Won't idle after installing a new battery! (searched) [Archive] - Bimmerfest - BMW Forums

Won't idle after installing a new battery! (searched)

12-16-2006, 06:48 PM
Been a while since I posted, but here's my problem. I didn't drive the car (92 E36 5spd) for a week because I had to use my truck to haul some things. Went to start it and the battery was dead. I knew it was getting time to replace the battery, but I didn't have time during the week so I let it sit for a second week and today I went and bought a new (Interstate) battery and put it in. When I went to start the car it backfired and now it wont idle or stay running at all. If I keep giving it gas, not holding my foot down, but give it gas and then let-up and keep repeating that, it will sort of run, but it misses like crazy. When I parked it, it was running fine and nothing else was done to it, but putting in the new battery.

12-17-2006, 09:10 AM

I'm having this exact same problem at this very moment. I haven't driven my e36 for about 3 weeks (been so busy :bawling: ). Went outside yesterday to go for a spin and found the battery dead. Gave her a jump start and she idled fine for about 10mins then just shut down no warning/coughing/stuttering. Tried to restart, revs fluctuate (misfiring) a bit then when it tries to stabilize at idle she stalls.

A vaccum leak was the first thing that came to mind so I checked out all my S/C piping and it looked good. Checked the MAF wiring, looked ok.

I ran out of daylight yesterday but today I plan to scan for engine codes and clean the idle control valve. I figure there could be some dried up crud in the mechanism since the car hasn't been used in a while.

The only other thing that I can think of that might cause this kind of behavior would be a fouled o2 sensor. But that seems unlikely since, as you mentioned, the car was running fine when I parked her.

It's a mystery!

12-17-2006, 01:37 PM
Do you have an aftermarket chip?

On my e30, it takes about 30 mins to an hour of driving for my chip to "relearn" after the battery has discharged. During that period, it idles very poorly, if at all.


12-17-2006, 02:42 PM

Well, I pulled the ICV and gave it a good cleaning. It was plenty dirty but that still didn't completely solve the problem. The car is running but still fluctuating at idle while running smoothlyruns smooth when held at 1000 rpms.

I checked the ecu and got codes for both the maf and the o2 sensor. My gauges show she's leaning out a bit as the idle fluctuates so the o2 sensor is now my number 1 suspect.

Truthfully, I just think she needs a good flogging to heat everything up and get the juices flowing again. This may also give the ecu a chance to re-learn the maps as BahnBaum mentioned.

Otherwise, I have inspection comming up soon so my trackpipe has to come off anyway. I may just wait until then to swap out the sensor.

12-19-2006, 12:44 PM
i have exact same thing. engine wont wont start , it crunks missfire like crazy and dies right away. and before everything was just fine. i dont know wahat to do

12-20-2006, 12:32 AM
the exact same thing happened to me. now car wont run:mad: its such a shame. i dont understand it after battery was switched it started. then next day wouldnt start at all. replaced fuel filter (pain in the ass) and sparkplugs.... well now it will start... but wont run idle surges then dies!~ if gas held down it will run.... but not well

the battery problem could be unrelated it sounds like it might be but its strange to me car running PERFECT prior to battery change

whos got the answer please:bawling:

12-22-2006, 12:31 PM
^^I'm glad to see someone already tried replacing the fuel filter and plugs. That was going to be my next stop.

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I took the car out to log some data and found that the o2 sensor isn't working right. At idle it's reading full lean, 21.0 which is "kaboom" territory. Under load, however, the readings are right around 12.5 where I want them. I'm not positive just yet if the lean condition at idle is the cause or the result of the misfire/stalling. Checking the fuel filter/pump would shed some light on this question. But since the ECU codes indicated a possible sensor problem I'm thinking it's the CAUSE.

The other thing I noticed is that as the RPMS are fluctuating so are the vaccum readings. From around -20 at normal idle to around -15 when bouncing around. This is what made me suspect the idle control valve first.

