Process flow for troubleshooting TBI?

[Nutro]

Been chasing a code 42 for a while in my 88 K5 blazer. I replaced the ECM and the truck ran ok for a day but then started stalling and idling rough. It finally would start but die immediately. Crank, fire, die. Over and over. I can make it start by pressing the gas pedal slightly then cranking it and revving it a little. It will then idle. I can turn it off and it fires right back up. No codes present.

Today I installed a new GM ICM (with the thermal paste) and a new GM TPS. I drilled out the plug on the TB to adjust idle, and jumped the ALDL connecter A to B then unplugged the IAC and started it, adjusted the throttle stop to get a nice idle. Shut it down.

I tried to adjust the TPS to .50 volts but could only get it down to .75 before I ran out of daylight and had to feed the kids.

Everything else related to the TBI has been replaced in the last year and half. Injectors, FPR, gaskets, plugs, wires etc etc.

So, What is the process flow for timing, setting TPS voltage to .50 and setting idle? Do I need to remove the TPS and drill out of the screw holes to allow for more adjustment? Do I set timing first, then do the base idle then set TPS voltage?

 

[dyeager535]

http://www.gearhead-efi.com/Fuel-In...tems-Min-Air-Adjust-TPS-set-and-Fuel-Pressure

 

[bp71k5]

Code 42 is the ESC module isn’t it?

 

[nitro_rat]

Ignition timing base setting being off (usually retarded <0°) can cause this code.

 

[Nutro]

Code 42 is the ESC module isn’t it?

Apparently. I've checked the wiring and replaced the ESC already. Wiring looks ok and I don't see any shorts .

 

[Nutro]

Well I will admit, I haven't messed with SBC stuff in ages. I'm more of an LS guy so I'm a little rusty. I went out today and checked timing with the timing connector disconnected. The timing tab shows 8-to-0 BDC then 0-to-8 After. The distributor hold down was not real tight. The timing showed to be at roughly 4 ATDC so that should be advanced? I turned it to 0 and the idle perked up and it seemed to idle much better than it ever has. I set it to 0 then killed ignition. Disconnected battery, reconnected timing connector and reconnected battery. I just drove it and it seems to drive better.

 

[bp71k5]

Well I will admit, I haven't messed with SBC stuff in ages. I'm more of an LS guy so I'm a little rusty. I went out today and checked timing with the timing connector disconnected. The timing tab shows 8-to-0 BDC then 0-to-8 After. The distributor hold down was not real tight. The timing showed to be at roughly 4 ATDC so that should be advanced? I turned it to 0 and the idle perked up and it seemed to idle much better than it ever has. I set it to 0 then killed ignition. Disconnected battery, reconnected timing connector and reconnected battery. I just drove it and it seems to drive better.

4 ATDC would be retarded and may have been causing the motor to knock or stumble which could cause the ESC to report knocks. Make sure you plug the timing connector back and lock the distributor down.

 

[Nutro]

I'm about to go drive it now. So the timing being 4-5 degrees retarded would throw that code?

 

[bp71k5]

I'm about to go drive it now. So the timing being 4-5 degrees retarded would throw that code?

Possible, but it will run like a dead dog. ESC code is spark timing so it’s related.

 

[nitro_rat]

Yes, retarded base timing will set that code.