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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 08-16-2014, 07:54 PM
kyle_e30 kyle_e30 is offline
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Troubles running my E30 318i

Hello,

I have a 1985 BMW 318i with a m10 engine. I recently bought it "as is" the engine seems off when I start it. On the first cold start started up after I fixed the previous owners mistakes it starts up no problem. Idle is bad and misfires/shakes as if it had a stroker kit.
Then it will just stall out after maybe 2 or so mins of having the car running. Afterwards I'm unable to start the car and keep it running. If I pull of the intake boot from the AFM it will start and idle but that's all. I've already replaced the AFM with a remanufactured Bosch oem one.
Things you should know:
My exhaust manifold is cracked in half causing now back pressure to build.


Could the lack of back pressure cause my AFM flap to not be able to open without "choking" the air supply?


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  #2  
Old 08-16-2014, 11:07 PM
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sixpot_simon sixpot_simon is offline
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Quote:
Originally Posted by kyle_e30 View Post
Could the lack of back pressure cause my AFM flap to not be able to open without "choking" the air supply?
Nope. The exhaust leak could be causing problems, but it should still run.

I reckon you've also got sensor problems, dying after 2 mins could be when the DME starts coming off its cold start cycle and begins actually listening to the sensors. This is just a wild guess, proper diagnostic tests are the best aprroach, of course.
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  #3  
Old 08-17-2014, 06:20 AM
kyle_e30 kyle_e30 is offline
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Would you think it's the coolant switch sensor? That sensor tells the vehicle that the engine has warmed up from the cold start

It's weird that after it stalls out
I can take off the AFM and take it up no problem. But can't drive it cause it bogs out


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  #4  
Old 08-17-2014, 10:07 AM
kyle_e30 kyle_e30 is offline
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Can anyone tell me how the cold start up process works? As in what sensors used and what the dme does and sees?

Really appreciate it!


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  #5  
Old 08-17-2014, 10:28 AM
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downhiller downhiller is offline
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Troubles running my E30 318i

if it has a cold start injector, it uses that to add more fuel until the ecu gets a signal from the o2 sensor to shut it off. then if i remember correctly, the ecu stays in an open loop fuel until the coolant temp opens/closes, then goes to a closed loop fuel. and i believe the difference from open loop to closed loop is the length of injector pulse.


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  #6  
Old 08-17-2014, 01:29 PM
kyle_e30 kyle_e30 is offline
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My 318i has a production date of 12/1984 made in USA. I'm not sure of whether or not it should have an O2 sensor but mine does not. My exhaust goes as follows: manifold(split in two but was terribly welded back together), resonator then muffler.
I work at a BMW dealership but never have worked on such an old car before. I've looked up parts through the dealership and it doesn't specify whether it should or shouldn't have an O2


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  #7  
Old 08-17-2014, 04:27 PM
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sixpot_simon sixpot_simon is offline
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Quote:
Originally Posted by downhiller View Post
the ecu stays in an open loop fuel until the coolant temp opens/closes, then goes to a closed loop fuel
Kyle, "open loop" = preprogrammed fuel map, not taking account the sensor information. This is why I think it might be a sensor problem. Or maybe it's somehow not getting enough fuel once the cold start injector shuts off.

How soon the ECU switches from open loop is either determined by the temp sensor or just after a set time, I don't remember which.
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  #8  
Old 08-17-2014, 05:05 PM
kyle_e30 kyle_e30 is offline
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Thank you for this great advise on where to search. Is there a way it can find out if the temp sensor is getting or sending the right information?
Oddly enough I already ordered a coolant temp sensor.
My plan is to replace all the sensors and the wiring harness for the engine because I bought this car used and not running. (Just want to be sure there no crazy surprises)
Could it be my injectors aren't misting properly?


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  #9  
Old 08-17-2014, 06:28 PM
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you could have clogged injectors. have you tried listening to the injectors with the long screwdriver trick?


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  #10  
Old 08-17-2014, 06:45 PM
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Have the injectors rig cleaned - always a good task to remove one possible problem..
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  #11  
Old 08-17-2014, 07:42 PM
kyle_e30 kyle_e30 is offline
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I have not tried that yet. I'm planning on getting new higher lbs injectors so ill use a injector cleaner and run it through the rail and old injectors and give that a go!



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  #12  
Old 08-17-2014, 07:56 PM
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sixpot_simon sixpot_simon is offline
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Replacing the wiring harness is a pretty drastic measure!

Sorry if this sounds rude, but I'm wondering why we're taking wild stabs in the dark here, when you work at a dealership (which I assume has diagnostic equipment...)
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  #13  
Old 08-18-2014, 03:14 AM
kyle_e30 kyle_e30 is offline
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Yes I work at a dealership but it's been at least 20 years since those cars were common in a dealership. We have little to no diagnostic equipement for these cars. Everything was thrown out or sold to a smaller shop


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  #14  
Old 08-18-2014, 03:47 AM
kyle_e30 kyle_e30 is offline
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And sorry I should clarify. I'm not changing it I'm only extending the harness to do an engine bay tuck/shave. But from the firewall the wires are being replaced


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  #15  
Old 08-18-2014, 04:30 AM
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Fair enough. Hope you get it sorted without too much pain.
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  #16  
Old 08-18-2014, 06:39 PM
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DON'T USE INJECTOR CLEANER!! Rig or forget it. Check the O2 sensor too. They go bad and cause problems.
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  #17  
Old Yesterday, 01:19 PM
kyle_e30 kyle_e30 is offline
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I don't have any o2 sensor on this car


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  #18  
Old Yesterday, 03:23 PM
kyle_e30 kyle_e30 is offline
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I don't have any o2 sensor on this car


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  #19  
Old Yesterday, 04:20 PM
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sixpot_simon sixpot_simon is offline
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Quote:
Originally Posted by kyle_e30 View Post
I don't have any o2 sensor on this car
According to this, your car is meant to have one.
http://www.realoem.com/bmw/showparts...64&hg=18&fg=10

An O2 sensor alone won't cause these problems, but it might be amongst the combination of factors.
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  #20  
Old Yesterday, 04:54 PM
kyle_e30 kyle_e30 is offline
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This does say it but when I look it up at work it gives me two options. One with and one without an o2. I don't see any connectors or wiring for one and the exhaust is original. There's no cat either


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