RE: Re: RE: Weird problem.,Now 3.9 engine power and driveability (long)

From: Steve Preston (steveophonic@yahoo.com)
Date: Fri Sep 28 2007 - 18:13:50 EDT


> >
> You say with the air ON. Vent or actual A/C (or in
> Defrost mode)?

> - Bernd

A/C on blowing right on me. Actually,it doesn't seem
to make a difference whether it's defrost or A/C.
Either seems to pull it down into four cylinder
territory (seriously). But when it's running well,it
runs good enough even with the compressor running
(still has adequate power). The issue with it is
pretty constant,but it'll straighten up for several
seconds or minutes right out of the blue and run
perfectly fine. Seems to be bump sensitive,I think.
Then it goes back. It's never good for a whole day or
even a whole hour,but it sometimes is constantly bad
for a whole day.

BTW,I didn't mean to go on an apparent diatribe
against 3.9's. I wasn't upset. :) I know yours has
been good all along,especially with all you've done to
it,and other people will defend their V6 to the death.
It just seems like there's 500 different possible
causes with erratic performance on a 3.9,according to
my extensive DML and Google research,and nothing is
panning out.

My next step is to scope the crank sensor or an
injector and see if I can watch a waveform scatter or
jump around while I drive. I really feel like I need
to see it before I can fix it.

Thanks!

Steve P.

> -----Original Message-----
> From: Steve Preston [mailto:steveophonic@yahoo.com]
> Sent: Thursday, September 27, 2007 9:19 PM
> To: dakota-truck@dakota-truck.net
> Subject: Was: Re: DML: RE: Weird problem.,Now 3.9
> engine power and
> driveability (long)
>
> <snip>
>
> Well,like my '99,this truck seemed to be okay for a
> while. But now it's running as bad or worse than my
> old Dak did. Like Don said,as I approach a slope I
> kick it down early,and it normally falls all over
> itself. I then keep the pedal down almost to WOT,and
> you can feel a jerkiness to the "pull" of the
> motor,like it's sputtering or slipping,and the tach
> kinda hangs for a split-second in different spots as
> it climbs. Sometimes it's so bad,I have to just mash
> the pedal down and keep it there. I back off when
> the
> engine sounds like it's going to come apart,or to
> let
> it upshift.
>
> There are times though,that I could describe as
> "glimpses of glory". Like yesterday,I drove up a
> fairly steep hill about half a mile long,and with
> the
> AC running it maintained 50 easily. No
> jerkiness,nothing. Smooth. Didn't have to kick it
> down
> into passing gear to go up the hill. I've also had
> it
> easily maintain 65 mph on those same highway slopes
> with the air on. But those times are rare. I don't
> get
> it. I've done plugs and wires,PCV valve,checked the
> distributor cap and rotor (cleaned,but nothing
> wrong),and changed the MAP sensor. Switched gas
> stations,tried fuel injector cleaner. Now I'm almost
> back to the point where I'm believing there's
> something inherent with the 3.9,or maybe PCM
> programming,that causes performance to change a lot
> for no apparent reason. Maybe others have different
> experiences,but my only good memory of a 3.9 Dak was
> not a Magnum.
>
> Steve P.
>
>

       
____________________________________________________________________________________
Building a website is a piece of cake. Yahoo! Small Business gives you all the tools to get online.
http://smallbusiness.yahoo.com/webhosting



This archive was generated by hypermail 2b29 : Tue Oct 02 2007 - 15:23:19 EDT