She starts when she wants!

[Kailua Carrera]

Anybody had this issue? I have a 85 Carrera and it starts about 95% of the time and only when I'm home it happens "cold" thank god! never when warm and I have asked around and the obvious answers such as fuse's, spark, fuel are all apparently fine
I think??!! when it does start she runs great and strong! any suggestions most appreciated.
Mahalo

[DRACO A5OG]

Aloha,

Your Starter may be heat soaked and solenoid is stuck in place until it cools off. If she push starts, then that verifies it.

Also next drive, check voltage reading then after your trip, an hour later check again. The hour wait is to see where the voltage is at rest.

You are looking for 12.5+ but I suspect Starter is ready to go out on you.

Aloha

[DanielDudley]

I'm assuming that it cranks, but won't start. Do you have a spare DME relay ? Most people would start there, and there are a lot of threads and Youtube videos on DME relay repair.

Sometimes it is just a bad solder connection.

[Kailua Carrera]

Mahalo Draco.. I apologize.. yes it cranks over and the voltage is 12.?.

Mahalo DD I will look into the DME, never heard of it and do they fail often??

Thanks

[uwanna]

You say it runs and starts okay when warm, but has trouble on cold starts? Check out the cylinder head temp sensor. Had the same trouble on my 3.6 , very hard start when cold but after a bit it would start and then hard to keep running till it warmed up. Check the resistance on the cyl head sensor and then OHM out the wiring from the sensor plug to the ECU connector block. The problem on mine was a poor contact connection
between the ECU and the connector block for the cylinder temp sensor contacts. Cleaned the connections with DeOxit D5 and reseated the the units several times and VOILA , problem fixed!

[Kailua Carrera]

Well the previous owner was smart enough to have a extra DME in the GB but it was empty and gets better whoever installed it left the old one bolted in and the new was flopping around under the seat so I will start with this.


Thanks uwanna but if the DME isn't the issue next will be the cylinder temp sensor!!

mahalo

[Kailua Carrera]

[DRACO A5OG]

CHeck to see if you have a dual wire CHTS or single, if single, it is time to update to the dual one.

No start at cold is signs of the CHTS going but measure the OHMs to be sure.

[TipToe]

I just experienced this same problem in my ‘86 911 Targa. Ill be replacing the DME this weekend.

[Driven97]

I'd rank this lower on the possibility chart, but also could be a bad/dying/incorrectly spaced crank or reference sensor. Car will crank but not start if these go too. Perhaps the heat aggravates whatever is failing, and when it cools it pulls back into position.

[TipToe]

Well, after being on a tender all week, the 911 didn’t crank right up with the old DME relay, but it finally did, and i backed it out of the garage and replaced the DME relay. Then it would not turn over with the new DME.....so I put the old one back in and it started right up. I opened both of the DME’s up (old and new) and I didn’t see any issues with the solder welds...they all look intact and no cracking).

So, I agree with Driven 97, I dont think this is a DME relay issue....I think its a sensor somewhere. BTW, the fuel pump was replaced in Jan ‘15 and the alternator was replaced in Feb ‘13.

Hummmm......

[Kailua Carrera]

reading TipToe's post.. im not clear on the DME purpose! mine cranks over strong but doesn't start and with the new DME installed its still doesn't start! WHAAAA

Driven97 how would a crank get incorrectly spaced??
mahalo
mike

[Kailua Carrera]

Thanks DRACO but what is a CHTS?

[DanielDudley]

Originally Posted by DRACO A5OG

CHeck to see if you have a dual wire CHTS or single, if single, it is time to update to the dual one.

No start at cold is signs of the CHTS going but measure the OHMs to be sure.

Makes a lot of sense. ^^^^

It is a lot easier to read a digital multimeter, and decent ones aren't incredibly expensive.

When I tested mine, it wasn't really that far off from what the new one read. However, the car was running poorly after a cold start up, so I plugged the new sensor to the harness in the engine compartment without even installing it. The car fired right up and ran well, so I pulled the old one and put the new one in. The old one should have been in spec, but swapping them out was night and day.

You can pull the old one by cutting the wires and using a socket, but there is a special socket available for this. I wound up cutting a slot in a box wrench to slip it over the wire when installing the new one. Captain Obvious says you will need a jack and jack stands as well.

[tmaull]

CHTS = cylinder head temp sensor
Top connector on the left hand side near #3 cylinder - goes to the lower side #3.

[Driven97]

Originally Posted by Kailua Carrera

Driven97 how would a crank get incorrectly spaced??
mahalo
mike

The crank and reference sensors sit in a bracket that is adjustable. They have to be a certain distance from the flywheel to read correctly. If the bolts aren't tight or came loose maybe the bracket self adjusted?

I would expect that a sensor is dying before that bracket moving, though.

[DRACO A5OG]

OP,

Sorry about the abbreviations, I assumed, which is my bad.

Okay, in the engine bay, locate the white connector ( may be yellowed now ), remove heater hose for easier access, remove locking plate of the three sensors ( 2 black 1 white ), take a close look at the white wiring to see if it is dual or single wire. Then more importantly, check the OHMs with a digital for meter and check with the chart in the Bentley or post here and we will chime in if the limits are correct and CHTS needs swapping.

+1, it could be the RPM Reference Sensor letting go, be prepared and if bad, consider changing but Ref and Speed Sensors as they age pretty much the same. BMW brand sensors are the same thing, cheaper and a bit longer. I really doubt it got lose but I have seen stranger things :-)

Break a Leg Brotha! Aloha!

[Kailua Carrera]

Mahalo guys for your help!!

Draco, I located the CHTS and it is a two wire..whew and I removed it and plugged it back in and was on my way to grab my meter and for the hell of it I tried to fire it up and yay she fired up!!

So because I am who I am I want to order all new sensors, is there and recommended ones that I should purchase.

she aint leaving the driveway till repaired!

I look forward to any advise.

You guys are all super smart !! love this forum

Mahalo again

[DRACO A5OG]

Like you said she is tempermental :-). Before you waste your money, please measure the OHMs on the CHTS.

For preventive measure, ref and speed, get the BMW sensors, they just unbolt via allen bolts. DO NOT LOOSEN Adjustment bolts. Ask me why?

Get this BMW sensor part number: BOSCH # 0.261.210.002
or BMW # 12-14-1-708-619
search pelican for the BMW # 12-14-1-708-619 and order 2 of these
(compliments of Scarseller)

[Kailua Carrera]

For some reason those part numbers don't match?? any ideas?