ECU remap for a Jetta TDI - first timer...

[bluefoxicy]

I've never done an ECU remap and don't know much about the basics. There's not going to be a power x economy slider in there or anything nice, so I'll need some low level understanding of engine dynamics to do anything I guess (unless I want to blow up the car).

Mostly what I want is to get a 2000-ish (2001-2005) VW Jetta TDI and an OBD2 or VAG computer, and make the Jetta output say 200ftlb@1500RPM, continuing to stay above 80% of that to about 4250RPM.

My assumption is that the VW redlines at 4500, and a Cobalt redlines at 6500; thus, adjusting the gearing, 1500RPM diesel would be equivalent to 2166RPM on the Cobalt, and 4250 about 6138. I'd want the Cobalt to peak at about 2000 and still deliver decent power to about 6000, though the non-SS model peaks at 4500 and delivers decent power to about 6250.

The other question of course is where does the VW idle, and where do I hold 80mph at in 5th gear? Also if the car's aware of what gear it's in (in the stick shift), can I adjust the fuel map based on individual gears? Personally, I would find it useful to tune a car to deliver more fuel and push more power in lower gear; but back off into an economy mode in fifth gear, only pushing more power above a higher threshold, or (if possible) when the throttle is thrown down hard.

Of course the turbocharger complicates this, because more fuel creates more gas (if it burns, of course; flooding the engine won't help) and drives it harder.

At any rate I can't just go mixing settings up willy nilly and hope I get some power output.

[pgarner]

hey and welcome to the site mate.
guessing you in america going by a 2000-2005 jetta as it was called a bora between 98-05 over here. whats the standard diesel engine over there 115bhp ? i know you didnt get the higer output 130 and 150 varients over there

the 1.9 turbo diesel engine gives between 90 and 150 bhp depending on varient and 155 - 236 ftlb of torque

if it is the 115 engine then your already looking at 210 ftlb of torque with a remap your looking at around 160-170 bhp and around 280ftlb.

remapping itself isnt tht easy as you need to know what the engines doing the whole time. exhaust temp is one of the most important rather than buying the software and spending ages trying to work it out yourself or paying for the maps go see a profesional tuner - APR REVO are 2 of the best VAG mappers and both are avalible in america.

Idle is around 700prm

gear selection isnt required for economy in a diesel as it runs mostly on air while cruising alone this is how they achive the massive economy figures. the PD varients are stunning especially if you can get hold of iirc ARZ engine this is the 150 varient with a remap your looking at 200bhp 322ftlb while still retaining around 60 mpg ( uk gallon is 4.5 ltrs think american gallon is 3.8 )

[bluefoxicy]

Originally Posted by pgarner

hey and welcome to the site mate.
guessing you in america going by a 2000-2005 jetta as it was called a bora between 98-05 over here. whats the standard diesel engine over there 115bhp ? i know you didnt get the higer output 130 and 150 varients over there

150ftlb@1900RPM; I don't care much for HP, it's a meaningless number. For any point on the torque curve, (HP = TQ * RPM/5252). So the peak torque 150ftlb@1900RPM is 54.25hp@1900RPM, just about. If it holds a steady 150ftlb up to say 3000RPM, or only drops as low as 140ftlb, the peak HP will be at a higher RPM and be higher than 54.

But you knew all that already.

Originally Posted by pgarner

the 1.9 turbo diesel engine gives between 90 and 150 bhp depending on varient and 155 - 236 ftlb of torque

155@1900RPM. 90hp@3750RPM.

Originally Posted by pgarner

remapping itself isnt tht easy as you need to know what the engines doing the whole time. exhaust temp is one of the most important rather than buying the software and spending ages trying to work it out yourself or paying for the maps go see a profesional tuner - APR REVO are 2 of the best VAG mappers and both are avalible in america.

Nods. I'd rather not pay a ton of money for that, plus it's more fun to learn to do stuff myself. Everything's easy, btw; the hard part is learning how to do it. Take it from someone whose job used to be breaking into computer networks (once you get your head around it, it's like you can suddenly walk through walls... no effort).

I guess I just like doing stuff myself.

Originally Posted by pgarner

gear selection isnt required for economy in a diesel as it runs mostly on air while cruising alone this is how they achive the massive economy figures. the PD varients are stunning especially if you can get hold of iirc ARZ engine this is the 150 varient with a remap your looking at 200bhp 322ftlb while still retaining around 60 mpg ( uk gallon is 4.5 ltrs think american gallon is 3.8 )

Interesting. I'd rather keep the original engine and just have the fuel map and such changed so when I gas it I get more power, rather than play with engine swaps.

[pgarner]

no wasnt on about swapping the engines just try and find an imported model if you can ( will also come with proper RHD )

price of a map from REVO $500
according to REVO you do get the 150 PD varient over there.
http://www.revotechnik.com/products/....aspx?pvID=326

they dont have any graphs there so here is one from a uk company called celtic tuning



yeah itll be easy enough but to get it right will take alot to time this is why so many companies charge around the £300 mark over here. the ones that are sold for £150 are generally the software and maps that you can get off ebay. yup these things give you a gain but can seriously wreak the engine.

if you do get a MK4 jetta get a copy o a program called VAGCOM this wil allow you to moniter every sensor in the car - think the license for the 409.1 version ( sutible for up to Mk4) is around $90 as it cost me around £50 when it was £1 - $1.91 and cable can be bought on the bay for around £10 . if you go for the newer Mk5 however you need to get rosstechs own cables and the software is a free download.

[bluefoxicy]

Originally Posted by pgarner

if you do get a MK4 jetta get a copy o a program called VAGCOM this wil allow you to moniter every sensor in the car - think the license for the 409.1 version ( sutible for up to Mk4) is around $90 as it cost me around £50 when it was £1 - $1.91 and cable can be bought on the bay for around £10 . if you go for the newer Mk5 however you need to get rosstechs own cables and the software is a free download.

Yeah, a friend of mine offered me his VAGCOM computer and license for some $200 or so, problem being I don't know how to use it (well ok, plug in, adjust numbers, but... yeah). I'm looking around 2001-ish, my eyes are on a 2003 today because the 2001 I wanted got sold. Of course, I don't have the money right now, so this is just general poking around.

Really my needs aren't that demanding. I'm mostly in it for self-amusement and learning. A friend of mine said if he got a VW Jetta TDI he'd have to retune it to throw 500ftlb 300hp and get like 14mpg (nah, he'd probably get 30-35; I've seen a BMW I6 do 1400ftlb 800hp at 25mpg). Definitely don't care for that

Anywhere I can look to find methodology for doing the actual tweaking?

[pgarner]

vagcom itself is a diagnostic tool itself and cant be used to tune the engine. it only allows you to moniter varibles.

not sure where to look for the help. try and get in touch with gadi on here as hes custom mapping his clio dci so might be able to help you out
i think the basic idea is to up the boost pressure slowly and then adjust the fuel to match but not sure. something id rather pay out £300 for and know ive got a warranty on it on top of it being a tested map.