# BMW 318is E36 M42 erratic idle problem



## rangelo (Jun 2, 2006)

My BMW 318is E36 M42 has a strange idle problem. Sometimes the engine starts out ok and works at regular RPMs for a while, and sometimes the erratic idle begins ass soon as I start the engine. The idle go up and down from almost stalling to 2000 RPM or so. At that time the Check Engine Light comes on. It goes on for about 30 seconds or so and then it levels up for a while. If I hit the gas pedal the Check Engine Light disappears and the idle levels up for a short time. I disconnected the Idle Control Valve and it seems to help a little. Then the Check Engine Light stays on. And even then if I just watch the RPM gauge there are variations in the idle, but not as bad. As the engine warms up the idle goes from about 850 up to 1200. Could it be a vacuum leak??? O2 sensor??? Temperature sensor??? Any ideas??? 
Any help will be appreciated.

Rick


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## B2M2W (Feb 20, 2006)

My dads car did this too and he had to replace the idle control valve and it solved the problem. Also your O2 sensor probably needs replaced, you can never change those to much.


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## rangelo (Jun 2, 2006)

Thanks B2M2W, appreciate that... I think I'm going to shotgun the problem... I just ordered a new idle control valve, O2 sensor and one knock sensor. I noticed that the plastic casing on the front knock sensor is cracked, probably from over-tighten it. Does anyone know at how much I need to setup the torque wrench when I tight the knock sensor??? 

Rick


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## bimmere46 (Jul 18, 2005)

The check engine light was coming on....did you use a code reader to see why?


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## rangelo (Jun 2, 2006)

No, I don't have a code reader... that's why I"m replacing 3 of the parts...


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## wawoola (May 11, 2006)

Check your spark plug cables, perhaps the problem could be there. At home we have to E30 318is and both had the same problem. The check engine lights came on because the car was running way to rich, code 1222. I tought there was related to the ICV, O2 Sensor, or MAF, but later we discovered that the spark plug cables were to blame. You should test it with some friends cables and see it for yourself. I did that with another 318is from a friend, and the problem went away.

Hope it helps


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## bimmere46 (Jul 18, 2005)

rangelo said:


> No, I don't have a code reader... that's why I"m replacing 3 of the parts...


uh...a code reader is cheap. why just replace random parts? Sounds like a pricey way to make repairs.


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## wawoola (May 11, 2006)

For an E30 you don't need a code reader. You can do it by switching the inginition to the on position, and then fully depressing the accelerator pedal 5 times, the computer will flash the codes through the chek engine light.

Perhaps you can browse or search in the forum for this procedure. It's also useful for E36 but I've read that the timing is a little bit harder.


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## bimmere46 (Jul 18, 2005)

wawoola said:


> For an E30 you don't need a code reader. You can do it by switching the inginition to the on position, and then fully depressing the accelerator pedal 5 times, the computer will flash the codes through the chek engine light.
> 
> Perhaps you can browse or search in the forum for this procedure. It's also useful for E36 but I've read that the timing is a little bit harder.


you're right...haven't worked on much obd1 stuff in a long while. certainly better to run the codes than to just replace random parts.


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## LOTTATHOUGHT (May 27, 2006)

Why would anybody want to shotgun parts on these cars?
If you are going to replace that many parts, then just take it to a mechanic.
Besides...you will be hating life if you replace all those parts and then find out that it was none of them.

I have a 95 318IS. 

The ICV can be cleaned. It probably does not need to be replaced.
All it takes is about an hour, some Q-tips and some rubbing alcohal and a little WD-40.
You are supposed to clean the carbon buildup every 80K or you can have the exact idle trouble you describe.
If that does not fix the problem, then yes, you may need to replace the O2 sensor.


Next..you can also read codes directly from the E36...not just the E30.
You do not need any special tools.
Put the car in the ON position without starting it.
Pump the brake FULLY up and down 5 times. You also have to get it just right.
You will then have a flashing light on the dash.
Count the flashes. It will be easy enough to see when one number stops and another starts.
When the number has completed, it will then repeat.

And I can not stress this enough.....
Buy the Bentley manual....and cruise the Bimmer sites.
I have now had my car for 3 months and I have been beyond impressed by the wealth of knowlwdge and resources that is out there.
DIY for just about anything.....Q&A...Forums....you name it.

Spend a little time and you can know every nut and bolt in that car...not to mention you can have a car that will last decades.


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## rangelo (Jun 2, 2006)

Thanks to all of you for the input... I'm glad I invested in the parts rather than mechanic/diagnostics/code readers... ICV - $117.51, O2 Sensor - $62.71 and knock sensor - $65.43: total of $245.65 online shopping... I spent all weekend working on this issues and it seems like my instincts were right... After replacing the ICV the idle was steady and I thought it was fixed. The RPMs remained steady after warm up, but the check engine light came on again. Same thing - push the gas - it goes away... Next, I replaced the O2 Sensor. Never saw the check engine light again. The sound of the engine, however, still had some "pinging" to it. Gas quality you would say??? Sure enough, after replacing the knock sensor that had the cracked casing, the engine sounds just perfect. Performance wise feels just a little faster and more powerful, but gas mileage/economy went way up... 
Considering I did buy this car at a car auction for under $1000, and have already replaced Starter, Front shocks(2), Wheel Baring Hubs, Water Pump, Radiator, Thermostat + housing and battery, the only thing left now is the AC/Heather Blower... that really blows... I hate it already... I actually consider getting rid of my 318... anyone interested??? [email protected] Body is perfect and tires are new...


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## andymartinez6 (Dec 7, 2007)

Hey Brother's I have a 325IS 195 and my computer got wet i dried it and it worked good but a couple of weeks later the car started stalling when driving just out of the blue.

I had to re start the car lake 15 times then it worked fine for another day it's been on and of like that and im getting tired.

When this happend the first time I took it to the shop and they did an inspection but it came out with boges codes from the time it got wet so they reset and y came back when itr did it again. so here i am know it poped a fuel injector code, mmmm but it shows all the injector so i yust ordered a penformance chip to see if it's the chip or the hole ECU.

What i whanted to know is if this can be related to other this because i have been reading and it looks like it could be ICV or O2 sens problem as well since it stay idlling for a moment at the time of falure rough so i don't know Ineed HELP... On this one...

OOO and what does the knock sens do when it is faulty?

Hey BMW Brother give me a hand on this one and i promise i will share all my experices from now on.... hopefully i don't have many to share.....


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## lnh106 (Aug 30, 2007)

*Vaccum hose*

Check your vaccum hose, my was broken. The engine was idling erradically, so I spent few hours checking spark plugs, cables, etc. But it turned out to be the vaccum hose:

Part #: Item: Price: Qty: Total Price: 
11 15 1 247 743 
Valve Cover Breather Hose 1994 318is $24.95 1 $24.95


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