Timing, Tuning, and Bug Hunting

I need help setting the timing, and working out the bugs (for a laugh remember the kid on the Little Rascals "bug hunting" with a hammer).

The 87 S-10 is now running code free on the computer. I took it for a short ride and it was amazingly gutless - struggled to get it up the driveway. I retarded the timing (turned the distributor) a few degrees (per a light from ~20 to ~15) and it seemed much better. I took it for another ride and was surprised that the 4 wheel drive is also working. It had great power too, except that it occasionally seemed to go into a sort of limp home mode. I messed it up again fiddling more with the timing, and can't seem to get it back like it was that 1 drive.

The last drive I got stuck in a little hump by the driveway and had to pull it out with the other truck. It only made it back to the parking space by putting it in 4-wheel-lo (lower gear). So I'm thinking I need to figure out:

  1. How to properly set the timing (ie: disable computer timing set it to the proper setting, re-enable the computer and verify). I noticed the test jumper seemed to set the timing to a closer to constant value - is this a good approach? There is also a single wire with a connector on one of the wires going into the ESC box on the firewall - is this supposed to get grounded?
Well I'm back from the 650 miles of the Binghamton trip. Gave > my daughter an Easter basket too. > > I HAVE A NEW COMPUTER and IT WORKS!!!!!!!!!!!! > It's a 1228062 from a 91 S-10 Blazer that had a 2.8L with Automatic, > 4x4, A/C, and everything looked the same except the MAP sensor was > mounted to the TBI rather than to the Air-Cleaner-Assembly. John, > I would have gone for the 1227429 if I could have found one - I > didn't. I believe the 1228062 is compatible only because I got > it chips and all (the link you provided shows they use different > base addresses for the PROMs - that's internal to the computers). > > So finally it's running w/o the CES light on. Stopping it and > reading for codes I only get the acceptable 12!!!. Running > with the jumper it does go into the debug mode (flasshing > according to rich/lean 02). Remaining bugs are that the idle is > inconsistant RPM and the check gages light is on. > The idle is probably from leaky vac lines (easy to fix - but > hasn't yet been prioritized - will be soon). I believe the check > gages light is either for the oil pressure or water temp gages > (both of these could use new sending units). > > I stopped at Harry's U Pull it in Hazelton on the way up, and found > the 91 Blazer with the computer, a fan shroud, and some Vac hoses > (all for the price of $2 admission + $22 for the parts). I thought > of Doc cause I saw a guy there pulling a wagon (convenient). I > asked on my way out if they had a yard-man and they said no (that > was the only drawback - they did have a nice collection of vehicles). > And I was reminded of the lacking value of my Truck on the way out where > they had several vehicles for sale including a late 80's Blazer 4x4 > for $1200. > > Later, at Gary's I got a dust-cover for the torque converter (though > the S-10 had a 4.3 - so I may need to modify to it if it > doesn't fit perfectly). That cost a whole $7 + $10 for the yard > man to cut the front Y pipe out of the way. They had other > blazers and S-10s so had I had more time I may have found it > all there too. The big advantage of Gary's was the yard-man. > They had 2 of them there Saturday - driving modified Ice Cream > trucks for their yard-vehicles. Plug: see
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> > Elliott
Reply to
Elliott
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I would personally never pay admission to a junk yard, even though I do use it as an amusement park....

~KJ~

Reply to
KJ

Comments inline...

Reply to
Neil Nelson

Thanks Neil that's the info I was hoping for. LOL - your last comment "everything" given the history of this truck - yea my sense of it too. I will go hunting for the "tan with black tracer wire at the set timing

Elliott

Neil Nels>

Reply to
Elliott

Neil, NG,

I wasn't able to find any tan with black wire/disconnect at any place under the heater case (there is a wire bundle there going into the firewall - near the computer).

Am I correct that you're saying to 'open' the Tan/BLK wire between the distributor and the ECM? Someone once before posted that wire ws the "IGN Bypass (timing set)". I can access a Tan with Black wire at the computer (though I'm not trusting my wire colors to match Haynes). Someone else was discussing this wire with Doc and was intending to install a switch - seems a good idea.

I did see a Tan with black wire entering the ESC (which does not match my Haynes schematic around the ESC wires). And I hotted the open connector that was bundled at the ESC (after ohm metering it first, and voltage testing it). It turns out that connector is the fuel-pump-prime.

Elliott

Neil Nels>

Reply to
Elliott

Reply to
Elliott

I was talking about that wire. Try to follow it from the dizzy to wherever it goes. I found mine under the brake master cylinder, but mine is a FS truck. I never installed the switch. Since *no one* seamed to be able to help me, I was *sure* my engine wires were non-OE, so I was going to attach a switch. But they were just fine, and I found the quick-disconnect.

~KJ~

Reply to
KJ

Reply to
Elliott

Not surprised that you couldn't find it... GM tended to put the set timing connecter in quite a few places, forcing one to go on a hunting expedition to find it. I'll check my Delco tune up manuals when I get to the shop and see what they say about it's location and what is the correct procedure. The Mitchell wiring diagram for your truck doesn't show the disconnect (odd) so maybe yours is a "ground the ALDL to set timing. It would be better if your truck had a tune up label to reference.

Yes, normally that -is- the procedure on Chevy trucks.

Yes, tan w/black tracer is the Ign bypass circuit from the ECM to the module.

Switch= bad, putting in your own disconnect via a set of male & female terminals would do in a pinch. But let me double check the procedure in my Delco books.

ESC and EST are not the same thing, the tan w/ black going to the ESC module won't do the job.

Now ya know...

Reply to
Neil Nelson

Why would a switch be bad. A nice water proof N.C. push on/push off switch under the dash would be just as good as the water resistant quick connect.

~KJ~

Reply to
KJ

Because it's one more mechanical device that can fail.

Reply to
Neil Nelson

I think a switch rated for FIVE HUNDRED THOUSAND mechanical cycles is less likely to fail than a quick disconnect that might have say 70 mechanical cycles if handled gingerly. But that's just my opinion.

~KJ~

Reply to
KJ

Reply to
Elliott

How about you disconnect it from each end, and have your wife hold on multi-meter lead on the dizzy end, and you touch the ECM end? I'd do anything besides a cut & splice, it's just so "hackish". Radio Shack doesn't carry water proof switches, I know this, I tortured myself there for a year.

~KJ~

Reply to
KJ

Reply to
Elliott

Reply to
Elliott

Yup, it's D-5

Reply to
Neil Nelson

Hi!

I'm thinking heat and grease would probably kill it. Might not be so bad if you put it in the cab somewhere though...

William The Guesser

Reply to
William R. Walsh

I don't know why everyone doesn't believe me, but the underside of my dash is within my truck. They make petrol-derivative resistant switches (Basically all that you normally run into) and IIRC most switches have temp ratings of say 150* plus. IE, they are just as susceptible as any of the other connections within the hood. The only downside I can see is your mechanic saying "what's this?" or other derivatives of this scenario.

~KJ~

Reply to
KJ

Reply to
Elliott

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