So, the dreaded limp mode returned, several times per week. Took car to dealer and they are saying the computer is wiped clean and there are no codes! WTF???!!! They have no idea how this is possible as they claim there is no way for the codes to be cleared out.

They also said the 5 month old Interstate MTP-93 has gone bad and needs to be replaced. They said the electrical system is operating perfectly.

Thoughts?

 

I would assume the throttle body is going bad.You could try cleaning it.The battery is probably fine.

 

Do you think the Jaguar WDS system is in error? They say the throttle body is fine. When I get the car back from Jaguar, I'll take the battery to Interstate.

How do you clean a throttle body on a supercharged motor?

 

The throttle body may test ok when they get it, but the error that causes the limp mode and code to be set may only last for a split second. There are a set of throttle position sensors in there and they all have to agree with each other all the time, if not they set a code and go into limp for safety. There is also a closed throttle spec that the computer needs to see. If the throttle body gets gummed up to the point where the throttle blade will not return to the specified position, then limp mode.Now the throttle blade may only be stuck one time , but it will go into limp all the time until the code clears.
As far as cleaning on a supercharged car, you will have to remove the pipe to access the throttle body at the rear of the motor. If you decide to clean it, be very gentle and DO NOT force the throttle blades open.Just clean around with a toothbrush and some brake cleaner.You will need to remove the throttle body to do this job properly.

 

Thank you!

I pushed the dealer a little harder and they finally got it to fail. New throttle body to be replaced under warranty.

Don't know about the battery yet.

 

I'm glad they are getting it sorted for you. Even if the battery is bad (unlikely) it will still be under free replacement warranty from Interstate.

 

Good for you , keep us updated ,kudos to the dealer as well

 

Okay after 2.5+ weeks got the car back from the dealer and took it to Interstate Battery. They said the battery was perfect and their diag printout is different from Jaguar's results. They gave me a new battery anyway.

HOWEVER later today, the car went into limp mode again and began shaking violently like it was going to explode. I turned the car on and off about 10 times and limp mode would not go away nor would the check engine light come on even though the LCD kept saying ENGINE SYSTEM FAULT. COuld not drive so had it towed to dealer. OF course they were closed for the day. The saga continues.

So if it is not a battery and not a throttle body and the dealership can't find why it keeps doing this, what do you suggest?

 

There is not much to go on with no codes. I suggest that the throttle body may still be the problem but it may be the harness, not the mechanical unit. Try unplugging it and spraying all the connectors with a good electronics spray. Another key would be if the shaking is primarily at idle, there may be a vacuum leak in the intake after the MAF.

 

By the way, there is a test for the P2135 code....turn on the ignition but don't start the engine, slowly press the accelerator to the floor over a 5 second period and repeat this three times, then turn off the ignition.

 

Teh code reads as follows:
Default action
ECM default
Throttle valve opening set to default
Idle controlled by fuel injector intervention
idle speed adaption inhibited

Causes
tp sensor failure
tp sensor to ECM open circuit or high resistance
tp sensor to ECM sesning circuits tp1 or tp2 short circuit to B+

 

The shaking I described occurs only when the car goes into limp mode.

There is also a rough idle issue when the A/C compressor kicks in. Dealer can't figure that one out either.

 

Interesting, I will pass this on to the Jag tech at the dealer.

 

Still sounds like a throttle actuator to me. Does the throttle body actually look new?

 

No idea, going on week three at the dealer.

 

I have little knowledge of the MY 2008 but if it were my car and I lived in Florida like you I would be checking electrical connections. I live in Ocean City Md and the salt air is not kind to any car.

I would first check the TB plug and clean it with CRC contact cleaner. Along with that I would pull the relays under the hood clean the contacts and swap with another relay and do it to all the relays and at the same time pull, clean and reinstall your fuses. Do not mix the fuses up. I use a small amount of Di-electric grease on any and all plugs I work with. I am pleased with it but others say it is not necessary. I will leave that up to you.

It is a small fix and with a little luck it will eliminate your problem. If the problem relocates to another area I would suggest replacing the relay associated to that problem.

As you continue with this situation I would recommend documenting when and what you were doing when it took place. Was the car cold, hot, sitting in traffic, cruise control on or off, lights on or applying the brake.

 

IT is very consistent. Always happens after the car has been driven for a while and always after it has been sitting for at least 30 minutes, never from a cold start. I can make a number of short trips with short resting periods without incident, but as soon as it sits for that period of time, the car goes into limp mode approx 1 mile from start, every single time.

The first time ever was last February around midnight, then again a while later. I replaced the original factory battery and had no issues for quite a while. Then it happened once more and about a month later, again and recently almost every other day. Dealer said battery was bad and even though Interstate said battery was fine, they replaced it, but the issue persists.

By the way they rang me yesterday afternoon to say they got it to go into limp mode and 4 new codes, so wish me luck!

 

Please tell us what you find.

 

The warranty inspector came out today and verified it was indeed an electrical issue with the throttle body and approved the warranty claim. To be repaired Monday. Hope this is the end...

 

Please tell us what they find.