Differences between cali emissions and fed and software

What are the differences between the california and federal emissions? I know there are 2 more cats and only 4 o2 sensors on the california emissions. I have a 2000 XJ with cali emissions and my brother has an 01 with federal emissions. his seems to have more power than mine. we have the same drivetrain configuration and i dont understand why his seems to run better than mine. I was thinking that the total of 3 cats on mine are too restrictive and thought about taking my cat off before the muffler seeing that there is no o2 sensor after it. Also what is the different software that the computers could have? i know there were updates where the compters could be flashed to have better software, one being where the fan comes on at a lower temp to reduce heatsoak. Thats another thing, mine does not seem to idle that smooth. i dont think its the issues with the injectors vapor locking like they had problems with, it will do it anytime. when you sit in the seat you can feel the engine "miss" like its not running exactly smooth. this is why im wondering what the best software is to put in my computer. when i accelerate going up long hills, the engine only seems to rev to 3000 no mater how hard i push on the gas...until it shifts down (converter unlocked the whole time) then it will rev up higher. im thinking again with maybe the converters arnt allowing the flow i need. i know its a lot of questions mixed up, but if anybody has some insight to any of this, id appriacte it! thanks! )

There shouldn't be that much restriction from the cats AFAIK. Just leave them on and feel good knowing you're emitting less pollution.

You could be having a problem with an O2 sensor, or spark plugs, or any of a number of things

You need to check with your Motor Vehicle Dept. or state agency that regulates air pollution to find out what it would take to "uncalifornicate" your emissions that would meet their requirements.

If you change it, do it right, or Obama and Al Gore will be all over your A**.

ok, so i wont take the cat off it. as for plugs, i replaced them with the ones called out on the catylist under the hood, champion plugs. i put in a "new" throttle position sensor, crank sensor and coil pack from the junk yard and it still acts the same. when i put my scan tool on and went for a drive, i found something wierd. The reading for the map sensor reads backwards of what it should be. when i get on heavy throttle, the vacuum goes up (numerically higher inches of mercury) and when i coast down a hill foot off the gas, the vacuum goes way down. is my MAP sensor messed up or what? Another thing i would like to try is timing my cam position sensor. can this be done with a generic scan tool? i heard of the tooth pick method, but i know to fine tune it, you plug the computer into a scan tool. i guess the cam sensor syncs the spark and the injectors. How about software though...does anybody know of what flashes are available? i know there are some out there just dont know how or where to find them.

Other posts indicate that the only flashing can be done at the dealer for the VIN. I guess it's not as easy as FOrd or GM. But this is hearsay, I can't prove it.

Why wouldn't you want to LEGALLY remove the CA emissions? Just how cheap do you think those cats are going to be to replace?

I'm fairly certain if you check it wouldn't be that difficult of a conversion to make LEGALLY. That is, unless you are going to move to CA.

The vacuum should be higher at higher throttle because the engine is sucking more

Edit: Oh wait you said higher inches of mercury... Well maybe the reading from the sensor is backward. The instructions for the Scangauge mention TPS being like that on some vehicles.

winkosmosis said:

The vacuum should be higher at higher throttle because the engine is sucking more

Edit: Oh wait you said higher inches of mercury... Well maybe the reading from the sensor is backward. The instructions for the Scangauge mention TPS being like that on some vehicles.

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You've got that backwards.

Chew on it for a second - vacuum (or suction) is the absence or reduction of pressure. In order to reduce pressure, you have to have a restriction to flow.

Theoretically, the engine moves 214.5 cubic inches of air with each revolution (I know it doesn't - but let's just say that it does for the moment.)

Now, will you get that 241.5ci of air more easily if the throttle is open or shut?

Throttle closed = higher restriction to airflow = high vacuum (closer to zero pressure.)
Throttle open = lower restriction to airflow = low vacuum (closer to atmospheric pressure.)

5-90 said:

You've got that backwards.

Chew on it for a second - vacuum (or suction) is the absence or reduction of pressure. In order to reduce pressure, you have to have a restriction to flow.

Theoretically, the engine moves 214.5 cubic inches of air with each revolution (I know it doesn't - but let's just say that it does for the moment.)

Now, will you get that 241.5ci of air more easily if the throttle is open or shut?

Throttle closed = higher restriction to airflow = high vacuum (closer to zero pressure.)
Throttle open = lower restriction to airflow = low vacuum (closer to atmospheric pressure.)

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Sorry, but you have it backwards. (I know, usually you are right.) Pragmatically, I know from running vacuum gages on cars for years that when you stand on the gas, the vacuum goes down, and when you back off on the gas the vacuum goes up. OK, theoretically, how does this happen? The engine is an air pump which is sucking whether the throttle plate is open or closed. Throttle closed, vacuum increases in between the throttle plate (restriction) and the motor. Throttle opens, air flows more freely and vacuum decreases.

OK, re-reading your post, the only thing wrong is that atmospheric pressure will read zero on the gage. With the gage not connected to anything, it reads zero. Vacuum gages read in inches of mercury. I guess you have it right though in that throttle closed = high vacuum. open = low vacuum.

winterbeater said:

OK, re-reading your post, the only thing wrong is that atmospheric pressure will read zero on the gage. With the gage not connected to anything, it reads zero. Vacuum gages read in inches of mercury. I guess you have it right though in that throttle closed = high vacuum. open = low vacuum.

