Map sensor problem
 

Hi, so the problem with my fd began when I would try starting it one day to find it would crank, fire up and run for all of 2 seconds then stall. I discovered that with engine off the boost reading on the power fc was showing a typical idle value ( -450mmhg) so if I unplug the vacuum hose to Map sensor the car will fire up and idle although rough of course. It has a Banzai map sensor which was calibrated when car was tuned by WGT. I have tried a replacement banzai map sensor only to find problem still exists. So my question is anyone have any ideas as to why this has suddenly happened and how to fix it. I have checked voltage at map is 5v and signal wire is 1.60v. when map disconnected signal wire also has 5v.

you either have a problem with the wiring or someone has changed your selected sensor. Use the commander to see which sensor is selected. If I had to guess I would say that it sounds like someone changed it back to normal, which is the FD sensor. I usually set the 3 bar up on option 2, but your tuner could have used any of the 5 choices.

Since the commander is reading vacuum, it is seeing the sensor. If it were unplugged it would be reading max voltage, on the sensor/ switch screen.

disconnecting the hose should not change the readings at all, unless you have mistakenly installed a 1-way check valve

I just tested my theory, I changed the PFC setting to normal on a car with the 3 bar installed. https://cimg6.ibsrv.net/gimg/www.rx7...0b6a7670b9.jpg

thanks for reply. How do I change selected sensor or calibrate map, thought I would need fc datalogit to alter.It was running ok after map install and tune up by wgt. With key on and engine off display is around -450mmhg.With engine started briefly vac reading rapidly drops more till shows ---- and then engine stalls/cuts out. Disconnected vac hose to get stable -450mmhg to allow at least idle. figured I need to get as close to 0mmhg with engine off, but how? thanks

You can change the map sensor selection with the commander, to enter calibration numbers a datalogit is required. If the tuner set up the 3 bar then you or someone else changed it back to the FD sensor in the PFC. If they never set it up then find a different tuner.

Settings ->PIM volt next

change to option 1, 2, 3 or 4 (normal is the stock sensor) and go back to monitor and look at your vacuum reading, when you see one close to 0, you have found the correct option.

Or Call the tuner and ask them which option they typically set up the 3 bar on.

page 23 http://www.banzai-racing.com/store_i...werFC_FD3S.pdf

Thanks again for your help, think your a credit to the forum. Seem to recall when I last checked it was set to PIM normal, strange as I'm sure it has always been set that way. Anyhow going to try that tomorrow and ill post back to let you know the result. cheers

If it has always been set up that way then your car was not tuned.

hi, thought I would let you know that it is sorted and car runs now. I went through the PIM options as you suggested and selected op 1 as that got me - 3 mmhg, close enough for me. one other thing you may be able to help with is the best procedure for setting up the TPS on a rotary works TB. I'm sure this needs improvement. thanks again

I can't help you with that, best thing to do is put the stock TB back on.

Quick follow up question here, I have the same problem. Purchased the GM 3 bar map sensor from Banzai with the wiring harness btw. Got the datalogit and set the PIM values in Option 2 to 41800 and the offset to 0 (though the cell only accepts 4 digits which then changes 41800 to a different number, not sure if that's normal). The car will start but run like complete garbage, super rich, dies, backfires when restarting, its a mess.

Set it back to the "default" in option 1, the car will start with the sensor plugged in but die after two seconds. Unplug the vacuum hose from the sensor and it starts up just fine, idles pretty well. Any idea what could be wrong here? just need this thing to run and be drivable so I can break in the new motor and drive it to get it tuned.

We provide the offset and scale on the packaging for the kit. You are using the newer version of the DL software 6300 offset 0

Hey, thanks for the reply. I did a deep search, and took me a while but I found a thread here that said to divide the 41800 by 6.6 to get the proper value, which I came up with 6330. put that in and the car started up fine. i'll go ahead and change the value to 6300 today and see if I can go for a spin, thanks for the help!

I had this issue on my AP Engineering PowerFC for my FC. Made the adjustment and it fired right up.