I've got a stock turbo and it will get 25* boost with no load @ WOT.Now my question is when I pull my trailer up a hill I get a loud pulsating "air" sound.(same blow off sound as when your on the throttle and change gears,but pulsating.)I changed all my intercooler boots and tightened all clamps.I haven't checked the intercooler yet because it sounds like air coming right at the passenger side?
Would I have an adjustable wastegate? Check intake gasket? or just check intercooler?
Thanks

 

Sounds like its surging, but i cant immagine why it would be. It is deffinatly a stock turbo?? Think were going to need pictures and videos of this one. It is a good idea to check the intercooler plumbing pressure. But if your holding 25 psi i dont think thats the problem.

I know of 2 scenarios were u will have compressor surge, the first is when u lug the engine hard, n have the pedal floored causing the turbo to try n force more air then the engine can accept.
The second is releasing the throttle FAST (like sled pulling) with the turbo turning full tilt.

 

What RPM is it happening at? With all that fuel on the stock turbo and a 5spd, I'm not too surprised. There are a few options to fix it; from the looks of your signature you need a bigger turbo anyway. A hybrid or HX35 will probably be too small for your truck too.

What are your EGT's and boost like? An S300 based turbo would be ideal, but they're pricey. Basically what you're looking for is a turbo with a map width enhancement slot cut in the compressor shroud. Depending on how much fuel you have, an HX40 may work.

 

Check the BHAF to see if it has a hole. If you can't see a hole use a little finger pressure all around the filter to see if a hole opens up, if it does it could be causing the surging as the turbo spools up and creates a suction on the element in turn opening the hole.

 

I'm pretty sure it's "stock" turbo.Truck has 291,000 kms on it.I can hold 20-25 pounds no problem @ WOT,but I come to a bit hill (with a trailer on cruise) pulling 70mph with 10* boost,the engine starts to lug,boost climbs but when gravity and weight take over I start slowing down.Truck starts "surging" when boost drops below 19* down to 10* then my EGT climbs to 1300 very fast...by then I've grabbing a different gear 'cause my HP droped to...
I will get some pics and video this Friday...thanks for your help.

 

I looked it over really good,couldn't see nothin,but just for a test I put on the orginal intake and K+N with a gutted box.didn't help.

 

RPM is cruising speed 70mph @ 2000 rpm,boost @ 6 and 800*EGT "unloaded" on level ground.At WOT boost can get 25* 2700 RPM and 1200*EGT "unloaded"

 

So your saying your loosing boost when your climbing a hill?
U need to get the Intercooling system pressure checked if thats the case. Others will chime in shortly here, im kind of baffled on this one.
Im going to ask about obvious things now, when is the last time u checked the fuel filter, or replaced a lift pump? Cause it almost sounds like your running out of fuel too.
One one side of the coin, your holding 25psi, but on the other, the truck surges, n u lose boost. typically u either have a boost leak, or r running out of fuel. Plumb in a fuel psi guage asap to see where your lift pump is at as well as psi checking the intercooling system.

I ran around for months on a blown ic boot and NEVER even realized it nor had reason to think about it.
My best friend ran around for a while on a bad lift pump, n we didnt know it till he got tired of it falling on its face in the higher rpm band. The VE can and will draw its own fuel.

 

Thanks for your help,I've changed fuel filter about 8000 kms ago,and I've never messed with the lift pump...(bought the truck used 1 1/2 years ago + 270,000kms).
The truck runs like a top when I'm not pulling anything...(no noise or mothing),but when I'm pulling a load and boost spike's the truck starts falling off and the surging starts.

 

I have had a chance to think about this today, check into your lift pump. You may be driving on a dead LP. Under load your using more fuel obviously, thus the VE/LP isnt pulling enough fuel. I suggest getting down to your local parts store n plumbing a fuel pressure guage with a needle valve/snubber valve (a good lp pulses, thus beating the guage to death) even if its an under hood and ideling check, u should see something.
If your LP is in fact dead, it would be a good opportunity to swap up to the piston pump like the second gens have.

 

Cowboy Customs-Thanks for your help again...I think I seen some pics for this setup on here or should a guy plum this gauge into cab? Is it true that a second gen.piston pump doesn't last as long? It shouldn't if alot of people are changing over...

 

Its a good idea to plumb a guage inside to keep an eye on things deffinatly. I havent heard of the second gen piston pump dying out "offten." The biggest reason why most guys dont switch is its like 200 bucks for the pump, VS. the cheaper LP we have stock. If ya look up in the sticky (i'll link to the article too) theres a write up on the swap with the low pressure piston pump we require.
https://www.dieseltruckresource.com/...ad.php?t=93722

Its a little involved n a small investment to do it, but worth it in my opinion. Figured id mention it to ya if u end up having a dead, or dying LP.
Sheid is listing a "fuel pump" for the second gen at 98 bucks. Im ASSUMING this is the LP, but they usually go for 200. May want to call them though and verfy it.

I hope thats what ends up being, im all out of ideas! Good luck to ya!

 

I had a near stock 91 with the Lagmaster21 that would surge- at the time I thought the flutter was just the nature of the beast.

If you are at peak boost and then drop boost as RPM drops, you have a fuelling issue. Usually, the torque backup will increase fuelling (to a point) as RPM decreases, letting your boost stay relatively constant.

Next time you are towing, try dropping into 4th at the bottom of the hill and get the RPMs up a little. You may just be lugging the engine for the load. Can you press the pedal down a little and maintain speed? If so, you may have a cruise issue.

Daniel

 

dpuckett-the last time I drove it I grabbed 4 about mid way up the hill and the truck was @ 2300-2400 rpm and I couldn't get the truck to stop fluttering,but once the boost dropped below 10* in was o.k. and if I was able to get it to climb over 20* I would be laughing-no more fluttering.On level ground and running through the gears to 2200 each gear the truck doesn't miss a beat.
I will take some advice...I'll plumb a gauge and take some pics+video and post for your guys.Thanks for your help

 

I think a stock turbo can surge like that, and the advanced time will aid in that as well. I think without a MAP WIDTH enhancement slot in the turbo you need to be darn near stock to keep from surging under load like that with bombs!!