Jump to content

Bargain Basement Bucket List Big Cat - LAWNMOWER UPGRADE FITTED! (19/02/24)


Recommended Posts

On Thursday this week, I took this along to an LPG specialist. He was picked because I saw he did a lot of El-Grand work, and those tubs are a difficult thing to do well.

En route, I stopped for a high powered exec luncheon


The chap was extremely pleasant, all the tools on a tool board, unit tidy and a MK2 Mondeo 2.0 petrol in the corner as a tinkering project. So far so good!


I brought the car in, and he set up to read it.IMG_20240201_132304840.thumb.jpg.fd9f09d9961b824f6f1e57eb470efc6a.jpg

The car has a top spec AC Stag sequential injection system. As such, he was able to attach a Bluetooth Dongle to the LPG ecu. All a fair bit fancier than the old single point systems I have had before.

The LPG ecu is piggy backed onto the main ECU and uses it's signals for airflow, pedal demand/throttle body positioning and spark timing.

Looking at the logs for when the system was last checked/serviced, it was last Accessed on the day after it was fitted in July 2019.

The car has done about 70+k miles since then..

The first thing we noticed was that the short term and long term fuel trims were all over the shop.IMG_20240201_1333130783.thumb.jpg.75b937ab8cbd726584d69e9d5ce8cf5b.jpg

His suspicion was that the AFM was not generating a valid signal.

He suggested that at idle, something at 4L should be registering between 4-5grams of air per second.


As we can see, It's only registering 1/10th of that. 

At this point, he said he was not prepared to try tuning the LPG until the car was running correctly on Petrol. I said I totally understood his position, and that it seemed a most sensible course of action.


He asked what symptoms I was experiencing - I explained the issues with it stuttering/ delayed response.

He decided to try and run a diagnostic program to check the LPG injectors. The ECU has the ability to add additional flow to each injector to balance the fuelling ( to account for wear/contamination from the oil/lubricant fraction used in the LPG)

The ECU can add up to a maximum of 25% additional flow. So the lower the number in the table the better.

The results?


So injectors 2/4/5 are gubbed, with 3/6 showing some wear. This was not entirely unexpected given the lack of servicing or maintenance since it was fitted.

Injectors are not too expensive and his costs for fitting/mapping the LPG seems very reasonable. 

He took a look at the fuelling curves and found another issue.


The blue line is the petrol curve, and the green is LPG. The way this was mapped when installed has made the LPG much richer - add in the failed AFM and then it's easy to see why the LPG setup was not smooth.

He pulled the LPG fuelling back a touch, and the car is significantly more driveable.

Now to find a replacement AFM...

Link to comment
Share on other sites

  • 320touring changed the title to Bargain Basement Bucket List Big Cat - Floody Hell!! (12/02/24)
  • 320touring changed the title to Bargain Basement Bucket List Big Cat - LAWNMOWER UPGRADE FITTED! (19/02/24)

As per @Broadsword's recommendation I have changed the spark plugs on this today.

These are the recommended plugs. They are also a common lawnmower sparkplug, so ideal for a big tractor like this🤣

They were £13.30 for 6 delivered. I checked each of the coil packs and they seemed ok, but I may consider fitting new ones If they can be found at reasonable cost.

Overall, I'm not seeing too much to worry about.




As @jaypee knows, I absolutely adore* changing plugs in multi valve heads...

Anyway, first step was pull off the coil pack cover


You can see the replacement coil fitted to #2 that seemed to help running.

All the plugs came out ok, but we're certainly not in the first flus of health, here's #6 Vs a new one


And counting down...













Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
  • Create New...