injector timing 6V92

[skihor]

 Our newly purchased MC7  ran great for the first 100 miles then a noticable lack of power, rough running, and much more black smoke. 6V92 with 9G90 injectors, 4 speed auto. I had a Detroit shop diagnose and replace a stuck injector. They did a full tune... Adjust the injector timing, valves, jakes, run the rack. They set the injector timing to 1.484
Now under even 1/4 throttle I'm getting HUGE black smoke. On the freeway before it only had the slightest dark smoke when floored. In town a little when first taking off then cleared quick. 
My question is: What could the shop have done to cause the black smoke to be so bad ?

Don & Sheila

[thomasinnv]

my detroit book shows you should have used tool J-26888, which is 1.466 timing. might be something there.

[luvrbus]

Different timing for different turbos with different A/R but 9g90's are smokers give us the turbo model with the A/R maybe able to help and 99% of the time changing to the Eco air cleaner system will help that set up needs 1300 to 1500 cfm check your air cleaner and get the cfm rating for your filter
If equipped with a fuel modulator check the setting but most likely it is a air problem.
You can change the hot housing on the turbo to spool faster but you give up the high end torque.
Control the smoke with your right foot if you want the 350 hp the 9g90's are going to smoke

good luck

[skihor]

On our MC 5A I have the same injectors, NG 90's and if I "ease" into it from a stop I can hold it floored through all 5 gears without hardly a hint of black smoke. By "ease" I mean about an intersection worth of distance, from stop to floored. The MC 7 if I put more than 1/4 throttle it is BAD black smoke. It wasn't that way before the shop "tuned" it. To drive it without making smoke, it takes around 1/4 mile to achieve 35 MPH.
Is the injector timing that critical ?

Don & Sheila

[luvrbus]

Take it back to the dealer and let them redo it those engines can be set a dozen different ways,check for exhaust leaks,air restrictions you could also have a bad injector or turbo but keep in mind the 7 is heavier than a 5 and the 692 is not going to give the same performance in the 7.
Do you have a boost gauge if so what does it read under full load when everything is according to Hoyle they run 20lbs + boost pressure

good luck  

[lostagain]

I would look for an air restriction first. Dirty air filter? Something struck in the air intake?

JC

[skihor]

I know the turbo is an M11 but where is the A/R ratio marked ? I have looked all over a spare and I don't see any other numbers. Is there another way to determine the ratio numbers ?

Don & Sheila

[luvrbus]

Look inside where the 4 bolt holes inside the housing should say A/R 1.08 the cold side will have the A/R with embossed numbers on the outside were you are getting the M11 number from, the model number is on a tag in the middle on the center block where the oil feeds that should read TV 7511


good luck

[skihor]

can't find any numbers or tags, on either turbo. HELP ! There must be another way. Maybe a picture ??

Don & Sheila