jeeptjstud

I am having issues with turbo lag. From a stop I cant build any boost until about 10mph. It smokes so bad up until this time I usually have to put it in second to avoid smoking out an intersection. Once I get up to 10mph-it does fine (30ish pounds), my problem is at take off.

No codes

I have replaced the MAP sensor, but was aftermarket (not cummins)

Even with my comp on 1x1-it still smokes like a chimney from 0-10 just easing into the throttle.

Ideas?

VADSLRAM

Check for leaks in the cooler boots. But most likely the bearings are a little gunky. Pull the air cleaner boot (while the engine is off of course) and spin the impeller with your finger. It should spin easily and turn over at least a couple of times with a single finger flick. If it doesn't then you have to push a lot more gas past it to get it to spin up.

AlpineRAM

How does it act when you start out in manual 1st gear?

The low stall converters are a bit tricky to get the turbo to spool because they put a lot of load on the engine at low vehicle speeds and low rpm. If your truck is in limp mode it will try to start in 2nd or 3rd gear from the line and will lug and smoke really bad.

And as VADSLRAM said, check your charger and intercooler etc for leaks, small leaks make a big difference at low rpm.

jeeptjstud

It lags the same. I dont think it is in limp mode because once I get to around 10-15 mph I can hit 30 psi very quick.

It wasnt like this before. My VP44 went out and I let the truck sit for a year or so before replacing it and now I have this issue. Any way it could be the comp module?

I did check for boost leaks using my compressor to pressurize the system and couldnt hear anything leaking. I am doubting a boost leak because I could hear anything leaking during the test and can hit 30psi, just like I used to before the truck sat once I am up to 15mph or so.

Would I be able to hear an intercooler leak

Truck has 180k on it. Wondering if the turbo needs rebuilt/replaced

Thanks for your help

AlpineRAM

I use soap water to check for leaks. Simply spray on, pressurize the stuff and look for bubbles.

Since the trouble came with the new VP44- did you use the correct key and install it the right way around?
(Could be that your timing is amiss, a probable cause for black smoke and bad spoolup)

Another possibility is that you get aerated fuel. This can be caused by corroded fuel lines from the tank to the lift pump, diagnosis is not too bad.
Replace the water drain hose from the fuel filter with a long transparent hose, route said hose into the
fuel filler neck, start truck and slowly open water drain on fuel filter. Watch for bubbles in the transparent hose, there must be none.
There are many different limp modes on these trucks, a transmission limp mode will not derate the engine. So, basically you have full power but less gears.
(Still easy to check with some pressure gauges)

Checking the turbo like VADSLRAM said and also checking the compressor housing for signs that the wheel rubs on the housing is a 2 minute job, could clear up the question whether your charger needs a rebuild or to be replaced. (If the truck was not abused and the oil was changed in time the charger has a lot of life left..have checked turbos with b-series cummins where the first charger was still good after 20 000 hours of hard running.. this would be a million miles at 50 mph)

VADSLRAM

Did you try spinning the impeller by hand? It could be that the bearings are stiff from coked oil.
I don't know if that was the case that a full rebuild would be needed. An old marine mechanic told me that he used to pull the oil lines and run straight engine flush through the turbo every 5k hours and that kept the turbo spinning easily. I don't know if we can do that on our turbos but I would think that if big marine turbos lag from oil deposits then our little ones would too.

jeeptjstud

Yes, I can flick it with my finger and the impeller will spin 1-1.5 times around and then stop...not sure if that is normal or if it should spin for longer. There is no play in the shaft.

I had a certified diesel shop install the vp44. At the same time they installed a new FASS and fuel lines up to the new VP.

AlpineRAM

Try it after the engine has run for a bit. Stop engine and within 2-3 minutes check how fast it stops.
A good turbo should spin a lot longer. (Like 10-30 turns after a quick flick with the fingers)

VADSLRAM

10 is about right for a basic turbo 30 would be a nicely tweaked one. 1.5 turns is your problem.
Are you running really heavy weight oil?
does it feel smooth when you spin it slowly by hand? If there is any feel of grinding/rasping/clicking etc. your bearings are shot. If it spins smooth but tight it could just be gunk around the seals or oil sludge in the bearings. The original turbo K-cars used to have a real problem with oil cooking in the bearings.