supercharged lt1 with ls1 computer maf question

[CranknChrome]

I have taken in a job on a 1994 LT1 that has the ls1 conversion on it from torqhead. It was a complete basket case when I got. The car and how it was installed has been a pain. And to top it off it has a vortech supercharger on it. After fouling plugs and almost melting the headers, I decided to pull the piping off for the supercharger and get it running n/a first. Got it to run on the 2 bar os fairly decent. Now I am working on it now with the supercharger hooked back up. I changed the timing and hopefully its going in the right direction. I have been tuning the MAF and i thought i had it going in the right direction also until it stopped changing. When I started it was really rich 7 to 8 on the wide band. I have done several road tests trying to get the maf error corrected. But it keeps saying its -16 or so every time. Been tuning MAF like goat rope garage and its been working up until now. Its also the first forced induction setup I have done. I feel that I am missing something critical but cant figure it out. Going to try tuning SD and see where it goes.

1994 lt1
355
vortech supercharger
torqhead ls1 conversion kit
2002 transam ecm
42# injectors
stock intake
hooker headers
running 93 octane

canada tune 5percent maf tuning step 4.hpt tune i have in now


drive1 on dyno.hpl


short run till dyno dropped out and long idle.hpl



canada tune 5percent maf tuning step 1.hpt tune where i started after reinstalling supercharger piping

[5FDP]

Part of your problem is that you didn't put your open loop eq ratio to 1.00 for all cells at operating temp. You have been attempting to tune the MAF with the commanded AFR richer than stoich the whole time.

[Ben Charles]

Love these setups!! Have one myself with EFi connection kit, the injectors are too small for this. If I can help with it let me know

[CranknChrome]

Part of your problem is that you didn't put your open loop eq ratio to 1.00 for all cells at operating temp. You have been attempting to tune the MAF with the commanded AFR richer than stoich the whole time.

thank you

[CranknChrome]

Love these setups!! Have one myself with EFi connection kit, the injectors are too small for this. If I can help with it let me know

any help would be greatly appreciated, customer who brought this to me was watching youtube and its been a nightmare. I completely started over from scratch and then put it all back in. it had been to 3 other shops before me. had to send the ecm back to canada to get fixed. It has taken a while but its getting there.

What size injectors do you think it needs? the second shop put those in. ev6 connectors wired in. 60 or 80?

i dont even know what hp its going to put out. everything on the paper he wrote down has been wrong.

[Ben Charles]

Best thing to do, is look and see what map sensor is on it, most likely want to do a SD tune!! Confirm map and Injectors, once you have those 2 figures in, disable the MAF sensor and start dialing in the VE table (go ahead and do a custom OS)

[Ben Charles]

I would do some deka 60s on this. Depending on what blower abs pulley size naturally (I always do backward math to decide about how much CFM the blower can potentially make and match fuel to that)

[CranknChrome]

I know for sure that it now has a 2 bar map sensor on it. Paper work said it had one on it when it came in but the numbers were not correct. i just added the injector pulse witdh to the log and its 6-9 ms. im going to get deka 60s on the way.


added injector pulse witdh.hpl

Just setup the sd tune file for it also. i was working on getting it ready at lunch, for if I finished the maf, but I will drop it in and start there. At least now it will move under its own power.

What do you think about the timing I have setup in it? I have it on the dyno and after replacing wire for the speed sensor, got it to shift gears. havent really tested it past that though. good thing though since the injectors are not right.

[Ben Charles]

Didn’t look at file but depending on compression and octane on timing, but lower CR on 93 keep it around mid 20s in upper cylinder airmass be close

[CranknChrome]

It has a 2.87 pulley on it. No intercooler. so 12-14 psi possibly?

[CranknChrome]

Tops off at 24 about 3600rpm.

[DrLoch]

Like Ben Charles I have an LT1 in a 94 Impala SS with an EFI conversion and an cog belt F1 Procharger boosting ~16 lbs. I'm using 60lb injectors and a snow boost juice setup, took the air to air intercooler off. With the boost juice set up I'm injecting at the inlet of the supercharger and ahead of the TB and IAT sensor, IATs are good.

What heads and cam?

[CranknChrome]

Paper work he filled out for me says 242/236 and .502/.520 114 lsa. 185cc heads ported heads, doesnt say what type and i didnt see a name on them when I had it torn down for the timing cover. he also put on here 9.8:1 compression ratio. and 8lbs of boost. So its no wonder why the first couple shops couldnt get it running.

[Ben Charles]

What crank? Probably around 7.65….

With no intercooler keep it safe…

[CranknChrome]

He left the Rotating assembly line blank. Im just going to get the injectors in and just take it easy on the fueling and timing. and let it be.

[DrLoch]

Put knock sensors on it, like Ben says keep it safe. at least with the knock sensors be able see if it's knocking. My guess the cam is probably a 236/242 comp. is it 1.5 rockers or 1.6? This is the part that sucks when a project is sent to a person.

If it's an automatic, what converter?

[CranknChrome]

1.6 and 2500 stall. it has knock sensors mounted on the base of the motor on each side. Knock sensor tables look stock, but as of right now it hasnt ever put anything out.

[Alvin]

1.6 and 2500 stall. it has knock sensors mounted on the base of the motor on each side. Knock sensor tables look stock, but as of right now it hasnt ever put anything out.

Heads up..

I've never seen knock sensors work on torque head or EFIconnection swaps. They always report nothing even with audible knock.

From college I know knock sensors are tuned to pickup on the ringing in the combustion chamber which depends on bore size and the speed of sound in the mixture and some other things. Perhaps not being able to tune knock sensors for a particular frequency is what causes it not to work.

[CranknChrome]

Got the deka 60lb injectors in. Trying to figure out how to use the spreadsheet for the injector for 43.5 psi fuel rail. everything i can find is with 58psi.

[Ben Charles]

Knock down flow rate.. that’s the main thing with PSI change