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Old March 6th, 2011, 04:47   #3
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AndyBees's Avatar
Join Date: May 2003
Location: Southeast Kentucky

Obviously, there is something going on with your TDI.....seems MPGs are low! The low MPGs could be related to the driving circumstances, i.e. mostly city and mixed vs on the road.

Statistics: I don't think a three tank usage after a mod will actually reflect the data you are looking for, unless the driving circumstances are the same as the previous three tanks..........and were all those tanks actually full...very important! Long term data is more reflective of any results, etc.

EGR mod: I do not have the Diesel Geek EGR, however, I did do the EGR mod via VCDS and the stats I maintain in Excel spreadsheet definitely showed a difference in MPGs. It is very reflective in the numbers as well as the MPG graph!

Oil: Why was conventional oil being used in the engine? I thought it was dealer maintained????? I seriously doubt that switching from the conventional oil to synthetic caused a MPG drop ....just no way!

Fuel: I have always purchased fuel where it is the cheapest...... really have not noticed a difference in the MPGs. I have burned QT diesel (my brother lives in Gainesville, GA ..QT stations there) and did not notice any difference........ lately I've been burning diesel fuel purchased from Kroger supermarket noticeable difference.

Additives: I'll get beat over the head for this: In my opinion, most "additives" are snake oil....regardless of the product or name brand! I do not use additives of any kind, unless a very cold weather system is moving in. Then I add Power Service to aid in preventing the fuel from gelling!

I have over 236,000 miles of data in my Excel Speadsheet! The Mod I have done that achieved the best results was to slow my average speed! Of course, other good driving habits can improve fuel economy. Avoiding jack rabbit starts, stay out of drive-thru lines (McDs, Banking, etc.), avoid idling the engine, make the best use of coasting in gear (approaching a stop sign, red traffic light, etc.), draft when possible/appropriate/safe, empty the car of unnecessary junk (weight), keep a skid cover on the bottom of the engine (reduces drag), avoid speeds in excess of 70 mph, avoid driving in lower gear when the next higher will be more appropriate for the circumstances (driving around with the RPMs up unnecessarily), etc.

Back to my first statement: A determination should be made as to whether the car is achieving the best MPGs under the driving circumstances before doing any mods.......i.e., does it need attention to maintenance issues: engine timing, air filter, accumulated oil removed from the Intercooler, Intake manifold & EGR cleaned (probably packed with crud due to using the conventional engine oil), ...........fuel filter? Well, I seriously doubt a new fuel filter will improve MPGs.

Keep us posted!
'84 Vanagon '02 ALH TDI engine Malone Stage 1 tune. CAT, SS 2" exhaust, E-vac system, DMF with upgrade pilot shaft, 4.57 R&P, fan assisted IC. (32 to 35+ MPGs consistently)
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