Hello everyone

Here are some (bad) news about my latest toy.

I have purchased this 96 X300 with ΰ 3.2L engine.

Since I have it, I have not managed to make it run properly.

I have swapped the engine (cyl N°2 had almost no compression) with a good unit (compression test performed and everything seems good). (https://www.jaguarforums.com/forum/x...advice-152112/)

The symptoms:

• Bad idle, with revs ranging from 600 to 800 RPM. When I first start the engine, the idle is fine. But when I first accelerate, it becomes instable.

• At idling, exhaust gas smells very bad, with signs of poor combustion

• When driving, the engine seems to be lacking power between 1000 and 2000 RPM

• Above 2000 RPM, the engine sounds good and seems powerful but it is hard to get there

• No error code showing on the OBD


Here is what I have done so far:

• 2 brand new O2 sensors. Signals checked and it seems OK (see previous post)

• Checked ignition coils. Each coil receives 12.2V when the engine is not running, 14,4V when it is running. All coils correctly mounted.

• Brand new battery

• Cleaned the throttle body

• Cleaned the Intake Air Temperature

• Cleaned and tested the MAFS: the output voltage is OK and the reading of the signal by the ECM is OK too/ I checked it while driving with the OBD tool.

• Checked fuel pressure: With contact on: 3 bars. With engine running: 2.8 bars, with small decrease (0.2 bars) when accelerating. So I assume it is fine on this side.

• Brand new fuel filter

• Checked the crankshaft position sensor. Its resistance is 1308 ohms. I have read that new ones should be 1350. I guess the difference is acceptable.

• 6 brand new spark plugs with correct specs. No oil or moisture within the plug holes
• Checked for air leaks (vacuum lines, exhaust, etc) with an home-made smoke machine and found nothing

So, here are my interrogations:

1. Do I need to do a sort of “remap” or reprog of the ECM since I changed the engine? I went to a local garage that seems to be into vintage cars and he directly told me I needed a reset / reprog of the ECU to be sure all sensors and so on were accurate. I am a little confused, to be honest.

2. To me and according to what I have been reading of this forum (and other ones), it sounds like a problem with the ignition. What do you think? How to get sure everything is OK on the ignition side? (coil packs, harness, signal, etc.)

3. Do you have any other ideas?

Thanks a lot for reading, the help and patience

Julien4020

 

Try swapping the O2 sensor connectors over, it's easy to mix them up - and if it doesn't fix things it's just as easy to swap them back.

Good luck!

 

I have already done that and it did not cure anything

 

Good morning everybody !

Does anyone has an idea ?

I need help 😂

Julien

 

Have a look at fuel trims, I think that's what I would do next.

 

Hello Mr happy,

Thanks for the answer. I will have a look at the STFT / LTFT this weekend. I am pretty sure it will be bad since the exhaust gas smells very "rich".

 

So I have been checking the fuel term. Here are the results at idling :
Short term 1: 24,2%
Long term 1: 36,7%

Short term 2: 24,2%
Long term 2: 36,7%

What do you think ?
I also checked for the TPS thanks to the tuto on this website and it was ok

Thanks for the help
Julien

 

My LTFT is usually around 50, but that is not for real. The ECU is not able to read them.

Does the STFT vary at all? Mine are low single digit +/_. If those are real numbers and they change with throttle application the suggest huge air leak, but they may also be false numbers.

 

Hi rj237,

I didn't notice that the ltft or stft were varying at all. But I will check again.

If these figures do not vary, that would suggest an air leak ?

Best regards
Julien

 

No, that would indicate the ECU is not able to register them. The X300 ECU is not fully OBDII functional. Some cars can display fuel trims, others have a problem.

Of course, it may be that your code reader does not interface with the ECU completely.

 

I will definitelly look at it, if there are some variations.

My obd scan is a cheap one.

 

Check the cats too

See my post HERE for more info

 

Hello everyone,

Finally one update on this thread ! I have found the origin of the problem with this car. There are 2:

One injector was faulty, so I replaced it. The car run better but still not perfect. At least it no longer stalled.

Then I tried different parts with no joy.

In the end, I bought a new MAFS and replaced the old one ! Hurrah ! It worked great but the idling was standing at 2000RPM. But at least it started well and was revving perfectly.

So I played with the little sensor under the throttle body (I do not remember the name, I read the tutorial on this forum) and now it is idling perfectly and revving perfectly too !

So, happy days.

Thank you all for the help and the precious info you gave me.


I am enjoying it on the summer now.


What I have done so far:
• cure rust on rear arches (I will put a post to present the results)
• Change steering wheel with half-wood one
• Clean interior
• Fit some adapter for MP3 on original radio

Next steps will be:
• Remake headliner
• Fit new speakers. Old ones are dead.
• Polish and clean
• adjust one pulley that is screaming

 

Noticed you have resolved the engine regulation but I will leave this on here as it my help someone else reading this post . Does the STFT go from the 24.2 toward 0.0 as you throttle up like mine ? I was told this indicates a vacuum leak on the intake manifold side . A leak in the exhaust from cracked manifolds and donut gaskets will allow fresh high level O2 to suck in between pulses and bias the O2 sensers to command a rich STFT . Mine had a damaged downpipe flair that the donut seats and you could visibly see black exhaust gasses escape . Suggest spray down downpipe nuts to free up spinning torque and tighten them up again for as you have been there before you know what a pain it is to completely remove and inspect .

I'll get you a cheap speaker repair and screaming pulley info later as I edit this reply after errands .

Thanks , Parker