stock map. How does the pcm add fuel for boost?

How does the computer know how much fuel to add as you start seeing boost? I have the stock map sensor and im curious if the car is tuned what they use to add fuel to 6 psi of boost.

Maf will add fuel, although will max out rather quickly. Other way is adding it via PE(rpm based) for wide open throttle, although that isn't the best way to tune it.

Yep as mentioned above the MAF will add fuel up to approximately 450rwhp. The PE tables will add a percentage of fuel based on rpm after the MAF maxes. Once you get above 450 rwhp and your at WOT it is pretty easy to get proper fueling +- .3 AFR.

Fueling is pretty simple and easy with a MAF and one bar map, however the spark advance is impossible to account for boost. You can either pull all the timing at 100KPA(0 vacuum) or get a boost reference ignition box and pull timing linearly with boost.:)

Not trying to hijack the thread, but has the MSD Boost Timing Master (MSD 5462 universal BTM I think) been used successfully with the stock ignition and boost?

I have used it and the best setting has been zero. The higher I go the slower the car gets. I made a 0-100 run at the 3 setting and did a 17 second time.

I see you have a PCM4Less tune also. Have you looked at your spark tables? Bryan pulls plenty timing at WOT and incrementally in my tune.


I have used it and the best setting has been zero. The higher I go the slower the car gets. I made a 0-100 run at the 3 setting and did a 17 second time.

Not sure what you mean by spark tables. Can you elaborate a little more on that? I have TTS Datamaster.

Not trying to hijack the thread, but has the MSD Boost Timing Master (MSD 5462 universal BTM I think) been used successfully with the stock ignition and boost?

Not sure if the 5462 will work with an LT1. I know for sure the MSD 6BTM will will work with the opti and it includes a soft pill type rev limiter and a multiple spark discharge below 3000 rpm. I basically use the stock timing tables and pull 1 degree of of timing for every pound of boost.

I have used it and the best setting has been zero. The higher I go the slower the car gets. I made a 0-100 run at the 3 setting and did a 17 second time.

At a zero setting you are not pulling any timing with the MSD BTM. The reason it is so slow at a 3 setting is because Bryan has already pulled timing in your tune. At seven pounds of boost Bryan probably pulled about 5 degrees of timing and your BTM is pulling 21 degrees.:eek: Your datamaster will not show all the timing the BTM is pulling. It will show whatever Bryan pulled and thats it. The only way to see how much timing the BTM is pulling is with an old fashioned timing light and a compressor.