Member Since: 22 May 2015
Location: California
Posts: 27
Loss of power and unstable rpms
After I filled up with premium fuel from Chevron today my car started to struggle to accelerate around 2500 rpms. Engine light came on.
Did a few read ups so this is what I have done so far:
1. Change filter
2. Clean throttle bottle with carburetor spray
3. Sprayed MAF with MAF cleaner.
Results: The car is accelerating better and faster response. BUT when I took it on the freeway it would not auto shift to 4th gear. I do notice a hissing sound coming from the driver side , possible air leak somewhere. It seems by cleaning the 3 items above the better airflow has made the problem worse. RPM still unstable and car is still lagging.
NEXT thing to do is read the OB2 codes and then possible clean fuel lines. After that possible spark plug wires, cap, and spark plugs replacement. It is running like there is a misfire in the engine.
Check the oil and possibly water temperature live values - I'm sure on the TDV6 (Which I know yours isnt!) that if the oil sensor is faulty the engine is a rough as a dog.Mark.
2006, D3 SE Auto - gone but not forgotten.
2014 BMW 530d M Sport Tourer.
1977 Triumph Spitfire 1500
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30th May 2015 6:29 am
Robbie
Member Since: 05 Feb 2006
Location: ¯\_(ツ)_/¯
Posts: 17932
Diagnostic codes and live data would help, but it does sound like an air leak somewhere so perhaps the original misfire dislodged something.
Try a spray bottle of water and spray around all the air pipes and vacuum lines, listening for a change in rpm and any sucking noises. If you do suspect a plug or ignition do a cylinder drop test.
The throttle bodies are notorious for gumming up and it often takes more than one clean to get them right but given that you can hear a hiss an air issue has to be at the top of the list. The temp data sensors are not that dominant in the fuelling of the big petrol engines, so it is unlikely to be the root cause. Again, live data is your friend if you can get a suitable tool.
Land Rover - Turning Drivers into Mechanics Since 1948
Member Since: 29 May 2007
Location: Dundee, Scotland
Posts: 20837
Also be worth checking the brake switch/bulbs, if it is not changing gear properly
If the car thinks the brakes are applied, it does odd things. Not sure about the petrol, but an ESF is displayed when the thinks the brake and throttle are pressed together
If you do hear a sucking noise, you may have a vacuum leak, or inlet air leak, as Robbie says My D3 Build Thread
Member Since: 22 May 2015
Location: California
Posts: 27
Thank you for the input.
After reading the engine codes (P0304) it pointed to a failed cylinder 1 & 4. Upon closer inspection I notice 1 & 4 had original coil springs, the other 6 had been replaced. I swapped 4 & 2 and then reset the engine codes, after switching #2 failed and #4 was ok. Went to local auto store bought two new coil springs and problems went away. I also purchase 8 new spark plugs but have not had time to change them out.
Cleaning the MAF and throttle body has allowed the engine to breath better and smoother acceleration.
Wet MAF sensor was the cause confused auto shift sequence.
I was getting 16.8 mpg before and with the failed cylinder it read 14.1 mpg.
Still hear an air leak and light whistle in drive train when driving. Any tips on that would be helpful for next weekend wrenching.
Thanks again, forum like this one is why I made the LR3 purchase.
BTW this is a 2006 LR3 with 4.4 V8 gas model.
30th May 2015 11:17 pm
Cellerdweller
Member Since: 05 Oct 2012
Location: Macclesfield
Posts: 1315
Just a thought a hissing sound can be normal on big petrol engines it can be the movement of air through the intake system .Because you are looking for a problem and listening to the engine running this may appear more apparent . Having said that I agree with Robbie have a squirt around where you here the noise and listen for the engine tone changing .live values would also be good in detecting an air leak eg long term and short term fuel trims You're not afraid of the dark are you ?
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