Engine/Transmission (1994 - 1998) Wastegate Removed

[MMcCallie]

I'm troubleshooting a drastic loss in performance after a turbo upgrade. I just had a mechanic install a Garrett Hybrid Stage 2/3 turbo and a Spearco 6. 0 Intercooler. My truck had previously dyno'd near 600 HP and 1,200 TQ with an HTB2 62/12 and stock 7. 3 intercooler. With an AirDog 2 200 GPH the truck was running better than ever just days ago.



Now that the truck has more new parts and is all buttoned up, the entire sensation of getting slammed back into the seat is gone noting a tremendous loss of seat of the pants torque, horsepower, and speed of acceleration. Surging is also drastically worsened so that at the right stage of speed, throttle, and boost it will surge up entire hills.



Good news is that the new ball bearing turbo now shows a couple psi of boost in Neutral with RPMs under 2k, and starts reading boost immediately off idle in Drive. Corresponding throttle response off idle is amazingly improved as well, as I can not only see the numbers rising I can also feel the air feeding the engine virtually off the line. However, under hard acceleration, smoke is increased, now a heavy gray instead of the previous black. Initial takeoff is just a small light gray puff under average acceleration.



I had told the mechanic to install the new Garrett with the wastegate on but to use a zip tie to pinch the line. Instead, he decided to remove the wastegate. I have not looked at what he has done and am not terribly familiar with wastegates. He used an 1/8" NPT threaded plug to seal one end where he figured air could leak. He said he could not move the actuator rod by hand and did not think it would move without being hooked up so he left that on the turbo.



I am hopeful that my tremendous loss in performance is directly related to the complete absence of the wastegate. Is it possible the actuator rod is still moving and that I have a huge boost leak? Does the rod move from a valve or flap internally, not just by the diaphragm or rod?



When driving the truck, the loss of power feels very much alike a boost leak. The turbo is producing just under 50 psi boost. The mechanic blew the boost hose off the intercooler on the driver's side on his way to show me his progress. Boost climbs slower than the old S300 and allows far more smoke. EGTs max 100 degrees lower than previous, but numbers seem high getting there. I pulled and covered the AFC and briefly test drove and found no improvements, just more gray smoke. A lot of gray smoke, heavy enough to block visibility across the road at all highway speeds.



We will try reinstalling the wastegate tomorrow. I've read the Garrett turbos usually come wastegated at 40 psi but I've been told that for my custom application, setting it at 50 psi would be a good tune. I have quickly checked smaller boost lines for leaks but have found none. If the wastegate does not solve my tremendous loss of power problem, does anyone have any ideas as to what else could be happening?



Peak boost is the same though it climbs slower, power is extremely low, EGTs are lower, gray smoke is increased.



Thanks,

Matt

 

[MMcCallie]

Update with the wastegate reinstalled. This morning it was driven with the wastegate set to stock or however it was set when delivered to me. Boost was just under 47 psi and EGTs were in the 1500 degree range. Power seemed just a little more snappy. Using zip ties to pinch off the wastegate line, boost reached 48. 9 psi at roughly 100 mph. This is where even more changes were observed.

First run with the line pinched was to about 48 psi with EGTs only hitting around 1213 degrees. Even on the highest boost run EGTs were in the 1200 degree range. The highest we could get EGTs to go was a little over 1,300 degrees on two attempts. Unfortunately surging has not improved. Smoke never completely cleans up on a hard run. Always at least a haze, a lot more black in color today. Still smokes very heavily with lots of throttle at low speeds. Fuel pressure generally floats in the upper 40s up to about 52 psi but under hard runs drops into the 20s, more frequently 30s.

Power is just slightly improved. Only two times when EGTs did exceed 1,300 degrees was there a hint of the familiar slamming back into the seat during hard acceleration. The improvement was noticeable but still not as forceful as with the old turbo. It almost seems as though the turbo might have a break in period and is just beginning to warm up but we can't imagine such would be necessary on a ball bearing turbo.

Boost is still showing very early, even in Neutral. However, when giving heavy throttle from low speed there is tons of black smoke and the truck takes a long time to accelerate or to see boost climb, which is then finally quick. When power braking and letting go once boost is strong, the tires do not even chirp, no black marks. It absolutely should be spinning the tires and slamming us into our seats. Stock turbo used to leave 60' of rubber when power braking.

Still no sign of leaks. I'm very impressed that EGTs have dropped so far. A month ago EGTs were exceeding 2,200 degrees and had melted my heater box. I'm wondering if the elbow coming from the turbo to the boost tube could be leaking. I've been told there is a small o-ring there that can be difficult to seat. Engine coolant was around 150 degrees before we began testing, reached over 200 degrees a few times, then fan would lock and bring the temperature down.

I'm also wondering if the intake plenum cover could have a leak somewhere. There is some oil on top of it but my valve cover gaskets appear dry. For now I'm still stumped but will be calling some Garrett dealers tomorrow for advice. I really think this turbo should rock and roll far harder than the S300 since the CFM is so awesome. Any ideas? I'm planning to dyno the truck tomorrow to verify the loss of power we agree is missing. I'd really like to be able to try some fixes and or some tuning before strapping down.

 

[hsmith]

2200 degrees?

 

[MMcCallie]

Yes, my heater box melted. A guy in Colorado had built me a custom intake manifold and I didn't know it was leaking and not getting air into the engine. 2,200 something degrees melted my heater box. I had to get an entirely new head that wasn't butchered.