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Discussion Starter · #1 ·
Hey,



I have had camshaft problem, one of the lobes has developed a flat spot. So I decided that i should install fast road camshaft from darkside development and rebuild the whole head because i want to exceed 270 bhp in the future . Which included oversized inlet and outlet valves, harder return springs, and black top lifters, higher duration and lift camshaft and a remap. After re assembly of the engine i noticed a huge drop in fuel economy and a rough start on cold engine with some white smoke. Before a used to get 36mpg and idle fuel economy was around 0.7l/h , now i get 26mpg and idle fuel economy is somewhere between 1.2l/h and 1.6 l/h . Since the head work i have tried changing coolant temp sensor , fuel temp sender and i have re adjusted distance between rockers arms and injector ( to the point where you feel noticable resistance then 180° back) before this work fuel economy was 18 mpg and idle fuel economy 2.2l/h . I have done a full VCDS Scan no error on engine module. We don't know what else to do , Darkside development states that they would expect a slight drop in fuel economy but not that much, my tuner adjusted SOI accordingly and torsion value is 0.6° - 1.1° which is spot on according to dark side development.
This is a 1.9 TDI ARL engine that has been remaped before head work and was running somewhere around 200 bhp and fuel economy actually grown since the first remap. But now it's gone downhill.
I don't know what else to do then seek help form forums , i have VCDS so if any of you have a suggestion what should I log and in which conditions so we can resolve this fuel economy.
Thanks in advance,
Hope to hear from any of you soon.
 

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No it wasn't i uses to get 36 - 40 mpg now i get at best 26mpg and idle fuel economy was 0.7l/h now it somewhere between 1.2l/h and 1.7l/h
36 to 40 out of a pd150 isn't good mpg imo.
Pretty sure, even with a bit of a tune, these should return closer to, or around, 50mpg.
 

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I would have them redo the mapping to make sure it actually has economy too... they might have gone for maximum performance.

And yes even before your car was using way too much fuel on average.
 

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Discussion Starter · #7 ·
I already did a remap and my tuner says that he can bring economy up this is the best he could do it must be something mehanical or some sensor is sending false data
 

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That would be pointless, your car is using to much fuel, and whatever you did after the 270bhp hardware and tune did not solve the fuel usage...

So the head has been done right which leaves the bottom block... a compression test would clarify if that part is good. Although you already stated it drives fine.... just have a compression test done....unless you've also upgraded the in-tank fuel-pump to supply more fuel at a way higher pressure and you've had way bigger nozzles installed in the injectors as that would explain the drop in economy.. but if they are the oem ones... the extra overlap shouldn't cause a drop in economy that big. at best you'd be off about 5mpg on average so you should see about 55 mpg on average with your hardware and a tune of 270bhp. and that is if you actually floor it all the time. but with normal driving it should sit at around 55mpg... that is with the stock fuelpump, upgraded injector nozzles and higher lift cams.
 

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Discussion Starter · #11 ·
I will do a compression test , but i think the compression i good because the car drives fine it doesn't burn any oil and when the engine was open without head on block you could see that the piston rings are fine and pistons are very snug and firm in the cylinders . But to double check i will do a compression test. Since i am going to my mehanic do you have any other suggestions while i am already there
 

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Nothing I can think about that will cause high fuel usage.. bad injector seals or dirty injectors come to mind but that is about it...a diesel purge should help with that... oww and a dirty sooted and clogged up intake but with all the work you've done I figure that lot is clean.
 

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I was going to say - if a tuner doesn't know if a sensor is sending bad data, he's not a tuner.

Also as above, these should be returning 50mpg, something else is wrong. Messing with SOI without back to back dyno runs is asking for a melted piston. You have a hardware issue - go back to stock software. Are the injectors set correctly? White smoke is incorrect injector timing or too much fuel.
 

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Any updates, quite intrigued to see the achievable mpg with this camshaft
 

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Discussion Starter · #17 ·
Hey, ECU has been remapped and injector adjusted . I have managed to lower the economy from cca 10l/100km to about 7.5l/100km . Running this camshaft with stock injectors and turbo isn't a great idea. I installed a GTB2260VKLR turbo and Firad 120% injectors this weekend and i am going to remap the car on Wednesday my tuner predicts that economy should go down a bit after remap to cca 5l/100km
 

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Hey, ECU has been remapped and injector adjusted . I have managed to lower the economy from cca 10l/100km to about 7.5l/100km . Running this camshaft with stock injectors and turbo isn't a great idea. I installed a GTB2260VKLR turbo and Firad 120% injectors this weekend and i am going to remap the car on Wednesday my tuner predicts that economy should go down a bit after remap to cca 5l/100km
Bump. 😉 How did you get on?
 

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Discussion Starter · #19 ·
Pulled the camshaft out installed FCP 276 and everything is fine now Darkside Development camshaft has more aggressive pd lobes which caused low economy. I think this could be compensated whit shorter duration but noone told me that at a time. Darkside Development was not help when i approached them for help.
 
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