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  1. #1
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    camshaft change after fuel pump

    as a matter of interest all you people that have changed your pump have you changed the camshaft to the harder one or is it a waste of cash here is the link http://www.autotech.com/download/fuelPump.pdf
    Last edited by aldo286; 10th March 2009 at 22:25.

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  3. #2
    tobycruse's Avatar
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    Quote Originally Posted by aldo286 View Post
    as a matter of interest all you people that have changed your pump have you changed the camshaft to the harder one or is it a waste of cash here is the link http://www.autotech.com/download/fuelPump.pdf
    This only really applies to the very early 2.0T engines.

    Does anyone know when the harder camshafts came out so we can see who is safe and who isn't?
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  4. #3
    warren_S5's Avatar
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    Lifted from another site:

    VAG have modified the design of the TFSi engine and that the new variants coming out will no longer have the camshaft driven fuel pump. Some of these engines are already in the UK and the result of the fuel delivery being improved is better efficiency on the engine among other things.

    In addition, with regard to the issue of cam lobe wear, it turns out there is a follower which connects to the fuel pump in side the engine. The earlier US GTi's had a slightly different camshaft design, and the follower which starts as black in colour, we found to be wearing, and as a result turning silver. Left alone, this will wear through and then start wear on the camshaft, hence the engine wear. This could develop on newer TFSi engines so attention needs to be given to this part of the engine it seems.

    It has been suggested that the pump be removed periodically to inpsect the follower beside the camshaft for wear and if it is anything other than black, that it be replaced (cost is around 18).

    Further, with regard to the fuel pump upgrades available where the internals are swapped for uprated equivalents, a lot of care needs to be taken when taking off the original pump, fitting the new internals and refitting it to the car as the tolerances in the assembly are so close. Also if not refitted correctly on to the engine, the camshaft may be in line for a good bit of damage. For those looking to do this modification, you need to be careful, or think about a pre-built pump from the likes of APR for approx 800.

    Also, with regard to fuel delivery and remaps, it seems that tuners codes are being written to adjust boost to counter the lack of actual fuel pressure vs required as on tuned cars, 125Bar of fuel can be requested but actual fuel pressure is 90 Bar or so. 80 Bar or less will see the fuel cuts come in that some have been getting. The net result of all this is that the car is not making use of the potential it has down to a fuel shortage. With the uprated pump on mapped cars, the areas where fuelling is short by 33% or so will see a marked improvement in that area of the rev range down to better fuelling. In addition, the pump is better able to deliver the 130Bar that is needed for stage 2 code. In addition to this, an uprated pump on standard code will work with no problems and as it uses the standard pump casing it has OEM appearance.

    By all accounts, it seems that the pump upgrade is potentially worthwhile so wear can be assessed on the cam, fuel shortage can be addressed and a stronger remap applied.
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  5. #4
    warren_S5's Avatar
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    Also (Quote from Keith at APR)

    Well, here's the situation with FSI's and recalibrations.

    Typically, VAG turbo engines, 1.8T, 2.7T etc. have plenty of fuel available to realize the full potential of the oem turbocharger. This is not the case with the 2.0T FSI.

    The FSI uses a rail pump in addition to the intank pump to deliver fuel AND pressure to the fuel rail. This rail pump is cam driven and moves a piston up and down to force the fuel into the rail. Deisel engines have been using this method of fuel delivery for many years. The rail pump generates pressure behind the fuel injectors and when the ecu tells the injectors to pulse or open to inject fuel into the combustion chamber a small amount of pressue and fuel is lost from the rail and the rail pump must then force more fuel into the rail to bring the fuel volume and pressure back up to spec. Simple.

    Basically, because the rail pump is driven by the cam shaft, the rate at which the rail pump is able to rebuild pressure and volume in the rail is determined by how fast the cam shaft is spinning or forcing the piston in the rail pump up and down. So the limitation in fueling for the FSI is greater at lower rpm's and in the midrange than in the higher rpm range where the cam shaft is spinning faster.

    Now you could say, well at higher rpm you are also using more fuel so why isn't the problem occurring there as well? The answer is because the rate at which the fuel pump delivers fuel increases beyond the engine's ability to consume fuel with the oem turbo at higher rpm's. Basically, the turbo provides too much power in the low and mid range than in the upper range as matched to the rail pump. The turbo runs out of breath still in the higher rpm's so fuel demand is less. Peak hp numbers are made up top as a product of torque over time where the rpm's are greater. More rpm's, more torque over time accumatively, less immediate demand on the fuel delivery.

    In the low and midrange, the fuel demand is all in torque or immediate requirement over less time. The rail pump simply can't get to a great enough speed to deliver the fuel that is demanded at peak torque rpm's. This is a very brief and momentary demand in relation to a sustained continual demand that hp requires in the high rpm's.

    So what happens is when the ecu is calling for more fuel pressure a very temporary situation can occur where the pump is not spinning fast enough to provide the requested fuel pressure in the low and mid rpm's. This results in the ecu enabling a safety feature that cuts spark and fuel temporarily to allow the pressure in the rail to build back up. This is the fuel cut some are experiencing. This is an electronically controlled safety measure that in no way means you are running lean or any threat to damage of any of your engine components may occur. The ecu is merely asking for more time for the rail pressure to build back up.

