BD Turbo stopped bulding boost

[Mag]

This is on a 10 800 pump gas kit. This sled has been ripping really well the last 1100 miles running 10-12lbs boost on 100ll. Towards the end of a ride Friday the sled stopped building boost and wont pull more than 6800 rpm. I've pulled the intercooler and charge tube checking for leaks, pulled the exhaust to check the donut, replaced the fuel filter,checked compression, pulled apart all connections and checked pins, checked the wastegate to make sure it's closed, checked the transducer and wastegate lines for kinks and leaks. If I blow into the ebc boost line the ebc reads boost but running the bd box shows -2 and sometimes will have a recall of about 1.5psi. There is no check engine light flashing. What's next?

 

[tdorval]

Is the turbo good?

 

[m1kflyingtiger]

Tps checks out ok? Also the stock egt probe? Does it go lean or rich when at 6800 without boost?

 

[Mag]

The turbo appears good it's not rubbing on the housing and spins freely, I havent checked the tps, it goes rich and I swapped exhaust probes with my other sled and nothing changed.

 

[m1kflyingtiger]

Did you check the wastegate itself or just the linkage? Could the flapper be broken?

 

[Super Dave3]

Check the throttle body boots?

 

[Mag]

I checked the flapper when I pulled the exhaust, I'll check the throttle boots and reeds tomorrow, it idles great and even on both sides unlike when I've ripped a boot before and it doesn't stumble or hesitate like a reed problem.

 

[Empire087]

If the wastegate and flapper check out, its gotta be a significant boost leak.

 

[m1kflyingtiger]

Can you unplug the ebc, and plumb in a mechanical boost gauge to see if it reads any different, possibly narrow it down to the sled or bd box? Another thing to try would be disconnect the pressure line to the waste gate and make a VERY short little run and see if it builds boost. Might be a moot point since it's bogging out rich instead of lean though.

I would get the TPS checked before wasting time on anything else. I had one go out of adjustment 3 times last year before going bad and not even holding a steady voltage while the sled was at rest. It can cause SO many weird thing with the sled.

 

[Kestrel2126]

My money is on either TB boots delaminated, or a cracked exhaust pipe. The IQ TB boots used to delaminated on mine pretty often, until I got a support plate installed. I also had a cracked pipe at one point too though. That one eluded me for a while, until I finally got the cutoff wheel and hacked the heat shield off, to find a 3" seam crack.

 

[Mag]

I pulled the exhaust shield and the pipe is fine, took the throttle boot off and checked reeds, boot is good I've always used the plate. While I had it tore apart figured I'd throw in some pistons. I had 1100 miles running spi's, exhaust side still looked great intake side had minor scuffing. Fired it up today and I still have the same issue, I never noticed before but the intake temp sensor in the intercooler isnt reading it just shows 000 in the display screen I checked the wires and ordered a new sensor. Any way to fool this thing with a resister or am I down for another week waiting for the sensor to get here?

 

[Mag]

I also reset the tps while I had it apart.

 

[Mag]

Hooked a manual boost gauge up to it today and it was building zero boost, at idle the turbo spins freely but as the rpm's go up the turbo stops turning let it idle back down and it spins again. There is a little end play so I'm assuming the bearings are junk.