Recently Purchased a Silverado 1500 with the following
LQ4 with Sloppy Stage 2 Cam 228/230
243 Heads
TBSS Intake
92mm Throttlebody
42 lb/hour Injectors
4l80e Trans with stock 1800 Stall
Im having trouble with the truck's RPM's dropping after warming up causing it to stall occasionally and as RPMs flutter lower AC compressor cycles on/off
Im new to tuning so please take it easy on me05 Silverado 6.0 working big test.hptBACKFRPARENTS.hpl
Idle>Airflow>Base Running Airflow is about 20% low.
Bring idle rpm up to about 750.
Fluctuations are from Proportional and Integral Idle corrections. Proportional Error>60 Integral>15.
Idle spark advance should be 18-20 not 25.
You haven't tuned MAF and VE either. Idle will be a lot easier to tune with accurate airflow models.
There's a lot of other stuff off. Injector timing, for example.
Needs a lot of work.
Thank you. I use this truck as my DD but don?t drive very much each day and don?t ride it hard. I live in Long Beach MS and it?s Cruisin the Coast this week and though it?s not a classic it?s not a common looking truck and I will be doing a little extra driving around. Yesterday I was in some traffic and it?s embarrassing to stall out.
I just got the HP Tuners this week. I have not had a non stock fast truck in 30 years and of course it was a lot easier for me to dial in with a carburetor back then and I?m starting to get aggravated because of my ignorance with tuning.
I?m going to play with the idle adjustments today.
Oh. I appreciate you not calling me a moron too.
If anyone is down here for Cruising the Coast and wants some information about the area feel free to hit me up.
What part of Mississippi?
Email Tunes, [email protected]
96 TA Blown/Stroked, 4L80E/Fab 9
15 C7 A8 H/C 2.3 Blower/PI
14 Gen 5 Viper
Custom Mid Engine chassis, AKA GalBen C
Long Beach. On the coast halfway between Biloxi and Bay St. Louis. We are on the west side of Gulfport
I went once, must have been early '90s, back then it was more like the world's longest traffic jam.
I stay away from Biloxi. Tried to go to the swap meet one year in Biloxi. Sat in traffic for an hour and couldn?t go to the meet because the Coliseum was out of parking.
Not much traffic in Long Beach. I tend to go to Bay St Louis and Pass Christian.
More laid back and a lot less traffic.
Usually over 10,000 registered cars and at least another 5000 just come on down.
Every make and model is down here.
To your idle problems...
You have wrong injector data. Only the flow rate has been changed. Min Injector Pulse, Offset vs Volts vs VAC, & Short Pulse Adder are untouched from stock. What are the injectors - part number? Source? Are they the shorty LS3 injectors, 12576341?
650 RPM is probably too low for that cam. 750 would be better. 800 probably better yet. More vacuum, easier for the PCM to control the idle swings.
Too much idle timing. It needs to be able to raise the idle speed by adding timing, if it's already got so much timing in it that the idle doesn't go any faster when it adds more, then it can't keep it under control. It needs something left in reserve. Spark timing adjustments are fast, almost instant. Throttle adjustments are slow, like glacial in comparison. If the spark timing can't get the job done it has no choice but to go nuts with the throttle because it has nothing left that's working.
Too much in both Idle (spark) Underspeed & Overspeed. You idle is jumping from 12-13* to 40* trying to 'catch' the cam loping, it misses and overshoots, then runs away too far the other direction, rinse and repeat. It gets stuck in a feedback loop. Try Underspeed & Overspeed going from 0* at 0 RPM error, to a max of 8*/-8* at -300/300.
Does this still have cats & downstream sensors?
I truly appreciate your assistance. I have not had this truck very long. Since it ran okay I have been working on some safety issues, mainly front suspension and put all new brake components all the way around. I adjusted the idle up to 750 at operating temperature, adjusted the timing down and added a little more air at idle.
It took 7 hours yesterday to get the adjusted tune to upload. It would erase the old one but would time out while uploading the new one.
It?s idling better now, of course with the stock converter it?s a little tight at idle.
Even after adding a little more air the STFTs are still rich. Wondering if there is some unmetered air entering or if the MAP sensor is not working correctly.
I?m a little hesitant to adjust the tune again this week with the issue I had uploading the tune yesterday and the fact that my buddy is coming in town tonight for Cruisin the Coast this week.
I will have to try and find a part number on the injectors because all the build info I have is a short list of what the person that built the engine gave the person that I bought the truck from. .
Prior to putting in the Lq4, this truck had a stock 4.8l with a supercharger on it. Needless to say that combo didn?t last long with stock internals.
No. Shouldn't have to touch the PIDs if it's dialed in correctly.Originally Posted by SiriusC1024
VE has not been touched. Dynamic airflow high RPM disable is set like someone is trying to run it in "MAF only" which can't be done in a GEN3. It is a dead ringer that whoever has had their nose pickers in there doesn't know what they're doing.
Need to start with correct injector data. Then dial in the VE by forcing speed density. After the VE, the MAF needs to be done.
Once everything is dialed in there are minor adjustments to be done in your idle adder tables, but PIDs should be left alone. Almost always all you end up doing is worsening the overshoot.
EFI specialist
Advanced diagnostics, tuning, emissions
HPtuners dealer and tech support
email=[email protected]
I agree with all of this.
Everything has to come full circle. If you don't address fueling (rich/lean) you'll never get it to idle right.
Tuner at PCMofnc.com
Email tuning!!!, Mail order, Dyno tuning, Performance Parts, Electric Fan Kits, 4l80e swap harnesses, 6l80 -> 4l80e conversion harnesses, Installs
First, I guess I should not believe everything I was told. The injectors are 36lb 58psi part number 12594512.
I am physically not able to do my old hobbies and purchased this truck to fill the void. I have never tuned an engine before so it?s all part of the learning process for me.
Yesterday I wished it was a carb setup after the problems uploading the revised tune but reminded myself why I bought it in the first place. I appreciate all of the feedback and will keep changing things until I get it right. The truck runs okay but not anything like it should do it?s going to be a long road.
Your file with 12594512 LMG/LC9 injector data:
05 Silverado 6.0 working big test - 12594512 58psi nonreferenced.hpt
(if you've made changes since that file was posted, copy in only these items shown in green)
screenshot.03-10-2023 09.58.03.png
(big ol' pile of GM Gen 4 injector data converted to Gen 3 format)
GM Gen4 Injectors v2.0.xls
I appreciate you Blind Squirrel.
First thing I learned is to visually inspect what parts are on this truck and not believe everything I was told. Like the different injectors. I can visually see cats on the truck but I?m not sure if they are just for looks.
I can?t seem to get any info from the O2 sensors when scanning so that?s something else I need to investigate.
I used the spreadsheets and copied the injector data you provided. I?m going to wait to next week, unless I end up with a different vehicle as there are a lot of cars/trucks for sale down here, to change any part of the tune after the problems I had uploading Monday. I want the truck to run while I visit all of the action down hear this week.
I?m sure I will be back for more guidance but I want to have my sh!t more together by then.
Thanks and come back down for Cruisin the Coast again. Stay around Gulfport to Bay St. Louis next time, there is a lot less traffic over this way and all the cars pass through the area.
Reply With Quote
