renix-obd1-obd2???

[amchornet]

I am building a stroker with a 4.7 t.b. and the larger chevy valves with 4.0 rods and custom pistons in a 76 hornet. Right now it has a 258 with a 4.0 head and a obd1 fuel system on it. My question is which system is easer to work with and will let me tweak the motor the most? Should I stay with the obd1 and use a piggy back controller or can I switch to the obd2 with the mass air flow sensor and possibly usa a bigger cam? I am not familiar with jeeps obd2 system yet.

[Cheromaniac]

OBD II is also MAP-based (speed density) but unlike the OBD I PCM, it can be reprogrammed so that you won't need to run a piggyback controller. Our resident tuner FlyinRyan can help you with the OBD II tune.

[5-90]

If you want full programmability, why not build a MegaSquirt and take full control?

[amchornet]

I thought about a mega squirt system...did not know if a obd2 system was adjustable like that or not with software.

[beiwulf]

on the O2 sensor line...

I've got a line on a clifford 4.0L header for half price but it's got 2 o2 sensors on it. My application is for a 95 zj running 1 O2 sensor on OBDI setup.

Got any suggestions for a work around / fix?

thanks,
B

[SilverXJ]

IIRC the ZJ O2 sensors are in the exhaust pipe. Just plug the ports in the header.

[beiwulf]

Shouldn't make any difference where it is in the line then? Flow or temp on O2?

It will all eventually hit it...(the idea)

And I was thinking about installing an AFR gauge once i get my adjustable map setup(radio shack didn't have it all on the shelf).

[SilverXJ]

The 99+ Cali & all 2001+ vehicles have two pre cat (upstream) o2 sensors. One for the first 3 cylinders, one for the last 3 cylinders. In that case it matters where the O2 sensors are placed. For OBD I it doesn't matter much as long as it is in front of the cat and hot much further than stock position.

In your case I would just leave the O2 sensor where it is. Possibly you could use a port on the header for your wideband. Do you have a pic of the header? Also, a wideband is always a good idea for anything other than the usual bolt ons.

[beiwulf]

clifford performance header (original purchase for a 2000 wrangler) -- now intended for a 95 ZJ

future purchase of a wideband being seriously considered (not sure for this project atm due to budget restrictions)
( http://www.ebay.com/itm/DM6-Gauge-SM-AF ... 32&vxp=mtr )

[beiwulf]

Another concern is the weight of the 2 individual - thinking of fabricating a bracket to fasten to the tranny (as per an idea from another post i saw) to help relieve stress/weight. Then have on the Y joint for the 2/1 the bung placed for the other O2 (wideband or regular).

The reason he didn't use this header 2 years ago was that is hung to low for what he wanted. Causing clearance issues - possible concern for me...

Another is placement of the O2 on the Y - the Y might require a bend into a 90 degree to tuck and run back to Cat. Where then is the ideal place for the O2 if feasible at all...(which sounds doable atm). Inside the elbow or outside radius? Just ranting about the entire process of it's doable.

[SilverXJ]

Never saw the Clifford for the later setups. Looks like it wouldn't really bolt on to their stock exhausts. You could even use the bungs on the header for your wideband. Personally I would see which bank ran slightly leaner then put the sensor there. There are widebands that run dual sensors, but there would be no real reason for that as you could only modify the whole bank.

[beiwulf]

Putting a wideband in only 1 port ... won't that restrict the full calculations. Does the OBDI system not require more information? Or is the O2 sensor enough on half of the equation (is it that dumb of a system)?

On my jeep the sensor is further down on the pipe. Almost right before the cat.

Thinking of getting a " Y " joint fabbed with a bung for the O2 and call it a day. Also thinking of performance sizing - pipes are currently 2 1/4". Thinking of keep a wide throat as far back as possible going with 2.5 or even 3" tube to the back.

Any ideas of how that will effect O2, cat, system/pcm (obdI) ? Less restriction, less heat, more throughput. Down the road planning on blown/force induction.

[SilverXJ]

Putting a wideband in only 1 port ... won't that restrict the full calculations. Does the OBDI system not require more information? Or is the O2 sensor enough on half of the equation (is it that dumb of a system)?

I'm speaking of your wideband gauge, not the stock sensor. Not all cylinder will have the same AFR. Some will be leaner than others. That is why I suggest putting it in the leanest pipe. That may take some experimenting put its fairly simple to unbolt a fairly newly installed sensor.

On my jeep the sensor is further down on the pipe. Almost right before the cat.

That is where I would leave the stock narrow band sensor.

Thinking of getting a " Y " joint fabbed with a bung for the O2 and call it a day. Also thinking of performance sizing - pipes are currently 2 1/4". Thinking of keep a wide throat as far back as possible going with 2.5 or even 3" tube to the back.

Sounds good.

Any ideas of how that will effect O2, cat, system/pcm (obdI) ? Less restriction, less heat, more throughput. Down the road planning on blown/force induction.

When the OBDI goes into closed look the exhaust gases will still be hot enough to keep the O2 sensor happy. If you are thinking forced induction 3" maybe a good idea. That is a road I will eventually need to cross on my XJ after I put the MP90 in.