Jump to content

2003 D2 v8 fuel trims o2 sensors & emissions


v8Dougie

Recommended Posts

Hi all, a bit of help please.  I am ashamed to say that my fathers D2 failed it's MOT back in April this year on emissions and I am only just getting round to sorting it for him.  It failed for the following reasons:

  • Exhaust emissions carbon monoxide content at idle excessive (7.3.d.4)
  • Exhaust emissions carbon monoxide content after 2nd fast idle excessive (7.3.d.3)
  • Exhaust emissions carbon monoxide content at idle excessive when tested on gas (7.3.d.4)

So a bit of back ground, this car was bought with a bad misfire.  Was found that the liners had dropped when the previous owner had the heads skimmed.  The engine was removed and refitted by Mechanical Workshop in Leicestershire under direction by John Eales who rebuilt the engine and enlarged from 4.0 to 4.6.  There were a few teething problems after as there often is and it has had a new ECU and all o2 sensors replaced.  All ran well then for a year, few minor disco hiccups but then failed the MOT for emissions.

I have borrowed a Hawkeye and had a look today, got the engine nice and warm and I found the below:

Fuel trim bank A hovers around 1:1
Fuel trim bank B constant on 1.25:1
Upstream O2 Bank A cycles between 0.1v and 0.9v happily
Upstream O2 Bank B constant on 0.06v
Downstream O2 Bank A cycles between 0.2v and 0.8v slower than the Upstream one
Downstream O2 Bank B constant on 0.45v

The car starts and runs ok, sounds a bit lumpy and I get a pop on overrun from the exhaust.  If I am right bank B is over fueling massively (1.25:1), because the upstream o2 is telling the ECU the car is running lean (0.06v).  From this it would seem the O2 sensor is faulty, however they are all new (less than 18 months old) and genuine Land Rover parts, any other thoughts?

Another issue seems to be that the cat on bank A is faulty.  I believe the reading should be constant around 0.45v as bank B is, however it cycles up and down, any other suggestions?

Are there any checks I can do?  I believe the O2 sensors are the same, upstream at least, so I am thinking on swapping them over and see if the over fueling follows the sensor, if so sensor is faulty.  If it does not, then what else could it be?

Could either of the issues stated above cause the high CO2 levels found in the MOT?  Just to be clear, the car has a new oil filter, fresh oil, new plugs and coil packs & HT leads.  Air filter is new too.  The car does have LPG however I am not using that at the moment.  It was working perfectly fine however seems to now have a bad misfire, so just sticking to petrol (no misfires) for now.

Look forward to your help!

 

Link to comment
Share on other sites

15 hours ago, Ally V8 said:

The missfire will have caused the 1.25 short term trim. If you do an adaptive reset and there are no missfires you should get both sides switching again and the shoort term trims should remain close to 1:1. 

Thanks Ally V8, without being dim could anyone talk me through resettiing the values using my Hawkeye.  I have done some searching and it seems it is possible however there is no information on how to do it.  I have borrowed the Hawkeye off a friend who has even less knowledge of how to use it than me!

Link to comment
Share on other sites

Okay, so it seems I need to upgrade the Hawkeye to get it to reset the values, currently on v4, and the capability came in on v5 of the software, now v7 is available!!

In the meantime the local garage swapped over upstream o2 sensors for me, and I can now confirm the below:

Fuel trim bank A constant on 1.25:1 previously 1:1
Fuel trim bank B hovers around 1:1 previously 1.25:1
Upstream O2 Bank A constant on 0.25v previously cycling
Upstream O2 Bank B cycles between 0.1v and 0.9v happily previously constant on 0.06v

So I am assuming that the O2 sensor which is NOW on bank A is faulty.  Any recommendations on where to get one? The ones in there were supposed genuine fitted 18months ago, sourced from FourPlus4 for £110+vat each! Local motor factor can get Bosch ones for £50, any suggestions?
 

Link to comment
Share on other sites

Sorry,can't help you with the Hawkeye, I have Testbook T4,the original LR system - so no experience with Hawkeye. I would suggest you find out how to do the adaptive reset before doing any more component swaps or replacements. If you do have to replace any of the sensors be VERY clear about the supplier and their sources,there are plenty of companies selling fake parts...

Link to comment
Share on other sites

Bit of an update...I got the OEM Bosch part from trusted local factors for £60, it has been fitted and has resolved the high STFT now both banks are sitting around 1:1 and the voltage is now cycling nicely on upstream sensor, and the downstream sensor is sitting level around 0.45v

The garage tested the emissions again and it still failed...but see below the previous values and values now

CO: Limit: <0.2%                  Previous: 4.11%  Now: 0.54%
HC: Limit: <200ppm             Previous: 155      Now: 45
Lambda: Range: 0.97-1.03  Previous: 0.891   Now: 1.008

So now at least it has only failed on CO, and also not by anywhere near as much.  Still no misfires or other signs, no EML on or pending codes.  My thoughts are now it needs a damn good thrashing to clear out all the excess fuel and crud in the system from the o2 sensor fault?  Any other thoughts?

Link to comment
Share on other sites

6 minutes ago, Bowie69 said:

Looks like it needs a bit more fuel...

 

But yes, thrash it, get really hot and re-test.

A bit more fuel??  High CO levels means unburnt fuel does it not, so either a misfire or too much fuel going in surely?  Neither of these are happening (I do not think) so I assume it is residual fuel as the car has not been used.

Fingers crossed it'll be that simple, a good thrash!

Link to comment
Share on other sites

31 minutes ago, Bowie69 said:

High CO is not enough oxygen to turn all the fuel into CO2.

If it was rich, the hydrocarbons would be high.

Now I am befuddled...if not enough oxygen causes not all the fuel to be burnt, the end effect would surely be the rich exhaust gas??  I do agree though that high hydrocarbons means running rich, so doesn't seem like I am right...I wonder if the cat has been killed :(

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...

Important Information

We use cookies to ensure you get the best experience. By using our website you agree to our Cookie Policy