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Author Topic: bad hessitation, bmw e30 325i  (Read 2369 times)
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Jeff Seabrook
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1990 BMW e30 325i 2001 Corvette


« on: Monday, June 06, 2005 - 02:07 AM »

this is my final resort.

I've changed the fuel filter, distributor cap, distributor rotor and checked the new low pressure fuel pump and sender.

I have a horrible hessitation in the car.

First happened last week, accellerating to 50mph in 3rd gear, and it hessitated for one second, about the time it takes for fuel to ignite in the chamber.

On the way home, after 8 hours of work, the car had serious problems accellerating over 3,000 rpm.

here we are, and it's progressively worse - so today, I added 2 gallons of fresh 93 octane fuel, still didn't help (I've ran this car on 93 octane since August of 1998, except twice (1/4 tank 87 and 1/2 tank 87).

Tonite, I let the car roll down the driveway, and tried to accellerate to the top, and it barely made it up.  It doesn't even want to run anymore.

Crankshaft position sensor?

I've already put $100.00 into this problem, and it's still not fixed - it's like this:  if I have a flat tire, replacing the trunk lid doesn't fix it, but I spend the money anyway...see?
thanks
-Jeff
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Jeff Seabrook
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« on: Monday, June 06, 2005 - 02:07 AM »

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DeanP
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« Reply #1 on: Monday, June 06, 2005 - 02:12 AM »

Does it make a difference if it is under a load?  In neutral will it rev freely above 3K?  Did it do this before you replaced the fuel pump?
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Peter 89 325iX
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« Reply #2 on: Monday, June 06, 2005 - 04:30 PM »

Hi Jeff,

This problem has come up a couple of times on the BEN forums. There haven't been any solid solutions yet...mostly because not enough info about what has been done prior to the problems arising.

If the engine revs freely in a no load condition, the crank position sensors are fine. This is most likely a fuel supply issue as the AFM seems to be working properly. That leaves only the fuel filter, fuel pump, fuel pressure regulator and the injectors.

What's with this low pressure fuel pump? Is this not the OEM one? If there isn't enough pressure; 2.5Bar(35psi) then the engine will probably be starved for gas under load conditions.

Don't replace any more parts until we nail the problem or you might as well get that new trunk lid Wink

Peter
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Jeff Seabrook
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« Reply #3 on: Monday, June 06, 2005 - 10:00 PM »

under load or in neutral - same thing.

Just went to start it just now, and it hessitates at any rpm now, can't even get to 3000 rpm now.
fuel pump is months old, and i've never had a problem with it.  If it was bad, the car wouldn't start.

unplugged the cable from the airflow sensor and it stalled out, which is what should happen.  plugged it back in, and it starts with it. 

Did the oil change when I replaced the steering rack, and only put about 30 miles on the car since that oil change.

(watch this topic if you think anything could come to your mind about this one)
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Jeff Seabrook
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« Reply #4 on: Monday, June 06, 2005 - 10:00 PM »

fuel pressure regulator - where is that and how much to replace?
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Jeff Seabrook
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1990 BMW e30 325i 2001 Corvette


« Reply #5 on: Monday, June 06, 2005 - 10:31 PM »

"reference sensor" ? is that the same as a crankshaft positioning sensor?  $96.00 - I'm sure I can get a better price on it, 2 minute install also.
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Jeff Seabrook
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« Reply #6 on: Monday, June 06, 2005 - 11:13 PM »

Any kind of code reader available to see if a trouble code is stored?  Just replacing sensors willy-nilly is very costly.  What about a vacuum leak?
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Peter 89 325iX
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« Reply #7 on: Tuesday, June 07, 2005 - 12:52 AM »

Jeff,

I mistook dsports comment about the idle being good as a fact not a question Embarrassed

Since the AFM seems to do the thing when you un plug it that means it's good at idle. Check it for smooth operation...pu sh the flap inside back and forth with your hand and make sure it isn't binding or sticking. If that checks out, it's probably good. You can do a further test of the AFM by following the advice in this article...http://frwilk.com/944dme/afm.htm. Tha twill either find a problem or eliminate the AFM as the problem.
The next item that should be checked is; as suggested; the crank position sensor on the front of the engine, down on the right side below the fan. Examine the wiring to make sure it hasn't gotten munched by the pulley near by. This isn't an easy item to test as you need an oscilloscope or something to catch the pulses it generates...mo st multimeters will be way too slow to see anything Undecided
Also check the big connector under the intake manifold, towards the front of the motor...all this wiring goes through it and it is known to corrode/self destruct.

Peter
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Peter 89 325iX
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« Reply #8 on: Tuesday, June 07, 2005 - 01:21 AM »

Also, you can pull any codes from the ECU by following this link for method and interpretation of the codes...
http://www.unofficialbmw.com/repair_faqs/motronic.html

Peter
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Jeff Seabrook
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1990 BMW e30 325i 2001 Corvette


« Reply #9 on: Tuesday, June 07, 2005 - 11:28 AM »

its my birthday today, so I can play around on the car, and finish my mom's a/c on her 325es from last night.
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Jeff Seabrook
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Jeff Seabrook
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1990 BMW e30 325i 2001 Corvette


« Reply #10 on: Tuesday, June 07, 2005 - 03:48 PM »

found the problem, and temporarily fixed it.

crankshaft position sensor.

the wire has been eaten by a belt, and the sensor itself was covered in grease and grime, blocking the signal from the crankshaft, pic's on this post:

http://bmwsport.net/smf/index.php/topic,294.0.html
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Jeff Seabrook
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Ilir
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« Reply #11 on: Tuesday, June 07, 2005 - 09:09 PM »

WOOHOO! Grin
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Peter 89 325iX
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« Reply #12 on: Sunday, June 12, 2005 - 01:43 AM »

Glad you're up and running Jeff!
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Jeff Seabrook
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1990 BMW e30 325i 2001 Corvette


« Reply #13 on: Tuesday, June 14, 2005 - 01:10 AM »

thanks for the help there - appreciate it all
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Jeff Seabrook
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