MAP Sensor question

[justdennis]

There are three MAP sensors right next to the intake manifold/supercharger on the right side of the engine. My question is are all three supposed to have a vacuum line connected to them, On my XLR V the first and third one have vacuum lines but the middle one does not. This doesn't make sense to me but what do I know. I could not find a hose that might have slipped off so either the previous owner removed it or there never was one. Any help?

 

[richardyoo]

The sensor you are referring to is measuring the actual atmospheric pressure... it'll be different if you're at sea-level vs up in the mountains.

 

[justdennis]

Thanks richardyoo, that was my guess but I had no way to confirm it. I'm still grabbing at straws trying to resolve fault codes P2176 and P1516. I'm trying to exhaust all other possibilities before I have to remove the throttle body for cleaning or replacement.

 

[richardyoo]

Could also be a wiring issue... there are a LOT of wires between the throttle body and the firewall... and the rats love destroying them... I have had to deal with rat damage 3 times in my XLR - so destructive.
Also - could also be a grounding problem - its common on this chassis (including corvettes) so might want to try cleaning and retigntening all the ground points - theres a diagram somewhere - fixes a lot of bizarre electrical roblems.

 

[justdennis]

I have been trying to locate and check all the connections and grounds but they didn't leave much room between the supercharger and the firewall, I'll keep at it. Thanks for the suggestions

 

[richardyoo]

I agree - I had to remove the supercharger twice due to rat damage to get around it to fix wires - HUGE pain.