[Diy_efi] Re: Diy_efi Digest, Vol 10, Issue 3

[Bill Washington]

  David,
	Just a thought - the pins you pulled from connectors and installed in different 
connectors - are they all holding in the connectors and mating properly? When 
I've done similar exercises the locking pins dont always engage in the new shell 
properly the first time and then when the connectors are mated one socket or 
spade will push half out the back of the connector and make intermittent contact 
- I even found one two weeks ago which had properly mated, but was open circuit! 
- the tensioning springiness in the phosphor bronze (or brass) of the socket had 
lost its tension - result: no brake lights! retension/remate and all is well! -

So that is two possible intermitent connection issues, and you know murphy's law!

Regards
Bill
> Message: 1
> Date: Sun, 11 Dec 2005 23:35:15 -0500
> From: "David Daniel" <ss396 at pinn.net>
> Subject: [Diy_efi] More 4.3L TBI Timing Issues.
> To: <diy_efi at diy-efi.org>
> Message-ID: <GPEPJIFKINGINCMGPDEJKEHNCCAA.ss396 at pinn.net>
> Content-Type: text/plain;	charset="iso-8859-1"
> 
> First, a quick run-down on the vehicle...
> '81 Malibu running a '85 Monte Carlo TBI 4.3 V-6, T-5 5-speed, and an '88
> S-10 4.3L ECM.
> 
> I replaced the ignition module, which took care of the stuttering/sputtering
> problem.  I'm still having some timing issues, though.  The car has lots of
> spark-knock, even under light acceleration, and the ignition advance still
> seems to be "all or nothing".  The engine revs smoothly, which is
> surprising.
> 
> When I disconnect the connector to set the base timing, the engine RPM and
> timing do not change, and the CEL does not come on.  Unplugging that should
> set a code 42, right?  Unplugging the ESC module sets a code 43 after about
> 5 seconds.  Running the engine with the diagnostic terminal grounded does
> not change the timing, either.  Could the ESC module be causing this
> problem?  If it could be, how can I test it before I drop $70 on a
> replacement?  I would also assume that I would get an ESC module to match
> the ECM, right?
> 
> This TBI swap has been nothing but a series of problems, even though I had
> good running, complete donor car.  ECM problems from day 1, which is why I'm
> running a S-10 ECM now.
> 
> SWAP PROJECT HISTORY:
> I started with a great running, but wrecked, '85 Monte Carlo with the TBI
> 4.3 engine.  I DROVE it into the garage, stripped what was left of the front
> clip off, removed the ECM, pushed the wiring harness through the firewall
> and coiled it on top of the engine.  Carefully remove the rest of the ECM
> harness from the dash harness, marking all of the circuit numbers and
> positions in the plugs.  I remove the engine & tranny from the Monte and set
> it aside until I finish stripping the Monte.  I DROVE the Malibu into the
> garage and remove the ECM, pushing the wiring through the firewall and
> coiling on top of the engine.  I remove the engine/tranny from the Malibu
> and set it aside.  I install the T-5 onto the 4.3 and set it in place in the
> Malibu.  I push the ECM wiring back through the firewall, plug in the Monte
> ECM and make the few connections left over for the rest of the ECM harness
> that used to be in the Monte's dash harness.  I modified the Malibu's fuel
> system using the factory Monte carlo fuel lines, fuel pump, etc.  So far, so
> good.  I turn on the ignition and hear the fuel pump whine as it should, so
> I cranked it over.  It fired up right away, but the CEL is on steady now,
> and I noticed that I had no "pump shot" when I blipped the throttle, which
> causes a bog.  I try to pull the codes, but only get a code 12.  Something
> is wrong...I check all of my grounds and connections, nothing wrong there.
> At least nothing I can find. I try another TPS, hoping that that is the
> problem.  No dice.  Just for giggles I plug in a ECM from an '87 S-10 with a
> 2.8L.  CEL light goes out once the engine fires, and I get a "pump shot"
> when I blip the throttle. The engine runs, but the fuel/ignition maps are
> way off, making the engine run lean and idle funny.  Now I'm thinking that I
> fried the Monte's ECM somehow.  I order a reman ECM and swap over my PROM
> and CALPAK.  Same problem...constant CEL, no pump shot, and cannot pull any
> codes.  What are the odds that I bought an ECM with the same problem as
> mine?  Slim, but I get it replaced under warranty anyway, and I also order
> brand new AC Delco PROM and CALPAK chips.  Still no dice.  No "pump shot",
> constant CEL, but cannot pull any codes.  Since the 2.8L ECM worked, except
> the for fuel/ignition mapping, I borrowed an ECM from an '88 S-10 with a
> 4.3.  The car ran like a champ with this ECM.  I bought that ECM and
> actually started driving the car about 2 months ago (I took about a year to
> complete the engine swap, body work and paint, working on it only a couple
> of hours on the weekends).  The current problems started about 2 weeks ago.
> I started getting a little hesitation and stutter under light load and
> steady throttle, and a little spark knock on acceleration. Things got worse
> quickly until I had a dead cylinder.  I went ahead and replaced the cap,
> rotor, wires and plugs.  The stutter almost went away, but It was at least
> firing on all 6 now.  The stutter/hesitation under load got worse quickly,
> so I checked the timing, which is where I was at the last post I made.  The
> new ignition module makes the car run great, with no stutter or hesitation
> at all, but I'm still getting lots of spark knock.  I can't seem to make it
> go to base timing, so I can't check or set it.  This thing is driving me
> nuts...I'm almost ready to pull the TBI and install my Q-jet intake, Q-jet,
> and HEI to get rid of all of my computer controls.
> 
> Any help would be greatly appreciated.
> 
> Dave
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