If you ever want to borrow the hardware and software for a week or two, just cover the trackable shipping to/from here. At $500, it would be a shame to lose it. That goes for all members who've been around long enough to trust.

Already took care of it!

 

You must not be mashin the pedal...so you can't stretch it

 

Uh oh... while driving it this evening I floored it a couple of times and experienced engine knock for the first time. I'm using 93 octane. I wonder if the engine computer needs time to adjust to the new throttle settings or something. I thought the computer would prevent knocking.

 

This looks like something to add to the "To Do" list Thanks guys.

 

...needs to loosen up, not used to those high RPMs Mine had some knock awhile back, but I've been goosing it lately, and it (along with a new gas brand - chevron, no more sheel) and its gone away.

That's my theory...

 

My wife and I are driving to the beach tomorrow and the needle is sitting on empty, so I think I'll pour a bottle of that octane booster stuff in there when I fill up and see if that makes any difference. I've always wondered if a tiny little bottle of octane booster really makes a difference when mixed with 15 or 20 gallons of fuel. I guess I'll find out tomorrow!

Speaking of octane, though, I have my pilot's license and I spend a little bit of time at the airport. Airplane fuel is 100 octane, but it is leaded. I was at the airport a while back and this young guy showed up with three five-gallon gas cans to buy the avgas at $4.50 a gallon. I asked the gas guy what that was all about, and he told me that lots of young punks show up there to buy 100 octane avgas thinking they will get more power out of it. He said that he tried to explain to them that it doesn't give them more power and it will ruin their catalytic converter, but they didn't seem to care. Now he just sells it to them knowing they are ruining their cars.

 

You know I'm not so sure it's as simple as tightening up the cable. The JTIS has a procedure that includes the use of some adjusting tool. I am attaching a PDF file that is excerpted from the JTIS.

Doug

 

That extra step must be so that you avoid over-tightening. I'm not sure what the 'holding the accelerator pedal thru kickdown for 5 seconds' will accomplish. It doesn't even say anything about readjusting after using it. Maybe it corrects itself at the extent of the adjustment? It mentions idle and kickdown...I wonder...I bet a tech will let us know when one sees this thread.

 

Thanks to the wonderful video this was less than a minute adjustment. My cable easily moved out 1.5".

The pedal sits higher. Pedal is more responsive. Didn't really notice a change under WOT.

Dave

 

Now that I think about it this is the same basic set-up that was used on my last car and the system is designed to be partially self-adjusting.

Without actually seeing it here is what suspect is going on. There are grooves or notches on the cable part that are sloped on one side and straight vertical on the other, thus creating a ratchet-like mechanism. The other part of the system is the device that fits into the grooves and creates the ratcheting. In this case it is the spring clip. You need to release the clip to move the cable outwards but. You then put the clip back on and when the pedal is pushed (thus pulling the cable through the clip in the other direction), the design will allow the cable to go back in (via the ratchet design) but not slip back out again (clip restrains against the vertical face of the grooves). In essence, you cannot over tighten the cable since flooring the pedal will properly "set" the final position. In fact, I (or someone) should try over tightening the cable, put the clip in, and press the pedal to the floor and I am willing to bet you will see the cable self-adjust into the correct position.

I believe the purpose for the special "adjusting tool" is to design just a bit more slack into the cable.

Doug

 

The kickdown switch under the pedal also effects pedal travel, and can prevent 100% throttle if incorrectly adjusted. It is a good idea to also check the kickdown throttle % after throttle adjustment. For 2002 and earlier I know it is 90%. The kickdown switch is adjusted directly from in the car under the pedal (procedure is in JTIS).

 

I did not see an adjustment procedure for the kickdown plunger in the JTIS other than to say it is installed correctly.

Doug

 

For some reason it only seems to come up on a Global search for "kickdown", and then only for 2002 and earlier vehicles. I do not know if it is non-adjustable on later cars.

 

After doing the adjustment to my throttle cable I was getting some engine knocking on hard accelerations. So yesterday I added a bottle of octane booster and filled up the tank (I always use 93 octane (the way it's calculated in the US)). My wife and I took the back roads to the beach and I had lots and lots of opportunities to pass people at full throttle. I experienced no knocking at all. So, either the octane booster worked, the engine adjusted to the new throttle settings, or I got some bad gas on the prior fill up.

But, the newfound power is amazing. I had a ball cap sitting on the dashboard, and every time I would floor it to pass someone, the cap would end up on the floor. I pulled up next to a 1970's Corvette at a stoplight and the guy driving the Corvette was revving his engine like he wanted to race me. I wasn't quite sure, and I didn't want to make an *** of myself by zipping away from the stoplight at full throttle, but I reached over and pressed the "sport" button on the transmission, just in case. When the light changed I waited to see what he was going to do. He took off with his tires spinning, so I floored it, and within a couple of seconds I was passing him! Then he completely backed off, and it left me wondering if he slowed down because he didn't want get beaten, or if he was just worried about getting caught. I dunno... it was fun, though!

And in response to SeismicGuy's post about the ratcheting cable, that's not the way it works. My cable is still three notches tighter and you can look at the sleeve and tell that the clip is supposed to hold the cable exactly where you set it.

Oh, one other thing: The gas pedal seems a little too "touchy" now. It's much more difficult to accelerate smoothly. When I'm stopped and barely press on the gas pedal, the car seems to leap forward, which is actually a little irritating. It's like what some manufacturers do to make their wimpy little engines seem more powerful; they put their throttle on a cam so that 10% movement in the gas pedal causes the throttle to open 25%. It makes the engine seem more powerful on a test drive, but it's irritating in the long run.

 

I got my XJR back from the detailer yesterday afternoon, and proceeded to adjust my cable. The older version is different, but works the same in the end. I adjusted the cable then went backwards to ensure it was just at the throttle stop to ensure that it will back off completely.

 

And???

Do you have more power now?

 

My test drive was a run to the store with a full load of relatives in town for the fourth, so I can't tell yet. I will report back when I've done a solo drive!

 

I still think there is some ratcheting or other self-adjustment going on. If you read through the JTIS procedure I had attached, you will notice the ONLY manual part of the procedure is to fully tension the cable (step 4) and then replace the retaining clip. The actual adjustment is in step 7 where you slowly push the pedal to the floor and then release it. There is no other manual adjusting going on so pushing the pedal must be doing something to set the cable in the proper position.

Doug

 

I had my able assistant push the throttle slowly to the floor, being sure to engage the kick down button each time. That way I could get the adjustment as close as possible and not overdone.

 

I really don't think you can overdo it. In step 4 of the JTIS, you fully tension the cable--in fact you need to make sure that at least 14 teeth are visible on the outer cable. You then reinstall the retaining clip and never remove it again!! When you step on the pedal and go all the way to WOT, this brings the cable back to the "correct" position. I believe the only purpose for the special "tool" which is nothing more than a device that pushes against the cable, is to build in some extra slack.

If you self-adjust and go too far the cable will hold that "incorrect" position UNTIL YOU PUSH THE PEDAL TO THE FLOOR. It is this full depression of the pedal that does the final adjusting and, in fact, this is the one step in the JTIS procedure that is in bold:

"The accelerator cable must be adjusted by pressing the accelerator pedal. Failure to follow this instruction may result in incorrect cable adjustment."

So, at the risk of beating this to death, it is clearly the pressing of the pedal to the floor that makes the final adjustment.


Doug