Grease Monkey Garage

[Shane¹]

So after some time off on the car, I went back to it today.
Here's what I noticed..
If I key it on, my AFR will bounce around probably between 18 and 22, start the car, it continues that for about 10 seconds, drops to 14ish then straight to 35 and stays there.
If I shut it off for a few minutes it will repeat this.
If I restart it after a shorter duration it just sits at 35.
I ran to town, got some oxygen sensor extenders and tried that. No change. I tried all 3 sensors I have and all do the same thing.
Pulled out the steel shim type header gaskets and installed some graphite gaskets. No change.
On doing this, I noticed my left header was barely warm to the touch. That's the side with my sensor. Right side normally hot.

I'm tempted to pull all the Holley wiring and plop in a factory harness. Not sure it would react well with the different cam though.
I can't come up with anything that could be causing this in my base engine build (mechanically).

The Holley forum for this crap hasn't provided much help. The last anyone responded to me was to tell me I have a bad sensor. When I asked about having 3 of them I got no reply.

My wife suggested i just yank the 6.0 out of my 12 plow truck and dump it in as is with the oem wiring. Im tempted to do it other than it has a 6 speed so im still screwed on the transmission control.

At this point I've given up hope on actually driving this down the road this year.

I'm open to ideas or suggestions on this.
@Steve @Canadian farm boy

I really can't come up with an alternative route to go that still won't be a ton of money when I already have quite a bit that would essentially just get flushed by purging the Holley stuff.
I'll spend the money but I'm very gun shy right now not knowing it will actually make this thing go down the road...

Man this is so frustrating do you have a stock harness and an ECU? I had lt1 swaps program an ECU for my cj and it seems to run pretty good it is just a stock 4.8 though. I wonder if your wife could be right in this situation just put a stock motor in it and get it driving that way you can take your dad for a spin then try to figure out the Holley setup when you have more time

 

[redline4]

Man this is so frustrating do you have a stock harness and an ECU? I had lt1 swaps program an ECU for my cj and it seems to run pretty good it is just a stock 4.8 though. I wonder if your wife could be right in this situation just put a stock motor in it and get it driving that way you can take your dad for a spin then try to figure out the Holley setup when you have more time

I have the factory harness from the Tahoe the engine came from. Issue is then I'm paying for HP tuners because it's not a stock cam anymore.
At this point I'm going in circles and I can't seem to prove to myself in my own mind it's not a base engine issue.
If I knew for certain it wasn't, I'd go that route and chalk the Holley Terminator to a $1600 mistake that cost me an entire summer.
So far in 2025 between the crazy BS I've been dealing with at work on cars I'm ready for the giant EMP to just render them all useless. I'll just fűckīng walk.

 

[nbbt]

So after some time off on the car, I went back to it today.
Here's what I noticed..
If I key it on, my AFR will bounce around probably between 18 and 22, start the car, it continues that for about 10 seconds, drops to 14ish then straight to 35 and stays there.
If I shut it off for a few minutes it will repeat this.
If I restart it after a shorter duration it just sits at 35.
I ran to town, got some oxygen sensor extenders and tried that. No change. I tried all 3 sensors I have and all do the same thing.
Pulled out the steel shim type header gaskets and installed some graphite gaskets. No change.
On doing this, I noticed my left header was barely warm to the touch. That's the side with my sensor. Right side normally hot.

I'm tempted to pull all the Holley wiring and plop in a factory harness. Not sure it would react well with the different cam though.
I can't come up with anything that could be causing this in my base engine build (mechanically).

The Holley forum for this crap hasn't provided much help. The last anyone responded to me was to tell me I have a bad sensor. When I asked about having 3 of them I got no reply.

My wife suggested i just yank the 6.0 out of my 12 plow truck and dump it in as is with the oem wiring. Im tempted to do it other than it has a 6 speed so im still screwed on the transmission control.

At this point I've given up hope on actually driving this down the road this year.

I'm open to ideas or suggestions on this.
@Steve @Canadian farm boy

I really can't come up with an alternative route to go that still won't be a ton of money when I already have quite a bit that would essentially just get flushed by purging the Holley stuff.
I'll spend the money but I'm very gun shy right now not knowing it will actually make this thing go down the road...

How involved is it to do a minimal OEM PCM connect to see if it could run even with the cam?
You've probably already looked at HP tuners, how well do they support the ECM that you already have?
I know there was a good repository of tunes that can be used for reference to get it running.

