EGR and ESC delete - 1991 Suburban

[jtrux]

Recently I discovered my factory TBI harness was getting pretty rough so I pulled it out. Everything from the ECM connector to the bulkhead connector.

I'm going through and replacing the handful of wires where the insulation was worn off and decided to delete the EGR and ESC. As far as I can tell, the ESC essentially relies in the input from the knock sensor to retard timing when necessary. I want to make sure that there isn't some other auxiliary function that is critical for the truck to run before I get rid of it. I know there's some risk by not running a knock sensor but for a bone stock motor I think I'll be okay and I'm okay with that risk.

Before I de-pin them and make them disappear forever, is there anything I need to be aware of?

I do realize that there are a few areas in the harness where a few 12v wires are all cramped together and obviously I'll be mindful of that. Just looking to see if anyone had any input.

Also, I'm having Hamilton FI send me a new PROM (I have all the stuff to do it, I just haven't dedicated the time to learn it well enough to trust myself yet).

 

[Bent77]

The ESCM is part of the total timing system. It does read knock to do knock retard as well as trim the timing up on lean cruise. I would leave that in

The new Prom would take care of the CEL for the EGR delete

 

[jtrux]

The ESCM is part of the total timing system. It does read knock to do knock retard as well as trim the timing up on lean cruise. I would leave that in

The new Prom would take care of the CEL for the EGR delete

On these aftermarket harness that people use to swap TBI into their old rigs, what are they doing about that because I haven't seen it listed on any of the sites I've been looking at it appears they use factory comp co trolled dizzys.

 

[Bent77]

That’s a great question. There are different spark tables for each side

So the prom burner could zero out all except the base table. It would have to be a bit conservative to avoid the ping. This would also make it have less timing everywhere, less power

In the end, the injectors in theory use the distributor to time them.

It’s not terribly hard to pull in new wire and repin your harness to keep it. Maybe that’s an option

 

[jtrux]

It sounds like I should keep it. I'll probably replace most of those wires since they just sit there getting baked above the intake. Maybe I'll try to stab it to the firewall or something.

 

[Blue85]

It looks like the ESC just sends a signal when it hears knock. Presumably if that signal isn't there, the ECM doesn't care and doesn't pull timing. You would need to cut the power and ground or redo the factory splices. If you remove a terminal from a bulkhead connector, be sure to replace it with a plug. But what's the motivation to remove it?



Apparently the L19 system is different.

 

[jtrux]

The knock sensor wires and some of the wires going to the ESC have rubbed bare in some spots they need to get replaced regardless BUT if it's something I can delete without some huge detriment to the engine I will do it. Essentially, I'm keeping the tbi going until I finish collecting LS swap parts and I don't want to tear it apart until I'm ready for this swap. I'm just looking for reliability and if the knock sensor doesn't interfere with that then it's gone lol

 

[dyeager535]

Look at the service manuals for codes related to ESC/knock sensor.

At least some applications the knock sensor is tested on startup via the ECM, I'm not sure the ramifications of that test failure. Could be nothing (like EGR failure) could be reduced performance. Absolutely no reason to remove the knock sensor IMO. Far more potential for damage without it than with.

Repair wiring, any exposed wires put inside OEM quality loom, secure loom with things that don't vibrate loose or fail rapidly from heat, and you'll be fine for decades.

I can't speak for everyone, but my wiring harness is 26 years old and considering the age, problems with wiring are minimal. Every failure I've had was at a connector, not the wire run. Granted, TBI injector wires are a known weak spot, but that's about it.