Hey so I recently picked up a 1989 325i. It had a misfire when I got it and was told it was the distributor cap and rotor. A used one came with the car so I replaced it with the used one that came with it. I just roughly cleaned up the contacts on both the rotor and the cap before installing them along with a good but used set of plug wires. It made it better but it still misfired so earlier today I got a used coil and installed it but it didn't seem to make a difference. Any ideas on what it could be or what I should do. Thanks in advance.
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Also forgot to clarify what I meant by misfire. some times it just a slight misfit you hear but other times when driving the engine will like cut out and take a few seconds before it comes back and it is totally random. it does not do it all the time and I think its more likely to do it when its wet or rainy out but I'm not 100% sure about that -
Check your plugs
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What's your fuel pressure reading ?Comment
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Im not sure how would i check. Also it looks like the fuel pressure regulator looks like it has been replaced recently. Also on a side not I tried to replace the main relay with a used replacement and it didn't change anything.Comment
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You need a fuel pressure tester, they are cheap enough.Comment
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Ok I will check that out tomorrow but another thing I forgot to mention is when this happens for longer than a second or two the tac drops to zero if that helps at allComment
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Then I would susspect the CPS, check to make sure it's clean. If the sensor face is dirtty or has picked up meta firstl particles it can act weird.
If you can borrow a known good one, even better.Comment
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Hey so I checked the CPS today and it was filthy. I cleaned it off and read around to find out how to test it. I checked it with a multi meter to check its resistance and i believe it is with in range it showed what I believe was 575 ohms. I will reinstall it tomorrow and see if this has fixed it.Comment
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Make sure it's routed correctly too. Behind the coolant hard line, not up over the distributor. It's a heavily shielded wire, but over the distributor could potentially add interference in the line.AWD > RWDComment
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So I just tried to reinstall the CPS and initially I installed it and tried to start it and it would start and it sounded like it didn't have any spark because it wasn't even trying to kick over so I checked and it didn't have any spark so I went back and look around the CPS and found out the yellow wire had popped out of the sensor so I assume that was the problem that wire was just a loose connection so thats why it would come and go and the stress of me pulling it out and trying to put it back in was enough to totally disconnect it. If anyone has a CPS they would be will to part with send me a pm trying to find a used one since I'm on a tight budget. Thanks everyone why helped and had input.Comment
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I wouldn't waste your money on a used cps over the internet. This is an item that is very important, as you can see.
fcp euro
steve@blunttech.com
They're ~$70.AWD > RWDComment
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Get a new cap and rotor. I have cleaned up the contacts in the past and it has done nothing, in fact in one case it made it worse. If you file or wire brush them you are removing material making the arc longer. Pull a plug (leave the wire on the plug), hold it to a ground, have someone crank the engine and see if you get a hot spark. a yellow tiny spark means too much resistance somewhere between the coil and the plug.
Also, check each plug to see if they are fouled.Comment
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