LQ4 trouble idling, especially on cold starts

[ovrebo2]

LQ4 6.0 Swapped into 97 Chevy pickup. Current performance wiring built the harness. ECU is from doaner vehicle (03 Savana 2500)

LQ4 mechanical Mods:
317 heads with 30k taken out of them
LS6 spring? the blue ones
F-body long tubes-no cats
Trail Blazer SS manifold with with stock injectors....I think from the 03 Savana? So not sure which injectors they are off the top of my head
102mm China TB
TS Stage 2 Low Lift Truck Cam 550/550 lift

Motor is drive by cable. So was the Savana

I'm posting from my home computer, so I'll get on my laptop and update with the tune that is in it now. Truck has trouble idling when dead cold, but runs fine otherwise and once its warmed up. Sometimes when coming to a stop (no matter the temperature), the idle will dip lower than it should.

What I think might be a problem is that the company who did the harness, for some reason sent it back with the connector for a later model MAF. When I look at O'reilly's site, it says that the MAF basically came on 07-08 trucks. When I look at those tune files, it has 2 MAF tables, where my older ECU has 1. I tried to re-create the curve and I followed Goatrope's videos on how to scale it, but I feel like everything I try to improve on just makes the truck run worse, so then I end up going back to stock parameters.

The MAF I'm referring to and is what is currently in the truck: https://www.oreillyauto.com/detail/c...213-4781&pos=0

[edcmat-l1]

Data log and tune. Feel like a broken record. This is me right now --->

[ovrebo2]

chevy trying more silverado SS stuff.hpt
first real log.hpl
cold no idel 2.hpl

[ovrebo2]

Sorry I don't think that posted like most people have them on here. This is my first time posting on here. I'm happy to follow anyone's direction on how to properly post

[ovrebo2]

Oh and motor has TS Stage 2 low lift truck cam. I will go back and put that in the original description

[ovrebo2]

Data log and tune. Feel like a broken record. This is me right now --->

posted

[ns158sl]

Something is wonky with the fuel trims. Po300 is pending. You said it doesnt idle when cold? It looks like it doesnt start when its cold lol. You will probably have to drill your TB being looks like hot ect, your IAC was in the 100's, not terrible but that isnt going to help cold start. Chinese TB's usually have terrible IAC passages/motors.

[ovrebo2]

Correct, I have to crack it with my foot and then it's fine. If I mess with the throttle screw stop then it ends up being too hi once the truck is warm

When I was tuning with goatrope he helped me set the screw by the numerical value the ECU sees, but I've probably fiddled with that since then

I've never heard the term "drill a throttle body". Is that in reference to the passages for the IAC? It's using an IAC I probably pulled from the doaner motor or the yard. I doubt the motor is Chinese.

I've learned my lesson in the past about Chinese stuff. I just happened to come across this one cheap while I was buying other parts. I'm not apposed to getting a different TB. It would be a little difficult to go much smaller since I made all my intake tubing

[ns158sl]

There should be a small hole in the blade already. You would enlarge that hole. But go as small changes as you can and only verify IAC when the the engine is operating temp at idle. You are shooting for around 50 to 70 counts. I use to adjust the stop screw, but Alvin on here converted me lol.

Id try to get a better log of a cold start, maybe with a wideband if possible to see where the fueling is at. Chances are this is fuel/spark related and not airflow, but getting your IAC counts lower when warm is only going to help.

[ovrebo2]

Cool thanks. I'll look around for threads where people have drilled it out and I'll pull it off tomorrow and try a size or 2 bigger

[ns158sl]

It will help, probably wont cure the issue. I would log a cold start and pedal it if need be to keep it running, but log it. 50 degrees isnt cold lol. It is definitely fuel related.

[edcmat-l1]

Correct, I have to crack it with my foot and then it's fine. If I mess with the throttle screw stop then it ends up being too hi once the truck is warm

When I was tuning with goatrope he helped me set the screw by the numerical value the ECU sees, but I've probably fiddled with that since then

I've never heard the term "drill a throttle body". Is that in reference to the passages for the IAC? It's using an IAC I probably pulled from the doaner motor or the yard. I doubt the motor is Chinese.

I've learned my lesson in the past about Chinese stuff. I just happened to come across this one cheap while I was buying other parts. I'm not apposed to getting a different TB. It would be a little difficult to go much smaller since I made all my intake tubing

If you have to crack the throttle for it to start that means there's too much fuel.

I haven't looked at anything. Have you dialed in the VE and MAF tables?

Is the injector data correct?

[ovrebo2]

When I was watching videos last night, people showed that the hole for the IAC on the china TBs is basically to abrupt. The videos I found, the sound their TBs made were way worse than mine, but mine does make a pretty audible sucking noise that doesn't sound right

I was going to try enlarging that hole a little first and especially smooth out the transition. If the IAC is still reading hi I'll drill a hole in the blade.

As a side note, I understand I have other problems I need to address first, but I live at 5k ft give or take a few hundred.

[ovrebo2]

If you have to crack the throttle for it to start that means there's too much fuel.

I haven't looked at anything. Have you dialed in the VE and MAF tables?

Is the injector data correct?

I tried messing with the VE and MAF tables and it never ran better, so I'd always gone back to more stock parameters.

I'm not sure what you mean by the injector data being correct. Can you elaborate?

I'm going to mess with the TB later this morning and later this weekend or next week I'll get another data log

[ns158sl]

What's the part number on the injector? Data would include Flow rate, offset, short pulse adder, minimum pulse.

[ovrebo2]

What's the part number on the injector? Data would include Flow rate, offset, short pulse adder, minimum pulse.

Thanks, I'll get that when I start in on the TB in a couple hours

[edcmat-l1]

I tried messing with the VE and MAF tables and it never ran better, so I'd always gone back to more stock parameters.

I'm not sure what you mean by the injector data being correct. Can you elaborate?

I'm going to mess with the TB later this morning and later this weekend or next week I'll get another data log

In your OP you stated "TBSS intake and stock injectors". What are the injectors stock to? A TBSS? Did you pull a TBSS file and swap over the injector data? "Stock injectors" is not a one size fits all.

[blindsquirrel]

'TBSS intake' is as bad as 'my Denali'.

[ovrebo2]

In your OP you stated "TBSS intake and stock injectors". What are the injectors stock to? A TBSS? Did you pull a TBSS file and swap over the injector data? "Stock injectors" is not a one size fits all.

Stock injectors as in stock to the doaner Savana. I have not changed over any injector tables. I did order replacement injectors in 2019 and I "think" I just got the same ones that came on the doaner motor, but I went back to ebay a minute ago and wasn't able to find my purchase. When I mentioned it was a TBSS intake, I'm using that term because I thought that was what people were most familiar with, with the later intakes. Its technically off an 07-08? 2500 from the yard.

here is the injectors currently on the truck:
PXL_20240503_131342303~2.jpg

[ovrebo2]

'TBSS intake' is as bad as 'my Denali'.

sorry, I'm still learning what info and phrases people want on here. I promise I'm not trolling