MAP Sensor Reading Vacuum When Off?
 

Hey guys,

I have a brand new Platinum Sport 1000 installed on an S5 TII. When the car is off, the internal MAP sensor is reading around -3 psi. Is that normal? Under cranking it reads around -2 psi.

I searched and couldn't find anything about this. The MAP source is set to Onboard, and the OBPS input is set to MAP. Is that correct? Is there any way to calibrate the sensor?

Thanks guys.

Sure it's showing -2 and -3 and not negative .2 (2/10)?

The reading normally won't be exactly zero with the key on engine not running due to variances in atmospheric pressure. However that is off more than you would normally see. In the end it is really just a number and doesn't matter much as long as you see an appropriate swing in values to represent idle vacuum and positive manifold pressure. You can skew the calibration manually to zero it but that would also skew any tuning you have done and would require that work to be redone.

What I would be most concerned with is what it reads with positive pressure applied. If it's skewed minus 3 psi across the board you would want to think you're running 16 psi because that's what the ECU says and actually be seeing 19 psi. If you have a known accurate pressure gauge I would check the ECU versus that. If the on board sensor is in fact skewed across it's range send me a PM and we'll get you straightened out.

Are you viewing PSI really, did you reassign the units in the Options setup? Or are you still viewing KPA (default unit)? since -3kpa is barely anything.

Just wondering.

Yes I reassigned the units in the Options setup (both manifold pressure and pressure); it's definitely at about -2.7psi. While cranking, it drops to about -3.5psi.

I'm having some other issues. There's a good chance my spark plugs are at least partially fouled, so I'm not sure how much that would affect the following information. I'm picking up new ones tomorrow. I'm going to feel really dumb if everything I'm about to mention could be fixed by putting in fresh plugs.

Trigger Angle: 45°... CAS as far to the RIGHT as possible (if looking from driver side).

Here is how my coils are firing:

L1: Synced to yellow timing mark
L2: 180° from yellow
T1: 180° from red
T2: Synced to red timing mark

I have a little bit of drifting going on while cranking, no more than +- 3°.

When I crank the engine with no fuel (with spark plugs in), I get the timing to line up perfectly. As soon as I let fuel back in the timing goes off again... About +20° or so (the yellow mark moves about an inch left of the pointer). What's the deal?

My trailing coils seem to be sparking inconsistently... I have a feeling its related to my plugs being fouled. Will the coil packs not send a spark to the spark plugs if the plugs are fouled?

Also, I swear my timing light only works on the trailing coils if the clamp is around the wire when it is close to the spark plug. Most of the time the timing light won't go off if the clamp is around the wire close to the pack... Does this mean anything? The trailing plugs are firing when they are out of the engine (and the timing light), but according to the timing light, they aren't firing when they are in the engine.

If you can answer or shed light to any of the above points that would be great.

Thanks guys.