2005 MINI Cooper S

The short and sweet: Car runs fairly well at the moment but I still get a DSC light occasionally and a CEL P1237. I'd like to test the MAP before pulling the BPV to check it. Does anyone know the procedure to check for proper voltage of the map sensor?

The long and winding: So I've been working out some big hesitation issues that I was having with my MINI after doing a large service on it last year which included a SC oil change and a WMW pulley. At first I thought it was a vacuum leak as I was hearing a hiss I wasn't sure existed before the service. Performance wise, I was getting a fluttering hesitation particularly between 2 and 4k rpms. It had gotten worse recently so I decided I would get to the bottom of it. Well after a light smoke out, I noticed a large crack in the intake boot that attaches from my stock air cleaner so I replaced it with a silicone SAMCO one that I'm fairly confident is making a good seal (clamps are *tight*). That didn't seem to fix the hesitation and after bringing it to a mechanic friend he told me there were two other codes I hadn't seen before. I had a 1688 and a 0301 (misfire, cyl 1). The plugs had been replaced so I changed the wires and cleaned up the terminals of the coilpack a bit, cleared the codes and the hesitation GREATLY improved -- almost completely. However I did get a recurrence of the P1237 and I'm trying to figure out why. I have also seen the DSC light come on, generally under heavy throttle even once still after the wires were swapped -- no idea what that's about.

Thoughts:
1. Still need to sand down corrosion/replace coilpack as the #3 term is pretty bad still (1 wasn't great either). Least likely culprit though I would think
2. Stock BPV feels like it springs back ok but haven't pulled it yet to see it in action
3. Problem with the MAP sensor/wiring. I hear this isn't too common but could happen
4. I maybe still do have a vacuum leak and need to resmoke it. Perhaps a crack in the plastic intake duct that attaches to the supercharger (the green profile gasket has been replaced but I don't think I screwed up lining it back up).

FWIW: I changed the throttle body gasket with the rest of that big service. Checked it more recently and it seems to be seated just fine. The belt is a brand new Gates 035 on a WMW 17% pulley. Plugs are cooler rated NGKs.

Looking to get some input on this and see what your thoughts are or if there's anything I'm missing here.

Thanks,
Nick

 

OK. Things may have just gotten much simpler. I finally got a DSC light to come on again while I was mashing it just now and before I shut the car off it was sure enough a P0108 came up indicating MAP circuit high input. Requested to borrow a Bentley from the library but if someone else knows how or can find how with theirs how to test the MAP sensor, I'd still like to test it before replacing it.

 

I think we are having similar issues. I had gotten that code replaced by tb and bpv. Nothing has changed. Does it almost feel like a timing retard when you go above 30% throttle?

Im about to rebuild my head but hoping its not that serious. Even mini couldn't figure it out.

 

Yeah it does. I found out that the MAP is an analog sensor so you should be able up backprobe it and manually pull a vacuum through it and watch the voltage. I'll let you know if I go experimenting with that.

 

Interested to know how this goes!

 

On the phone right now with the auto parts store to see if I can get my hands on a handheld vacuum pump to help test it. I'll update if get to testing it middle of this week.

 

OK, I'm in the middle of a full writeup on how to test MAP/TMAP sensors and can probably post it up tonight. In the meantime, I seem to be getting 4 volts of supply on the MAP sensor with the car on but engine off and voltage drops when vacuum is pulled through it. On the TMAP, I'm getting about 2 volts on the supply line and voltage also drops when vacuum is pulled through it so they both SEEM to check out ok.

The question remains why I might be getting a 1237 (SECNDRY UPSTRM MANIFOLD AIR PRES SENS LOW INPT) and 0108 (Manifold Absolute Pressure Circuit High Input) code still.

 

OK so for fun I replaced both MAP sensors and it still throws a code. I think that leaves me with it being either a BPV issue, a vacuum issue or a throttle body issue. I'll likely check the BPV first and then if nothing happens there, perhaps I'll clean the throttle body and if nothing there, I'll pull off the front end and check the supercharger for vac leaks or other oddities. Still looking for any input if anyone has any. Thanks.

 

I pulled the BPV and although it felt and looked like it was operating in normal condition it was only until I went to reinstall it when I realized what the problem could be here. The vacuum line that runs out of and back into the unit has separated from the plastic portion and thus the valve likely stays shut 100% of the time.

Attached are pictures. Now I should note that the line was not pulled out as you see it in the pictures, it was sitting loose "inside" the plastic housing so as to appear to be connected properly. A light tug made me realize it was not connected at all. When the new one goes in, I'll report back.

 

I should have also mentioned there was a ton of oil in my intake manifold/intercooler which is surely related as explained in post 12 here. I guess a good Sea-Foam or two is in order once everything is all back together. Recommendations on how to clean things up in the meantime while they're apart?

I should also mention that a symptom that happened once or twice started happening more frequently the past week (perhaps due to the colder weather). If there was snappy shifting (quick off the throttle, quick and fairly hard back on), there would sometimes be no power on re-acceleration. It was as if fuel was cut-off for a fraction of a second but as long as a full second in some instances. This is likely related and hopefully will be remedied by the new BPV.

 

And while I have it on my mind, if you suspect a bad BPV or are throwing a 1237 code:

If your BPV feels normal, try starting the car and have someone rev the engine high enough where it should open and watch for operation. If you don't see it, check your line to see if it hasn't pulled loose like mine. I'll try to remember to confirm this once the new one is in as well.

 

I said I'd follow up and forgot to. My problem was 100% the bypass valve. The code is gone, performance was restored and there was no more large hesitation on snappy shifting.