 

[FergusonTO35]

So, the left header was barely warm. Is this a TBI setup? 90's Chevy trucks would do that if one of the two injectors died. Sounds like you have something similar going on

 

[redneckhillbilly]

left side header cold. what do your spark plugs look like? might have to bring home a set of injector nodes and see if there getting signal, i had issues with the plug for the coils on one side (cant remember wich) when I swapped my squarebody.

how does it run with the O2 unplugged

 

[Mycamaro_68]

So after some time off on the car, I went back to it today.
Here's what I noticed..
If I key it on, my AFR will bounce around probably between 18 and 22, start the car, it continues that for about 10 seconds, drops to 14ish then straight to 35 and stays there.
If I shut it off for a few minutes it will repeat this.
If I restart it after a shorter duration it just sits at 35.
I ran to town, got some oxygen sensor extenders and tried that. No change. I tried all 3 sensors I have and all do the same thing.
Pulled out the steel shim type header gaskets and installed some graphite gaskets. No change.
On doing this, I noticed my left header was barely warm to the touch. That's the side with my sensor. Right side normally hot.

I'm tempted to pull all the Holley wiring and plop in a factory harness. Not sure it would react well with the different cam though.
I can't come up with anything that could be causing this in my base engine build (mechanically).

The Holley forum for this crap hasn't provided much help. The last anyone responded to me was to tell me I have a bad sensor. When I asked about having 3 of them I got no reply.

My wife suggested i just yank the 6.0 out of my 12 plow truck and dump it in as is with the oem wiring. Im tempted to do it other than it has a 6 speed so im still screwed on the transmission control.

At this point I've given up hope on actually driving this down the road this year.

I'm open to ideas or suggestions on this.
@Steve @Canadian farm boy

I really can't come up with an alternative route to go that still won't be a ton of money when I already have quite a bit that would essentially just get flushed by purging the Holley stuff.
I'll spend the money but I'm very gun shy right now not knowing it will actually make this thing go down the road...

Did I catch that correctly that you are only using one O2 sensor? Does the right header have a bung for an O2 sensor? It seems odd that one header would be cooler then the other. It might be worth checking temps on all 8 header pipes while running. It's been years since I messed with air/fuel numbers, is higher number lean or rich?

 

[redline4]

It's port injection. Zero misfires.
The bung in the right header can't be used because it points right at the 4l60 servo and there's no room. I could weld one in further back but still don't think that's my issue. The Holley system uses 1 wide band 02.
I haven't pulled plugs lately but last time I looked they were black because 35 afr indicates lean so the system starts dumping fuel to compensate.
Think of the AFR number as the stoichiometric ratio. 14-15 is kind of right where you want it. Kind of.

 

[redneckhillbilly]

i hate even the thought of my redneck ass giving you advice, with dealership experience youve probably forgottten more than Ill ever know.

i would be looking at the harness closely, follow wires to ECM pins, check for stupid stuff like a plug thats the same as something else plugged into the wrong sensor

any sensors changed durin the swap would be suspect.

NGK plugs from a year or so ago when china was selling them.

MAF sensor have good signal, and the honey comb still in it. if it even has one, hook up a vacum gauge and watch it.

vacum leaks at throttle body.

I have a hunch your gremlin is gonna be one of the stupid things you overlook a half dozen times, and than all of a sudden you notice it and correct it and sham wow shell be running good.

 

[Stump Shot]

I have the factory harness from the Tahoe the engine came from. Issue is then I'm paying for HP tuners because it's not a stock cam anymore.
At this point I'm going in circles and I can't seem to prove to myself in my own mind it's not a base engine issue.
If I knew for certain it wasn't, I'd go that route and chalk the Holley Terminator to a $1600 mistake that cost me an entire summer.
So far in 2025 between the crazy BS I've been dealing with at work on cars I'm ready for the giant EMP to just render them all useless. I'll just fűckīng walk.

Should set up camp straight up Holley's wazoo and wouldn't leave until it either worked or they bought it back and have a definitive direction to work towards.

 

[Mycamaro_68]

It's port injection. Zero misfires.
The bung in the right header can't be used because it points right at the 4l60 servo and there's no room. I could weld one in further back but still don't think that's my issue. The Holley system uses 1 wide band 02.
I haven't pulled plugs lately but last time I looked they were black because 35 afr indicates lean so the system starts dumping fuel to compensate.
Think of the AFR number as the stoichiometric ratio. 14-15 is kind of right where you want it. Kind of.

It just seemed odd that the left header was way cooler than the right and that is the side the sensor is in. Too bad it wasn't a simple swap to put the sensor in the other side to see if it makes a difference.

