[V8] MPG - long overdue update

[Buchholz, Steven]

... the thing that I find a bit incredible in this sort of discussion is that if you have VAG COM or whatever ProDiag is now called ... the car will tell you what's up.  Why change a temp sensor on suspicion?  I can read exactly what the ECU believes the coolant temp to be ... and if it is incorrect I can troubleshoot.  I can take the car for a drive, log the ECU parameters and read out the engine parameters from the drive.

The data provided by the V8 ECU is not as extensive as that on newer cars, but I find it very helpful for troubleshooting this sort of situation.

Steve B
San José, CA (USA)
> 
> Ok - thanks for the replies.  To answer the few questions - I changed the
> FPR with a low milage, known to work one; I also spliced in an O2- but
> have not had problems with that in the past, plus the wires looked good,
> and I checked the output at the terminal on the engine - it seemed to be
> reading there - the code basically tells me that there is another problem
> with the engine, and that it is so far out of range, that the o2 can't
> sense the actual o2 content because it is either too high or too low.
> This leads to the other comment about the coolant sensor behind the pass
> side head.  Someone mentioned that it may be bad - I checked it but I
> think I will replace it with a known good one just to be sure.  This thing
> has me baffled.  One more thing, I know that I have said this but, One
> cylinder is low on compression - I know this could cause this problem, but