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Go Back   Bimmerfest - BMW Forums > BMW Model Discussions > 3 Series / 4 Series > E30 (1982 - 1993)

E30 (1982 - 1993)
God's Chariot. The E30 was produced primarily from 1982 through 1991. The cabriolet was the one exception which was produced through 1993.

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  #1  
Old 03-06-2016, 04:56 PM
KyDollaSign KyDollaSign is offline
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Mein Auto: BMW e30 325is
e30 hard misfiring, I'm stumped

I have an '87 325is and have been trying to figure out this issue for some time now.
First, I had a hard bogg occurring, that was fixed with a refurbished AFM.
Second, I was getting a cutting out intermittent misfire. I replaced the spark wires and dist. cap and it seemed to temporarily fix the issue (plugs and rotor were replaced under 1k miles ago).
So after this happened it seemed to run great and then not long after a similar but different misfire thing started happening.
I pulled my plugs and #1 and #3 had oil all on the threads which made me believe that oil was getting in the plugs. It looked like oil or dirt had puddled up a little bit so I then changed the valve cover gasket and also put in some brand new injectors. I was hoping this would solve my problem but after driving it 8 or so more miles the misfire came back.
It is not a bogg: I've already been through that. I'm not losing ignition or anything: I've been through that. It doesn't feel at all like it is related to air/fuel.
It runs perfect before it does it and It basically occurs on heavy acceleration when warm, and sounds and feels like all the sudden I am running on 5 cylinders or less. It almost sounds like the engine is literally purring loudly . It's awkward to diagnose because it only does it when I am getting' it or going up a hill.
I'm stumped at this point and could use any info or ideas. Thanks in advance

Last edited by KyDollaSign; 03-06-2016 at 04:59 PM. Reason: typo
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  #2  
Old 03-07-2016, 03:06 AM
deSwede deSwede is online now
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Mein Auto: 1998 328is
Check the electrical 7 pin connector under the intake manifold for corrosion
wiggle on it when in idle and see if you get any missfires, had this on my
320 -88 and just cut the connector off and use other wire couplings to solv
the problem, other possibility is bad dme main relay.
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  #3  
Old 03-07-2016, 06:38 PM
KyDollaSign KyDollaSign is offline
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Mein Auto: BMW e30 325is
Sounds good let me check those out as soon as the rain lets up.
It's actually more like a governor hitting than a misfire, it'll cut in and out like something is loose and runs perfect before it does. Any rpm too it's super weird
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  #4  
Old 03-08-2016, 12:34 AM
deSwede deSwede is online now
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Mein Auto: 1998 328is
The injection harness includes wires to the dme coolant temp sensor as well, if that circuit
acts up you might get some wierd symptoms i guess, my experience is with
the motronic system, bmw changed from L-jetronic to motronic sometimes in 1987
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  #5  
Old 03-08-2016, 08:43 AM
KyDollaSign KyDollaSign is offline
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I let the car sit at idle and checked and wiggled all around under the intake, injectors, and CTS areas and nothing changed the idle or looked bad. I'm assuming if the relay was bad it would just not start to begin with? It would either work or not work?
I had to take the car to school yesterday because my other ride is down right now too. It drove ok the way there and did it maybe 5 times, but on the way home I barely made it. I know these cars don't have 'limp' mode but thats what it feels like is happening. I was driving home and it just started powering down (if i put the clutch in and rev it it will wake and go normal). The CEL popped on for a second at the worst of it so I pulled over but once I stopped the code went away. 2 minutes later it was fine and I bounced off the rev limiter. I have a midterm to take today so hopefully I can figure it out but I am pretty confused now.
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  #6  
Old 03-08-2016, 01:55 PM
deSwede deSwede is online now
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Did you disconnect the injector harness coupling and check on the male and female
pins in there for possible loose connection or corrosion, you have to undo a bracket
to make it easier to work with the harness, try to pry on the pins to make them
to fit tighter, i am talking about the big round plastic harness connector under
the intake manifold that's comes apart with a twisting movement.

