Loss of power and warning lights

B

Behr

Member
 Gloucester
Early 2003 2.5 M54

Last night I was out in the car and whilst under (rare) hard acceleration I had an immediate cut in power and a trio of warning lights on the dash. I pulled over and dipped the clutch and noticed an erratic idle. As if I was blipping the throttle repeatedly.

I haven’t plugged it in yet but wondered if anyone had any experience of this and likely causes.

Photo

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Amazing how we have almost the same car and problem that occurred the same time!!!

2003 2.5 as well

My symptoms:
Whether sport or not sport mode, in D, step on gas pedal hard (even without the kickdown mode) until rev goes to 4000 rpm, then bang Brake, EML and DSC lights all on and suddenly lost power and rev goes down to 1000 rpm and pulsates thus jerking the car continuously.

Put in N or Park to stop car from jerking, turn car off and restart. Lights gone.

Car functions properly, can go to speeds up to 100 kph without problem as long as you do not hard accelerate.

A quick hard acceleration and it triggers the trio of lights and same rev problem once more.

I have a video of it. Will post the link soon.
 
markplant said:
Could be a coil pack
Click to expand...

^^ this, my 2.5si had a coil pack 'go' under hard acceleration too, I was only a couple of miles from home & so limped home & plugged my laptop in which told me I had a misfire on cyl no1, a quick trip to GSF to pick up a genuine Bosch replacement coil pack & I was back on the road within an hour of the fault happening :thumbsup:

Annoyingly I'd only just had an insp2 service at BMW who kindly told me that a coil pack was cracked when I collected the car, when I say cracked, the lower part was missing, my guess is it detached itself when they changed the plugs.
 
melbs said:
https://youtu.be/3kgZqIb2-hU

Link to the same problem

Had mine checked by an indy, so far fault codes appear to be an air leak :o Mechanic found a cracked intake hose. He is starting there, then MAF and DISA before checking the coils
Click to expand...

I had the exact same situation occur on me once in my Zed. I was trying to keep up with my mate in his M3 (failing hard obviously) and then this happened. Panic ensued thinking i had broken my fairly new Z trying to keep up with the M3 until an engine off and back on cleared the fault. Never had the fault since - even with some encouraged driving in sport mode. Very odd.
 
swilsco said:
melbs said:
https://youtu.be/3kgZqIb2-hU

Link to the same problem

Had mine checked by an indy, so far fault codes appear to be an air leak :o Mechanic found a cracked intake hose. He is starting there, then MAF and DISA before checking the coils
Click to expand...

I had the exact same situation occur on me once in my Zed. I was trying to keep up with my mate in his M3 (failing hard obviously) and then this happened. Panic ensued thinking i had broken my fairly new Z trying to keep up with the M3 until an engine off and back on cleared the fault. Never had the fault since - even with some encouraged driving in sport mode. Very odd.
Click to expand...

Lucky you, it didnt ever happen again

Mine keeps getting the same problem everytime i hard accelerate to 4000 rpm :cry:
 
Ok, so being a bit lazy about this, and knowing my cars history pretty well, I took a punt on 6 new Bosch coil packs before plugging in to GTS. Unfortunately this didn’t do anything to fix my issue so out came the laptop.

I have these two codes, the latter of which is what I assume to be the source of the EML lamp, power loss and erratic revs -

27B5 / P0010

bmw_screen1.png

And ..

28A2 / P16A7

bmw_screen2.png

Search function on here and google points me towards checking for inlet air leaks first then look at the MAF, or is this more CCV territory?

The CPS issue I assume is separate so I’ll look at that in isolation?
 
Easiest way to check MAF is unplug it and go for a drive. The engine will run rich but if it isn't erratic idling that's your issue.
 
A minor update on this.

I had some time to pour over the Zed yesterday so dug her out of the garage and had a good prod around.

I ran INPA and DIS and cleared the two fault codes then had a good look round the MAF and inlet. All looks good in terms of potential air leaks. No cracks or splits that I could find with a good torch and inspection mirror.

It did occur to me that both faults (CPS and MAF) are for components fed out of the same junction box area beneath the inlet so I began to trace wires from said junction and low and behold, found the intake VANOS solenoid was unplugged. I doubt this jumped off on its own and is probably down to the BANOS rebuild I did last year. Needless to say I reconnected it and ran the codes again. This time the “27B5 Inlet camshaft, activation“ was gone.

The code is in fact for the intake VANOS solenoid, not the camshaft position sensor! Hopefully this piece of information might help someone in the future.

Regardless, with everything blindingly obvious taken care of, a short test drive revealed that the problem with immediate power loss and the trio of lights (inc. MIL) is still there. I ran DIS ‘live’ and viewed the MAF input values with the engine idling and on revs and it seemed to give a fairly consistent kg/h value. I also unplugged the MAF, and whilst this didn’t seem to make any difference to the way it ran, I did get multiple MAF codes come up (which I then cleared).

Next move is to replace the MAF in the hope that it is just out of range. Any suggestions welcome for other courses of action.
 
excellent, theres already a thread on this!

Was doing a trackday at Donington yesterday, and after the first three flying laps, dash lit up, and had no power. had to essentially coast down the main straight whilst restarting the car, but not happy, pulled off to the inside of redgate and sat there. Erratic idle as mentioned. Limped it back to the pits and got the code read - pending P16a7 code for MAF.

After checking everything and deciding all looked ok (including the MAF itself) decided to just unplug it and see how went. seemed to work - car started fine and then completed the rest of the day and the drive home with the MAF unplugged.

One small problem though - with the MAF unplugged, I could no longer heel and toe?!? normal driving fine, clutch in and blipping the throttle fine, but the second you dab the brake and blip the throttle - no blip. do you need to have a MAF plugged in to be able to heel and toe? Seems a strange connection to make to me. But will try replacing the MAF soon, really want to be able to heel and toe in three weeks time at Silverstone!
 
hmmm then again... given a decent MAF is £300, gonna try cleaning it with some £4 spray first!

if that doesn't work, then it will remain unplugged, cos while I like heel and toe, its not worth £300!
 
I can’t speak to the whole heel and toe thing, but I can’t imagine running with the MAF disconnected long term is going to do the longevity of the engine and it’s ancillary sensors any good. I assume it will also adversely effect economy and emissions, and performance too...

I have found an OEM VDO MAF on eBay for £160. I cross referenced it from the BMW part number to the Siemens part number. The seller is Mister Auto, who I have used before and they came through for me ok. If my wanted thread doesn’t bear any fruit in the next few days then I will order a new one from them.
 
Just to update this thread to its conclusion: the replacement MAF came through from Mister-Auto ok. It was a genuine VDO unit in the VDO box and label but with the VDO part number milled off the MAF leaving only the Siemens number. Usual OEM parts malarkey and weirdness.

I fitted it this afternoon. Quite literally a 5 minute job. A quick run up and cleared the old code then out for a good warmup and a little blast. It’s safe to say that normal service has been resumed. What a cracking engine this is. I love BMW 6’s.

I thought the driveability gains from doing the VANOS rebuild last year along with the DISA upgrade really made little difference and have to say I was a little disappointed with the results, but now it seems that everything has been brought together. The little hesitation flat spot that I had has gone and the power really comes on right the way through - without the warning lights. Chuffed :D

Hopefully this will be useful reference to others in the future with the same code and issues.
 
2387ECC7-61DD-455B-AE3C-CBF53B8AFB21.jpeg

Seems I’ve had the same problem. Giving the car some beans in order to overtake and exactly the same problem as the OP. What was the fix in simple English? Clean the mag?
 
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