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 Erratic idle, +30' vacuum, looking for help.

 Created by: oldoar
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 Posted: Feb 27, 2020 06:42AM
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CA
Quote:
Originally Posted by RedRiley
Sorry, every time I see the title of this post, I think it's going to be something about Monty Python.

.

"Hang on a minute lads....I've got a great idea."

 Posted: Feb 27, 2020 04:12AM
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US
Sorry, every time I see the title of this post, I think it's going to be something about Monty Python.

 Posted: Feb 25, 2020 06:25AM
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Thanks for the answer.  

I removed and cleaned both Vanos sensors and cleaned them thoroughly.  The exhaust side had a tiny spec of something on it, it could have been just something from clothes (and I didn't test it to see if it was magnetic).  The intake side looked brand new on the inside portion, no debris at all.  On both the oil was clean and resembled dipstick oil; the plunger on both moved freely.

I ordered the diaphragm from the Russians for the valve cover.  Several people wrote to me and online on how it worked well for them, and for $35 it seems like a fair chance to take compared to a new cover.

I also tested the cam sensors, both passed and both had ground and power at the connections.  I ordered two of those just in case one is failing intermittently.

On restart, I got a P054B (exhaust side) and a pending P0015 - exhaust side position too.  So I ordered a Vanos for that side as well.  A couple of test drives, then cleared the code, then the reduced power warning for an hour, then that cleared.

Mechanically it seems to be pretty much the same after the cleaning and checking - pulsing idle, light hesitation on any kind acceleration.

This morning after 90 minutes of driving, no codes, none pending, reduced power light off.  Parts should be here next week.

 Posted: Feb 25, 2020 04:50AM
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Not sure if there is anything 'obvious' causing the symptoms you described...  Strange that there are no CEL or codes in the system...

Nothing definitive, but I would continue looking for vacuum leaks or checking the PCV system...  I think a big clue is the change between closed vs open loop..

Let us know what you find. 

 Posted: Feb 24, 2020 05:46AM
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2012 Mini Cooper S (turb

1.6 litre direct injection, 6MT

202K km/125K miles

 

I’m hoping that someone could help me with direction to solve this issue with erratic idle and related problems:

 

Symptoms:

 

Erratic or surging idle between 500-950 in closed loop only (normal start-up, no bouncing in open loop)

Idle fluctuates low enough that the lights rhythmically dim in coordination with the idle, also the rear defrost relay sometimes clicks, sometimes the brake/ASR lights flicker too.   

No issues if I hold the idle 1200 and above

Defrost works, brake fluid level is good and clean, alternator is 1 year old

No detectable detonation or stalling during idle

No codes, no pending codes

Vacuum of the brake booster line pegs out the gauge at +30”   This is off the pump directly and with a  “T” in the brake booster line.

Vacuum lowers with brake application, five pushes bring it to 0”.

Vacuum lowers with the depression of the brake pedal at first, then it lowers again with the release.

Very rarely (three times in the last three weeks) the motor has cut out for a second or two during driving, then back to life as normal.

Low (-15%) ST fuel trim at idle, but varies wildly to +15% too.  Honestly seems erratic

Low -2-3% LT fuel trim

 

Recent work: 

 

HPFP replaced with a MINI dealer pump three months ago.  FRP seems right, 800-2000 PSI in concert with RPM.

Fuel filter, coils, plugs all replaced within the last three months.  Plugs look good this weekend, maybe a little dark

Air filter is new.

Cleaned MAF

Checked vacuum lines visually and with brake clean.

 

 

I’ve tried chasing down vacuum leaks but haven’t been able to find any yet.   I haven’t found any way to test it, after searching online and calling a few shops,.  Anyone successfully replace their diaphragm on the cover?

 

I also suspect injectors, but I don’t see how that would max out the vacuum reading.  Maybe more than one problem here.

 

Oil consumption is high - 1 quart every 2K - but dealer & shops say some version of “not to worry” or “it’s normal.”   Also, I’ve been told that the PCV/Valve cover is known to fail pretty often due to the high heat coming off the turbo, and the vacuum pump fails regularly too - thanks to being cam-driven, it takes the whole top end with it when it does.

 

Any other PIDs I should look for?  I want to stay away from just hanging parts on it until the problem goes away.

 

I’m sure this is obvious to someone, or at least obvious where to look!

 

Thank you.