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L18 8.1L swap resource thread

Does the ecm need programed after the throttle body is changed? I have no throttle and it's running worse than before. I'm suspecting it may be the ecm.

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it does learn, when the throttle is change adjusted, but it should run decently until throttle minimum air is learned.
 
SpeedlabDan said:
Does the ecm need programed after the throttle body is changed? I have no throttle and it's running worse than before. I'm suspecting it may be the ecm.

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According to the service manual, if the throttle body is replaced no programming is required. It does recommend that you plug in a scan tool to monitor the following:
  1. Connect a scan tool in order to test for proper throttle-opening and throttle-closing range.
  2. Operate the accelerator pedal and monitor the throttle angles. The accelerator pedal should operate freely, without binding, between a closed throttle, and a wide open throttle (WOT).
 
SpeedlabDan said:
tac module on order. no throttle right now and same assues as before
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Make sure the TAC module is for the same application as the throttle body. The early throttle bodies with the big round motor use a different TAC module part number and have different drivers in them than the later one like you installed. It’s a pisser you’re having so many issues with this but this is the exact reason why the 8.1 recipe here includes using a cable driven L29 454 throttle body. Plus the pedal feel of the DBW 8.1s feels weird off-road, especially with a manual trans
 
Sadly, I've pro been chasing these issues due to this the entire time. It has been a long road but at least at this point I know everything except the block at brand new... Here's the part number and application I ordered. It covers a lot of models but should be correct for my application.

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Hello all!
Is there a flywheel / dust cover for the 8.1l and 4l80 combo? My beast is moving, exhaust next and then..... :burnout:
 
My bad, I did search but did not have that part number.... :whistle:

Now I need to find one as it looks like part number 15000206 is hard to find....
 
Can the 2001-2002 ecu drive the tac module for the 2003-2005 throttle body?

I have used it but I had range issues in the pedal but on the trip back we developed the dropping cylinders issue again but worse. The ecu is getting replaced as there aren't any more parts to change and it still has intermittent problemstthat aren't coming back on the scanner
 
SpeedlabDan said:
Can the 2001-2002 ecu drive the tac module for the 2003-2005 throttle body?

I have used it but I had range issues in the pedal but on the trip back we developed the dropping cylinders issue again but worse. The ecu is getting replaced as there aren't any more parts to change and it still has intermittent problemstthat aren't coming back on the scanner
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I'm going to say no. Looking at the factory schematics, the early tac modules had app sensors to monitor. The later ones only had two. The early module may not recognize the later tac module with less information. Maybe a tuner could address the difference but I don't know.

Unless you got a corrupted common ground between the injectors or coils and the throttle body I can't put together the dropping of cylinders being caused by a throttle control issue. It don't add up.

Which probably means you have two issues to sort out. Throttle control and the dropping of cylinders.
 
ZooMad75 said:
I'm going to say no. Looking at the factory schematics, the early tac modules had app sensors to monitor. The later ones only had two. The early module may not recognize the later tac module with less information. Maybe a tuner could address the difference but I don't know.

Unless you got a corrupted common ground between the injectors or coils and the throttle body I can't put together the dropping of cylinders being caused by a throttle control issue. It don't add up.

Which probably means you have two issues to sort out. Throttle control and the dropping of cylinders.
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Sorry I should have specified they are two separate issues.
 
Larry said:
On the rear seal installation I have no suggestions as I’ve only used the GM factory tools for the front and rear main seal R&R’s.
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Is the rear main easy to do if you already have the crank out of the engine? I'm gathering parts to replace the crank and rod bearings (https://ck5.com/forums/threads/quadrasteer-8-1l-suburban-tow-rig.339146/page-10). It looks like the rear main has been leaking a little. Over the years I've grown tolerant of small leaks (sometimes they get worse when you fix them...), but thought this would be the perfect opportunity.
 
I think the way the tool works it's best if the crank is in place.
 
The tools are too expensive to buy. If they're absolutely necessary then I have to find a place to rent or pay somebody to change it. I see guys on Youtube pulling the old one with sheet metal screws and installing with various objects like automatic transmission clutch steels. Just seems like with the rear cap loose the whole job becomes very easy, but I'll look it over more closely.
 
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