Quick distributor question...

[5Tractorguy]

Some new developments this week...

Got the new Delco alternator installed this past Wednesday. All went well with that.

Thanks for the tip 400/400, I checked the positive cable and it wasn't that great. Cable was moving around some in the post clamp and the other end going to the starter wasn't great either. So I made new 1/0 positive and negative cables with crimped on ends, ran the negative straight to the engine block with another cable going from there to the frame. Thing cranks like a son-of-a-gun now! Click-start thing is very minimal, radio only blipped once and that was it.

So, after all that, the truck still runs the same... go figure! Not as much ignition skip upon startup, still has hesitation, no power on hills, weak acceleration on highway, blows through fuel...

I did some digging around here this AM about timing and stumbled upon this post below from rfmaster from a few years back about setting the IAC. I had a feeling it might not be correct because if the truck wasn't warmed up fully, you put it into drive and begin rolling forward, the idle would jump up (would also do this rarely during regular driving).

So after I reset the IAC per his description, the engine immediately ran smoother when I re-started the truck. Took it for a quick drive and it made a significant difference. Still some hesitation upon take-off and when you lay into the pedal, but there is definitely more pep/power. Feels like the ECM is properly advancing the timing now...

I'll know more once I get it up on the highway again and/or go for a longer drive. I'm telling ya, if nothing else, I sure am getting familiar with the working of a TBI system!

Originally Posted by rfmaster

2) You'll need to reset IAC. ECM does not know position of the IAC so it needs to be reset after repair. To do this you need to put a jumper between pins A and B of the ALDL connector in the cab. This puts the ECM into ALDL test mode. Turn ignition key to run position (not start) and the IAC should drive completely closed. You should hear a buzzing noise from the IAC. If you have the winaldl up and running on your laptop, you should see the IAC went from 145 to 0. Now unplug the IAC connector. Turn the ignition key off. Remove jumper from ALDL plug. Start motor. If the idle is too low you may have to keep it running. On the front drivers side of the throttle body is the adjustment screw. It may be behind a silver plug. If so just use a nail or punch to poke it and remove it. Then use a #20 torx bit to adjust the idle speed to at least 100 rpm less then your warm idle speed. If 600 then set to 500 rpm. You are looking for the lowest consistant idle your motor will do. When set, turn off motor and reconnect the IAC. Done - ECM will now be able to control idle RPM.