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Now you've got me doubting myself... We are referring to a standard P-V gage, here, right? Reads pressure on one side of the scale, and vacuum on the other?

You'd have higher vacuum (lower absolute pressure) at idle, since the engine is trying to move its 241.5ci of air every other turn, but there is a large restriction preventing it from doing so. At WOT, the vacuum would be low (higher absolute pressure) due to the removal of the restriction to intake airflow. Right?

This, natch, leaves out the slight "choking" effect of exhaust (backpressure is an impediment to air throughput,) and half a dozen other practical concerns, but I do believe the basic theory of the premise remains sound. Bear in mind I'm referring to actual absolute pressure here, and not differential from atmospheric (since vacuum should properly be read WRT atmospheric pressure - 14.7psia/29.92" water @ STP - anyhow.)

Or am I off base, and my wires hopelessly crossed? I've got to see a neurosurgeon to get all of this untangled...

Now you both have given me a headache.

Let's make this more confusing. OK, we ARE referring to a standard P-V gage here. But in your third line, you switch to "actual absolute pressure". Doing Quality Assurance work during product launches and testing, made it obvious that often engineers wouldn't properly specify between PSI (absolute) and PSIG (gage). As you realize PSIG is actually the DIFFERENCE from atmospheric. As far as measuring this and as a MAP sensor would read it, the only thing worth talking about is PSIG. To make things more confusing, with vacuum (or negative pressure) we switch over to "inches of mercury".

At any rate, to keep my head on right, I have to correlate to something I have seen. This is that the vacuum gage shows zero with the motor off, reads high at idle and higher if you back off the throttle while going down the road, and goes almost to zero when you floor it.

Using a vacuum gage is the best way to learn to drive to save gas. When I had a Mercury wagon with a 429 (obviously dating me), I had vacuum gage on the dashboard to remind me not to get too deep into the pedal. During normal driving, I had my own limit which I forced myself to stay above. A lot of vehicles during the seventies gas crunch had an economy light. Chrysler mounted in in the trim on the drivers side fender. If your gas pedal made the vacuum get too low for economy, the light came on to remind you to back off.

One thing is for sure, you guys left that poor OP way behind in a cloud of dust, or was it a vacuum (which of course would suck, LOL!)

To the OP, I have been puzzling over a week powered 4.0 for 4 years and 25,000 miles. It has gotten incrementally better as I fixed about 2 dozen issues over the years, but is still about 1/2 of the peak torque of my daughters 4.0, at 60 mph and WOT. Before I fixed those 2 dozen issues, it only had about 25 peak HP, and it ran real hot real fast. So don't expect just one problem. It may be several.

Ecomike said:

One thing is for sure, you guys left that poor OP way behind in a cloud of dust, or was it a vacuum (which of course would suck, LOL!)

To the OP, I have been puzzling over a week powered 4.0 for 4 years and 25,000 miles. It has gotten incrementally better as I fixed about 2 dozen issues over the years, but is still about 1/2 of the peak torque of my daughters 4.0, at 60 mph and WOT. Before I fixed those 2 dozen issues, it only had about 25 peak HP, and it ran real hot real fast. So don't expect just one problem. It may be several.

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25hp? Are you serious? Mine is making 55 hp to cruise at 65mph

Other things worth checking when looking for power comparisons between two vehicles could be compression and timing advance. Normal tolerance on block head deck height alone is +/- 0.005". And probably the same on the head face itself back to the combustion chamber button. So you could have 0.020" difference from the piston top to the combustion chamber top at compression TDC. And then you have the positioning of the CKP (Crank Position Sensor). How many degrees of variation on the ignition advance does that allow?

winkosmosis said:

25hp? Are you serious? Mine is making 55 hp to cruise at 65mph

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When I bought it (87), it was up shifting at 1300 rpm, never got above 1300 rpm till 4th gear. Took 3 minutes to get from 0 to 60 mph, at WOT or 1/2 WOT. TPS was bad on the TCU side. Had many other issues too. It's only remaining problem is it still can't keep up at WOT with my 89. May have a tranny pump wear, or leaking internal seal issue (does not like cold start up weather). Compression may be lower, as it has twice the miles that the 89 has. 89 has a new head too.

Winterbeater, XJ timing is computer controlled! Not adjustable, except for a possible timing chain, or severe dizzy issue, on basic mechanical timing.

Is everything the same? Same gearing, same tires, same lift, same bumpers, etc?

I have a feeling your butt dyno is telling you his is faster because you want to believe it is.

Run them on a dragstrip against eachother to really see. Of course there's still driver error and reaction time to take into account.

Ecomike said:

Winterbeater, XJ timing is computer controlled! Not adjustable, except for a possible timing chain, or severe dizzy issue, on basic mechanical timing.

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What triggers the computer? The signal generated by the flywheel notches going by the CKP. If you moved the CKP radially along the path of the flywheel notches, the timing could be changed.

winterbeater said:

What triggers the computer? The signal generated by the flywheel notches going by the CKP. If you moved the CKP radially along the path of the flywheel notches, the timing could be changed.

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While I am quite the experimentalist, even I would not mess with the CPS position. They are finiky enough.