Hi all,

I’m not a pro forum navigator, so please forgive if my question is covered somewhere else. I’ve just purchased a 2006 mini S, 6 speed, 155K miles. It drives and rides really nice. But, it does have an issue. Once the car gets up to temp, the idle will slowly start to creep up. Once it hits a certain point the idle will begin to surge. Probably 1100-1700 rpm( give or take a little). I first assumed a vacuum leak to be the problem. I’ve not been able to locate a leak. When the car is cold the idle is around 700rpm I’d guess. Sounds/feels like a good idle speed. The car has catback exhaust, CAI, and the replaced the supercharger valve.

There are some codes.
P0507- idle air control system rpm higher than expected
P1498-
P1109-manifold air pressure higher than expected under deceleration
P1692

Any help is appreciated.

Thank you

 

One way to find vac leaks is to spray carb cleaner on suspect areas. The idle will change when you hit the leak. I suppose WD40 would work too. Other low cost / low risk actions would be to clean the throttle body & maf sensor.

 

Looks like a MAP sensor issue.

 

^^ Ditto ^^

 

I was curious about the map and TMAP sensors. Are they actually the same sensor? I know they have different purposes, but can they be swapped to see if the issues change? I disconnected the TMAP sensor with the thought that mini would do the same as other vehicles and input a fixed signal. When I disconnected the sensor, the idle did drop like I expected, but it kept surging. I tried spraying for a vacuum leak, no success.

And thanks for the input.

 

No, they are not the same sensor.

 

The TMAP is on the front of the intake manifold, right behind the radiator, looking right at you when you open the hood. It has four wires. The MAP sensor is topside toward the right and usually under a wiring bundle. It’s got three wires on its connector. They’re different part numbers, too, and have different performance specs. The TMAP represents higher pressure.

Ive never had much luck diagnosing vacuum leaks with combustibles. So this time out I made a paint can-soldering iron smoke machine and was able to find mine. I did it with charcoal once and the car smelled like BBQ for a week.

 

Well, I do like BBQ. I’m going to try to smoke test the system this weekend. Does anyone know of a way to check the map & TMAP? I’m not a fan of just throwing parts at a problem.

 

Just google “test map sensor” and you’ll find some decent videos. You need a multimeter, a vacuum pump and a 5v power supply. I’m guessing based on your codes, it’s not those sensors. I’d be hopeful it’s a vacuum leak, maybe for the line that runs up to the MAP sensor, which is notorious for leaking, or one of the lines running to the supercharger manifold, which are notorious for leaking, or the line running to the throttle body, which is notorious for leaking. But it’s probbaly not the brake booster.

That P1692 is a concern, though, since it points to throttle body electronics. I haven’t seen anyone (searching NAM say they fixed that one by fixing a vacuum leak first).

Another option would be to be to get a Scangauge which can at least show you TMAP pressure. I watched mine go to 0.0 when it lost connection, and when I had a totally dead sensor. I don’t know if it can show the MAP value, too. I’ve also gotten the ISTA software running with the correct cable and can run diagnostic procedures. Basically, it tests the sensors in place and lets you see the provided voltage converted to pressure, and tells you the acceptable range. I use it a lot. Took awhile to get working, but I can you through it if you’re interested.

 

Thank you for the info. I will look into those this weekend. Hopefully smoking the vacuum system will reveal a leak.

 

Alright, smoke test revealed no leaks. I did find something that got me going down a path. When the idle surges the throttle body doesn’t move. I cleaned the throttle body (just because I was there). I know the previous owner installed a detroit tuned supercharger bypass valve. So I started thinking maybe they messed up. One thing I tried that I found interesting. I put the palm of my hand over the throttle body. Now, in my experience the car should start to stumble and try to die. But, my little mini just sat there and didn’t change a thing. I could feel the vacuum against my hand. But there wasn’t a change in the idle or anything. I’m planning on retracing the steps they were supposed to use to install the valve. Maybe I’ll find where the little 53 is getting air from.

Any thoughts?

 

Hello! I have the same problem and i have almost replaced everything on the car, literally. Did u manage to solve the issue? Thanks in advance