hi, i have a 2004 jaguar x-type 3.0 and i just recently put a used engine on it, i noticed that everytime i accelerate the car to merge a highway or any street fast enough, the rpm gets stuck at 3000. with the original engine it wouldn't do that. i took it back to the mechanic who installed the new motor and he said that it was normal. that the ecu is programed not to past 3000. to be honest i don't think thats normal. has anyone experiecend this, if so, how did you guys fixed it. it also does it while the car is parked.

 

No that is not normal. There is some condition causing it to run in "limp" mode. This happens when the ECM detects a problem that could cause engine damage if allowed to rev to higher RPMs. Are you getting an engine light or a message that says "crusie not available"??? Have a scanner connected and see if there are are any codes stored in the ECM. It could be anyhting from a simple vacuum leak to something more involved.
Hard to belive a mechanic would think any car would be programed not to rev beyond 3000rpm!

 

Jagxv6
so i decided to take the maf sensor off and clean it with that special maf sensor spray. i put it back on and turned the car on and still did the same, gets stuck at 3k rmp. i noticed that a hose that runs on the other side of the maf sensor was not connected so i put it back. the next step i took was to disconnect the positive battery cable for a minute or so. when i put it back on, i started the car and the problem was gone. not sure if the the computer got reset or something. i just hope it doesnt do it again. i know, its the last time i take him a car to fix. better find another mechanic. thanks for your information, by the way, the check engine light is still on, but not the other cruise control not available. i never got that one, how much are does code scanners cost, it would be nice to have one just in case.

 

You can rent a code scanner from auto parts places like Advance and Autozone there are some cheap ones for a few hundred, I myself knowing that I will keep my Jag am looking for a good one. I definetly wouldn't use that mechanic ever again.

 

"I took it back to the mechanic who installed the new motor and he said that it was normal. that the ecu is programmed not to past 3000."

So, he lied to you to try and get rid of you? "Not my problem," eh?

You should have a Restricted Performance message on the dash. Makes me wonder what else he didn't hook up correctly.

"I noticed that a hose that runs on the other side of the maf sensor was not connected so i put it back."

And he did not properly reassemble the engine components? What a hack!

Wow, just wow!

Get a scanner, I'm sure you have some stored codes.
Vector

 

If you've got an Android phone then buy a simple Bluetooth OBD dongle from EBay and use an app called 'Torque' - total cost $20. You do need a code reader.

 

Any Advance Auto Parts or Auto Zone store should read engine codes for free. As steveinfrance said, the Bluetooth readers are very affordable—I recently bought one on Amazon.com for around $20. It came with a CD that had several different basic OBD-II software options, so I was able to connect it to my Bluetooth-enabled laptop and get pretty much any information I wanted from the engine computer. USB models are available for around the same price as well, if you don't have a Bluetooth-enabled laptop or smartphone around.

 

Thank you guys (jagxv6,retroxk, vector, steveinfrance, and carluva) for your help, i will definitely buy a buetooth reader to see what codes im getting. So yeah pretty much that mechanic sucks. Its weird howi didnt get that restricted performance light on my dash, just the engine light and its still on. Would it be wrong to drive the car with the engine light on, since the problem of the limp mode went away??

 

Well, the engine light means there is (or at some point was) a problem, and if you ignore it for too long, you can definitely end up with a really expensive situation on your hands. Also, in most states, your car won't pass inspection if the engine light is on. You should at least find out what trouble codes you have as soon as you can.

 

Yeah i need the smog check, im going to order that code scanner. Gotta get rid off that check engine light. Thanks CarLuva

 

The problem might, for example, be with the fuel trims and you risk permanent damage to the catalytic converters in that case.
Wise to sort it before you drive it.
The Torque app is excellent - you can monitor all sorts of live data with it.
Once you've paired the dongle + phone you need to go into the Torque menu to activate the link.

 

My experience runs with the 3.0 S-Type, but the engines are pretty much the same.

There is a 3k RPM limiter when the car is in neutral. That may be what the mechanic is talking about. So, if you are trying to rev up the car in the driveway the limiter will kick in. Now, if it does it while driving that is a MAJOR issue. The first step is like many others all talking about. Read codes and capture live data while it does it. Any decent scan tool will data log. Make sure you get one that does.

 

So the obd2 scanner will get here this friday till then i will know what codes i get. One thing i notice is that the new and old engine have different throttle bodies. The original motor has one connection on one side and like a glass seethrough circle on the other side. The new engine has two connections on both sides! Since the new engine harness was messed up they used my old harness. Soo on the new motor, the mechanic thransfered the old intake manifold with throttle body(the seethrough glass one) could this affect the "limp mode"??

 

sorry but besides limiting the rpm how does the car drive?

 

The car while is parked the idlle is kinda funky, wont stay stable. While in drive it drives ok even though i died on me three times while making a stop. I got the obd scanner and got those two codes p0171, p0174. I erased them and the check engine light dissapered. I know i shouldnt done it cuz i still havent figured out the problem. The rev limiter keeps coming back. Im checking my time one step at a time, today i cleaned the throttle boby seems to work. Im just worried about the limited rev mode coming back again. Could a broken air intake box be the problem too? Forgot to mention it. Part of the corner top is broken.

 

You've got an air leak after the MAF. The filter box needs fixing but isn't the problem.
If you can't see or hear it then follow the steps in the first post here
https://www.jaguarforums.com/forum/x...1-p0174-44579/
Can your OBD reader do live data (STFTs and LTFTs)?