[Diy_efi] Hesitation, backfiring, jumpy blues :-(

Thu Aug 17 05:35:05 UTC 2006

Yessss!  i remember my friend with a Pontiac Formula having the same
issue...   damn opti-spark ignition, and yes, that could very well be what
your seeing as we couldn't tell by the codes or the running conditions.  he
actually rebuilt his whole motor expecting to find something only to fire it
up and have to take it apart to replace the opti-spark system...

-- LL

On 8/16/06, Brendan Patten <bpatten at centurytel.net> wrote:
>
> Ohh yeah I remember the second time my friend had to replace his
> distributor, one of the pins on the 4 wire connector was badly corroded.
> We noticed after he had already got it replaced (under warranty) so not
> sure if it was the pin or the 2nd distributor.  Any ways
>
> Good luck.
>
> -----Original Message-----
> From: diy_efi-bounces at diy-efi.org [mailto:diy_efi-bounces at diy-efi.org]
> On Behalf Of Brendan Patten
> Sent: Wednesday, August 16, 2006 6:20 PM
> To: diy_efi at diy-efi.org
> Subject: RE: [Diy_efi] Hesitation, backfiring, jumpy blues :-(
>
> Sounds like the case of a bad opti-spark distributor.  I had a 93 LT1 I
> swapped into my truck, then sold to a friend.  Not too much later it
> started exact symptoms you are describing.  Sometimes it would hardly
> start.  He replace the distruibtor on it and it ran like a charm, at
> least for about a year.  Then same thing.  Again, replaced distributor
> and it fixed it.
>
> The 93 was a non vented distributor.  Later models have a line that
> draws intake air through the distributor and into the intake. Any
> moisture build up can cause them to go bad.  Sometimes pulling the cap
> and drying it out will help a lot, but not always.
>
> Anyways, good luck, they are expensive, but most likely the cause.
>
> Brendan Patten
> www.lt1swap.com
>
> -----Original Message-----
> From: diy_efi-bounces at diy-efi.org [mailto:diy_efi-bounces at diy-efi.org]
> On Behalf Of 93 Formula
> Sent: Tuesday, August 15, 2006 7:48 PM
> To: fourth-gen at lists.f-body.org
> Cc: diy_efi at diy-efi.org
> Subject: [Diy_efi] Hesitation, backfiring, jumpy blues :-(
>
> Anyone out there care to offer any other ideas of where to look for my
> problematic car?
> Its been years and I haven't been able to drive it.
> I have both diacom runs and datamaster runs.
> If anyone wants to take a look, let me know and I'd be glad to email
> them.
> I have run VE-MAster 4 times on datamaster data with not enough change
> to
> make it go away yet.
> I see some things I don't like in the data but don't what to make of all
> of
> it.
> Also - could the egr effect anything?  I don't have one hooked up
> anymore.
> Should I turn something off or change the on/off values in the ecm?
> (I've
> put this back to stock now)
>
> Here are the symptoms -
> 1. Doesn't want to keep a "running" idle -aka wants to die when you put
> in
> gear or turn on the A/C...
>
> 2. When driving it - open or closed loop - from a stop to anywhere in
> the
> part throttle range, there is always like a jerk of the car like it
> wants to
> die (I thought it was going lean) and then it surges forward
>
> 3. the rpm's seem to have the jitters looking at the data, the  LTs seem
>
> wrong - not near 128 usually.
>
> 4. the only time it seems to run ok is when I mash it but even then
> something doesnt sound right.
>   I also noticed that one LT was stuck at 130 instead of 128 - seemed
> weird
> if using WOT
> I also noticed LT counts hanging around 108-114 range for a 9 second
> period
> when I let my foot off the gas after a 10% TPS yikes.
>
> 5. popping in the exhaust - especially when letting of the throttle but
> even
> at part throttle driving this happens.
>
> 6. still starts hard - long crank and then wants to die for the first 10
>
> seconds unless I keep in the gas - reminds me more of my 73 Charger
> before I
> upgraded the ignition.
>
> What I've done... (besides aging 30 years in 3)
> -------------------------
> changed programming like no tomorrow, went back to stock programming and
>
> started over, tried VE master 4 times - Is this something you should
> have to
> run a lot before it gets right?
> chk'd or changed coil, coil wires, spark plugs - although that was a
> year a
> go and they may be "fouled from too rich tests"  Would these really need
>
> changing or would just a good hot romp burn em off? (which I've doe a
> few
> times)
>
> 1. I've helped the idle problem by adjusting the throttle stop out some
> to
> raise the idle speed.
>     I tried raising #s in the ecm but it didn't help.
>
> 2. usually the only way to keep it moving when it does this is to
> feather
> the throttle until it finally gets going.
>
> 3-4. it does better to touch it at say 20% rather than a 5-10% throttle.
> I noticed in the data that the tps changes even when I don't have my
> foot on
> the throttle ???
>
> I know there is some exhaust leak in the driverside Collector pipe since
> it
> never was a perfect fit
> I don't know if that is enough to cause all of these problems though.
> I did have problems with it starting and had to replace the battery -
> thought the pcm was dead, but apparently it was just my proms so I went
> back
> to my DOS program to make sure and it works but it
> I run 30# f*rd injectors in it now and they are programmed according to
> the
> formula someone posted here a while back - I think its is like 31.xx as
> the
> constant.
>
> Jeff  http://FindFastCars.com 93 Formula
> Mods: 355 forged for NOS, LT4 HotTop, 58TB, SLP Cnvrtr, 3.73s,
> Mufflex/Spintech 4" exhaust, Hooker LTs, 300+ Ign, Injctrs, MSD Adj Win
> Sw &
> 3 Ign Ret, K&N CAI, Diacom, CATSTuner...
>
>
> _______________________________________________
> Diy_efi mailing list
> Diy_efi at diy-efi.org
> Subscribe: http://lists.diy-efi.org/mailman/listinfo/diy_efi
> Main WWW page:  http://www.diy-efi.org/diy_efi
>
>
>
> _______________________________________________
> Diy_efi mailing list
> Diy_efi at diy-efi.org
> Subscribe: http://lists.diy-efi.org/mailman/listinfo/diy_efi
> Main WWW page:  http://www.diy-efi.org/diy_efi
>
>
>
> _______________________________________________
> Diy_efi mailing list
> Diy_efi at diy-efi.org
> Subscribe: http://lists.diy-efi.org/mailman/listinfo/diy_efi
> Main WWW page:  http://www.diy-efi.org/diy_efi
>

-- 
Sincerely,
Lee M. Lemoine
KB1NQI  - Amateur Radio
http://www.turbochargedsoul.com/
'06 Subaru Legacy GT Limited - 250/250 AWD 5EAT
'93 Chevy Cavalier Z24 Convertible - 300/330 FWD 5MT (Mclaren Turbo!)