This has been pointed out before: disconnecting the battery clears the PCM's KAM (keep alive memory) but does not clear the TCM's memory. The PCM will then have to re-learn the engine's characteristics.

I don't recall anyone posting authoritative data as to where the learned/programmed shift points are stored. If they're in the TCM, you need a dealer-type tool. If they're programmed in the PCM you again need a dealer-type (reflash/tuning/whatever) tool.

 

too bad these aren't like many other cars that a new pcm file can adjust the shift points. So is the consensus that all of these cars short shift or only the older ones? Are the 2005 on programed more aggressively as far as shift points? I"m shopping for one now, so I want the best performing one. I'll go 2005 if it'll perform better.

 

You want one with VVT, if you can afford it. More torque lower down and 10+hp more as well. Was added about 2005 or 2006 - look for the wires from the cam covers. (Look at a 4.2 car to see where they are.) The older STRs just have a flat recess instead.

In-depth data on the shift points is missing so far. It may be the calibration of TCM or PCM or both (or even the revision level of the circuit board in one or both) but it may be whether the car has VVT. If it does, it also has a newer type of PCM and of course a calibration to handle VVT that can't be put into the older PCM (or if it can be put in it is inevitably operating differently).

Some OBD tools can read the CALID (calibration ID) so we could compare those if people had the tools
Even an ELM327 and hyperterminal will do.

I think VVT was essential to pass the changed emission laws but jag got the extra hp since they were in there changing stuff.

 

If you want VVT on a S Type R then you MUST get a 2006 to 2008 model. I have a 2005 and found out that 2006 was when the "R" got VVT. Still trying to see if it upped the power any?? It seems that Jaguar did increase the engine rating to 400 HP and 412 TQ but I find different numbers in different places?
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+1 on the different numbers

I *think* the STR was originally called 400hp but was more like 390 - though it depends a bit whose hp you use (SAE, ISO, DIN, whoever) - and got another 10hp or 20hp (I've seen both mentioned) some time later, which I think was with the 2005 or 2006. 2006 would make most sense. But it could equally be that a newer calibration squeezed out another 10hp for all the facts I have!

Those are engine hp, which aren't that exciting as you lose a fair chunk in gearbox, diff etc.

 

Don't forget SAE changed testing standards in 2005 resulting in different horsepower ratings for most cars. Some of the published hp numbers may only be a change on paper but hard to way since it coincides with actual changes made to the STR around that time.

 

Forget? I didn't know! Thanks for pointing that out

 

No need too, it just affected the US (I think)...But I DID forget about that.....But now I remember....It was funny because some cars went down (Toyota I think) and others went up like Honda...

 

The SAE change was made in 2005, so many 2006s were retested and restated with different horsepower numbers from 2005 even though the car did not change at all. Some manufactures chose not to restate. Many engines from Toyota and Honda decreased, while higher performance engines tended to increase. This change makes it very difficult to determine the actual difference in horsepower between 2005 and 2006 STRs. Might be more than 10 horsepower or less? Another change that year was that engines were now rated to the exact horsepower. Prior to that, horsepower was rounded to the nearest 5.

 

From the research I have done 05 + has that extra 10hp either from VVT or a revised pulley. Can anyone confirm DEFINATELY if it was 05 or 06???

 

The pulley was the same size, I believe, but was revised with the belt etc to reduce noise. The VVT was 2006. Now that I know about the SAE change I don't know if there was any change in HP, though the press/brochure figure changed.

Now... I guess the VVT changed the torque curve a bit.

I can probably find data about the 2006MY changes if you're keen (pm if so).

 

Since this thread is narrowing down on the HP differences between the 03-06 motor (somewhere between 390 and 400 HP), anyone know where Jaguar picked up the extra 30 HP in the 2008+ AJ34S motors in the XF? They are rated at 420HP with the same AJ34S 4.2 motor. Perhaps a combination internals, VVT, pulley(s), intake, exhaust and ECU re-mapping?

 

I understand there's a less restrictive throttle body elbow.

At most it's probably only 20HP more and I don't know that I really believe that figure lol

Could well be a PCM tweak.

 

#1 Where can i get said elbow?
#2 Would it work on our vehicles?

 

Jag must have it as a part for the XF, so be nice to a parts guy
Or, hunt online for XF parts.

I am a bit doubtful that it would fit the STR, but you never know. It may be part of the throttle body, in which case the cost would be scary.

You've seen where the throttle body is on an STR.... not exactly easy to take apart and rebuild!

Even if it fits and is cheap enough, just fitting that part feels kinda unlikely to add 20HP without some other tweak(s).

Er.... it would be wise to check my vague recollection about this is actually correct!!

 

I have no idea, nor begun to look, but has anybody considered/looked into the possibility of swapping an 05' PCM into an 03' to resolve this, or are teh PCM's too tighly tied to the car?
Pete

 

You'd need a dealer to reprogram the various modules to each other. Also, around 2005/6 the PCM changed (as did the cluster) and the connectors won't even fit. Obviously you'd have to avoid taking a PCM from an STR with VVT and putting it on a car without VVT.

Overall - forget it. Much easier to reprogram the earlier one with later software. Jag's IDS should auto-detect which later version is allowable.

 

Remember the pulley change was because the belt was changed to be ribbed on both sides. The original was only ribbed on one side. So this also required several pulleys to be changed from smooth to ribbed surfaces. This was a factory TSB and I had it done when the car was still in warranty. Note the supercharger pulley was NOT changed.

The problem was a small amount of belt squeak when cold starting. I was amazed at all they changed when I complained about the noise. I really thought it was minor and almost did not bring it up when I took the car in for service. Glad I did because it's about $900 for parts and labor!!
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I know a lot of the ford vehicles with the m112 are very sensitive to inlet side pressure and that less restriction on the inlet side does pay off on those vehicles. I wouldn't imagine that ours would be different.

 

Yeah.... but which restriction? We know the intake up to the air filter isn't particularly restrictive. But from there on.... who knows? There again, the twin-screw apparently boosts more so maybe that points more to the M112 as the weakish item.