 

[davidwyby]

There used to be a shop out here called pacific fab that did a lot of LS. I think they went under a because of the owner and the main brains shop guys came back as something else.

 

[redline4]

Wire harness has been checked multiple times. All terminals checked for location in connectors as well as terminal tension. All wiring comes in at .4 ohms.
No mass air flow sensor. This is a volumetric efficiency system that relies on the wide band oxygen sensor to determine fueling needs.

Now that I've swapped it to a factory intake and changed the fuel system plumbing for the 3rd time I think I might pull the fuel rails and injectors from my plow truck just to rule out any injector issues. I will also bring home our PowerSmoke machine from work. It has airbags to seal off intake and exhaust and I can put pressurized smoke into it to find any vacuum or exhaust leaks.

Holley tech support is open 8-5 mon-fri...
Last time I called I set my phone on my toolbox on speaker and it took about an hour before I finally talked to someone. Depending on what I've got going I can't always do that.

Did some searching, would cost me $1500 for an intake, Edelbrock carb and controller fir the injectors plus another $1200 for a stand alone TCI trans controller so that route is off the table.

 

[Mastermind]

Wire harness has been checked multiple times. All terminals checked for location in connectors as well as terminal tension. All wiring comes in at .4 ohms.
No mass air flow sensor. This is a volumetric efficiency system that relies on the wide band oxygen sensor to determine fueling needs.

Now that I've swapped it to a factory intake and changed the fuel system plumbing for the 3rd time I think I might pull the fuel rails and injectors from my plow truck just to rule out any injector issues. I will also bring home our PowerSmoke machine from work. It has airbags to seal off intake and exhaust and I can put pressurized smoke into it to find any vacuum or exhaust leaks.

Holley tech support is open 8-5 mon-fri...
Last time I called I set my phone on my toolbox on speaker and it took about an hour before I finally talked to someone. Depending on what I've got going I can't always do that.

Did some searching, would cost me $1500 for an intake, Edelbrock carb and controller fir the injectors plus another $1200 for a stand alone TCI trans controller so that route is off the table.

We put an LS in a truck....but after reading a few horror stories, we sold the project.

 

[Shane¹]

@redline4 possible if you have a bad injector dumping fuel? If left side was that much cooler could you swap the injectors from one side to the other? Might be easier than taking them out of your other truck for no reason

 

[redneckhillbilly]

Ive never seen a holley LS system before, thats a bummer it wont run right. with having that style of engine control I am not familiar with it and know exactly diddly squat about those.

but I will try to think of some of the random stuff Ive encountered.

any chance power brake booster is causing a vac leak.

can a good scanner perform a KOEO test with the holley stuff.

I would imagine its got a map sensor, any way to replace rubber hose to it with a piece of steel pipe

if your motor is 2004ish fly by wire and you have a factory harness I could loan the computer out of my squarebody if that helps any.

 

[redline4]

If it were an injector dumping fuel I'd think I'd have a misfire. It doesn't seem to have that.
The Holley ecu uses an internal map sensor. It does have a connector for a oem or aftermarket sensor. I can change that parameter and try it.
Brake booster leak was ruled out as I pulled the vacuum line and capped it at 1 point.
Scanner is nothing more than laptop and the holley terminator software.
If I take a rag, spray it with brake clean and wrap it around the 02 sensor my AFR changes. I can pull off the right side exhaust and weld in a sensor bung as I have extras.
At this point I really think I need to smoke this thing. We were supposed to go for a ride on the bike with my parents today but it's raining and not appearing to stop so maybe I'll run to work and bring the unit home.

 

[redline4]

And, I have a couple different factory harnesses and ECM's here I can cut apart to use if needed.

 

[redneckhillbilly]

does your dealership have the ability to disable VATs on a factory computer?

will the car start if you unplug stuff like the IAC or
coolant temp sensor.

smoking it would be a good thing to do, rule out any vacum leaks.

i dont use my swapped squarebody very much, so if you did wanna try a factory harness I could pull the confuser and mail it to ya if you think itll help ya, not sure it would do much tho if youve put a cam in yours.

 

[redline4]

So far holding at 10psi, no smoke noticed. Sprayed soapy water on intake and exhaust as well...

 

[Canadian farm boy]

Well, śhît..
View attachment 460707

Ed, have you done a tps reset? In this pic your tps position is at 11% at idle. Iirc it should be 0-2%. If it’s above 3% you loose idle control with the iac and the system will start to pull timing and fuel to try and hit the target idle rpms