Ive got a built R with some compression, slight overbore and pro 1's.

around 8500 we were having trouble getting the afr's down.

Why would my 310s be maxing?

 

how's your fuel pressure looking at WOT?

 

52 @ idle, 72 @ WOT. That was an issue and I didnt like it, I bumped it to 60 @ idle and 80 @ WOT to fatten the top end up. It works. Duty cycle on the injectors was like 140%

 

so you're saying that even after bumping it up to 72 at WOT it was still maxing out on the duty cycle and your air/fuel was lean?

 

I went to 80 in the end. We fattened it up and it was 13.4 ish AFR at the high end.

 

My setup is similar to yours.

81.5mm, 11.5:1, shaved head and block (not sure how much), SMSP tri-y, 2.5" test pipe, 3" Thermal RnD, S2 IM, S2 68mm TB, S2 Pro1s. Some other things, but This setup shouldnt be maxing my 310s.

 

That's odd... When you say built R, is it still a 1.8L or is it sleeved and more like a 2L? What tuning system are you using?

 

What fuel pump are you running?

 

Holly

 

Stock sleeve, .020 over.

Crome Pro

 

Now I don't have any personal experience with Crome but I thought I read somewhere that their tables/duty cycle readings were off? Someone correct me if I'm wrong.

 

Possibly. But then again, we added more and more fuel and AFR's hardly moved.

 

I'll have to wait for someone else with experience with that system to comment. Were you tuning on a dyno at the time? Using a wideband in the tail pipe or upstream?

 

upstream, about 4 inches before the collector. and yes it was on a mustang dyno.

 

Well, IMO, I'm thinking it's something to do with the way Crome reads the tables or the O2 sensor may be on it's way out... Did you have the correct injector size entered into the ECU program?

 

all the technical stuff in crome was correct. WB was brand new. Im a little unsure of what is going on. Im fine with the 13.2 afrs, just thought it was odd that it seems that Im maxing them out.

 

Something is off as my build is very similar to yours and I'm still using my stock pump and regulator (= stock fuel pressure) with RC 310's making 192 whp and not maxing out my dutycycle.

 

192 on what dyno?

 

I surely dont want to pay for my dyno time just to put 440s in the car. lol. seems stupid to me since what I have no works. I may try a different management soon to see where it gets me. Seems stupid to pay for it when I get others for free, ya know? But not I guess I see why people pay for them. lol

 

The duty cycle is not accurate on crome

 

dynojet.

 

What would explain me trying to throw more fuel at it and the AFRs not coming down?

Sweet. Is it true what I hear about the differences between a Dynojet and Mustang?

 

A/Fs not moving could be a couple of things? malfunctioning WB, leak at the headgasket, etc.

How much power is this set-up making?

 

200/146 on a mustang dyno.

Everything is in good order with the car. The WB was the dyno's and is brand new.

 

sounds like an issue with your pump.