ECU pinout diagram

[kspec5]

Does anyone have a ecu pinout diagram, I was hoping to install an air fuel controller to go with my wideband.

Also how does the ecu tune? closed loop, open loop or is it a little bit of both depending on throttle/load, thanks.

[gradon]

The afc will usually use a rpm vs map graph to tweak values. You get the rpms from the camshaft position sensor output and the pressures from the output signal of the map sensor. You can zero out the fuel trims in closed loop but not change the pcm's target 14.7:1 afr ratio during part throttle. In wot open loop, you will be shooting for a 12.5-12.8:1 afr ratio to achieve best N/A power. You'll want to specify what year electronics you're working with.

[Talyn]

What year?

[kspec5]

The afc will usually use a rpm vs map graph to tweak values. You get the rpms from the camshaft position sensor output and the pressures from the output signal of the map sensor. You can zero out the fuel trims in closed loop but not change the pcm's target 14.7:1 afr ratio during part throttle. In wot open loop, you will be shooting for a 12.5-12.8:1 afr ratio to achieve best N/A power. You'll want to specify what year electronics you're working with.

When does the ecu define the open/closed loop? as in at what percent throttle does the ecu switch from open to closed loop.

Is there not a wire in the ecu that carries the rpm signal since I think the auto tranny needs a rpm signal does it not?

I have heard many a theory on wot afr's and done my own N/A and turbo tuning, I hav found that 12.9 was giving me the most power n/a and as for turbo I have never tested for max power but I played it safe with a 11.4 at wot.

What I was really hoping for was a ecu pinout diagram so I can find the wires I need.


I'm workin on a 99, is the ecu the same for all the 97-01 jeep xj's?

[gradon]

Dunno if the 99 is the same, but from a 97 fsm: You have three plugs at the pcm(driver's side front by airfilter). The black plug is the A plug: A18 tan/yellow is the camshaft position sensor output (for rpm). A27 dark green/red is the map sensor output. I found that my 96 obd2 xj switches to OL at part throttle once the rpms were 3100-3200.

[gradon]

Just checked--99 is the same

[kspec5]

Thanks for all the awesome info

Is the fsm avaliable as a pdf anywhere or is there somewhere online where I could buy one?

[karstic]

I bought my FSM directly from Chrysler.