4.7L stroker versus the OBDII computer

[flazz85]

Hey guys, have not been on in a while, life comes at ya like a bitch sometimes, heh. Anyway I was searching for a thread similiar to this but none have come up. Lately I have been wondering as to how i want to take my jeep to the next level. I have been looking at novak adapters and their ls1 xj builds but I was also looking at ATK and their 4.7L strokers because it costs less (at first glance). I say this because I just see the OBDII computer being a royal pain in the ass. With a stroked motor obviously the stock computer layout won't do. I am running into this problem where I can't seem to find anyone who can either flash the computer or what not. I was told by guys over at AEM and Painless wiring that I need to get in touch with a guy in socal who works on all the jeepspeed contenders and does computer work on them. My next problem is if the guy only works on OBDI computers because every pic I see of the jeepspeed xj's are the first gens. I have a 1997. In any case I gotta call the guy obviously but not tonight, I was figuring to see if anyone out there has any advice regarding how to tackle the OBDII problem when or if i decide to go with a stroker and whats a good way to tackle this. Hope this made sense to anyone who reads this. Thanks guys

 

[Goatman]

What is the OBDII problem? Have I missed something?

I thought you built a stroker and installed injectors big enough to fuel it properly.

 

[gradon]

I purposefully built a high comp(10:1scr, 8.57dcr) 4.6 stroker in my 96(obd2). Tuning open loop(>75% throttle or >3100 rpms) is simple enough with a fuel calibrator and a wide-band o2 sensor. Even a simple $10 map adjuster can get your open-loop afrs down to the 12.5-12.8:1 best power range for NA motors provided you have the proper size injectors. The problem I personally have is compression knock pinging at the end of closed loop(2500-3000) because the obd2 pcm keeps the afrs to 14.7:1(I need it to be 13.5-14.0:1 in that band and/or else lose some ignition timing). It doesn't matter how big your injectors are or how much you add fuel in the piggyback/calibrator programming, the pcm will pull fuel out to maintain 14.7:1 in closed loop. Learn from my first build error and make sure your dcr's don't go above 8.5(shoot for 8.3-8.4:1 if you want to make the most out of 93 octane).

 

[Talyn]

OBD II plays nice with the strokers. Even using a "non fuel injection" cam. I actually haven't heard of a single instance where the OBDII has been a problem for a stroker.

 

[flazz85]

Thanks for the heads up guys, Im definitely gonna do more h.w on that jeepstroker website and figure things out a bit more.

 

[FlexdXJ]

Thanks for the heads up guys, Im definitely gonna do more h.w on that jeepstroker website and figure things out a bit more.

Bmyohn runs a Golen 4.6 in his 00. It runs like a dream. It runs good enough to blow up his D30 too!