Engine tuning/ FI setup.

[Weasel]

Not sure if this is the right place but it seems "advanced" enough.

Running the painless injection system on my new 4.0. Current injector setup is the 89 stock Ford injectors at 19lbs/hr. I've bumped the fuel pressure up to 45 (might be 49psi) on my adjustable regulator so I know the injectors aren't correct.

I need to check the pulse settings to see if they are close, how would I go about that. Anyone got any how-to's on engine tuning for the 4.0's?

What about A/F ratios, I found an article from Ken Bell that says they run 12.4-12.6 but they are charged setups (@3psi). I also have several opitions for the O2 sensor, currently have a wideband NGK and run it in wideband or wideband closed loop mode. When in wideband mode the A/F ratios sits right at 16 which seem to high(lean). In wideband close loop I can set the ratio at 14.7 or 13 and it run pretty close to the set value.

Currently run ok, stumbles right off idle but picks up as you lay into it. back off the gas and then back into it and it will stumble again and then smooth out.

MPG also suck right now, maybe 10 or so.

So any thoughts, sources I can read up on. First time I ever really messed with engines so need to learn up o this stuff.

 

[Talyn]

16 is very lean. The leanest you want is 14.7:1 at cruising (closed loop). Under WOT (open loop) you want 12.5:1-13:1 or as close to that as possible with out pinging.

If the painless injection system uses a stock OBD II PCM the only way to check it is with a scan tool, PC based would probably be the cheapest to do what you need. You are looking for long term and short term fuel trims.

 

[Weasel]

I can do everything from my Netbook so thats not an issue. Really just not sure where to start.

 

[Talyn]

What do you mean? You need to get the AFR straightened out. How do you program this system?

 

[Weasel]

plug my laptop into the system and adjust the injector pulses, spark values on the various tables.

To start with I need to get my injector rates correct. Any feeling on which injector rates or fuel pressure are better?

I have the tables for stock and was looking to run Ford 24lb/hr at ~52psi to get the same ratio as the stock injector rate for 96-99 4.0s. Or I could adjust the fuel pressure to the 89 era setup of 39 psi but since I'm running the 96-99 intake and engine style I should run the factory injector setup as well??

 

[Boostwerks.com]

If you have the means to adjust pulse width, the fuel pressure should be set at the factory setting, simply to keep the pump/lines/regulator as reliable as possible. Adjusting the pressure and/or injector size should only be done if changing the pulse width isn't an option.

The size of the injector doesn't really matter as long as your duty cycle is less than 80%. Past 80% there is a tendancy for an injector to stick open and the injectors ability to precisely meter fuel goes down. I personally shoot for a 60-70% duty cycle when selecting injector size.

Bryson

 

[Weasel]

Okay I think I understand that. But it seems easier or less for me to screw up by switching the injectors to closer match the stock setup and getting the injector rate table closer to correct.