1997 BMW 318 Transmission Issue

Tiny
CARDINAL2389
  • MEMBER
  • 1997 BMW 318
  • 1.9L
  • 4 CYL
  • 2WD
  • AUTOMATIC
  • 123,000 MILES
I have a 1997 BMW 318ti with an automatic transmission. It hesitates when cold. It takes up to 3100 RPM's to shift into second. Normally, it shifts at around 1900. When warm it has minimal shifting issues. I had the transmission serviced, and it was low on fluid. I thought that all my issues would be fixed with the service and right level of fluid, but I was wrong. The mechanic said that the transmission was in good shape with not much debris in the fluid. Here's the odd part, when I start the vehicle there is a 20 second period of odd humming from a canister at the front right of the engine and a feeling of an air leak. When I shake the canister and pull on it the sound shifts a bit. The kicker being that when I do that it turns off the traction control and the transmission shifts like a dream, even when it's cold, and even when it was low on fluid. When I manually turn of traction control, it makes no difference. Any ideas as to what is causing my shifting issue?
Sunday, September 20th, 2015 AT 6:02 PM

11 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 108,179 POSTS
It sounds like you have a vacuum problem. The canister you referred to, are there vacuum hoses going to it?
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Sunday, September 20th, 2015 AT 6:16 PM
Tiny
CARDINAL2389
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Yes, there is a hose coming from the air filter that attaches to the top of the canister.
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Monday, September 21st, 2015 AT 8:08 AM
Tiny
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Have you tried repairing the leak? That could be causing several problems.
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Monday, September 21st, 2015 AT 5:51 PM
Tiny
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Not yet, I'm going to get it diagnosed within a week. Mainly wondering if that can affect the transmission. I just found info that the odd noise accompanying the air leak could be a timing belt issue.
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Monday, September 21st, 2015 AT 6:39 PM
Tiny
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Since the noise changes when you move the hoses, I'm confident it isn't the result of timing.
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Thursday, September 24th, 2015 AT 5:38 PM
Tiny
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I'm getting it diagnosed this week. The suction noise changed, but there is a womping pumping type noise that adjusts with rpms and goes the length of the leak noise. It's quite loud. But, could the leak be causing the transmission shifting issue? I appreciate your help, I'm new to BMW's.
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Thursday, September 24th, 2015 AT 7:51 PM
Tiny
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On the newer cars, it's unlikely that the leak is causing trans problems, but anything is possible. Also, the vacuum noise will change when the RPM's chance.
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Thursday, October 1st, 2015 AT 4:24 PM
Tiny
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It's a 97 and a shop stated that it could be the air leak. Had my mech fix the leaks and he says it runs much better, but I haven't driven it to see about shifting. He stated that the noise is from an air pump that warms the catalytic converter for emission purposes, not vital.
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Thursday, October 1st, 2015 AT 4:49 PM
Tiny
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Let me know if it's good.
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Thursday, October 1st, 2015 AT 5:23 PM
Tiny
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Air leak was fixed, plugs were changed. Car is running better and responding. There still are a few small leaks causing issues. Didn't adjust transmission shifting issue. But going off my prior experience with the transmission working while the traction control was off I unplugged it. Transmission is shifting great. What is causing this?
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Friday, October 2nd, 2015 AT 4:45 PM
Tiny
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Wow. It could be so many things. An ABS sensor, speed sensor (input or output) different size tires.
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Sunday, October 4th, 2015 AT 7:31 PM

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