antwan
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| posted on 2/4/11 at 06:45 PM |
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ECU and fluctuating idle
Hi all,
I started my car for the first time today. Things went great. The car is an MNR vortex BMW 318is powered.
I let it run upto temp, fan kicked in... all good.
I then gave it a few beans (as ya do) and when it returned to idle, it started pacing between about 800 rpm normal and 1500 rpm, cycling every couple
of seconds. What the hell was it doing??
I have heard stories of ECUs struggling if powered down for long periods of time but cant find anything on t'interweb. I had a head gasket go on
an old 320i E30 and after three weeks or so of tinkering, the ECU didnt have a clue and kept stalling.
Any ideas or experiences?? Do I have to follow a certain start up procedure?
Thanks
(and on another topic, sorry, but how do I copy a pic into this message) thanks!
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Dingz
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| posted on 2/4/11 at 07:06 PM |
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Does this engine have an idle control valve? (it leaks air past the main butterfy) If so they can stick, the usual cure is to take it off, spray some
carb cleaner or similar in, move the actuator back and fore a few times and then reassemble.
Phoned the local ramblers club today, but the bloke who answered just
went on and on.
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flak monkey
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| posted on 2/4/11 at 07:10 PM |
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Idle valve stuck or an air leak.
Sera
http://www.motosera.com
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perksy
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| posted on 2/4/11 at 07:15 PM |
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Air leak on inlet maifold or idle control valve ?
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norfolkluego
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| posted on 2/4/11 at 07:26 PM |
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quote:
Originally posted by Dingz
Does this engine have an idle control valve? (it leaks air past the main butterfy) If so they can stick, the usual cure is to take it off, spray some
carb cleaner or similar in, move the actuator back and fore a few times and then reassemble.
+ 1 to that, once had a Ka as a daily driver, had exactly that problem, was the idle control valve
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avagolen
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| posted on 2/4/11 at 08:38 PM |
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I had a similar problem on a Honda once - it was caused by the o2 sensor not responding fast enough.
When cold, the ECU was using open loop and it was fine.
Once the engine was warmed up, the O2 sensor was being used. it was sluggish and caused an annoying hunt.
About 500 rpm if I remember correctly.
Replaced the sensor and back to normal.
(that was after honda said it was the idle control valve sticking and they cleaned it.
Said it could not be the o2 sensor as there were no fault codes !!!).
Len
[Edited on 2/4/11 by avagolen]
The Answer for everything, but never the last word....
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