Weird- DVT Commands not working

So it’s been a while since I’ve been on here needing help... I’m really scratching my head on this. I changed my truck to run a Magnacharger and have been struggling with it starting, idling, surging. I’ve went thru idle tutorial on setup- I’ve changed surface area for bigger 90mm TB- I’ve been struggling with these Deka 60lb injectors - when I changed the data from what I found on a HPTuner forum- truck ran little better but when I changed pulse offset due to voltage it went crazy rich....

Anyhow I found a happy medium right now but noticed lastnight when using the DVT commands I couldn’t control idle by rpm- I could adjust the IAC and it messed with rpm- second part was command afr- I would be idling at 14.1-14.6 when I command 14.7 it went really rich....12.2-12.4 afr

Another thing that is weird is when motor would be over 130 degrees and running just SD 2 bar truck would not restart after a reflash- fought this for a week or two- I plugged maf in off to the side and it would allow it to restart... confuses me- I have it set to fail 1 hz - dtc non emission-

What gives? Injector data wrong? Iac to far out of range? TB not adjusted right? Anyone run into this?

1999 GMC Sierra
Lq9 243 heads-ls9 headgaskets (10.6:1)
BTR stage 3 truck cam
Mp122hh with 3.6 pulley (5-6 psi)
LT WORY
60lb Deka injectors
Efans
Cos3 with 2 bar

Also thought about b4403 I didn’t adjust for 90 mm Tb

If your injectors are the mototron/deka 60's that get supplied with some superchargers then do yourself a favour... throw them away and get some decent injectors. I've personally seen flow imbalances up to 8% with those injectors and have heard of even higher imbalances. They're so bad that I refuse to tune an engine if they are fitted.

Check for airleaks.

Those injectors are not letting enough fuel spray when you attempt starting, see what statesman said.



Some PCM's don't respond to all the DVT commands or have conditions that have to be met first.

That is good to know, I do know the highest flowing injectors are on cylinder seven and eight when I bought the supercharger they didn’t give a name of who makes them... I need to get a part number and cross-reference, I do have a pair of 42 pound injectors from an 81 marine but I think I will be close to maxing those out

Vac at idle when I get it too is 14 in.hg

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Originally Posted by Trxmxzx

I do have a pair of 42 pound injectors from an 81 marine but I think I will be close to maxing those out

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A pair won't do.... you'll need 8 of them.

I'm guessing you meant "set" :laugh:

Lol true yes a set

Didn’t get much time to tinker with truck this weekend- but was thinking about it - I never scaled the IAC effective area for this 90mm Edelbrock TB, could I use a ls2 scaling? I’ve read that it might be a option

Another thing is my IAC STEPS are 150-160 on start up and 120 when warm- I looked up the TB and there is a idle bleed screw I may need to adjust also.

Edelbrock 3864 is what I’m running if anyone is familiar with it...

IAC counts should be around 50 when warm.

That’s what I thought thank you

For those injectors I’m still waiting to get time to tear into this thing but figured check these other settings first

so I had about a hr lastnight to tinker, I adjusted the iac scaling to a 90mm Holden car specs and opened up the bleeder screw a decent amount on TB and wow it made a difference... scaling more than anything

My iac steps are now 42 at 195 ECT

So this truck still hunts a little for idle with no load if I bump the throttle- if the efans are on (commands more air flow) or ac is on (commands more air) I can bump throttle and it goes right back to 800 rpms.

Would that be a spark or desired airflow issue at idle no load I need to tweek more? It idles around 14.2-14.4 afr right now

Your warm engine IAC counts are now where it should be.

Return to idle can be hard to get right... first you need to make sure your base airflow is right, then you need to look at controlling how fast your rpms come back down towards idle after the throttle blip. You need to have enough air in your intake to maintain idle as rpms drop towards idle speed, so watch your MAP readings and use them as your guide.

ok so its been a few weeks and finally have been able to get back to this truck. had to leave town to help family.... anyhow I got the PN off these injectors and am having no luck finding out which ones they are...it says this


C1A and below that 2054B all post a pic in a few.

Also when I do calc.maft process for ve table it says im lean in areas via wideband but still pulls more air out of ve in those areas im lean which in turn is making it leaner..... so my data I have is junk- back to the board of finding info on injectors

Ill attach what I have now. and what has worked best for this to run ok.... ve I have about 20% added to it just incase... lower rpms is where my lean spot is between 1100-1500 rpms and about 35-55 kpa. I think it might be a offset for these injectors I need to tweek.

Attachment 22974

Dug through forums from back in 2008 from when my buddy upgraded these injectors- they are multec 2 truck injectors made by Delphi - now I need to find the data.. getting somewhere

Well I got a offer for the supercharger setup, so I took it off the truck lastnight to make it N/A again. I flashed in my latest tune from being all motor with 42lb injectors. Started right up perfect for 10 seconds then shut off like I turned the key- restarted and it was running super rich- 10.6 afr - 40-45 kpa on map sensor- KOEO it was 98kpa one code that came up was po106

Do I need to remove the custom cos3 ? Or should I be fine just flashing my last 02 os in? Running 1 bar map again

This thing has been giveing me headaches over and over-

I flashed back to a 02 os and reflashed my last an tune in it all works now

Thank you guys that tried to help

Did Calc.MAFT work ok...?

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Originally Posted by joecar

Did Calc.MAFT work ok...?

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So I