Re: Bad Knock Problem was:Misfires -- STILL NEED HELP!

From: Alan Short (ashort@flash.net)
Date: Fri Jan 22 1999 - 19:29:21 EST


fawcett@uism.bu.edu wrote:
>
> O.K. I misdiagnosed this... What I thought was a misfire is actually heavy
> spark knock. It was very intermittent on a mild highway incline so I found
> a steeper incline and I'm still nervous after what happened. I had the
> cruise pegged at around 65 or 70 and about half way up the hill it started
> to knock really badly... Before I could pull over the check engine light
> (MIL) started to flash rapidly (limp-in mode?!) and the engine was running
> incredibly rough --almost like it was going to stall at around 50 MPH! I
> got over into the right lane, switched the O/D off and was able get up the
> hill and off the highway... The check engine light stopped flashing as
> soon as I got off and has not come back on since. Man, I thought I had
> really screwed up my Kota!
>
> I got back home and yanked every plug and checked the gaps as best I could
> with these Bosch +4's... They have four ground electrodes so it's kind of
> hard to check but they all looked consistent... The only thing I found was
> a slightly higher carbon buildup on the plug in #3 cylinder and the #5
> cylinder plug looked like it had never been fired (no carbon whatever).
> All the others looked fine.
>
> I checked all vacuum lines and wires and everything seems OK... I'm also
> running the Magnecore 8.5mm wires which seem fine. This is the first V8
> I've ever owned... With the V6's, straight 6's and 4 bangers I've worked
> on it's been obvious as soon as you start the engine if one of the plug
> wires is shot (or you connected them wrong)... Does a V8 still run smooth
> with only 7 cylinders firing??
>
> Is there an easy way to check if a plug wire is good or not? Any ideas on
> what the heck is going on??? At a minimum I'm gonna' run out tomorrow and
> get some dielectric grease 'cause I did not use it. Any other suggestions?
>
> Thanks!
>
> Tom
> ______________________________ Reply Separator _________________________________
> Subject: Re: DML: Misfires -- Need Help
> Author: <dakota-truck@buffnet.net> at smtpout
> Date: 1/23/99 3:52 PM
>
> You may have damaged the spark plug wires when you pulled them off. Did you
> have to wrestle to get them off? I've had this problem on 2 different Daks. On
> 1 of them I had to pull the wire off the plug by bits and pieces. USE
> DIELECTRIC GREASE ON ALL CONNECTIONS AND ON THE INSIDE OF THE BOOT.
> Dr. Pat
> ----------
> >From: fawcett@uism.bu.edu
> >To: DAKOTA-TRUCK@buffnet.net
> >Subject: DML: Misfires -- Need Help
> >Date: Sat, Jan 23, 1999, 2:06 PM
> >
>
> >I installed the Bosch Platinum +4's this past Monday and I noticed what I
> >think were several misfires at high speed -- about 65-75 MPH. It happened
> >going up a very slight grade with about 1/2 to 3/4 throttle (auto tranny
> >did not downshift or come out of O/D) and does not seem to happen at WOT...
> >
> >My truck is a '98 318 with ~10k miles on it so I don't think it's the coil,
> >distributor, fuel injectors or other stuff that can cause this. I did put
> >my FABM 10" back on at the same time I put in the new plugs and I did reset
> >the computer...
> >
> >Is it possible/probable that the computer just needs more time to adjust
> >and I should just wait this out or should I just go ahead and start yanking
> >the plugs and check gaps (even though they were "factory preset")??? Is
> >there a better way to diagnose the cause of a misfire?
> >
> >Thanks in advance for any help.
> >
> >T.
> >
> >P.S. I wrote to Dave (Fish) who also recently installed these plugs and he
> >does not have the same symptom/problem... Thanks for checking for me Dave!
> >
Did you replace the plugs & wires one at a time or all at once? If all,
did you mark them somehow? Could be out of order since this problem just
developed with the plug change.Alan S.



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