Mileage Loss

[Mike F.]

Recently I have noticed some loss of mpg. Normally I will get about 300 to 320 miles per full tank. The last time I filled up, I reset my tripometer, and noticed only 230 miles on that tank of gas. That seems significant to me. There is no noticible difference in the way it is running. Last year I replaced a bent pushrod on the intake of the #5 cylinder. At the time I felt fortunate there was no other damage, but I wonder if there is a connection. If the valve is bent, or the lifter was damaged wouldn't the cars performance be off? Could there be damage to the camshaft itself? Perhaps the lifter was damaged and it has worn down the lobe. Would something like that generate a code to the DIC? What should I check? I really do not want to remove the head just to see if there is a problem. Any ideas, or am I being paranoid? 2000 C5/A4 Longtube LG headers/Halltech CAI/LS6Intake/ Yella Terra 1:8 to 1Roller Rockers/Comp Cams Hardened Pushrods. Thanks!!!!
Mike F.

[c4c5specialist]

HI there,
First thing you should start with is a compression check.
All 8 cylinders should be within 10% of each other.
If you had a bent pushrod, then the cylinder might be compromised.
Normally, if you bend one, more are there.
Once a compression test is done and you see a problem, a cylinder leakdown is the next course of action, to better determine what exactly is leaking.
Allthebest, c4c5