03 xjr

Hit 250 km/ h today or 155mph and the yellow light and check engine light started flashing. Message was restricted performance.

No response to gas pedal until the car slowed down to about 120 km/h or 70 mph.

Then everything resumed to normal....

I am assuming this is the speed limiter ?

 

I don't think it is normal, as I have cruised for several miles at the top speed. The limiter just holds it there, it doesn't slow it down. Get the codes read and see what you get.

 

Will I pull a code even if the check engine light is no longer on ?

should I try again to see what happens ?

 

The speed limiter blocks you from going faster (very subtly), so you had an issue, better to read the codes soon, it should be still there.

 

ok,

pulled the codes p0303 p0308 p1313 p1314 p1111

any thoughts ?

 

Use the search tool on the toolbar and see what it gives you Also check the FAQ section as I think there is something there regarding codes.

 

Thanks stu !

I know for sure I have an issue now as I took it for a spin again and at 130 MPH it did the same thing....

Will research codes...hopefully nothing too bad ...

 

Holy mother of god -- please tell me where you guys are driving that fast so I can stay out of your way! LOL

 

ok... so again no symptoms until speed of 130 mph is hit...( even with rpms at redline at lower speed nothing feels wrong)


p0303-misfire cylinder 3
p0308-misfire cylinder 8
p1313 Misfire Rate Catalyst Damage Fault - Bank 1
P1314 Misfire Rate Catalyst Damage Fault - Bank 2
P1111 Intake Air Temperature (IAT) Sensor Circuit Intermittent High Voltage

soo I have a misfire on cylinder 3 and 8 but why does this only happen at 130 mph or higher ?

p1313 and 1314 related to p0303 and p0308? I would assume so ?

and p1111 is IAT sensor high voltage...again im confused as to why it would only happen at high speend only????

So where should I start guys ? Replace spark plugs ? replace ignition coils ??

Let me know where you guys would start ...

Thanks in advance !

 

it's very strange that it only happens at high speed. maybe it has something to do with airflow forcing something into some wiring. like the plastic under the front bumper coming up and touching a wire or something. Just a random guess.

as far as the misfires, what I do on other cars when I start having that issue is to move the coils around. drive for a while and then see where you get codes for. that way you can determine if the ignition coil is the issue or if it is something else

good luck

 

Well it's time to take the cam covers off, coil's acting up can be a bad boot connection to the plug. Have a look at the plugs also, do you know how old they are?

As suggested, swapping the 'bad' coils to other cylinders will confirm if they're dying.
The P1111 is a 'nothing to worry about' code.
The 1313 has a check spark plug gap/fouled/failure, and it's rather dramatic title of cat damage would only be if driven for a long period while the fault is there. And it's flagged by a misfire so related to the dodgy coil or plug, or plug boot connection.

Hope this helps, let us know how you get on, and make sure the engine's in tip top shape for the high speed runs, i.e. a full service, oil, plugs and filters. (I'd suggest the best stuff you can get, not cheap shat)

 

Another weird thing...pulled to codes and they arent for the same cylinders as for the first time this happened....weird !!! i still get misfire codes but for different cylinders....

Will put new plugs and take for a spin and report back to you guys....