http://s228.photobucket.com/user/s13...-2157.jpg.html
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  #7  
Old 03-09-2016, 05:08 AM
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BigBoy740il BigBoy740il is offline
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Sounds like a fuel starvation issue. Change fuel filter. Check fuel pressure regulator as it should maintain the pressure at 3.0 bar and slightly more under acceleration. Check both fuel pumps. One in tank and one external on the driver's side in front of rear wheel. They're are a low and high pressure pump system with the high pressure in tank pump feeding the external pump. It sound like one or more pump is not functioning properly and the system is struggling to keep up the fuel flow to the injectors.
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  #8  
Old 03-09-2016, 11:22 AM
KyDollaSign KyDollaSign is offline
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Quote:
Originally Posted by BigBoy740il View Post
Sounds like a fuel starvation issue. Change fuel filter.
Both pumps are new and filter was new (replaced that first). I just got s new one so I'll pull that and check my fuel pressure. I kinda out ruled fuel since nearly everything there is new. I'll check pressure tho! Thanks for input.
@deswede I didn't examine it THAT closely.. I will for sure when I get home. Thanks
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  #9  
Old 03-09-2016, 02:31 PM
KyDollaSign KyDollaSign is offline
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Quote:
Originally Posted by deSwede View Post
i am talking about the big round plastic harness connector under
the intake manifold that's comes apart with a twisting movement.

http://s228.photobucket.com/user/s13...-2157.jpg.html
Turns out my '87 has the earlier wiring harness that doesn't have that connector.
I stopped by a local shop and they gave me a ECU to try along with suggesting to check fuel pressure next. I think If those check out it comes down to wiring
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  #10  
Old 03-11-2016, 11:21 AM
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BMWFatherFigure BMWFatherFigure is offline
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Undo each plug and apply a liberal dose of contact cleaner (I used Wurth) to alll parts of the plug pins and sockets. With the physical retainer disabled assemble and separate the plug as many as 30 times. This will displace corrision on the connections. There might not be much to see but it worked for me on my E38.
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I've just changed my wiper blades and now my reverse lights don't work. Should I change my fuel pump relay?
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  #11  
Old 04-12-2016, 04:45 PM
KyDollaSign KyDollaSign is offline
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Thanks guys for the suggestions... I hate coming across solution-less threads so here is my update.
I threw a fuel pressure gauge on and have been driving it like that for the past couple weeks or so and here is what I've discovered.
As soon as I get just below half tank of gas the hesitating buckling stuttering begins as well as a loss/inconsistent fuel pressure. This has happened more than once. Drive to the gas station, fill her up and he's happy. Keep her above half tank and zero problems with fuel pressure whatsoever.
I picked up a new fuel tank from a '89 (mine is dented and filthy) so I will be putting that in at some point and will then hopefully have a solution to my problem.
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  #12  
Old 04-12-2016, 05:25 PM
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hornhospital hornhospital is offline
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Have you pulled the in-tank pump to check the sock filter? Sounds like it takes about half a tank for the filter to get clogged. Refilling the tank stirs it up enough that the debris is dislodged until it works it's way back to the filter.
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  #13  
Old 04-16-2016, 07:20 AM
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BigBoy740il BigBoy740il is offline
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I hate to be the bearer of bad news but the fuel tank of an 89 E30 is different from that of your 87 325i. Most notable are the single pump/level sensor hole vs the dual hole, the 14 gallon vs 16 gallon size, and the S pipe vs siphon jet action in return line of the newer tanks. The newer tank can work, but will require a bit of modification and the installation of a DS fuel level sender.
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  #14  
Old 04-17-2016, 09:16 PM
KyDollaSign KyDollaSign is offline
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Quote:
Originally Posted by BigBoy740il View Post
I hate to be the bearer of bad news but the fuel tank of an 89 E30 is different from that of your 87 325i. Most notable are the single pump/level sensor hole vs the dual hole, the 14 gallon vs 16 gallon size, and the S pipe vs siphon jet action in return line of the newer tanks. The newer tank can work, but will require a bit of modification and the installation of a DS fuel level sender.

Thanks for looking out buddy! I got the tank from a BMW mechanic locally who has a couple spec e30's and he informed me of the modifications that I need to do and the differences between the tanks. I haven't swapped it yet but will do so when I get a extra day or two so I don't have to rush it.
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  #15  
Old 04-17-2016, 09:17 PM
KyDollaSign KyDollaSign is offline
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Quote:
Originally Posted by hornhospital View Post
Have you pulled the in-tank pump to check the sock filter? Sounds like it takes about half a tank for the filter to get clogged. Refilling the tank stirs it up enough that the debris is dislodged until it works it's way back to the filter.
pretty sure that is exactly what Is going on haha.. Thanks for the help!
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misfire, misfire diagnosis, running on less cylinders, spark, spark plug


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