ok... my friend's car is only running 10psi, but the power fc is reading 1.22 bar! It is hitting 10s on the wideband a/f gauge! At idle, it is usually around 11 - 11.5. I switched out the pressure sensor with one from my rx7, and it still does it. Could it just be a wrong pfc setting, or do you think the wiring harness is messed up?

The car was tuned at a very very reputable rotary shop (I don't want to throw out any names). It has had a ton of problems so far caused by them and the previous owner of the car. Could this be just another problem in the tuning? They keep telling him that it is a hardware problem and not their fault, but with the PFC reading stuff like that, I seem to think otherwise.


Also, while we are on the subject... I put in a new alternator for him a few months back. Now the car started acting up again. At idle, it drops to 11volts! If it is revved to 1500 rpms it goes back to 13.5-14 volts. Could this be a grounding issue or is this alternator messed up?


Thanks for your help,
Jesse

 

You need to check which map sensor he is running and how the PFC is setup for it.
If setup wrong, it will read wrong.

 

It is running a stock map sensor. The PIM voltage setting is on option 3... I set it back to normal today, and it started reading boost correctly..... buuttt... it was running very lean. I think it definately needs retuned, what do you think?

 

If it was on the wrong map sensor selection when they tuned it, they messed up.

The PIM selection has changed and this determines which pressure row is used for fuel, what do you think? You said it is now running lean!

The engine should not be boosted at all untill it is retuned.

 

oo yea.. its sitting at my garage until a retune and after figuring out all the electrical gremlins it has, lol. As soon as I started boosting at the afr went lean.. i let off and drove back down the street to my garage, lol... and there it will sit.

 

Isn't there a setting in the Datalogit for PIM calibration under PIM option 3? If it wasn't calibrated right to start with, then you would be reading excessive pressure with your PFC. Cewrx7r1 can you please confirm this.

 

Could it be that if the AFR is really lean that the boost gauge is wrong and not the PFC? If it is abnormally lean then there is excessive air going in which correlates more with 1.22 bar than 10 psi. I take it they didn't tune based on AFR.

 

no, its the opposite of that in option 3, where the car was tuned at... it runs extremely rich because it is thinking it is getting 1.22 bar of boost... it runs to 10:1 afrs then goes off the scale rich. When put into "normal" it does the opposite, it runs lean, because it wasn't tuned at all there.

 

There are 5 PIM options for different map sensor or sensor values. The only way to calibrate is with an accurate pressure gauge(Autometer etc), a compressed air source (home air compressor), a pressure regulator (mini 0-25 psi), and the DL. That is how I do it except I also use the Blitz internal 3bar map sensor pressure values.

 

Yes, the calibration is what I was talking about. If the calibration was off, it could be the reason for the mismatch between PFC and Boost gauge.

What could cause a previously well-tuned car to suddenly go lean though?

 

yea man, its all over the place... after you talked to the tuner, he said option 1... I put it into option 1 and it jumps everywhere, 10.3:1 afrs at idle, and option 1 causes a lot of richness throughout the rpm range. At 7 psi, I was reading 1.04 bar. When put into "normal" it reads the boost correctly, but that is where it leans out, so it's undrivable there. Is there any way that he tuned it using a 3 bar map sensor, then for some reason removed it???? Maybe somebody stole it after the tune and replaced it with a stock 2 bar before your car was shipped back?? Call the guy you bought the car off of and find out what map sensor he had on there, because that is the only thing that really makes sense to me.

 

You said it was hitting 10s...that rich not lean

 

Leans out when set to PIM option 1. Rich (10) at other options.

 

Yes, I know. Thats what I said in my last post. It's lean in "normal" but rich in the other options (10afr)