPH w/trailer - if possilble

 

[Alexdring]

I have no codes, that is checking by the turning the key trick. I have other post about the codes. Here is what happened.



Had dead pedal, pump went out with about 6 codes. Had Cummins Northwest diagnosis it to verify. They said the boost sensor was bad too reporting bad readings.



Took it to another shop to save about half the price of Cummins, had the Vp replaced, along with the Boost sensor (which is supposedly a new sensor requiring a new wiring harness) and a FASS95 installed. I drove it home (about a 100 miles) from the shop and checked the codes again. Most of the same codes were there but a new one had shown up. Something about the wastegate staying open too long. I wasnt sure if it was related to anything with the pump install so I had all the codes erased by an auto parts dealer. Since then I have not had a single code.



Could my brand new VP not be "timed" or "turned up" enough"? I remember on my '91 there was a simple star screw you turned to get more fuel. Anyhow since I got it back about 25% of the power before the shop seems to be gone, sucking *** in mileage and the low boost, which I cant verify since I didnt install the gages until right before it went into the shop.

 

[Alexdring]

WOT-

Sorry I didnt see your other post. Your examples would be, assuming in 6th gear



Cruising flat ground at 60, not sure what rpm at 60 though

EGT 800 Boost 6psi



Upgrade WOT flat ground

EGT 1000 Boost 19 psi (eventually)



Towing 6. 5k trailer at 60 flat ground

EGT 900-1000 Boost 10psi



mileage according to dummy gage by review mirror states around 9 when towing with those conditions.

 

[WOT]

I'm trying to remember what my Y2k truck ran, but it seems like the 800 @ 6psi (60 mph empty) seems a tad high. I wonder if your boost line to the gauge is pinched - is it possible the boost is coming up faster but the gauge isn't reacting as fast? Does it "feel" like it is coming on slow? Do you have another gauge you could hook up and compare it to?



My Y2k could hit 1200 on a steep grade with the camper in tow, but that was about max so 1000 max does seem a bit low. I'm trying to remember if a 2002 wastegate can be pinned back with an anchor bolt or not... if so maybe you can make sure it doesn't come into play and try that to see what your boost looks like there (to rule out wastegate opening early).



Another thing to consider about the EGT is no baseline - perhaps the gauge is just a little off or the probe is too deep in the hole or too shallow? I'm assuming the probe is pre-turbo.

 

[Alexdring]

Correct the probe is pre turbo. Ya mine wont budge past 1000, I know this because I watch it like a hawk most of the time.



You might have something with the hose to the gauge being pinched. It was sort of a pain to install. I will double check that line this weekend.



Speaking of the wastegate, which i am focusing on since i had that new code after the shop, are you supposed to be able to move that rod that comes out? I tried and couldnt budge it.



Also another site suggested taking vise grips and pinching off that line to the wastegate to see if its a boost climbs faster (I am assuming so boost cant open it) What do you think about that WOT? Is it safe to do that? What about overboosting when you let off the throttle? Or is that what the blow off valve is for or are they one in the same?

 

[telliott]

at 60mph, 800 is probably a little high. on my 01, i typically see about 600 but with similar boost. I also have a lot more fuel than you, so maybe its not comparable. However, with that being said, more fuel usually means higher egt's. So theoretically you should be seeing lower egts than i am, not higher.



you would be fine pinching off the line to the wastegate (so the wastegate does not see the pressure and open. ) You can get different boost elbows coming out of the turbo that have smaller holes, or are adjustable. they basically do the same thing by keeping the pressure away from the wastegate.

 

[Alexdring]

Boost elbows? I will have to see what those are. I thought they were from the airbox to the inlet. Apperantly I dont know squat.

 

[WOT]

the boost elbows effectively bleed off some air pressure to prevent the wastegate from opening until a slightly higher pressure. You can test the canister by connection the line to shop air and a regulator. Slowly bring the air pressure up and you should see it move as you get to "max boost" ~ 20 psi.

 

[Alexdring]

Thats a good idea, i will do that this weekend with the air and regulator.

 

[DCreed]

pull the back off the housing and remove the actuator. get a flashlight in there and look for cracks in the housing or a warped or otherwise damaged puck that would make it not seal the hole when closed.

 

[EForbes]

2001 and 2002 have solid metal boost elbows to waste gate, you can smash them with pliers, or you can get a j-hook, which slows them down. The elbows that come with most performance add ons tells you they cant be used on late 2000 and up. And with no performance add ons you should have low egt. I have edge ez module, and on lvl 3 i have around 700-800 degrees driving flat unloaded with 6-7 psi boost. WOT 1100 and solid instant 21 psi boost, same when towing, except for higher egt with my 9k 5er. Check boost line, and exhaust probe as the others told you, you will figure it out.

 

[AWeaver]

you can always shut the wastegate... thats what I did. If you drill out the stop in the shaft that the wastegate rod screws into you can shut it all the way. I can get 30-31 psi out of my hx35 with my edge on level 5. Thats with the stock intake plenum and grid heater in place. Also lowered my egt's about 200 degrees at wot too... about 1100 max and the pyro is pre turbo.

 

[dknoch]

From my experience with a problem I had on mine: The hose from the intercooler at the driverside bottom, rubbed on the inner fender causing a hole that released air resulting in low boost. Since the waste gate was not seeing high enough boost to open for a long time, it froze shut resulting in high boost numbersafter I replaced the hoses. I freed this up with lots of penatrating oil and the air compressor with a blow gun shoved into the hose that the boost elbow attaches to to force air in. Good Luck!!!

Dan Knoch