LT1GMC

Can you remove the heat shield without taking the turbo off? I am having a severe richness at idle and poor performance overall, sensors good but found the factory downpipe(Cast iron 90 elbow off of turbo) is loose from the turbo. Bottom bolt tight but a gap or .030" or more at the middle of the flange. I believe it is pulling air in there at idle right in front of the O2 sensor, causing it to go rich. Any ideas? Want to try and tighten flange bolts. Thanks,

RJ_RS_SS_350

Haynes seems to say yes. Turbo R&R section
1. drain coolant to below turbo
2. Remove turbo and exhaust pipe heat shields
3. - 7. Blah Blah
8. Remove turbo
9. Reinstall reverse

they don't have any pics, but yeah it looks like heat shields are pretty much the first parts to remove.

LT1GMC

Yes, I found out you can, just take off top pipe to intercooler and you can access the bolts. Top 2 turbo flange bolts were loose. Hope this is the issue.

donbrew

Seems to be the same as 2.2L. Here is the Alldata pic.

Oldblue

The shields appear to be removal in this picture

Dbeluscak

Drawing air would certainly cause a lean condition. I doubt it could draw much, if any with exhaust gases being expelled.

Top two turbo flange bolts? Which flange? The manifold-turbo flange or the turbo-downpipe flange. If the turbo was loose on the manifold that could spell trouble. Not so much as a code, but it would excessively heat and cool the turbo. Resulting in a poor shelf life.

Hopefully this isn't the case and you'll let us know what clears it up.

LT1GMC

When Idling the exhaust pulses are separate enough that there is a slight vacuum pulled between cylinder firing, and that is where air is actually pulled in. Have seen that issue on cars where they added headers and did not get a good seal to the head. Not really any great pressure when idling. Seeing that there is a gasket in there makes me less likely to think it is the main problem, but there was some minor evidence of exhaust leakage around the flange. Was able to tighten top two nuts on part 9 about 2 turns and close the gap between turbo housing and the exit manifold.