Startup Map sensor issue
10-31-2020, 09:11 AM
#1
Member
Thread Starter
Startup Map sensor issue
When I purchased my E55 it was constantly throwing a map sensor code and bogging the car. I replaced the sensor and the car runs rough on cold start then fixes it self but then bogs throttle again. I have to clear the code turn the car off and restart and the car is back to life. It will sometimes happen after I clear the codes but almost every time when I do a cold start. Any help?
10-31-2020, 11:50 AM
#2
Super Member
Was it a factory or aftermarket sensor? These cars are really sensitive to having the correct MAP sensor and there are multiple aftermarket brands claiming 'OEM' for fitment.
Did you remove the SC to replace it? If so I'd double check for vacuum leaks.
Did you remove the SC to replace it? If so I'd double check for vacuum leaks.
10-31-2020, 12:06 PM
#3
Member
Thread Starter
This is the map I used https://www.fcpeuro.com/products/mer...8aAqcREALw_wcB
I removed the supercharger as I was going to change all the gaskets, I’m guessing I’m going to have to buy a smoke leak tester to see if I have a vacuum leak.
I removed the supercharger as I was going to change all the gaskets, I’m guessing I’m going to have to buy a smoke leak tester to see if I have a vacuum leak.
10-31-2020, 12:09 PM
#4
Super Member
This is the map I used https://www.fcpeuro.com/products/mer...8aAqcREALw_wcB
I removed the supercharger as I was going to change all the gaskets, I’m guessing I’m going to have to buy a smoke leak tester to see if I have a vacuum leak.
I removed the supercharger as I was going to change all the gaskets, I’m guessing I’m going to have to buy a smoke leak tester to see if I have a vacuum leak.
10-31-2020, 01:08 PM
#5
Member
Thread Starter
Yep that's the right one, so I'd look into vacuum leaks. Makes sense on cold starts too, as the engine heats up aluminum expands and could seal a small leak that is present on cold start. Easiest/most common place to check first would be that metal tube on the drivers side, make sure its seated in that channel/hole that's hard to see. Then smoke test after that.
10-31-2020, 01:16 PM
#6
Super Member
It's not that the tube would be bad, just not seated in the rubber grommet correctly. It's got that 15 deg turn so it's a bit awkward to get it seated sometimes versus a perfectly straight tube. I've found it helpful to use a flashlight and a small mirror when I've had the SC off to help me see it guided into the grommet, and then you should get nice feedback as it finally finds the hole and seats in about 1/2" deep. Good luck!
10-31-2020, 01:19 PM
#7
Member
Thread Starter
It's not that the tube would be bad, just not seated in the rubber grommet correctly. It's got that 15 deg turn so it's a bit awkward to get it seated sometimes versus a perfectly straight tube. I've found it helpful to use a flashlight and a small mirror when I've had the SC off to help me see it guided into the grommet, and then you should get nice feedback as it finally finds the hole and seats in about 1/2" deep. Good luck!
I just remembered I crushed that pipe and had to cut it to get it back in. That actually might be why my car is doing this stuff ahah.
