My 98.5 seems to run great, strong towing and really no complaints, except I never see more than 8lbs boost on the hardest grades. My only other 24valve always ran up to 20 or better on long grades. I can't find any obvious leaks, it has a new inter cooler the PO had installed. The wast gate is welded shut. It is running an HX35. Currently running the stock 3" exhaust. I'm contemplating putting on a 4" system to see if it would wake up the turbo. On all my older 12 valves I have run up to 20 psi but they all had 4" systems on them also. What do you think? It makes a bit of smoke under load, but not too bad, but none of my previous trucks belched it, and I prefer not too.

 

If it runs good perhaps it's an indication problem as it don't think 8 psi of boost under load would be enough to say "it runs good".

 

Trust me, I've been towing with the CTD's for 20 years. Had them stock and hopped up. This trucks performs with the best of them. I am wondering if it is a gauge problem too. All my other trucks I put in mechanical gauges, this one has an electrical sending unit and I am not completely satisfied that it is not the culprit.

 

I assumed it was a mechanical gauge but if it's an electrical gauge then I would put money on it being indication.

 

Definitely the gauge. Borrowed a mechanical gauge and ran a long tube up to the cab to watch it as I drove. Truck is actually doing twice what the electrical gauge is showing. So at least now I know I'm getting plenty of boost. So now if I go to a 4" exhaust it will be just for better flow. Maybe a bit of MPG gain?

 

The stock exhaust is not extremely restrictive and keep in mind an aftermarket exhaust without an aftermarket exhaust manifold is only worth so much. I would check your intercooler hoses as they can seem tight but leak under boost. The boot from the turbo to intercooler tends to slip off. In stock trim you should still be getting 20-22 psi under load

 

YEP, the mechanical gauge confirmed that I was getting at least 20 when I got on it going up a hill close by with no load. Problem is evidently in the sender for the electrical gauge.

 

Glad to hear it seems like something simple.

 

Ok, found the problem. I had the sending units reversed for the fuel and boost. Since the fuel pressure gauge reads up to 60 psi I figured the 60 psi sender was for it. Now I show around 20 boost, but I only show 9 on the fuel gauge. Was showing 23 and that felt good!