Twin turbo difficult to start

eng622 · Post by **eng622** » Sun Sep 24, 2023 6:17 pm

Professional scanner codes results
0029F2 - high pressure fuel system
002FBF - fuel pressure on release of injection
Also a code on low battery voltage which was not thought relevant but maybe it is. I'm thinking the problem may well be electrical.
This is what happened next. Codes were erased but while idling the EML came on and when I drove off the half eng light. Mechanic started the car and did note it took several cranks to start Only 1/4 mile back home. Switched off and restarted. EML on and quickly the half light came on and the engine went into very rough idle backfired in the exhaust badly on revving up and then would not idle just stalled. Tried numerous times and would not idle for more than a few seconds. So looks as if it will not go anywhere as DCT.
So plugged in my scanner and got 3 new codes saying random/multiple misfire and misfire on cyl 3 & 4. Not surprised by this result as car looks like it will not drive anywhere.
Now I erased the codes and the car started quickly idled at 700 rpm and very smooth. Revved up gently to 1500 rpm and no lights came on but did not road test as worried about stalling.
I'm reading that the misfires were due to lack of fuel and it is the HPFP that is not delivering correct amount but may not be the pump.
Mechanic said first to check the fuel filter but these are said to be for life (car only done 40K miles) and with the pump/filter in the tank a difficult job.
So think should measure LPFP pressure.
The fault does look intermittent and could be electrical. Where is the pump connector located.
Also could be the positive battery terminal lead which is a recall, not done but booked in for Thursday if I can get the car there.
T

raymond.harper · Post by **raymond.harper** » Sun Sep 24, 2023 7:34 pm

Low voltage makes me think about the recall viewtopic.php?t=124384

matsmith749 · Post by **matsmith749** » Sun Sep 24, 2023 7:53 pm

You don't mention the age of the car?

The z4 is super sensitive to degraded battery, which presents as all manner of issues which are actually not issues atall - but the battery is the problem.

If the battery is over 5 years old, I would start there & get it replaced.

Then see if your other issues dissappear.

HPFP is a common failure on these cars, I would be thinking on that direction TBH if still a problem with a known good battery.

If your car is a 2009/2010 35i then there was a recall for this in the US, and the HPFP was replaced. Not sure if valid inthe UK.

eng622 · Post by **eng622** » Mon Sep 25, 2023 12:46 am

The car is 2009. Checked if HPFP has extended warranty and it does but limited to 10 years old so no good for me.
The battery is the original as far as I know, purchased when 3 years old. I had the battery tested and said to be good. The engine spins over with ease so cannot see it is at fault. But other connections could get lower voltage when cranking due to high resistance which could be the difficult start problem/fuel starvation if that is the problem. Hoping to get the recall cable done this Thursday only a few miles drive to Sytner Nottingham. If it stalls on route is there anyway to get it moving with DCT or will I have to call breakdown.

B21 · Post by **B21** » Mon Sep 25, 2023 9:21 am

If it’s a 2009 battery then it should be replaced as a matter of course…there are quite a few faults created by aged batteries on E89s despite their ability to spin the engine..

DCT will set itself to Park whrn engine stops..

It’s possible to move from Park to Neutral buts it not a owner based task..so it’s a lift recovery if it can’t start

Looks like given your lack of skills and knowledge that you just let Synters sort it out and suck up the bill..

matsmith749 · Post by **matsmith749** » Mon Sep 25, 2023 9:35 am

Yep - these batteries degrade a few percent every year (no matter what your tester says) - it's physics.

After 5-7 years they are borderline, 10 years they are toast. If you had a >10 year old battery 'tested' somewhere & they said it was ok, you need to stop going to that place

They may seem to be ok & start the car, but the voltage they are putting out wreaks havoc with the voltage sensitive computers & sensors dotted around the car - and they run EVRYTHING.

It needs replacing regardless of other issues - but if you are lucky, this is the root cause.

Regards teh HPFP, there were 6 versions used in the e89 AFAIK, with the earliest being the most problematic (what you have). It got changed every couple of years to newer versions / software, but was never exactly perfect.

eng622 · Post by **eng622** » Mon Sep 25, 2023 10:06 am

If it will start doesn't the alternator keep the voltage up to what is normal when running.

