Crank no Start Issue Resolved!

[billyboy740]

I've got a 2000 740il which started an intermittent crank no start condition about 6 months ago. I got progressively worse as time went on. It would crank and crank and would eventually start after 15-20 secs. if you let it go. I checked the codes and there was a #2O2sensorheateraftcat. message. reset that. After about a month I checked codes again and got #2 O2 sensor heater again and I had a #2 cam sensor code. reset that and replaced cam sensor. Didn't stop the problem. Replaced other cam sensor after getting #1 cam sensor message about 1 month later. Still didn't solve problem. Replaced Crank sensor on advise from Bav. auto tech. that said crank sensor often will not trip code. Didn't solve it! Kept getting O2 heateraft cat code. Looked at TSB's and an old one for e-38 said if DME program went bad it would give false signal of O2 sensor. Brought car to dealer had them reprogram(flash) the DME with latest software. Seemed to help for about 4 days and then began intermittent crank no start again!
Started looking through Electrical diagrams on pwr to ignition coils and found unloader relay terminal 15 in Bentley manual. This relay is in the E-Box Right Rear engine comp. (ECL-27 in Bentley manual) This relay controls power to all the ignition coils! I checked power out of relay with DVM and found that it was intermittently not putting pwr. out. Took relay cover off and confirmed that relay was not closing all the time. I cleaned the contacts on the relay and could not get it to fail again. So I think I may have solved the problem! $350 worth of Sensors and $200 for an unneccessary DME reprogram later but it was worth it!

So if you get an intermittent crank no start check that unloader relay terminal 15 in the ebox first! It will save you some serious headaches and $$.
Any questions let me know! I left some small details out for sake of time but if you want all the details email or call me, I'm happy to help!

[Edwin NL]

Glad you fixed it! the parts you change would have craped out anyway

Damn $200 for a recode, I charged $25 when I was in the USA

[black740ia]

good info

[njdjh2o]

Nice fix , isn't it wonderful to get back into the 7

[007 40i]

thanks for the information! Glad to know your up and running again.

Nice fix and good luck


- John

[Chief Jimbo]

TXDarth needs to see this post.. I think he had the same problem awhile back??

[Smedley]

Now this is why we are on this forum, good work. I tip my flat hat to you.

[AnthraciteE38]

I started having these intermittent no start issues with my e38. It happens completely randomly. Always cranks, but randomly won't start. Does anyone know which one is exactly the "unloader relay terminal 15" in the E-box? I'd like to figure out this issue without randomly replacing parts. Thanks in advance.

[Mayorchuck]

Here it is but this only thread I have ever seen where it caused a no start condition.

K6326, X6326


rear RH side of engine compartment in E-Box

K6326	Unloader relay terminal 15
X6326	Component connector (9-pin, Black), Unloader relay terminal 15

[AnthraciteE38]

Thank you very much for the information. Do you have any suggestions for troubleshooting this issue? Or what are the most frequent causes for this random no start issue? To provide some more info: the engine always cranks, so no issue there. Battery is fully charged. The engine either starts without any hesitation or won't start at all (well not in 15 seconds, at which point I stop cranking). Generally when this happens, it starts on the second attempt, but sometimes I have to try again. So far it has always started on the 3rd attempt. The issue is completely random. The car may sit for days and will start without hesitation. Other times, the issue happens even after a the engine is off for short time (10 mins). I suspect either this unloader relay or the ignition switch. Any suggestion is much appreciated.

[Mayorchuck]

Those are tough to diagnose as it could be many things. Ignition switch, crank sensor, fuel pump or filter, etc. It would be good to know if you are getting spark when this happens. Might pull the cover off the coil/spark plug area on one side. Keep an extra spark plug in the car and when it's not starting, pull a coil and put the plug in it to check for spark the old fashion way. A dying or aftermarket crank sensor will not always throw a code. DME will not provide spark or fuel if it's not getting a good reading from it. You can go wrong replacing the relay and iggy switch either. Neither are expensive and are easy to replace.

[AnthraciteE38]

Well, I think I can rule out the unloader relay. I swapped it with identical from the trunk. No change in behavior. Started on the 3rd try. Next is the ignition switch. Should I get the Febi Bilstein one from oembimmerparts ($63) or the genuine BMW from ecstuning?

https://www.oembimmerparts.com/BMW-I...cB&click=25211

https://www.ecstuning.com/b-genuine-...h/61326901962/

[AnthraciteE38]

I think I have an issue where the EWS module and DME are out of alighnment. Here is what I found:

relevant section from EWS 3.3 operation:

If the “Codes” do NOT match, the DME “rolls forward” to the next code according
to the “Rolling Code Table” and makes the same calculations. The DME continues
this “forward roll” up to a maximum of 200 times or until a match is found. Failure
to find a match will result in the engine cranking but not starting.

