The alky injection kits come with a 2 or 3 bar MAP Sensor and add alky based on boost. It also has a gain **** that allows you to change fueling on the fly assuming you have a wideband. Its great having your own AFR **** in your car.

I do the big adjustments to AFR with the PE Tables and do the minor adjustments with the gain ****.

 

I did not know this! So you're not actually adding fuel (in the form of gasoline) but you're adding alcohol. However, since alcohol has a lower stoic AFR, what sort of overall AFR do you shoot for on your wideband?

 

Tough question. you need to figure out how much methanol you are adding and how much gasoline you are squirting in percentages and work it out mathematically. It becomes more difficult because the better kits inject the methanol progressively. So if you want a gasoline equivalent AFR it will probably end up richer, but what number - I couldnt tell you. It is also more weird if you have water in the methanol. If you want to try and figure it out, the wideband sites have discussions in their support forums and there is some information on the sites that sell the alky injection kits. I use Lambda to tune cause it seems to make more sense, but some of the tuners say go for 12.5 without meth/h20 and 12.0 with the 50/50 meth/h20 - thats just what I heard. I'm sure as hell no expert on this even though I have been dicking around with it for about a year and a half. My problem is that I run a lot of boost non-intercooled, so I cant really tune the car just on gas. No one with a dyno seems to want to tune it on meth. Its fast as hell, but I'm probably leaving a lot of power on the table cause its still too rich.

 

Wideband O2 sensor messures unburned oxygen in the exhausts, it doesent matter what fuel you run, Think of it this way, If you aim for lambda 0.80 thats 0.80 * 14.7 (stoich for gas) = 11.8 A/F on gas
If you run on straight metanohl and aim for 0.80 you will have 0.8* 6.5 (stoich for meth) = 5.2 A/F on meth
So if you blend meth and gas you dont have to calculate wich A/F to aim on, just look at the lambda value...

About tuning stock PCM widh boost, dont bather to try twin MAFs etc, Just use the 100kpa tabell in main and extended spark advance vs rpm vs map for WOT spark advance.
Adjust lambda widh %change to a/f ratio vs RPM at wot, if that table arent enough, go for the %change to a/f ratio vs cool temp at wot.

Dont forget to check the minimum spark advance vs rpm if you try to set timing really low in the begining.

 

See - use the lambda, LOL - Lisa says so

Lisa - Americans are hung up on AFR for some reason

 

hehehe didnt read everything in youre earlier post, i just stopped at the "matematic".

About A/F vs lambda, those who runs V8 engine mostly talk about A/F here in sweden also, those widh european aftermarket injectionssystem talks lambda...

 

Well I'm basing my AFR off of a dynojet wideband commander which reads lambda and converts it to AFR. The AFR I read on my pillar guage is 11.8 but if it was adjusted for alcohol it would probably read 10-11. I basicly shoot for 11.8 on the guage regardless of how much alky I'm spraying. On hot humid days I will take it as high as 12.5 on the guage. It really makes the car come alive when you hit the "Gspot" on AFR.

 

For closed loop control, low speed, I dropped the MAF curve 2%, and set the BLM update trigger to 60kpa on a 1 bar MAP. This helped the idle and low speed AFR to run @ 14.7:1, so, it would not learn and change much (pcm was compensating rich). I also use a dyno_jet WB O2 which helped alot. I could not get the engine to fuel @ stoic without re_cal of the MAF, so, I had to do it. For WOT, I just use the PE curve and dropped it to run @ 12.8 (zeroed the PE vs. temp). Full timing (like stock) untill 90 to 100 kpa @ high rpm (32 degrees max). I finally got it running good. I use the ZEX plug and a 2-boost bypass valves. The BOV valve did not work after the MAF sensor. Hope this helps. (97ss 383 LT1 - D1 AFR_190 72# Seimens Inj). B.

 

I'm using tunercat for OBD2. Where do I find this option "BLM update trigger?"

I left my MAF Calibration stock and limited my short terms to +-5 and long terms to +-0. When I do this the idle fluctuates between 16.0-17.0 AFR as the computer modulates the timing to hold idle speed. Just cruizing around town it stays at 14.7 all the time except when decelling.

It seems with a cam at idle the car likes to throw a bunch of fuel at it when it senses oxygen in the exhaust from overlap. So I limit the BLM's to the point where they can't do anything significant except for adjust small deviations in AFR.

 

I use LT1 edit version 2.2 for OBD2. Limiting the Lg and short learn modules should hold the BLM near 128 closed loop mode. I don't know if setting the limits the learn modules applies for all MAP pressure values in tuner_cat. LT1 edit v2.2 also has a BLM lock @1 when WOT is active, and, the MAF high threshold frequency can be extended (60+k)in closed loop (stock is 10.7k). To maintain idle @ 14.7:1, I adjusted the IAC counts larger. If the AFR is 16 to 17, possibly a reduction in IAC opening (less air) may drive the AFR down to stoic @ idle. B.

 

I think AFR 16-17 at idle would be ideal but I did not think our stock PCM's would allow it to be any leaner than stoich? Same with cruising conditions...
So is it then possible on these cars to have an actual cruising AFR above 14.7? I know I've seen the LS1 cars do it, but never an LT1 car

 

Yes 16-17 is where mine idles the best. If I let the computer bring it down to 14.7 at idle you can start to smell the unburned gas.

 

How are you getting it to do that - open loop?

 

Nothing special just a closed loop tune with the short terms limited to 5 and the long terms limited to 0. I'm using the stock MAF calibration tables. I've basicly taken away the computers ability learn. It will only make minor temporary corrections. Maybe this is not an option on the OBD1's.