Direct Petrol Injection Stratified Lean Burn Mode #
Posted by Eddie Zyla on February 4, 2014, 10:00 pm
Year of Manufacture *: 2006 Onwards.
Hi all, i am currently working on a new LPG project involving direct petrol injected vehicles and would welcome any valued technical assistance from any UK Autotalk members.
I read in an earlier post that the VAG FSI engines do not run stratified lean burn in the UK because of fuel quality. Is this true and if so, what is the problem, is it the octane rating or to do with something in the fuel or maybe emissions related?
I did hear some early LPG systems specifically designed for direct injection engines in the UK were only suitable for non lean burn, therefore stratified fueling must have been in use at some time.
We recently purchased a BMW 5 Series 525i fitted with the 3.0 litre 6 cylinder N53 lean burn direct injection engine installed with Piezo injectors, this vehicle is being used as a test mule. I have already started analyzing how the 4 different stages of fueling operate using our rolling road, a 4-gas analyser and 4 channel lab scope, some readings contradict the vehicles live data.
If fuel quality in the UK is a problem to VAG then why is it not a problem to BMW, might it be that their engines run on a lower compression ratio? I am aware of some of the Piezo injector and high pressure pump problems BMW are having often being blamed by their owners for the engines misfiring and cutting out. These engines have a compression ratio of about 12:1 so surely they should be run on a high octane fuel such as Shell V-Max?
Could it be that some vehicle manufacturers originally released vehicles into the UK running lean burn but following customer complaints recalled them and re-flashed their ECU's to run homogeonous lambda 1 without even informing Main Dealers?
Any information regarding any make and model of direct injection engines and ongoing problems and fixes would be much appreciated.
Regards Eddie Zyla. Technical Director CRD Performance.
Re: Direct Petrol Injection Stratified Lean Burn Mode #
As far as I am aware the first VW FSI vehicles did run Stratified mode in the UK, but I believe that the later vehicles don't and there is also a software update to remove Stratified mode from the earlier vehicles.
The engine was designed to use Super Unleaded (98 RON)They would run on 95 RON but at reduced performance and fuel economy which generally led to complaints from owners regarding poor fuel economy.
The VW 1.4 & 1.6 FSI also runs a 12:1 compression ratio.
I have some VW Self Study docs on the 1.4 & 1.6 FSI engines if the are of any use to you.
Tommy
Re: Direct Petrol Injection Stratified Lean Burn Mode #
Hi Tommy and thanks for your reply. Just as i thought, some of the early vehicles were sold as lean burn but their owners probably used an incorrect cheaper octane fuel and then complained when they didn't run well.
As these vehicles may qualify for a lower tax band due to their claimed low co2 emissions it may not be common knowledge that the Dealers are re-programming them to run on a less problematic standard 14.75:1 lambda 1 map.
And yes Tommy, please do send me all the information you have available.
Regards Eddie.
Re: Direct Petrol Injection Stratified Lean Burn Mode #
Thanks Tommy for all the information on VW FSI you have sent me, from what I've had time to read up to now this is exactly the type of information i need.
If anyone is able to supply me with data and info on the BMW Piezo lean burn system (N43, N53 etc) it would be greatly appreciated.