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73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: Thermal Izod on March 12, 2009, 02:13:41 am

Title: diesels at shutdown
Post by: Thermal Izod on March 12, 2009, 02:13:41 am

i'm noticing this, only in warm weather lately.....when i shut off, i get occassional dieseling/knocking for a second.....anyone have any ideas why?

it's an 82 k10, 305, 4bbl QJ, mild cam, headers/exhaust....

Title: Re: diesels at shutdown
Post by: Prong on March 12, 2009, 04:39:09 am

Idle speed too high or a too low grade of octane in your gas.

Title: Re: diesels at shutdown
Post by: Thermal Izod on March 12, 2009, 04:54:31 am

i'm thinking the idle could be it.  i've had issues with that since i bought the truck.  i don't have a tach on it, so i adjust by ear, which is hard.  the motor has a decent bog effect when it's in vs, out of gear, and the idle seems to be inconsistant.  where the screw is now is the best i've had it, it doesn't ever stall, however at times it seems to idle up too high.  does anyone have any advice on how to fine tune this?  seems that if i bring it down, which at times could help, i will lose drivability at other times when it wants to idle lower...

Title: Re: diesels at shutdown
Post by: VileZambonie on March 12, 2009, 10:27:31 am

Make sure the choke is fully opening and the idle speed is correct. Check your timing also.

Title: Re: diesels at shutdown
Post by: eventhorizon66 on March 12, 2009, 11:33:43 am

I had an issue with dieseling with my old 305.  The choke was occasionally sticking.

Title: Re: diesels at shutdown
Post by: Thermal Izod on March 12, 2009, 12:02:10 pm

both good points....thanks.

Title: Re: diesels at shutdown
Post by: the_legend_1981 on March 12, 2009, 05:29:58 pm

what should you do if the choke sticks? I have that problem.

Title: Re: diesels at shutdown
Post by: eventhorizon66 on March 12, 2009, 06:19:47 pm

We are talking the factory electric choke right?  In my case, I ended up simply replacing the choke coil.

Title: Re: diesels at shutdown
Post by: Russ130 on March 13, 2009, 06:05:45 am

If the choke and timing are ok I'd check for vacumn leaks next. A vacumn leak can make it run with a high idle in park and neutral and very low in gear.

Title: Re: diesels at shutdown
Post by: Thermal Izod on March 13, 2009, 02:09:28 pm

i've already fixed a lot of bad hoses etc that were leaking...i'll have to really look at the intake seal, b/c that's just about all that could be leaking still...first off though, I'm gonna try to readjust the idle screw, and check the choke.  Thanks for all the good input guys.  I've gotta work all weekend, so i'll get around to posting an outcome ASAP....