I have been farting around with a Stealth Ram and chip burning for years but only recently started making a real effort to try tuning one. I have a 10:1 350, XM276HR roller cam, World Sportsman II 64cc chamber 200cc runner heads, and long tubes. It's a 6E MAF system with a custom 3" intake tube with a huge K&N filter on the end. I now have an Innovate LC1 on the car.

LEAN is the order of the day on this combo. I have tried 2 sets of injectors, 24 lb/hr Multec II LT1 injectors and today I installed cleaned/flow matched 24 lb/hr denso (Ford) injectors.

The car runs horrible cold, surges at idle, and has a lean tip in pop if I run close to stock fuel pressure and 24 lb constants in my tune. If I bump the fuel pressure up 4-5 psi over stock, the car runs MUCH better, or if I run stock fuel pressure and I lie to it and tell it I have 23 lb injectors it runs well.

Has anyone else with an HSR and a simliar engine to mine noticed they needed to bump the fuel pressure or make global changes in the tune like messing w/ the injector constants to get it to run right so its not super lean? I have heard of people saying they needed very little tuning on a maf HSR'd car to get it to run right but I am not finding that to be the case...maybe they had a much smaller cam. The car runs STRONG but I hate having to "fudge" a tune by jacking the fuel pressure or using injector constants...but when this thing is lean it's lean everywhere if I don't do so...idle, cruise especially. I can't even start tuning AE or adjusting the maf tables until I do one of those two things, it's not that my bumping the fuel pressure or adjusting the inj. constants is bandaiding one problem like lean AE.

Thanks

Steve

 

my combo was a we bit more radical... I had 30# inj with a aeromotive pump that ran very lean,,, I installed a AFR meter and used my scanner to tune... I ended up tuning to 50# inj

 

telling it a higher injector constant would make it leaner?

 

no.. increasing the single / double fire.. will offset the lean condition.. increase your IAC steps Mine (144) & IAC startup delay mine (1000) just for starters... I did much more

 

my understanding was decreasing the single/double fire will increase injector duty cycle, enrichening it. My logging shows this. I have done a bit tuning this but was just trying to figure out why it's so far off w/ the correct fuel pressure and injector constants...I guess just because I am no longer running 29" long runners??

 

yes... in your case you would want to decrease to correct your lean condition

 

is your FPR connected to vacuum ? changing injector size to value that is different to ones installed is wrong idea, you have to paly with AE (VE), IAC and warm-up enrichment to get it properly tuned on idle and cold

best regards

 

I am using a new Delco stock type rising rate fuel pressure regulator (vacuum). I don't like the idea of fudging the injector constants either but the wideband and driveability don't lie, I either need to turn the fuel pressure up or fudge the constants to get the car even close to driveable to beging tuning it. If I don't do that I have to turn everything up rich - maf tables, startup enrichment, open loop, AE, everything.

 

that is the proper way of tuning, but if You dont know these basics better go to any shop that do this for You right

for example, my HSR loves 13.5:1 AFR at idle, cruise properly at 14.7-15:1 AFR and WOT@12.7-13.1:1 AFR

best regards

 

lol @ going to a shop. Not why I build these cars. I am 12.5-13:1 @ WOT and cruise in the high 14s-low 15s idling around 15:1 with this car if I turn the fuel pressure up 3-4 psi over stock. Just curious why it seems my setup is across the board lean without a little overall enrichment.

 

mayby some problems with sensors (IAT) or IAC faliure ?

best regards

 

It sounds as if you have your verdict from the engine. If you're running lean up top with 24lb injectors at base pressure that's stock you need to either get some bigger injectors or "fudge" them as you're putting it. Personally I'd just bump the pressure and let it be as it's as valid of a tuning technique as the next when you can take care of the fine details in the chip. That's a hell of a lot of engine it's very easily plausible you're maxing them up top. Do you have a decent pump as well? I'd think so but figure I'd ask.

 

It's a new Walbro 255 pump. I just picked up another HSR today and it came loaded with newer Accel yellow top 30's. I may stick those in and see if it runs better. Thanks.

Steve

 

All squared away....I had a pretty decent vacuum leak for the hose that goes to the fuel pressure regulator (oops) where I had to step it from one size to another. Also when I tried installing a Bosch made in germany brand new AC Delco non adjustable regulator on my Holley Stealth Ram to get rid of the cheap crappy Holley adjustable reg, I assumed the new Delco reg was going to hold 43-44 psi and it wasn't...it only held 40 psi. That was the lean-ness, assuming I had stock pressure and I didn't. I put an adjustable reg back on and set it at 44 psi @ WOT and put the injector constants back to the correct # (24 in my case) and the car runs fine. I am waiting on a new billet adjustable buick regal regulator from a buick speed shop so I can get rid of the Holley.

There's always a mechanical explanation when something weird like "car wants more fuel than it should" happens eh?

 

even a bad battery can do that, good that You managed to solve it already

best regards

 

Thats the way it should be done. Keep injector constants the same as the injectors you are using and tune the other tables to get your fueling correct. Fudging numbers is not the correct way to make it work. You can use those to quickly make global changes to see if your motor wants more fuel or not but after you figure that out, you want to work the MAF tables if MAF or VE tables if SD. There are a few other fueling tables that need adjusted for variety of conditions you may see such as cold start, hot start, wot fueling, open loop fueling, etc.