View Full Version : Intermitent no start troubles, need input....

10-11-2003, 09:34 PM
I have a 1985 325e with 208,400 miles that just recently is having a problem starting only ocassionally. It happens after the car is sitting, either overnight, or while at work for 9 hours. The weather is warm, about 75. It just cranks without turning over, if I keep trying and then wait few minutes it will slowly putter to life. Also, the engine idles rough all the time.

There are no vacuum leaks, the plugs, wires, distributor cap, rotor, coil, both fuel pumps, fuel filter have all been replaced in the last 6 thousand miles or less. Also both reference sensors on the transmission bell housing are new. I also recently pulled the head and had it rebuilt, with new t belt, water pump and seals. A compression test revealed 205psi on all cylinders but one, which was 190, thats what I figured was causing the rough idle. I also have a bootleg performance chip from ebay, and a cone filter, 2 1/4" exhaust with high flow cat and flowmaster muffler.

I believe that spark is lost when this no start takes place.
Does the cranks sensor on the front of the timing cover produce a signal for the ecu? or is it just for diagnostic? Could that be the problem? It hasnt been replaced.

What else could cause this no start? Any ideas, let me know, thanks.

Jay Stock E30
10-12-2003, 09:29 AM
I recently had a no start problem/ rough running problem on my '87 325is. I finally traced the problem back to a loose wire on the coil. After I thghtened the wire down it started fine and ran much much better...go figure...So I might suggest to check all electrical connections both ones that have current accross them, and the ground wires (a loose engine ground wire will cause a no start condition). I am not as knowlageable about the e motor..but I think that the crank sensor on the front of the engine does send a signal to the ecu, so if there is a no start problem that could be it. I think I have one I could send you. Hope this helps.

'87 325is Twin Turbo
'87 325is

10-12-2003, 09:43 PM
I checked both wires at the coil when it wouldnt start and they were tight.
I gotta glance at a wiring diagram, because that front crank sensor runs straight to the diagnostic plug on the engine, that why I thought it was used for diagnostics.
I'll check on it.

10-12-2003, 09:59 PM
The wiring diagram just looks like the front sensor is wired to the terminals on the diagnostic plug, it doesnt look connected to any other terminals on the plug.

10-13-2003, 03:58 AM
Had the same symptoms on my 89 325i. I traced it down to a coolant temp sensor for the DME
CHanged it and the car was fine.
The car would start and sputter real bad and die sometimes,Idle was rough.
WOuld start fine when warm though, thats why its the sensor, it defines the amount of timing and gas mixture

10-13-2003, 12:51 PM
if you test the coolant temp sencors and there fine then maybe check your fuel pressure. sounds to me like your FPR is dead. its not holding static fuel pressure and its taking a while to get it up to pressure.

the coolant temp sencor also determines how much timing to advance from static. if the coolant temp sencor is bad the ecu will retard timing and that oculd make the idle bad, also it would kill driving performance as well.

10-14-2003, 12:04 AM
I replaced the FPR about 6ooo miles ago, so I'll check the coolant sensor first, which one is it? There are like 2 on the radiator and like 3 in the thermostat housing.

Also, I don't have any power problems, its pretty quick.
The car has been starting and driving fine the past few days, just twice it wouldnt start. Im trying to catch the problem before it gets worse.

10-14-2003, 05:20 PM
I just checked the coolant temp sensor and according to the book, its faulty. At operating temp I measured about 73 ohms, the book says it should have 270-400. So I will order the sensor and let you guys know if that does the trick.


10-15-2003, 04:42 AM
Im not sure about its placement in your engine but the Fuel Rail was in the way of getting any kind of socket on the sensor. I removed the sensor by using big wrenches from on top and sideways using a screwdriver to twist the wrench in order to turn the sensor. :roll: It sounds complicated but hopefully you have offset wrenches or the sort.

10-16-2003, 06:55 PM
Yea, I wont have to take the sensor out, it checks out fine. I identified it by checking the color of the wires and indexing them to the wiring diagram in my manual. The sensor is good.

12-16-2004, 07:59 PM
I had the same problem...

Check your thermo-time switch & your cold-start injector.

I found that the connectors to both were shorting out to the sensors which was causing my occasional no-start problem. After I roll of electrical tape to them, I never had a problem.