Freelander 1 SOLVED - Freelander 2.5 V6 idle problem when engine hot. No power loss.

Hello,
I have been searching the forum for some time and I did not found a similar thread.
I have a 2003 Freelander 2.5 V6, the engine model with the ignition coil on each spark plug.
The problem is that when engine is warm the engine is not idling well... It drops 200 revs back and forth about each second.
When the engine is cold, the idle is ok. The start is ok both hot or cold.
The idea is that the engine does not seem to have any loss of power when driving.
No engine check light is on, the engine temperature is ok.
I have replaced all the spark plugs. is it possible that the ignition coils to fail when hot? Visually they seems ok.
Anyone has any idea about this issue?
I have recently replaced the engine as it has developed a low frequency crankcase knocking noise few weeks after the same idling issue happened.
Now, I'm afraid to drive it in order not to damage it once again... I must say that all the accessories from the previous engine, are now installed on this one.
Regards and many thanks.

Have you cleaned the IACV? That's normally responsible for fluctuations in idle speed.

Did you strip the old engine down to trace the knock? The KV6 bottom end seldom gives trouble and is generally good for 1/4 of a million miles.

Nodge68 said:

Have you cleaned the IACV? That's normally responsible for fluctuations in idle speed.

Did you strip the old engine down to trace the knock? The KV6 bottom end seldom gives trouble and is generally good for 1/4 of a million miles.

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Hello, all the accessories and parts were stripped down from the old engine. Everything was cleaned before mounting them on the new engine.
Due to the high labor costs, I did not bothered to trace down the root cause of the knock. The noise was at 2000+ RPM, and it was really bad.

FlightBooster said:

Hello, all the accessories and parts were stripped down from the old engine. Everything was cleaned before mounting them on the new engine.

Click to expand...

Sounds like you moved the fault with the old engine ancillarys. Are you sure the IACV was cleaned? There're often missed and do gum up causing the issue you describe.

Nodge68 said:

Sounds like you moved the fault with the old engine ancillarys. Are you sure the IACV was cleaned? There're often missed and do gum up causing the issue you describe.

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The throttle body for sure it was cleaned... I sow it before the mechanics mounted the engine cover... But thinking twice I think you're wright. I believe that they miss it. Tomorrow I will give it a try to see if it is the case.
I will post back the result after cleaning the IACV.
Thank you for your help!

Nodge68 said:

Sounds like you moved the fault with the old engine ancillarys. Are you sure the IACV was cleaned? There're often missed and do gum up causing the issue you describe.

Click to expand...

Today I took my tools and went to the car to check.
I took off the engine cover and started to dismantle. For the ones who are wondering how clean the IACV, I took some explanatory pictures.



I have dismanlte the IACV


Ok, so you're right! The mechanics did not cleaned the IACV.

Nor the interior...




I have cleaned the IACV and the body interior of the IACV

That is the cleaner that I have used (Disclaimer: this is not a commercial... I'm not a vendor)







What happened? I have successfully manage to have a relatively sable Idle...

Now I have a hiccup like on the same frequency an before, when the idle was dropping.

Please see in the movies that will upload soon. It feels like from time to time one spark is missed. It's like a small shock that is happening so fast that the rev gauge almost miss it to display it.
Could this be from ignition coils?

Thank you for your suggestion!
It still remains the hiccup. It is the same as before engine swap / replacement and before IACV cleanup, but, with the smaller impact on revs, as now the IACV is compensating better.

Any idea???

Regards

FlightBooster said:

It still remains the hiccup. It is the same as before engine swap / replacement

Click to expand...

The ECU will flag up a faulty coil or plug. Run an OBD2 diagnostic to see if anything is flagged up.

Nodge68 said:

The ECU will flag up a faulty coil or plug. Run an OBD2 diagnostic to see if anything is flagged up.

Click to expand...

Hi again!
Problem SOLVED!

Short sorry:
The main problem was generated by the ignition coils, so the engine hiccup was solved by replacing them. I have decided to replace all because the silicon that is right next to the spark plugs was aged and, at any gentle squeeze, all of them have cracked.
Secondary problem was the 200 RPM dropping at any engine hiccup. That one was caused by the dirty IACV and it was solved as described above.

Thank you Nodge68 for your help and info. By the way, I was not able so see the logs from the ECU as the service had problems with the computer, and they were not able to connect to the engine computer. Everything was available on screen (airbag, abs, etc.), except engine (some message; "wrong keybyte. please select different model...") )) It was my decision / feeling co change the coils.

I hope that this topic will help others with the same issue.

Regards,
Mihai