Thread: How to completely get rid of MAF on de-EGR'd TD5

Originally Posted by Dougal

The ecu has lookup tables for limp home if the maf is disconnected.

A simple diagnosis of a bad maf is to see if it runs better disconnected. If limp mode is better than the connected maf them you have a bad maf.

Dougal - mine is definitely not going into limp mode (if it is then I am impressed with how good limp mode is), and the MAF is not bad either based on the readings I am getting. It actually runs the same with the MAF disconnected and since posting the performance data several days ago I have repeated the test and even disconnected the MAF for 2 cold start to fully warm cycles over 160kms and neither saw nor felt nor measured any change in performance.

Those look up tables for running with the MAF disconnected must be predicting the mass air flow incredible well and with impressive accuracy without the MAF to be able to do this. That is what I am finding totally amazing as I expected disconnecting a good MAF would have an impact given how important the MAF's role is in this discussion.

David

Originally Posted by DiscoDB

Dougal - mine is definitely not going into limp mode (if it is then I am impressed with how good limp mode is), and the MAF is not bad either based on the readings I am getting. It actually runs the same with the MAF disconnected and since posting the performance data several days ago I have repeated the test and even disconnected the MAF for 2 cold start to fully warm cycles over 160kms and neither saw nor felt nor measured any change in performance.

Those look up tables for running with the MAF disconnected must be predicting the mass air flow incredible well and with impressive accuracy without the MAF to be able to do this. That is what I am finding totally amazing as I expected disconnecting a good MAF would have an impact given how important the MAF's role is in this discussion.

David

You must be running in similar conditions to the base tables and not currently limited by airflow. If you were at high altitude, very high temperatures or running closer to the smoke limit you might see something.

Originally Posted by Dougal

You must be running in similar conditions to the base tables and not currently limited by airflow. If you were at high altitude, very high temperatures or running closer to the smoke limit you might see something.

That is a good point Dougal. Would suggest that in many cases, running with the MAF disconnected would see little to no change in performance. No doubt helped by the larger intercooler.

Tombie - you mentioned your experience with the MAF disconnected lead to poor running. Was this with a remapped ECU or any other engine mods, or was it under high temp conditions?

David

As a comparison, the V8 has over 200 different tunes available. All depending on market, options such as gearbox, ace, air etc etc. Some are version revisions and were upgrades so theres a version upgrade for EVERY model variant and market build there is.

And that doesn't include TD5's or other engine variants available.

At least you can access and tune yourself.

Originally Posted by DiscoDB

That is a good point Dougal. Would suggest that in many cases, running with the MAF disconnected would see little to no change in performance. No doubt helped by the larger intercooler.

Tombie - you mentioned your experience with the MAF disconnected lead to poor running. Was this with a remapped ECU or any other engine mods, or was it under high temp conditions?

David

Hi David

The first time was after collecting from old LR dealer in Adelaide on what I believe was about a 30° day.

Vehicle drove ok on the tablelands and only played up once it had got a bit warmer and had climbed the hills. Replacing the MAF plug sorted everything.

What was happening was noticeable delays on take off, bogging down, then erupting with power and associated smoke cloud. It would also shiny between gears. (Manual TD5 defender with no EGR and of course no waste gate modulator).

Fitting the plug cured all this behaviour.

I then tested it again as I gained more knowledge of the systems and had the same result. The more load the worse it behaved...

I had the vehicle chipped soon after and had fantastic performance until the MAF aged and failed. Disconnecting it to default value had less of an effect this time on lag but substantial smoke production!

Cooler the weather - or more correctly, the more dense the AP the less smoke, but the off line take off was always impacted.

Hope that helps...

Appreciate the info Tombie. Given my testing was at sea level, cold weather, and with the larger intercooler would explain the difference in results as I would still be getting plenty of dense air. Good to test these things when they are working well. I wonder what else I can disconnect and it still runs. (-;

maybe my car is strange but just made an interesting test... bridged the MAP's signal to MAF input and seems more responsive than with the original MAF ...no EGT difference so far.... dont blame my curiosity and insistence in this MAF emulating thing it's a kinda obsession of mine ... i've previously compared the signals with two voltmeters on both(MAF and MAP) outputs with running engine but revved it to 4000rpm only stationary didnt watch voltages under load just drove it few miles

Great to see you have the EGT gauge hooked up. What sort of peaks are you hitting?