Attached is a nice engine bay from an '89 currently for sale on e-bay.

I believe the two blue-capped aluminum tubes appearing either side of the engine are C02 test points - is that right?

I've noticed when folks post their engine bay pics - alot of our cars are missing these tubes (87 and on....).

Anyone know why that is?
Are they especially fragile? Is it a common casualty when pulling the engine?
What's the impact to performance, if any, of not having them?

In comparison to my own car, an '87, I'm missing both aluminum tubes - although I did find the driver side tube broken in half and dangling by a thread the first time I replaced the air filter.

I'm also missing the driver side, black plastic fuel rail cover on mine...assumed all this time it was normally uncovered

Had I known what a tremendous group Rennlist was before I acquired mine, I would have done like many here have and asked a member's opinion prior to purchasing a 928.

 

You need to go to your exhaust manifolds where they connect and replace it with a small ball bearing and seal it back up. Being disconnected it will screw up your A/F readings due to it allowing un-metered air to enter causing you car to run lean I believe. It may cause it to run rich but someone needs to chime in about this either way you need to correct this problem. They are used to measure C.O from each bank from the factory, it not necessary to keep them.

 

Maybe these will help ---

Link -

https://rennlist.com/forums/showthre...mog%27+testing

Link -

https://rennlist.com/forums/showthre...light=egr+line

 

Incredible detail - there's nothing you guys haven't seen already. Thanks Don! Mike

 

The tubes rust out. They should have been made of stainless steel like the rest of the exhaust system.

Ball bearing is a good idea. The thread is 14 x 1.5, if you are using a plug, I used some brass plugs from a Mercedes(?).

The latter is true.