4.7 stroker with OBD2 and ax-15 trans

Performance mods and Advanced Stroker discussion.
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xjeepers2
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4.7 stroker with OBD2 and ax-15 trans

Post by xjeepers2 »

So, I’m looking to build a 4.7 stroker out of a 97 Cherokee motor. I will be putting it into a 95 Cherokee.
Things I want:
4.7 stoker
OBD-2 ECM
AX-15 trans out of 95 xj or similar. (finding 96+ cherokees with ax-15 not an option)(don't want to run AW-4 at this time)
How many guys have run a OBD2 with a ax-15 while maintaining tuning ability?
What are things I need to look out for? I am looking for guys that have done this or similar builds.
Thanks,
xjeepers2
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Re: 4.7 stroker with OBD2 and ax-15 trans

Post by Cheromaniac »

I still have OBD I. Didn't see any need to change it.
1992 XJ 4.6 I6 - 5MT - Stroker build-up, Stroker "recipes" Sold
1995 Mustang GT - 4AT - Modded Sold
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jsawduste
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Re: 4.7 stroker with OBD2 and ax-15 trans

Post by jsawduste »

Respectfully Dino,
you know I ran OBD1 SBEC for 10 years. Last winter I switched to OBD2 JTEC with a tune from Jensen.

Whereas I thought it ran pretty well with the OBD1. The difference that OBD2 made was incredibly profound. Sure the tune was part of it but the JTEC ECM processes inputs/outputs so much faster and more precise it really makes a difference. The drivability improvements are well worth the effort to switch over. Not to mention with the tune zeroing out the trim delays makes the engine happier.

The wiring logic between the two harnesses is very similar. You could splice the OBD1 SBEC ECM inputs/outputs into the OBD2 JTEC connectors and run it that way.

OR

You will want to look for a 96 plus XJ harness. The 96 harness has an early and a late build. The early has the same pin outs for the sensors as the OBD1. The later still uses the same connectors at the sensor but the pin out differs. In 97 the harness and sensors all changed to OBD2 JTEC. I got lucky and found an early harness and everything plugged in.

Also, the gages in JTEC run off can-bus communication from the ECM. The SBEC harness has the gages wired to the sensor(s) bypassing the ECM.

The ECM doesn't care about the transmission. Yes you will get a CEL but a tuner can turn the transmission inputs/outputs off and turn the CEL off.

I run an NV4500 and simply cut away all of the transmission circuits except for the VSS which is common between SBEC and JTEC.
xjeepers2
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Joined: November 13th, 2016, 8:00 am
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Re: 4.7 stroker with OBD2 and ax-15 trans

Post by xjeepers2 »

jsawduste wrote:Respectfully Dino,
you know I ran OBD1 SBEC for 10 years. Last winter I switched to OBD2 JTEC with a tune from Jensen.

Whereas I thought it ran pretty well with the OBD1. The difference that OBD2 made was incredibly profound. Sure the tune was part of it but the JTEC ECM processes inputs/outputs so much faster and more precise it really makes a difference. The drivability improvements are well worth the effort to switch over. Not to mention with the tune zeroing out the trim delays makes the engine happier.

The wiring logic between the two harnesses is very similar. You could splice the OBD1 SBEC ECM inputs/outputs into the OBD2 JTEC connectors and run it that way.

OR

You will want to look for a 96 plus XJ harness. The 96 harness has an early and a late build. The early has the same pin outs for the sensors as the OBD1. The later still uses the same connectors at the sensor but the pin out differs. In 97 the harness and sensors all changed to OBD2 JTEC. I got lucky and found an early harness and everything plugged in.

Also, the gages in JTEC run off can-bus communication from the ECM. The SBEC harness has the gages wired to the sensor(s) bypassing the ECM.

The ECM doesn't care about the transmission. Yes you will get a CEL but a tuner can turn the transmission inputs/outputs off and turn the CEL off.

I run an NV4500 and simply cut away all of the transmission circuits except for the VSS which is common between SBEC and JTEC.
Thanks for the input. So the plan was to run a OBD2 ECM and harness from the 97 if I need to re pin that is fine because I already plan to thin out the harness. This will end up being a race vehicle so all my gauges will be different and run directly to sensors. I know the ax-15 isnt ideal for racing but its what I want! So with the JTEC do you know what wires need to be saved in thinning out to make sure the ecm is still tunable?
jsawduste
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Re: 4.7 stroker with OBD2 and ax-15 trans

Post by jsawduste »

Just what controls the engine operation is ll you need.

You can keep the SCI to the underrdash plug for DTC's.

Send me a PM with your phone if you want.

Nothing wrong with the AX-15
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Re: 4.7 stroker with OBD2 and ax-15 trans

Post by Cheromaniac »

jsawduste wrote:Respectfully Dino,
you know I ran OBD1 SBEC for 10 years. Last winter I switched to OBD2 JTEC with a tune from Jensen.

Whereas I thought it ran pretty well with the OBD1. The difference that OBD2 made was incredibly profound. Sure the tune was part of it but the JTEC ECM processes inputs/outputs so much faster and more precise it really makes a difference. The drivability improvements are well worth the effort to switch over. Not to mention with the tune zeroing out the trim delays makes the engine happier.
I'm glad it worked out for you John. :)
xjeepers2
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Re: 4.7 stroker with OBD2 and ax-15 trans

Post by xjeepers2 »

Update: Alright everyone, so we have been looking for some time now for a 96+ OBD2 XJ with a 4.0 and ax-15 trans and we found it!! Closing the deal tomorrow! So we will soon be starting the process of pulling the motor and having our race stroker built. Stay tuned for updates!! check out gearmonkeyracing.com
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Cheromaniac
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Posts: 3180
Joined: March 8th, 2008, 12:58 pm
Stroker Displacement: 4563cc
Vehicle Year: 1992
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Vehicle Model: Cherokee
Location: Cyprus
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Re: 4.7 stroker with OBD2 and ax-15 trans

Post by Cheromaniac »

Sounds exciting!
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