Author Topic: Erratic throttle at low revs  (Read 4556 times)

guest2031

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Erratic throttle at low revs
« on: April 06, 2011, 09:19:37 PM »
I have owned 2 Jazz's in my time: originally a CVT 1.4SE and more recently a 2003 manual one purchased from a friend.

Over the past 12 months or so we have had a worsening problem with erratic throttle at low revs. The symptoms seem to appear once the car has warmed up and when using very low revs e.g. manoeuvring in a car park. Despite the throttle position the revs would bounce around resulting in kangarooing. The other way to show it up would be to hold the car still on a hill just using the throttle and the clutch and you could see the revs fluctuating randomly by 500-800 rpm.

The car has been seen at a Honda dealer, twice at a general independent and once at a independent Honda specialist. The dealer said it was the EGR valve which was replaced with no real improvement; the independent said it was a sticking throttle which might have made a temporary improvement and the Honda independent said it was the spark plugs but "they are all a bit rough at low revs".

Since we are trying to teach our kids to drive in the car I was not happy and was going to resort to selling the car. However, I tried a few things and seem to have solved it:

1. Temporarily blanked off the EGR valve as suggested in this thread: http://clubjazz.org/forum/index.php?topic=5345.0 in case the replacement was faulty. No improvement (but drove about 20 miles with it like that and triggered the emissions warning light which fortunately reset itself after a week or so...).
2. Purchased a 2nd hand throttle body from a breaker for £60 (note that if doing this you need to ensure you get the correct version - mine has ECTS but the first one I bought had a traditional throttle (fortunately they refunded me without a problem). This didn't appear to have any effect either.
3. As a last resort I thought I would disconnect the battery to reset the ECM having read this thread: http://clubjazz.org/forum/index.php?topic=1366.0 and then used the directions to "retrain" the ECM. Bingo - the problem seems to be solved!

I have no idea if just retraining the ECM, without having changed the throttle body, would have cured the problem but I thought I would post this in the hope that it might help someone else with the same problem.

Nick

DV

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Re: Erratic throttle at low revs
« Reply #1 on: April 06, 2011, 09:24:57 PM »
Misread.
« Last Edit: April 12, 2011, 06:52:27 PM by DV »

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