I got my TB back from Maxbore who bored it from 75 to 82.5.

I installed it back on my car. The other changes made were port matching the intake elbow to 83mm and porting/polishing the intake manifolds.

I re-assembled the car, started it and it ran really poorly and went into Engine Failsafe mode

Did a hard reset, let it idle for 15-20 minutes to do it's diagnostics and at the end of the 15-20 minutes it was purring like a kitten.

Then....I pressed the gas pedal, the car revved hitting the rev limiter, again went into failsafe mode.

When I put the key to the on position I can see the TB butterfly open fully and close during the systems test.

I swapped the throttle position sensor off my other jag also a 2002, but xj8, and my xjr throttle position sensor worked normally on the xj8, and after installing the xj8 TPS onto the xjr, the situation there was unchanged-engine failsafe mode.

I am out of my depth here. Given the car was able to idle smoothly until I pressed the gas pedal, what do you guys think it could be?

I am thinking worst case I could send the TB off to that ACI place to be fully checked out, but I was hoping someone reading this could offer suggestions.

In a few days day or so I hope to have the time to try swaping the entire TB off the XJ8 on the XJR, but was hoping someone might have the solution to this problem...

help...

 

Ok,

So my car is fixed. It was something with that TB.

I swapped the TPS, no change.

I swapped the TB from my XJ8, all was fixed.

I put the Maxbore TB on my xj8, same result-engine failsafe mode-even by just turning the key to the on position.

So I'll be having a conversation with the Maxbore guy. He seemed very honest, respectable and very interested in doing a good job, so I am confident he will work with me to solve this issue. I will update the board with the results of that conversation

At any rate, good to have the XJR back on the road.
Thank you again for all those who helped, by board posts and PMs <-- you know who you are.

It's when you need help that you find out who the good and not so good people are.

I've got some pretty amazing not "been done before" mods I will be revealing over the next few months and I will share the information sooner to those who helped me

 

Let us know what he says about the TB... did you send in a random core or was it your personal unit?

 

You can position the TPS, so place it slightly turned clockwise. Then do the test I suggested in the other thread, so ignition on, no start, and press the pedal to the metal and see when (os % throttle opening) it fails. Reporistion the TPS the other way, and see what effect that has.

 

+1 on Andre's tip - the 'setting up' of the TPS is vital, if out by a couple of degree's and it's fault mode.
I hope the max bore treament didn't damage any sensitive electronic parts either TPPS/TPS. If so there surely would be a code.

If you get it running on the XJ8 it should work on the R.

Good luck and of course update with your findings.

 

What does "os % throttle opening" mean? Please clarify During the system check the butterfly opens 100%, and when I floor the pedal, the cable is adjusted so the butterfly is also at 100%

I will definitely try re-positioning the TPS and report back.



And Maxbore responded to my email by saying of course he will work with me to get all fixed quickly. He is a good guy to work with. A+ for customer service. And XJR prototype, it was the working unit off my car I sent in.

 

as not os, not sure what happened there.

 

To update/close this thread, I looked at my two TBs side by side and the problem became obvious...

...maxbore re-assembled the bored out TB with the throttle assembly oriented 180 degrees off. He said ship it to him and he will fix it asap.

Problem solved, case closed

The Scrappy WaterDragon lives to tell the tale another day

 

Goopd job you spotted it mate....otherwise you wouild be driving yourself mental and everybody else ;o)=)

 

Well, glad you had an extra laying around. Small delays suck.

 

[QUOTE= and everybody else ;o)=)[/QUOTE]


Oh I will continue with driving everybody else mental heh heh

 

I'm glad you got to the bottom of this one, since a maxbore is on my to do list for the XJR....

 

Are you sure? even after a schoolboy error like that? I'd be in a good mind to bill him for my time....
Good to see you got to the crux of the problem

 

Um...yes.

Who else is offering this service?

And now that it happened once, i'm sure he's learned not to do it again

 

Very annoying to happen, but what matters is how it’s being dealt with, I mean mistakes can happen.

Am with Cambio531 here, so far he is the only one I know that does this for relatively low cost, and this is one mistake he probably won’t be doing again.

@SeanB,
do you have an alternative?

 

My local machine shop guy has quoted £80 for the job. I'll leave one with him and see how it goes. I have to do the strip and rebuild though, meaning no issues like the one WD found...

 

Well, in his defense, there was zero hesitation in admitting the error and offering to fix it the minute he gets it, so I don't think customer service could get any better than this.

I would definitely recommend him without reservation. He will not duplicate this mistake a 2nd time I'm sure.

I'm just happy the problem was revealed and easily fixed.

 

Yes, I have an entire extra 2002 XJ8 parked in the garage

....somehow the wife sees it differently though, the XJ8 is her daily driver.

 

Thanks Avis!

 

Before you do that.. I think maxbore also uses a new, larger plate to match the port?