E85 - E86 Told my ECU needs Replacing/Programming

[Tad]

Hello

Problems first started the next day after a long drive on a cold start. The car cut out just after startup. Hadn't had this before and didn't really think much of it. The problem happened again shortly after and the car had a really rough idle. So as I was in the middle of wales I gave the car a minute then tried again. The car then ran with no problems for the rest of the day.

Got home and a couple of days later tried the car and again the rough idle had come back. The car would start but if i didn't get going or keep the revs up the car would cut out. My thinking on this was that it was something to do with when the car was cold because once the car was running for a little while it would continue with no problems. I then noticed that the car after a short amount of time being on would jolt like it wanted to cut out and the traction control and engine light would come on. The car went into what seemed like a safety mode and gave me no control over revs. Revs would then bounce between 1000 and 2000. Then after turning the car on and off a couple of times, it went back to as if it hadn't ever had a problem.

Engine light then stayed on. So I got it booked into a place that always has a number of BMW's outside in the hope they would have had the problem before and nail it. Unfortunately, that hasn't been the case. At first, I was told it was the throttle body, for this I was told it would be just over £800 supplied and fitted. Seemed a little high but wanted to get the car back on the road. Found out that hadn't worked and was told I would need to have the ECU sent away. When questioned about the throttle body I was told that was needed anyway and that it could have damaged the ECU.

ECU has now been sent back by two companies saying that it's the programming because when they put my cars programming on another ECU it comes up with the same problem. The garage has suggested getting a new ECU but I'm wondering if it can be reprogrammed.

Costs are starting to come close to the value of the car and I would love to see my Z4 back on the road.

So Any help is REALLY REALLY appreciated.

 

[srhutch]

What condition is your battery in?

 

[Tad]

Is this a problem that can be due to the battery!?

As far as I'm aware battery is all good but would you try another one?

 

[tomrdy]

Did the garage check for fault codes? Or did the companies who took the ECU read them? That would be the first step.

Best way to get some more conclusive clues.

I would suggest getting a cheap code reader yourself like a c110+ off eBay or Amazon.

 

[mmm-five]

Is this a problem that can be due to the battery!?

As far as I'm aware battery is all good but would you try another one?

I'd stay away from the garage you've been to as they seem to just want cash by throwing parts at it without actually diagnosing or fixing anything. They can't have known it needed a throttle body if they don't know the cause of the problem.

Don't take this the wrong way, but a garage with lots of cars outside doesn't mean it's a good garage - they just may never fix them - look how many you see outside BMW Dealers

If it's still on the original battery, I would start there.

A lot of common problems are caused by a poor/failing battery or an alternator/charging issue.
Plus, the battery is something that you can easily check yourself without costing too much cash.

Mine had different, random issues (e.g. cutting out on full throttle, stuttering n part throttle around corners) and we replaced MAFs, TPS, swapped ECU (on a loan basis), and finally got the battery/alternator checked out - and it ended up being the original battery on its way out...but probably knackered by the overcharging alternator as the digital voltage regulator had failed.

 

[Tad]

I feel like I'm in for a penny in for a pound with this garage. I'll have to get it back from them and see if I can get any kind of discount seeing as they haven't solved the problem. How would you guys go about finding a good garage?

 

[Smartbear]

I feel like I'm in for a penny in for a pound with this garage. I'll have to get it back from them and see if I can get any kind of discount seeing as they haven't solved the problem. How would you guys go about finding a good garage?

Why don’t you state your location & ask for recommendations on here?
Rob

 

[Tad]

Haha, Good point Rob.

I'm in Bournemouth, Southwest.
Any good garage recommendations would be much appreciated.

 

[mac27040]

sounds like a bad MAF sensor

 

[Kernow-Z4]

Ive had not too disimilar issues casued by battery issues in the past, albiet not on a bmw...

Just had a search of the recommended dealers/garages section and these 2 popped up which aren't a million miles away from yourself, all seemingly with people saying good things.

Iridium - Southampton: https://z4-forum.com/forum/viewtopic.php?f=4&t=62181
Emtec - Salisbury: https://z4-forum.com/forum/viewtopic.php?f=4&t=95450

 

[LittleZ4]

I'm in Salisbury, I have Carly and can get my hands on a good code reader.
Emtec is well known, there's also bromspec (localish) who deal with bmw's, the owner used to be the head mechanic and a BMW indie specialist in Southampton.

 

[Tad]

Thanks, guys!! I'll put a comment up when I get to the bottom of it. I hope no one gets the same problem its a bit of a pain in the ass!

 

[MACK]

Who are the two companies you sent the ecu to for testing?

 

[beekeeper]

Hi Tad,
I was having similar problems on and off. It started with a cough and stall on startup from cold, then went away, got worse to the point that you would lose control of the revs and it would vary between 1000 - 2000 revs all on its own, with EML light on and ABS light. I bought the cheap OBD cable and included software from fleabay to try to diagnose, and had lots of errors that weren't always consistent (however, had lots of throttle adaption errors and some crank position sensor errors).
While deciding how to proceed, I had a slight leak from the rocker cover, so replaced VANOS seals while I was there, stripped down the air intake down to the throttle body looking for leaks (found one on the intake boot) cleaned the TB and ICV and changed CCV. Though it seemed to improve things a bit, the problem came back. I continued with fault finding, and replaced the throttle body as the throttle adaption errors were consistent all the way through (I bought one from a breaker to eliminate this from the equation) and again, things seemed to improve for a while, but in the cold weather, it came back. :headbang:
I noticed that the problem was worse when it was cold, and especially as I started the car while it was in storage for the winter, it started to throw DME checksum errors. That got me on to searching for posts about cold starting issues, and I found a really interesting thread on bimmerforums that pointed me in a new direction. (I'm a newbie, so I assume posting a link to another forum is bad etiquette...)
Their symptoms seemed to be the same, and had been advised that a new DME(ECU) was required, so he sourced another DME and was going to re-flash it. In the end, he reflashed the original, with the replacement as a backup.
So that's what I did, I used WINKFP (I downloaded the most up to date Daten files I could find, but the ones included with the software included with the cable would have been OK I think) and I reflashed the ECU with the latest files - program and map.
Of course, this was a risk, as it could have bricked the ECU :!: , and then I would have had to send it off, but as the car was in storage at the time, it was a risk I was prepared to take. The update took 45 minutes, so make sure your laptop is plugged in and the car is on a charger. Alternatively, ask your indie to re-flash it.
The explanation (not proven of course, and expecting some comments on this one) is that the eprom in the ECU loses its programming over time - I suppose it's akin to a cassette tape losing it's definition over time - and if you reflash it, it re-imprints the programming.
Once finished, the car has run a sweet as a nut, even on the coldest of starts. I'm now getting the full benefit of the VANOS seal replacement and fixing the leak in the intake boot. I'll replace the throttle body from the breaker back to the original.
Whatever the explanation, that's my experience, and I'm happy the car is running well again.
Hope that helps
Pete

 

[RJ237]

This sounds like the same problem I had last year. I sent the DME to one company and they were unsuccessful, but RPM Motorsport in Victoria BC repaired and reprogrammed it for about $500 US.

 

[Tad]

Ok everyone if you get this problem it was the programming. The ecu was reprogrammed and the car has been working with no problem for months! Think you all so much for your comment beekeeper you got it spot on!