    Now knowing this, how do calibrators still extrapolate the full potential of the turbocharger in the low and mid rpm's?

    There are a couple of different ways and philosophies to accomplish what everyone wants, the most power possible.

    APR's engineering team chooses to follow the recommendation of Bosch, Audi and VW engineers of maintaining the oem specified air fuel ratio of 10.5:1. The reason for this requirement is that direct injection engines run a higher compression ratio over standard injection engines due to the benefits of FSI which results in higher exhaust gas temperatures. Turbocharged engines have always resulted in higher egt's that wear the head, exhaust valves, exhaust manifold and turbocharger itself more rapidly than a normally aspirated engine will. Engineers have combated these higher temperatures with sodium filled valves, high nickel content manifolds and inconel turbo housings, etc. The best strategy for controlling high egt's however is richer afr's to cool everything down in lieu of expensive parts that oems can't typically provide at a reasonable price. So unless you plan on changing out your valves, exhaust manifold, turbocharger and even the headgasket, you can only maintain safety to your components by maintaining the OEM specified afr's.

    What this means to APR clients is that APR is doing everything within the reccomended specifications of oem teir 1 suppliers and VAG/Bosch engineering reports to ensure no deterioration of life occurs to any of your engine components. This results in greater demand of the rail pump and to maximize the potential of the turbocharger at low and mid rpm's, fuel pressure must be maintained and this is much more difficult at the oem recommended afr spec as opposed to merely leaning it out and watching the egt's climb but no fuel cuts will occur.

    Other companies have chosen to lean out the air fuel ratios to as much as 12.5:1 to avoid the fuel cuts. This results in egt's that are well above Borg Warner's specification of 970deg cel max preturbine egt's. This spec was put in place by BW for VAG engineers to ensure no loss of life to the turbocharger. During BW's testing and development of the turbo's found on VAG FSI engines, egt's outside of their spec was proven to show accelerated wear and even total failure well before the normal lifespan of the turbo as per its design requirements from VAG.

    EGT's are so important to FSI engines that Bosch, at great expense, integrated an egt model into the ME 9 ecu to calculate preturbine egt's. If the egt's climb out of spec as per the ecu's model, the ecu then dumps fuel to cool everything down for a period of time until the egt's come back to spec. This is known as the hardware protection map to most engineers familiar with Bosch EMS.

    APR engineers find themselves walking a fine line between maximum power output and safety. APR WILL NOT lean out afr's that result in egt's outside of the specification. APR WILL NOT provide an irresponsible product to the marketplace.

    This philosophy results in a difficult position in the marketplace as our competition chooses to ignore these basic engineering principles and recklessly provides products that are known to result in loss of life of your engine. They don't hit fuel cut because they are running leaner mixtures that result in less fuel demand and therefore less demand on the rail pump at the low and mid rpm's. EGT's however, are not safe at these afr's. APR recalibrations will always maintain safe egt's and if they do climb out of spec the hardware protection map will kick on and bring everything back very quickly. Our competition circumvents or disables hardware protection and allows the egt's to continue to climb.

    This is not merely speculation or arguable. It is proven fact. To satisfy yourself, please data log lamba, egt's and fuel pressure. This is especially concerning for track enthusiasts that find themselves hot lapping during driving events or participating competitively. The street enthusiast may be able to get away with higher egt's for longer periods of time as typically you are at wot in relatively short bursts where on a road course you are wot almost the entire time. All client situations must be considered and please know that with APR calibration you will enjoy safe operation in any circumstance.

    Now that we understand why the fuel cuts occur you may ask well, what is APR doing about satifying the concern as fuel cut is not fun.

    We have discovered opportunities in the ecu to increase fuel pressure from 110 bar to 130 bar. This results in higher overall fuel pressure so the demands in the low and midrange can be satisfied by having more pressure so when the pressure dips due to the demand it will not dip as far and fuel cut will be avoided. This is a relatively new discovery that is currently being integrated into all of our calibrations. In the USA we have been offering a "beta" version of our stage 2+ programming that incorporates the additional fuel pressure and fuel cuts are greatly diminished and only occur very rarely with significantly more power delivery in the low and midrange. The testing is complete and we are now working to provide new files with absolutely no fuel cuts but with almost all of the power available to be had by the oem turbo.

    Further development has resulted in a new higher capacity rail pump that will be the ultimate end all be all to the fuel cut problem. The addition of the APR rail pump results in 15-20 more hp and 20-25 more lb. ft. of torque over the beta file in the mid and low rpm's and the oem turbo is fully optimized.
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  6. #5
    Iggu's Avatar
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    I've read this many times - it seems to be more a commentary on APR remaps than fuel pumps though. It is talking about releasing greater fuel pressure in the ECU through reprogramming - this is not a hardware issue but a remapping issue.

