how do i richen stock ECU? mods as follows

[Grizzly Racing]

i pocketlogged my 91 GSX. shows i'm lean across the RPM band. also getting a lot of knock (20 count) and its retarding my timing. all the way from 4k-redline.

i have stock ECU, ported 14B, 95 pistons, ported head, 7-angle valve job, ported 95 manifold, full exhaust 2.5", webcams, walbro 255hp pump with rewire, 2.5" upper IC pipe, 2.5" TB elbow, colder plugs.

i have my MAS screw backed all the way out and usual honeycomb removed.

i am only running 15psi of boost but want to run 20psi.

i do not want to back my MAS screw back in.

i read about Installing a 10k pot near the ecu i think wire PIN #8 which is the air temp sensor and basically it tells ecu air is colder then what it is and then adds more fuel. i have this link.

i also read somewhere about putting a POT into the MAS and richening it up that way. what sensor does this affect?

does anybody have links to the MOD that involves the MAS?

are these 2 mods the same mod? just using different locations to install the pot? or is it 2 different sensors that you are adding resistance too?


which of these MODS is the better choice?
is anybody currently using any of these mods?

thanks for any help

 

[BatmanGSX]

You shouldn't run 20psi on a 14B, there is a huge heat spike around there. I wouldn't go over 18 or 19psi probably. In theory, if the heatspike happens around 17psi in Denver it should happen at about 19.5psi at sea level.

Secondly you need to properly hack your MAS (backing the screw out is NOT hacking the MAS) which does involve putting a 10K pot. on baro line. This is the one that already has resistor looking thing on it. You put the pot. in series.

 

[Quacylla]

are these 2 mods the same mod?

Yes same mod.

which does involve putting a 10K pot. on baro line. This is the one that already has resistor looking thing on it. You put the pot. in series.

I think that's the intake air temp sensor actually. The resistor looking thing is a thermistor that changes resistance with temperature. You can put the pot in series with it here or better yet where that line goes into the ECU because then you can mount the pot in the car.

It will work to an extent but don't got bigger then a 10k pot or the sensor will output an error code.

Why the heck don't you want to put the screw back in?

I am quite concerned that you are running lean with these mods. What fuel pump is it?

If you want my official advice its go buy an new style S-AFC.

Post the links you have please.

 

[BatmanGSX]

Baro, temp line, I always get those confused. But in any case the line with the thermistor (looks like a resistor) is the line you want to put the pot. on on a 1G.

I am also concerned about why you are running lean with those mods. If anything, in your case, you should be fuel cutting before you find the limits of the stock pump or injectors.

 

[Grizzly Racing]

i updated some of the other mods in my first post, maybe it will help you figure out my problem here.

maybe i'll try putting the MAS screw back in and see what kind of difference it makes.

well i guess i will try the 10k pot mod also in hopes that between the POT and the MAS screw i can run around 20psi at a good air/fuel ratio

i do NOT want an afc. I am trying to keep this car simple so it is fun to drive and always goes fast. I see everyone with those AFC's always being out of tune when weather goes from 70 degrees to 90 degrees. car back firing, etc. thats just a headache i dont need. nor do i have the patience or money to go that route. maybe one day down the road.

i figure since when the car had only an IC pipe, test pipe, catback, boost at 17psi, weight reduction, and some octane boost. it ran 12.9@ 102

so with these other mods and new engine i am excited to see what it will run.

 

[BatmanGSX]

Yeah, I wouldn't get an AFC unless you had bigger injectors.

What is your base timing set to? If it's more than 5* I would set it back to 5. This is a huge cause of unsolveable knock problems.

Also what I want to know is how you are not fuel cutting. That's a mystery. If I were you I would consider getting a true Blaha MAS. It worked great for me with the stock injectors and no AFC. Either that or swap in a known good MAS. It may be possible that yours is bad and missing counts, therefore your IPW isn't what it should be for the actual airflow. You may find that with the new MAS you will fuel cut, which is good, it means your MAS is bad and now you need a Blaha MAS which in the longrun will work out really well.

 

[Enigma_Man]

Doesn't removing one of the honeycombs on the MAF reduce the amount of counted incoming air, thus making it run leaner?

I thought that was usually only done when changing to 550cc injectors?

-Jesse

 

[Quacylla]

Yes removing the lower honeycomb in a 1G MAF will lean it out some but not a lot. The stock a/f ratio is actually quite rich and could use a little leaning. 550s will richen the a/f ratio a lot more then removing the lower honeycomb will. When you go to 550s you get an S-AFC or equivalent.

"i do NOT want an afc. I am trying to keep this car simple so it is fun to drive and always goes fast. I see everyone with those AFC's always being out of tune when weather goes from 70 degrees to 90 degrees. car back firing, etc. thats just a headache i dont need. nor do i have the patience or money to go that route. maybe one day down the road. "

That is not an accurate representation of most cars with the AFC installed. I know because I have one. I think you should go do some research on them before you make comments like that. BTW if you add a resistance to the IAT you are also going to make your car less able to react to changes in temp so your reasoning not to go to AFC should apply to this mod too... why doesn't it?

What are your o2 sensor values all the way thru a 3rd gear pull?

 

[Grizzly Racing]

well my base timing is set at 10 degrees so i'll try turning that back to 5 degrees and see what i come up with.

the o2 readings i was getting were .87-.89.... before most of these mods it was around .92. the o2 sensor is old and i should probably pick up a new one. knock continues to get worse as RPMS climb and my timing goes down hill from 4000 rpm. down to around 8-10.

i'll try putting the timing at 5 degrees base and see what happens, then i'll back in the screw if that doesnt work. and as last resort i will put that 10K pot inline.

i'll let u know if i see any differences

 

[BatmanGSX]

Originally posted by Grizzly Racing
well my base timing is set at 10 degrees so i'll try turning that back to 5 degrees and see what i come up with.

I'm thinking that's it. 10* is way to high with no fuel control to speak of. In some cases, even with fuel control, and plenty of volume, this still poses a problem.

 

[Grizzly Racing]

batmangsx..... you were right on the money with the timing.

i set the timing to 5 degrees base.

did a full pull. my o2 shot upto .96 volts. and my knock was ZERO all the way to redline.

thanks for the help. now i'm off to turn up the boost.

 

[BatmanGSX]

I rule.

 

[Quacylla]

10 degrees is insane. I had trouble even at 8. Just keep the timing at 5.