Chippie · Post by **Chippie** » Mon Sep 25, 2023 10:08 am

I’d definitely be looking at replacing the battery, there can be so many battery related problems that for the sake of £120 or so it’s not worth ignoring it. Possible misfire could be oil in the spark plugs wells.

Chippie · Post by **Chippie** » Mon Sep 25, 2023 10:24 am

eng622 wrote: ↑Mon Sep 25, 2023 10:06 am If it will start doesn't the alternator keep the voltage up to what is normal when running.

You would think so but it doesn’t, the system is very sensitive to slight variations in voltage and current.

B21 · Post by **B21** » Mon Sep 25, 2023 10:53 am

eng622 wrote: ↑Mon Sep 25, 2023 10:06 am If it will start doesn't the alternator keep the voltage up to what is normal when running.

No because the alternator does not decide when and how to charge the battery..that rests with the engine’s ECU and the intelligent battery sensor,,a duff battery throws a major spanner in the works..

These cars are incredibly complex electrically so without a full understanding of the architecture and the subsystems you are floundering in the dark…hand it over to a professional

matsmith749 · Post by **matsmith749** » Mon Sep 25, 2023 12:02 pm

In this case - with this user - I'm inclined to agree with B21.

Take it to an expert.

DIY & forum guidance only works if the recipient is able to undertake the steps described, not everyone has tools / knowledge / skills in this area.

We have some facts that are not up for debate:

(i) Decent code reader that understands BMW specific issues is needed if you want to DIY the e89
(ii) Batteries degrade over time - the e89 is super sensitive to that & any issue that needs electricity could be battery related

I've lost count over the years how many posts on here have appeared unrelated (coses thrown for windows / boot / lights / cluster / engine) that ahve been eventually fixed by changing the battery. Usually after half a dozen other things have been tried.

eng622 · Post by **eng622** » Mon Sep 25, 2023 10:33 pm

Looks like I have made a few mistakes with my battery as assume it is an AGM type. Do not use the car for 4 months over the winter and charge it once a month but with a standard charger across the battery terminals, which I read is the wrong method. Never had any problems until now. The terminal voltage is 12.2 V lower than a lead acid at say 12.6 but has always been like that. The only malfunction in the past has been on starting where an image of a car jacked up of the ground appears sometimes appears and the clock trips with no display. Not done this for some time though.
Should I be buying another AGM or any 096 type.
Understand a new battery needs to be registered and coded to the car computer. Can any competent mechanic/garage do this as do not want to take to the likes of Sytner.
Hoping to get to Sytner to have the recall battery done first.

Pondrew · Post by **Pondrew** » Mon Sep 25, 2023 10:51 pm

eng622 wrote: ↑Mon Sep 25, 2023 10:33 pm Looks like I have made a few mistakes with my battery as assume it is an AGM type. Do not use the car for 4 months over the winter and charge it once a month but with a standard charger across the battery terminals, which I read is the wrong method. Never had any problems until now. The terminal voltage is 12.2 V lower than a lead acid at say 12.6 but has always been like that. The only malfunction in the past has been on starting where an image of a car jacked up of the ground appears sometimes appears and the clock trips with no display. Not done this for some time though.
Should I be buying another AGM or any 096 type.
Understand a new battery needs to be registered and coded to the car computer. Can any competent mechanic/garage do this as do not want to take to the likes of Sytner.
Hoping to get to Sytner to have the recall battery done first.

AGM just means 'Absorbent Glass Mat'. ALL car batteries (unless Li-ion) are lead acid. AGM are standard on pretty much all modern BMWs. AGM is just a way of getting more 'juice' into a given space.

Personally I wouldn't let Shytners clean my windows, let alone touch my car, but that is a different matter. The E89 needs a new battery coding because of the IBS (not Irritable Bowel Syndrome but Intelligent Battery Sensor).

Chippie · Post by **Chippie** » Tue Sep 26, 2023 7:43 am

If you fit the same amperage battery then it only needs registering to the car so that it knows it’s a new one, most garages should be able to do this with their scanner, it’s not critical to have this done immediately but better sooner rather than later, it’s not difficult to change the battery yourself so either order a new AGM one online or call into a local motorist shop ASAP and get it changed

matsmith749 · Post by **matsmith749** » Tue Sep 26, 2023 6:42 pm

You might be super lucky, the battery reading 12.2v means it is fooked.

Could it be all that's wrong? It could be.

Absolutely needs to be changed before doing anything else.

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