Weird problems with Speedpro fuel ...

[vtec4gs]

I'm so lost ...

lil 4 banger, I used a GM map sensor from 90 Pontiac Grand Prix, have a feeling this map is not working, should I just go get the one ont he FelPro manual for 1 BAR ?

Here are the problems, I start up the car, BP is around 12% and she likes that, it then comes down to 2-3% and she doesnt want to stay on. Now, I don;t have an intake manifold I have this thing called individual throttle bodies where each cylinder port has its onwe butterfly, kind of like Weber carbs but fuel injected instead. Anyway, I didn;t hook up vaccum box, my VE table is always at 100kpa even when the car is idling at 1500rpm on speed-density. I had to use values from 95 to 120 to ge tit to even rev to 2500-3000, so I'm figuring the injector calcs are wrong, I put my displacement in for 124cid (Honda motor), 4 cyl, 1bar map, 44# injectors (I have the balancing charts which show they are 450cc) ... now I can't put my O2 sensor in because I hav eot make a custom downpipe, is that my problem ?

I need the car just idling and driving to move on/off trailer when at the body shop, should I just convert to a Alpha N for the time being ? and create a table of the PW that I need to get it to drive ?

what do you guys think ?

Am I just making it complicated becasue I dont have my O2 hooked up so I cant tell what a/f I have and how much fuel she likes ?

thanks,
Greg

 

[TurboTR]

Yeah it's probably just a/f related. But your situation is complicated with no intake manifold. I think alpha n might be the way to go here Depends on how ugly the MAP signal would be hooked up to an individual runner I guess.

TurboTR

 

[Craig Smith]

You CANNOT run a speed/density setup on an individual runner manifold unless you create some sort of plenum with a vacuum signal from all the runners. If this is a race car, you should just switch to alpha-N.

If you switch to alpha-N, just make sure that the MAP sensor is set up for 1 bar in the software. Don't connect any hoses to the MAP sensor, just let it read ambient air pressure. In Alpha-N mode, the MAP sensor could even be disconnected completely if you want.

 

[vtec4gs]

craig,

I connected vaccum hoses across all runners and even connected the brake booster to the #1 port. I did not, however, use a canister to connect all of them to "collect" vaccuum. Perhaps that is my problem. Couple guys out in Cali are running in Speed-Density with their TWM ITBs ... I'm using their program too, i personally think its my GM Pontiac map sensor.

Also, if I bite the bullet and convert to Alpha N tables, hwo do I account for a/f ratios at various gears, i.e. more load ?

thanks,
Greg

 

[Craig Smith]

Without a plenum, the signal to the map sensor will be pitiful at best. Alpha-N really is the way for you to go here, I think. If you see enough of a change in load from one gear to the next, you can run in closed loop and the ECU should add fuel as needed. I can't say that you DON'T have a bad map sensor, but from the description of your setup, I would say that even a known good map sensor would yield marginal results at best.

Food for thought... hope to hear that this works out for the best for you.

 

[vtec4gs]

thanks craig, much appreciated. I'll try it on the car, for giggles I just converted to AlphaN on my laptop but didnt try on the car yet, I do like the layout with simply typing in PW at %/rpm. That will have to suffice for now, too bad I'm using a Toyota TPS and only get 24% closed, 75% WOT.

thanks again,
Greg