    The only issue I have been able to identify with the Autotech is that early (2006/7) versions were made of harder material than than camshaft lobe and so caused premature wearing. The design was re-engineered some time ago to overcome this.

    I'm no expert but that's my understanding.
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  7. #6
    warren_S5's Avatar
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    There don't seem to be any hard fast rules as to which models / engine codes are more at risk than others. Certainly seems to be earlier cars in the main, but then a 2008 Leon 200PS 2.0TFSi reported issues earlier in the year. Pot luck it seems.
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  8. #7
    S3-N's Avatar
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    This was one of the posts that put me off the Autotech, there were others

    found on Briskoda.net

    Hi guys, this is a copy of a post I done for another Forum as this has been asked before. Botton line is, if you already have a pump dont worry.

    JKM appreciate that some people would like to know more about why we have made the switch from KMD & Autotech TFSI fuel pump internals over to the complete APR pre built and tested unit.

    Where we have been using KMD/Autotech internals I will detail what process we have been going through for each fuel pump prior to sending it out to a customer, so you will get a feel for the process that needs to be run through by JKM to ensure that the pumps are of sufficiently high quality to sell to a customer.

    After receiving the fuel pump internals from the manufacture (say for example KMD) we first check the machined parts for known manufacturing problems by measuring and a general visual inspection any problems here and the pump internals are rejected.
    We then hand assemble the parts together and with a light lubrication between the piston and bore, the clearance and general feel is assessed. The internals are then hand assembled into a test fuel pump body - any problems here and the pump internals are rejected.

    Assuming that all is good on the above, we can then begin an up rated fuel pump internal build into a brand new OEM pump.
    Cleanliness is paramount here as any debris etc will ruin the piston shaft. This is something that we only do in an extremely clean environment to ensure the utmost quality.

    Once the fuel pump is built, we then move onto the next main step Testing.
    To ensure that each TFSI fuel pump that we supply is of the highest quality we have been testing each pump built by JKM, on our own TFSI car.
    Therefore every time we build a new pump Kates nice new shiny MK5 GTI is pulled apart and the test pump is installed for performance testing under load. Following the install we analyse each fuel pump in detail.
    We will look at the fuel pumps Quantity Valve differential angle, Total Compression volume, Fuel pressure and more again comparing the results against known good units.
    With our experience of these pumps it is possible to analyse the results and detect possible problems with internal clearances as a result of machining tolerances, but this is a very complex area. If we suspect problems we will remove the fuel pump, disassemble and inspect it again any problems found here and the pump internals are rejected.

    Following all of the above, assuming that the built TFSI fuel pump is functioning correctly, we will remove the fuel pump from our test car, seal it into a bag and box it and send out to the customer.

    The main reason we have chosen to swap from KMD/Autotech is that the above is very costly to us (time wise) to get a good pump together. We have sometimes had to build 3 pumps to get 1 good unit.
    We appreciate quality engineering, which APR provide with their fuel pump,
    Our equivalent of the APR test rig, is our own MK5 Golf GTI engine and our diagnostics knowledge.



    APR does have a superior hardware design, changing much more than just the piston and bore. The complete internals are re-engineered, right down to the balanced seal rings and main spring assembly. This design puts less stress on the rear balanced seal than the other pump solutions the APR pump design is along the same route as the OEM pump only obviously containing larger internals for increased fuel volume.
    APR route out bad pumps themselves during testing at their own facility, and the pumps have even been used by VW Motorsport on the VW Scirocco GT24 which won the ADAC 24h Race without any fault.
    For those interested more information on this can be found here: http://forums.vwvortex.com/zerothread?id=3855643

    JKM will only bring to market the quality items. If we find that the quality of an item is not acceptable we will first try and work with the supplier for a solution but ultimately if we would not be happy to use the product on our own car we will not sell it to a customer for use on their car.
    For JKM the up rated internals route (only) is too inconsistent from the manufacturers.
    APR provide a quality fuel pump out of the box, and the customer is in the knowledge that there will be no issues.

    The APR pump can be bought in 2 ways; we will be updating our website shortly to include the cheaper core exchange route.

    1) An outright buy of an APR pump, where by you can remove your stock TFSI pump and retain it somewhere safe and simply install the APR pump. This route costs 624+Vat excluding postage back to you.

    2) The second route is a core exchange, where by if you send us your TFSI pump we will send it to APR for a pre built unit, this route costs 509+Vat excluding postage back to you and you are responsible for postage of your pump to JKM intially.

    More information is at the following link: JKM Performance - TFSI Products - Fuel Delivery - APR Fuel Pump

    For those customers already with a JKM built KMD or Autotech pump, you do not need to worry as we have done the above testing process on your pump to ensure you have a good unit.
    I hope this helps clear up the questions in this area and hopefully you will appreciate why we have made the switch to the APR unit.
    For those who wondered, our own car does use an APR fuel pump but the K04 conversion car that has been on long term testing (20,000+ miles) has been, and is still using a KMD pump without fault due to the above testing process that we have performed.

    Keith
    Phantom Black B7 S4 + Milltek

 

 

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