2010 R57 N14 Mini Cooper S Convertible - 70,000 miles

It started stalling while warm. After 20 minutes, it would restart and run normally. Would stall about every mile, and now it does not start. Full crank. For more details, https://www.northamericanmotoring.co...errerid=184311

Specific Question - I attached a BlueDriver OBD and was storing LIVE data on the way home. What I noticed is that 2 things happened each time about 3 to 8 seconds before the stall:

• Intake Manifold Pressure jumps from normal to around 30 Hg AND STAYS THERE WITH NO RPMS AND WHILE I AM CRANKING THE MOTOR
• Ruel Rail Pressure drops from normal (1300 to 1600 PSI) to around 50 PSI. It will increase to around 250 - 300 PSI while I am cranking the motor

The increase in Intake Manifold Pressure usually occurred a couple of seconds before the drop in fuel rail pressure.

Seems strange that the Intake Manifold Pressure would stay high in the absence of crank or RPM's? Now, the car does not start at all...

Any thoughts??

Thanks all!!

 

Perhaps this video will help:

Its out of my diagnostic abilities but you seem pretty sharp.

 

I had seent his video - thanks. I don't have a lab scope, but have tested the relay and fuses.

The car starts with starter fluid. In my gut, I feel like it's not electrical. I have visually inspected all fuses and 'fuse boxes.' Have looked at the DME and did not see anything obvious. But, again, don't have the tools/expertise to test it.

Looking for something more obvious - what would cause the pressure in the intake manifold to double? Thanks!

 

I get confused pretty easily --- you talk about intake manifold "pressure" then reference it as "HG". My external gauge uses inches of Hg to measure vacuum. The only time I get "pressure" is during boost, then it's measured in PSI. So, if I were to measure 30 inches of Hg, it would be a huge vacuum. My cold idle is about 15 inches of Hg and as RPM's increase vacuum approaches zero inches of Hg, but ALWAYS a vacuum, never pressure, unless turbo is working. Or, if you insist, refer to it as negative pressure. If it truly is a positive "pressure", you have a serious problem.

If 30 inches of Hg is minimum for your gauge, and it jumps there while driving, there's a good chance your MAP sensor is bad or you have a loose wire. That might cause the ECU to quit pumping fuel --- low fuel pressure. Altho 250 - 300 PSI is also what a failing HPFP produces --- it should be closer to 700 PSI minimum when cranking, according to most posts I've read.

If you live data includes more than just MAP and fuel pressure data, is there any chance you can post your data log? Usually a spreadsheet format works best.

 

Everything you say makes perfect sense - I had not stopped to think about it. I was just looking at the spreadsheet header information from the LIVE data feed and misinterpreted it...

I thought about both the MAP and the MAF. Most of my attention right now is on the LPFP and/or the JBE. Like the amateur that I am, my first reaction was to replace the HPFP, the most expensive part... Did not help...

I am thrilled that I can add attachments - I had tried once before and it was not successful. Even more thrilled that someone "who gets easily confused," aka, someone who knows a LOT more about this than me will look at it! Thank you!!

 

I checked out both datalogs, looking for "cause / effect" but couldn't find anything definite. There does seem to be a problem with fuel pressure tho. Was your replacement HPFP new, rebuilt, bought from a reputable source? I've read that rebuilt units have a very high failure rate.

I couldn't see any cause for the manifold readings to hit max vacuum. When mine did that recently, I found broken wires at the MAP sensor connector --- sloppy workmanship on a splice. Maybe you have a loose connection?

Then there's "Commanded Evaporative Purge (%)" --- I have no idea what this is, but guess it relates to fuel system --- maybe the return line to the tank. If you have faith in your new HPFP, try checking all the fuel lines for kinks and binds. Also the gas cap and it's gasket / plumbing. Then the LPFP and its filter.

I really appreciate your faith in me, but it's not deserved. All my Mini experience is with my own build, and I can't count how often my advice to others has been off track. There are others on NAM with much more experience and Mini knowledge, they just haven't responded to the datalogs.

Best of luck and keep us posted ---

 

Thank you so much for the time and interest in looking at the data sheets! I'll take a look for loose wires at the MAP sensor. But, the car won't start at this point, and it's still not throwing any codes so it's a guessing game. My gut is telling me it's fuel delivery too...

I saw a couple of other posts that point towards problems with the JBE - specifically a faulty relay that is integrated into the JBE for the LPFP. I checked and am getting no voltage to the LPFP so that's where my attention is now.

Since I had just replaced the Valve Cover about three months ago, my attention was also on the vacuum system, etc. But, in my very limited experience, it would not stall the car, nor keep it from starting now? When it was running, the idle was smooth, and it ran well. Until it didn't... haha But, those intake manifold numbers still have me perplexed...

The HPFP was a new unit from ECS tuning. I'd love to take it off and return it but might as well keep it on at this point...

Again, thanks for the time and the thoughts, oldbrokenwind!!

 

Were you able to get it started? Try jumping lpfp with 12 volt charger, if it starts and runs, chances are it's the jbe relay (the one that's hardwired in the fuse box)

 

Yes! Due in part to another one of your threads, I replaced the JBE, and it started right up! Thank you!