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Old 01-01-2011, 04:24 PM
BMWS441 BMWS441 is offline
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Transmission/catalytic converter problems

So here's the deal. I have a 97 740i. It has 172k mi. The transmission was replaced in February with A used/rebuilt transmission. It was 2200$! . So In aug of 09 the cars catalytic converters were replaced with aftermarket ones and 7 months ago I got a cel with a cat code in both banks. I just didn't worry about it for a while bc I didn't have to pass emissions til jun 2011. Then almost 2 months ago I started getting a sort of rattle shuddering noise from the car when the engine was under load and you kept at the same rpm and it sort of surges or hesitates. I figured this was the cats that apparently weren't right for the car and bad cats are known to cause back pressure and all sorts of problems. So I got with a friend of ours that works on cars constantly, can do just about anything and has done it, and his wife has an 01 740il. He read the codes and I was getting a misfire (sorry I forgot which cylinders) and I thought that this must have been the problem I was experiencing. Also I had used regular gas and he said it could've caused the car to start pinging. So he changed the sparks and did some sort of cleaning thing that cleaned the fuel injectors and such and from now on use only premium. Got the car back with no cel and no apparent issues. Then, of course got the cel and started experiencing the same problem. Brought it back, still a misfire thought it was either coils or fuel injectors. So we changed the coils around to c if it would say on different ones. Sure enough car did it again and cel back. Read codes. No misfire! Just cat on bank 1. But the car was still acting up so I took him for a ride to show him exactly what I'm talking about. He said this was the transmission that it was trying to decide which gear to go into(rattle noise) and that there must b a clutch or something messed up. He suggested taking it to an amco or something and having it flushed and the fluid changed but he cannot deal with auto transmission especially the one that the 740 has. Since the transmission was already replaced! I obviously went back to the place that put it in. Strictly German. I dropped the car off and told them the problems I was experiencing and they said they would look at it and drive it. I called and called finally 2 days later they said they weren't sure what i was talking about and that I needed to come up and go for a ride with the tech to show him what I was talking about. So I did. The tech drove and was driving the car hard so the car did not do it as much. Finally it started to do it up a hill but not nearly as bad as I had experienced. They acted like it was not that big of a deal and I shouldn't b so worried. When they got the car apparently there were numerous faults for the trans-torque converter, speed sensor and some sort of lock up with a clutch. They cleared it so now I had no codes. So they told me to drive it until I got a fault. I drove it about 50 miles. Still no fault. I gave up. The next morning after another 60 miles it finally came on. On both trips the car was acting up worse and worse the more I drove it. so I had codes read immediately and what was it? Cat faults in both banks. The tech said it must b the cats then but we need u to drive it again until we get another fault to make sure it is the same. He also said he thought they had a 740 come in and I could buy the exhaust system off it but he'd have to check This was Thursday. The light just came on again today(sat). Strictly German is also a BMW junkyard that it's what I meant above by a 740 coming in. Anyway my ? Is what is most likely the issue? I trust my personal mechanic more who says it's transmission. I think it is too. But strictly German could b right too or could b trying to deny that they would put a faulty transmission in my car. Please help! Idk what to do... Also. I'm selling it in April and will be buying an 04 745li from my uncle who ordered a Maserati . Thank you for ur input/response and apologize for posting such a lengthy post.
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  #2  
Old 01-01-2011, 06:00 PM
balance balance is offline
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I don't think the cats are the problem sinse from what I'm reading, the car was running with a cat code fault for about five months before you actually had a problem with the car shuddering. If the cats were causing the problem, they should have caused a problem right away. On the other hand, they could have just broken and gotten clogged recently, so I would go under the car and try hitting them with my hand to see if you hear any sort of rattling noise.

Is the shudder happening at around 40mph? This is usually the speed where you would feel a torque converter shudder, and it looks like a fault code was thrown for it. I wouldn't be surprised if it is the transmission but without actually driving the car, there is no way for me to know over the internet. You should call Kirt Koeller at www.autosportsunlimited.com and explain what is going wrong with your car. From a short conversation with one of the guys there, I got the impression that they know lots of information about the transmissions that are used in these cars, and maybe they could give you a better diagnosis than me.

Almost forgot. BMWS441, PARAGRAPHS!

Last edited by balance; 01-01-2011 at 06:01 PM.
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Old 01-01-2011, 06:36 PM
BMWS441 BMWS441 is offline
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I have tried hitting all parts of the exhaust and have heard nothing. My mechanic even did this while the car was hot... Lol.

The shudder happens really at any speed but it does happen around 40-45 frequently. I will defiantly be giving that place a call on Monday. Thank you for your help and I will put it in paragraphs next time. Haha
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Old 01-06-2011, 11:07 AM
BMWS441 BMWS441 is offline
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I took it back to strictly german on tue. Got codes read and it was the cats. I asked the tech to check if there was any trans faults. There was some sort of pump, he said this wound not cause an issue.

I told him how I didn't think it was the cats. They're just leaking is what I think. I asked if it would make the rumbling shutter noise that it is making could b the cats. He said no so i asked if I could show him. This time I drove and I feel like this tech was worth a damn. Well that's until he told me it was suspension!!!! I'm pretty sure he thinks I'm stupid. The problem stops when u take ur foot of the gas.

I tried calling all sports and didn't get anyone so I left a message with my number to call me and they haven't.

Please help! What should i do? I'm not trying to throw money at it bc I'm getting rid of it in April. But then again it would probably sell for more with no issues. The car is in great shape except for this problem.
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Old 01-06-2011, 11:59 AM
balance balance is offline
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April is still a few months away, so you have some time to diagnose and fix the problems. I would try calling Auto Sports Unlimited a few more times to see if they had any useful information for me first. If they didn't, I would go to an exhaust shop like Meineke, and ask if they could cut the cats and put straight pipes on it so that you could drive with NO cats and see if the problem is still there. In some states, this is illegal, but it is what I would do to help diagnose the problem.

If the problem is fixed when you put straight pipes, then the cats were the issue. If the problem is still there, then the problem is with some part of the drivetrain (driveshaft, transmission, engine).

BTW, there should be no fault codes stored in the transmission. If you got a fault code, and the tech was trying to act stupid/ignorant to the fact that they replaced a transmission in your car that is now throwing codes, I would go to another shop, tell them exactly what is going on, and see if they can tell you if that code that is stored could be causing the issues you are feeling.
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Old 01-07-2011, 09:12 AM
BMWS441 BMWS441 is offline
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Yeah that's probably a good idea. I should defiantly go somewhere else and call them back. And I should just have my personal mechanic do that with the cats.

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