David Jenkins
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 posted on 21/4/05 at 02:27 PM |
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Pop on stop!
My car's running well, and generally everything's OK. Runs at the proper temperature, doesn't 'pink', accelerates
well.
The only problem I've noted is that I get a significant 'pop' or 'fut' from the exhaust when I turn off the ignition
after a run.
Is this significant? Should I worry? Does it indicate some lack of adjustment that I could fix?
cheers,
David
P.S. I plan to take the car to a rolling road in the not-too-distant future, but in the meantime I'd rather not mess up the engine!
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locoboy
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| posted on 21/4/05 at 03:00 PM |
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is there a leak in the exhaust anywhere?
My car used to give an occasional 'guff', i fixed a slightly blowing downpipe joint and it didnt do it afterwards.
ATB
Locoboy
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white130d
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| posted on 21/4/05 at 03:02 PM |
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You're rich
Well, maybe not you personally, but the car is running a little rich leaving residual unburnt fuel in the exhaust that Ignites/pops when it gets hot
from sitting iin the pipe. Bare in mind this is only my opinion...
It the exit of the tailpipe black and moist?
D.
"There's only 2 things that money can't buy, and that's true love and home grown tomatos" Guy Clark
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DarrenW
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| posted on 21/4/05 at 03:05 PM |
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Me fathers xflow Mk has a pop when you turn off engine. Pop maybe slight understatement! Its a bang in my book. Its known to be jetted wrong and
running rich. He too is waiting for rolling road.
It doesnt do it every time, 1660 cammed up xflow with twin 40's.
Tailpipe is black and moist (ooeerrrr missus) and even wheel arch is sooty.
does this help?
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David Jenkins
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| posted on 21/4/05 at 03:10 PM |
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Those symptoms all sound familiar... looks like a visit to the rolling road should be sooner, rather than later!
thanks,
David
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DarrenW
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| posted on 21/4/05 at 03:12 PM |
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Am, i right that running rich is better than running lean when you first get them running and havent had chance to go to rolling road??
I was told that running lean can put a hole in the piston whereas running rich just covers everything in soot / oily grime.
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JAG
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| posted on 21/4/05 at 03:23 PM |
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Darren,
you're dead right - rich is way better than lean.
If the engine is running lean then more Oxygen is burnt (from the air that's drawn in) and this raises the combustion temperature and the extra
heat CAN melt pistons.
ECU managed engines have a default Lambda setting (normally 1.05) that ensures the engine always runs slightly rich if/when the lambda sensor fails.
Justin
Who is this super hero? Sarge? ...No.
Rosemary, the telephone operator? ...No.
Penry, the mild-mannered janitor? ...Could be!
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David Jenkins
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| posted on 21/4/05 at 03:25 PM |
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One thing I must do is get a plug out to check the colour - trouble is, I have a bad track record for breaking the insulation on these plugs when I
take them out 
David
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rusty nuts
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| posted on 21/4/05 at 05:52 PM |
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Running slightly rich may be better than a weak mixture but too rich will cause " bore wash" . This will cause any oil on the bores and
pistons to be washed off causing metal to metal contact . NOT GOOD , can also dilute oil causing crank/cam wear etc Book the rolling road session
HTH Rusty
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jonbeedle
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| posted on 21/4/05 at 06:34 PM |
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Definitely running rich. I had a ZZR1100 that did the same thing. It was easily fixed.
Cheers
Jon
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Marcus
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| posted on 21/4/05 at 07:20 PM |
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The bore wash thing is a significant risk, and crossflows are more prone than most especially with twin carbs. All too easy to run your big ends!!
Keep checking oil. If it smells of petrol, change it. If your oil level goes up, change it.
Marcus
Marcus
Because kits are for girls!!
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stevebubs
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| posted on 21/4/05 at 10:07 PM |
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When I still have the DGV on it, my Crossflow used to do this.
It was a case of
- Park Up
- Turn Engine Off
- Count to 3
- Start laughing as a *huge* bang scared the living cr@p out of anyone within half a mile
BTW it did it because it was running way too rich
quote:
Originally posted by David Jenkins
My car's running well, and generally everything's OK. Runs at the proper temperature, doesn't 'pink', accelerates
well.
The only problem I've noted is that I get a significant 'pop' or 'fut' from the exhaust when I turn off the ignition
after a run.
Is this significant? Should I worry? Does it indicate some lack of adjustment that I could fix?
cheers,
David
P.S. I plan to take the car to a rolling road in the not-too-distant future, but in the meantime I'd rather not mess up the engine!
[Edited on 21/4/05 by stevebubs]
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britishtrident
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| posted on 22/4/05 at 06:51 AM |
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Ignition related -- switching off the ignition is causing a spurious HT spark what kind of ignition set up are you running ?
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David Jenkins
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| posted on 22/4/05 at 07:35 AM |
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Ign system = Bosch Valencia dizzy.
Plugs are showing the correct colour (biscuit), so the running mix is not far wrong. My suspicion is that my idle mixture is too rich, but I'll
check that on the weekend with my colourtune.
DJ
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