So does anyone know the alignment procedure for the EWS and DME using INPA? I would much appreciate the info.

[Mayorchuck]

If the DME and EWS were out of sync, it would not eventually start. It stays out of sync until fixed.

[AnthraciteE38]

well, I tried to realign with inpa. Now it won't start at all. Damn this car.

[Mick3831]

Hi, just found this thread... I'm experiencing exactly thed same on my 2001 740il sport. Cranks all the time but will only start eventually. And here is the wired thing... it starts right up every time when I release the fuel pressure... heeeelp please... :'(

What I did so far and what's my next step:
Replaced fuel pump and relay, fuel filter, cam shaft pos sensor, crank shaft pos sensor, relay #15, throttle body

Next I'm going to send in the DME, EWS and key for a check up...

[AnthraciteE38]

Got it to start again. INPA was not able to align the ews and DME. I also have DIS44 on my laptop, but it wasn't properly configured and wouldn't communicate with the car. After about 2 hours of struggling, I managed to get DIS to work. Performed the ews dme alignment, all went well. Car started up on first try. Phew!

[AnthraciteE38]

Just wanted to provide an update and hopefully conclusion. After performing the EWS DME alignment the car was working fine for a few days, but then the same issues were back: random stalls, now also while driving, intermittent no starts. So I decided to replace the ignition switch even though I did not have high hopes that it would fix the issue. I got positively surprised. The E38 has been working flawlessly for the past 2 weeks. What is strange that when I measured the resistance of contacts of the old switch, it seemed to be working fine.

[LVe38]

Came across this thread and noticed AnthraciteE38’s posts. I am currently stuck with the “Cranks but No Start Issue.” Some background - I have not used my E38 as a daily driver for over 12 months. I would move it once a week for the weekly street sweeping in my neighborhood. About 3 weeks ago, I was re-parking out onto the street and placed the car in Drive when it drove a few feet and the car stalled. I tried to re-start and it will not start. I have since checked all the fuses and relays in the trunk and EBox, replaced fuel pump & fuel filter, verified that my battery is in good condition, battery safety switch is still intact, replaced ignition switch, cleaned fouled up spark plugs, and replaced crankshaft sensor.

How do you perform the EWS - DME alignment, and what scan tool / diagnostic equipment did you use to date alignment? Response is greatly appreciated.

- - - Updated - - -

Came across this thread and noticed AnthraciteE38’s posts. I am currently stuck with the “Cranks but No Start Issue.” Some background - I have not used my E38 as a daily driver for over 12 months. I would move it once a week for the weekly street sweeping in my neighborhood. About 3 weeks ago, I was re-parking out onto the street and placed the car in Drive when it drove a few feet and the car stalled. I tried to re-start and it will not start. I have since checked all the fuses and relays in the trunk and EBox, replaced fuel pump & fuel filter, verified that my battery is in good condition, battery safety switch is still intact, replaced ignition switch, cleaned fouled up spark plugs, and replaced crankshaft sensor.

How do you perform the EWS - DME alignment, and what scan tool / diagnostic equipment did you use to do alignment? Response is greatly appreciated.

[Timm]

That sounds like the engine is flooded - classic cause of moving it a few feet and the stopping when the battery voltage was low - and then it refuses to start. More info here:

https://www.meeknet.co.uk/E32/Flooded_M60_Start.htm

[TNLB7]

Hi Edwin,

I have no idea if you're still reading this topic (I hope so since you live in Amsterdam as well).

But I somewhat of the same problem where my E92 will crank but not start anymore, this is after I was dumb enough to try and update/flash the DME with a K+DCAN cable from one-stop-electronics..

I had been doing some coding with succes in NCSExpert and decided to remove the s843 - power reduction option by editing the FA/VO and then updating the DME with a ZUSB without the power reduction option. If you or someone can help me that would really by appreciated a lot!

[purplecty]

Hi Edwin,

I have no idea if you're still reading this topic (I hope so since you live in Amsterdam as well).

But I somewhat of the same problem where my E92 will crank but not start anymore, this is after I was dumb enough to try and update/flash the DME with a K+DCAN cable from one-stop-electronics..

I had been doing some coding with succes in NCSExpert and decided to remove the s843 - power reduction option by editing the FA/VO and then updating the DME with a ZUSB without the power reduction option. If you or someone can help me that would really by appreciated a lot!

What year? Did the DME update successfully? Using WinKFP?

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