Idle surge was fixed by replacing the idle control valve(ICV) with a used one about three months back. After that the car kept creeping up in idle speed until the surging started in again (1000-2000 rpm). I replaced the ICV with a brand new one which did not fix the problem, still surging. If I disconnect the ICV wire plug it really surges like 1200-3000 rpm. If I disconnect the mass air flow meter it idles down really low but still surges hard. Before I could do this to idle it down but it would not surge. I notice that when I rip on the car it performs great but the catalytic converter smell is noticeable while coasting or after I stop. I'm not sure how to check for air leaks or how to check if the ICV relay could be the problem. It's very frustruating to drive around with this problem. I have not found any solutions in the postings and I'm looking for advise. Still searching the e36 threads. The car has had extensive DME harness repairs(by me) and the o2 sensor is thought to be bad. How do I test that? I mainly want the car to idle close to 800rpm or so. Thanks for any help.
Ok, with a little reading in the Bently manual, I find that the vacuum hose to the fuel pressure regulator has good vacuum. According to the manual, when you disconnect the hose the fuel pressure should increase, it does not say how much. My idle problem does not change when I remove the hose. Im leaning towards the regulator being bad because of no change in rpm when its disconnected. Anyone ever try this with a fuel pressure gauge installed? Does the idle go up with the increased fuel pressure from disconnecting the hose, as the manual explains? I feel that the surging is the O2sensor hitting its limit and cutting out the engine. The problem is getting worse sometimes surging up to 3000rpm. The codes I'm getting are O2 sensor #1, and sensor limit codes; over and over until I shut the key off. The book says the light goes off for long period eventually, mine keeps spitting out the same code/codes over and over. Update
Alright, the problem isn't fixed yet but I was able to get codes from my car by stepping the gas down all the way five times, with key in run, within 5 seconds, and count the four digit codes. 1221 kept repating. That means the O2 sensor is bad. Also 1211, which means the O2 sensor has bounced off it's limits. That makes sense because of the rich condition making it rev up. I also learned from Mr. Bently that the O2 sensor is heated to 600F+ before it starts sending signals. This might be my problem because before the car's exhaust heats up the idle is only slightly high. Thats what I know so far. I will get to the bottom of this and post all I know on this thread. After O2 I'm going to hunt around the fuel pressure regulator/vacuum system; but not until I fix the problem that the car is telling me it has.
O2 sensor was replaced and the codes reset by disconnecting the battery for 30 minutes. Also the vacuum line I thought was going to the fuel pressure regulator was actually going to the vanos system, oops. The car has better power and gas mileage after replacing the O2 sensor. Still surging, but no codes are comming up even after 90 miles. I notice now that when I disconnect the mass air flow meter it idles way down without the surge, so the O2 was part of the problem. I surges a little tiny bit because the air flow reading is all messed up with the sensor disconnected. I get a mass air flow code and check engine light if I disconnect the mass air flow meter. With it connected it surges just like before. Also, just like before, when I let off to grab another gear the rpm goes up momentarily. Weird. I figured out that I need to remove the fuel rail to get at the fuel pressure regulator, but first I'm going to try disconnecting the vacuum line to it to see if that makes any difference or if its even working. I also have a thermostat that is stuck open, and wonder if this could be part of the surging.I doubt it but I'll replace it anyway. More later.
I have the same problem with my o2 sensor. I am in new zealand and I contacted BMW NZ, they quoted me 500$ NZ for the part to steep for me. so I am importing 1 from the US (car Stuff.com) 28$ something US much more reasonable price. the cheapest price I got here was 280$ NZ. Oh I have to also replace my fan blade which was only a few months old (106$NZ) as it broke due to high rev of engine 32$ US
Hope you sought out your prob
the problem isn't fixed yet but I was able to get codes from my car by stepping the gas down all the way five times, with key in run, within 5 seconds, and count the four digit codes. 1221 kept repating. That means the O2 sensor is bad. Also 1211, which means the O2 sensor has bounced off it's limits. That makes sense because of the rich condition making it rev up. I also learned from Mr. Bently that the O2 sensor is heated to 600F+ before it starts sending signals.
well if the O2 sensor says that its in rich condition could it not mean that some or one of the fuel injectors could be bad, and they are fowling out the spark plugs thats just a gess, you can also do a smoke test to so you can check for leaks.
the car revs real high when you fiirst start it the idles slightly high. as it warms up it increases in idle speed until it starts to surge when warmed up. I think its a fuel delivery problem, but where? The shop seems certian that it is not the fuel pressure regulator. No answer on what test they did. Cant wait to have my Champion back.
Im worried about the bill. I want to get the car back and fix it myself. I need to check the power and signal to the 02 sensor to make sure the main feedback sensor is working on account of the extensive wiring harness repairs. Mechanics are cool but shop salesman suck.
The car performs to good to bad injectors or anything secondary like that.
Last edited by 612wade; 01-09-2010 at 09:02 PM.
Reason: add thoughts
they say they needed more $ to further diagnose. The bill was 125 to tell me that the idle driver in the DME is gone or the soldered connections on the DME harness(repairs) are goofing up the signals, the latter not too likely but a burnt out DME is because after all the harness was totally cooked. Ebay $100,its on the way.
I had a very similar prob with my e36 320, I have just fixed the problem my self last week.
First I had taken it to my local auto sparky and he put his computer on it and said it was the o2 sensor, so I got a new 1 and put it in returned to sparky to clear fault on computor but still surging.
checked on net again and found that the idle control valve may be faulty so started pulling out air box etc
then found some freyed wires they came from the camshaft position sensor, I wrapped them in electrical tape and problem solved.
So I would check all sensor wiring in the engine bay to make sure they are all good
I hope this helps you out as my car is running sweet now
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