My first thought: "Maybe a piston ring has unseated causing a loss in compression. :cry:" But we won't go there yet... I'm leaning away from this hypothesis at the moment because I'm still getting full boost when I drop the hammer and right now this problem seems isolated only to the idle condition.

I'm still leaning towards the o2 sensor as the culprit. When the engine cold starts the ECU is operating in open loop mode, then when it warms up it tries switching over to closed loop mode. This could expain why the car idled for 5-10mins then just cut off with no real warning.

I have an extra o2 sensor laying around. But with the holdiays comming up I have no idea when I'm going to have time to get under there and swap it out.

If one of you guys gets to it first let us know how it goes!!

12-23-2006, 05:03 AM
Guys, I can't help but you might get some advice from www.e36coupe.co.uk. ?

Worth a try as one of those guys might have had the problem

Good luck

12-23-2006, 05:19 PM
Well today I checked the codes via the key-on, flashing check engine light method and all I got was code 1221 (Oxygen Sensor-Which was replaced in May with a brand new Bosch unit)over and over. This went on for over 1/2 hour and I never got the "end" code where the light goes out. I finally just shut it off. I then disconnected the exhaust system and tried to start it, same problem as before (only really loud!!!). I tried unplugging the O2 sensor and starting it with the exhaust still undone and still no change. I hooked everything back up and still no change. I ran the codes again and still get 1221 repeatedly for over 1/2 hour. I also check all the electrical connections at all the sensors and all of the vacuum lines and they are all ok. Does anybody have any other ideas???

12-24-2006, 12:26 AM
i am gonna check the camshaft position sensor today.
my friend said for missfiring there would be few things :
1. spark plugs (had new ones installed today)
2. coils (tried to swap with another ones, didnt help)
3. camshaft sensor
4. computer (i dont know how to check if it works or it doesnt)
i just so depressed with situation

12-25-2006, 01:17 AM
yeah! dont have that problem anymore!
that was knock sensor! i couldnt buy new one since the dealership was closed,
but i went to the junk yard ,20 min from my house and i found 325i same as mine
smashed big time but has engine and some other parts, so i took these two sensors
installed on mine and it works just fine. all coast me 5 bucks.

12-25-2006, 02:29 PM
yeah! dont have that problem anymore!
that was knock sensor! i couldnt buy new one since the dealership was closed,
but i went to the junk yard ,20 min from my house and i found 325i same as mine
smashed big time but has engine and some other parts, so i took these two sensors
installed on mine and it works just fine. all coast me 5 bucks.

Knock sensor...I hadn't thought of that one. I guess I'll check that out. I did order a new O2 sensor just incase.

12-28-2006, 12:22 PM

12-29-2006, 08:25 PM
i fixed mine too it was the MAF. nice work on knox sensor too inexpensive things to check before replacing 02 sensor which may not even help

so how did you find out it was the knock sensor

ahhh yeah feels good i was getting pretty depressed with my situation as well car problems seem to be that way often all you can do is have patience and try not to do anything too stupid in your rage LOL

:banana:congratulations to us LOL:banana:

12-30-2006, 01:55 PM
today I changed the O2 sensor and the camshaft position sensor and there was no change. I also disconnected the battery for about 30 minutes while I pulled out the ECU and gave it a visual check. The ECU was nice and dry and the connection was tight. When I re-installed the ECU and reconnected the battery and tried to start it, drum roll please................... NO CHANGE! I ran the codes again and now all I get is a long flash and a short flash then a long flash and a short flash. I am now ready to pull what's left of my hair out! Does any body have any other ideas or suggestions?

01-07-2007, 07:42 PM
Well the problem is solved. It turned out to be the crankshaft sensor that probably started the problem. Then, when it backfired, it blew the upper hose off of the ICV causing a vacuum leak that kept making it miss once I finally got it to run. I couldn't see the hose being disconnected at first, but after I finally got my my hand up in there to check it out more closely, I found that it was disconnected, but sitting atop the connector so it looked like it was still connected. Thanks to all who gave advice!!!