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Fixing rough idle on a 2500cc V-6?
Posted: Sun Mar 18, 2007 6:16 pm
by twinrider
Hi all, nOOb here

I've had a '97 Bongo V6 for a couple years now but just discovered this site tonight. Wish I had found it sooner!
Lately my Bongo's started to idle a bit roughly when the transmission's in drive and the car is stopped at red lights, etc. The tach needle hovers around 700, then suddenly dips down to 600 or so, then back up. The car starts up no problem and seems to run fine at speed. I replaced the air filter but no change in the idle problem. Thanks in advance for any advice on how to fix this.
Cheers,
jim
Posted: Sun Mar 18, 2007 6:25 pm
by Peg leg Pete
Welcome to the site

not able to answer your question, sure someone will know.
Posted: Sun Mar 18, 2007 6:25 pm
by francophile1947
Hope you get a response. Unfortunately, you are very much in the minority with a V6.
Posted: Sun Mar 18, 2007 11:20 pm
by dandywarhol
Hi twinrider - a TDM eh??

...sounds like the idle control valve is sticky. It should be on the inlet side of the engine before the butterflies and is there to stablise the idle.
It can usually be removed and cleaned out with carb spray - it gets gummed up and affects the bypassed inlet air flow.
Keep it on the black stuff

Posted: Sun Mar 18, 2007 11:25 pm
by francophile1947
Sounds good dandy, I'd forgotten about that. I used to put some petrol treatment stuff in when my tickover went a bit lumpy.
Posted: Mon Mar 19, 2007 1:32 am
by twinrider
Thanks for the advice. I'll look into this. Any idea if cleaning the idle control valve is something that someone with little mechanical experience can do themselves? Will a gasoline additive work or do I need to remove the part and manually clean it?
Thanks again.
Posted: Mon Mar 19, 2007 1:41 am
by francophile1947
twinrider wrote:Will a gasoline additive work or do I need to remove the part and manually clean it?
It used to work on my son's Daewoo Matiz.
Posted: Mon Mar 19, 2007 2:17 am
by twinrider
Not sure if the same brands are available here but any recommendations on a good additive?
Posted: Mon Mar 19, 2007 11:48 am
by dandywarhol
After you locate (and I don't know where it is on the V6) the idle control valve, remove the rubber air intake hose leading to it and squirt in a dose of carb/injector cleaner - it should loosen off the gum around the valve.
If it's still "hunting" at idle you'll need to remove/strip/clean the valve.
A worse senario is that the electric servo motor for the idle control valve is faulty or that the ECU is giving it the wrong instructions.
Posted: Mon Mar 19, 2007 12:06 pm
by twinrider
Thanks dandy. Btw, do you think new spark plugs and wires would help? The Bongo's got 150,000km on it. I bought it at 136,000km, and have no idea when the plugs and wires were last changed.
Posted: Mon Mar 19, 2007 12:11 pm
by francophile1947
Sounds like they may be due, just depends on if you know when it was last serviced. I'd still try injector cleaner in the tank if you can't find the Idle Control valve as do as Dandy suggested.
Posted: Mon Mar 19, 2007 2:21 pm
by twinrider
I started up the Bongo tonight in the driveway to check out the problem again. On closer scrutiny I realized that in park it idles perfectly steady at 700 rpms (the top of the tach needle is at the bottom of the 3/4 mark on the tach).
The problem starts when I shift into drive and keep the brake down (as I would at a stop light). Then the RPMs drop down to about halfway between the 3/4 and 1/2 mark and get unsteady.
Any new theories?

Posted: Mon Mar 19, 2007 3:42 pm
by dandywarhol
Nope!
Posted: Mon Mar 19, 2007 3:59 pm
by mikeonb4c
In the old fashioned world, you might try scewing up the tickover stop (oooh matron!) a tad as a get-you-by and if it doesnt leave the tickover too high in P and/or cause a lurch when you put it into D. Dont know what advice Dandy would give on that

Posted: Mon Mar 19, 2007 4:28 pm
by francophile1947
twinrider wrote:The problem starts when I shift into drive and keep the brake down (as I would at a stop light). Then the RPMs drop down to about halfway between the 3/4 and 1/2 mark and get unsteady.
Naughty twinrider - think of the poor b*gger behind you!!