I can't quite cope with your thrift me body!
You wouldn't necessarily get codes if the cat was blocked.
Something is giving -ve fuel trims - the upstream O2 sensor is seeing too little O2 so it's trying to reduce fuel.
This either means a stuck injector (which would be unlikely since it is both banks) or back pressure.
I don't see how the TB would cause this but if you swap it we will see.

 

Ok the 98 has a round black vacuum type canister on the top and the 99 does not. So can they still be swapped?

 

ugh- don't think so.

 

Your other option is to have the one you have rebuilt. This is a link to my rebuild and the company. Are you sure it is a TB problem?

Link JagRepair.com - Jaguar Repair Information Resource

 

I don't see how a naughty TB would affect those trims, Gus. What do you think?

 

Could a bad connection on the TPS throw those out?

 

No, I don't think so. The MAF and the upstream O2 sensors do the stoichiometry.
The TB determines how much air goes through the MAF.
Does that make sense?

 

It totally makes sense, I just wondered if an intermittent connection could cause fuel to be sent erratically and cause bad readings. You are probably right though, just thinking out loud. Sometimes gets me into trouble.

 

I agree!

 

Can the problem be provoked by flooring it stationary against the brakes? If so, what do the instantaneous OBD readings say?

Also, does it misbehave all the way up the rev range or just in the midrange? For example if you gently bring it up to say 5000rpm in a low gear, then floor it, does it still stutter?

The first item in Jag's diagnostic flowchart for hesitation problems is EGR valve. A bad EGR valve can cause -ve LTFT too. Is your EGR known to be good? That flowchart's been posted somewhere here, by the way, probably by jlombardi.

You refer to the throttle flap not moving when you push the pedal, but say that's with the key off. That's normal. The flap is electrically controlled, not connected to the cable - it won't work with the ignition off.

 

concentrate on this:

 

If you are trying to rev your engine with it in park the rev limiter will prevent it from going over 2000rpm.

 

Okay good info guys. Where is the EGR located? Dummy me didn't turn the key on to get the flap open ughhh. You can gently bring it up and it won't hesitate but if I was wanting to pass a car and stomped it then it would kick and stutter. Make sense?

 

Actually scratch the EGR valve I don't have a supercharged engine.

 

Vac leak's inconstent with -ve LTFT, but I can't think offhand what else would cause sucking noises.

Sorry, just assumed all US cars had them. Red herring.

 

coastaljag98
Here is the throttle body part numbers and vin ranges:

Per the JEPC (parts catalog) here are the throttle body part#:
now C2A1470EK (C2A1470) - Vin Range from 812317 to 853925 (AJ26) $1189 new

now C2A1444 - Vin Range 853926 to F59525 (AJ27) without supercharger $1904 new
now C2A1445 - Vin Range F00035 to F59525 (AJ27) with supercharger $1720 new.

Jim Lombardi

 

Thanks. I'm going to live with it til it gets worse. Ill get an eBay tb this summer for spare. I need to find my vac leak as I guess that's the sucking noise.

 

You probably haven't got a vacuum leak, that would give +ve FTs (this is counter-intuitive I know, you'd think the extra air would lower the trims but the O2 sensor sees more O2 than it expects - O2 flow was measured in the MAFS BEFORE the leak - and bungs in more fuel to try for stoichiometry).
The only scenario involving a leak I can suggest is leak>too much fuel>cats damaged and what you're seeing now is back pressure from blown cats.
I don't know (apart from dismantling) how to check your cats.

 

Yes makes no sense. The exhaust coming out te rear flows way to good or then to be damaged. I rechecked the live data and still getting the negatives tho. I just need to find this stutter problem.

 

The other possibility is your MAFS screwed and is reporting a falsely high airflow so the ECM expects to put more fuel in than is actually needed (the opposite of a post MAFS vac leak).
Have you cleaned it?
Can you swap with the other car?