SDI - 86mpg!

[decvalts]

My best result yet. Can't believe a 20+ year old car just seems to be getting better with age, SDIs are like a fine wine 😆. Filled up after 580 miles and the fuel light hadn't even come on. It would have easily done 600+ on the tank taking it to the line. Maybe the warm temperatures are helping. Flatter terrain than my usual routes through the Scottish Highlands, but not totally devoid of some hills either.

I reckon 90mpg might actually be possible on a very flat route, perhaps with some weight shedding, I even had the windows down the whole journey... 

Edited August 14, 2022 by decvalts

[tchouki85]

it's beautiful with an sdi especially personal with my Lupo tdi which is remapped to 115hp I manage to do 680km with my full tank but with a full tank I basically get to do 5l/100km

[mk2]

Yes it's true. That is why I have more than one SDI. I'm convinced that the SDI is still one of the most efficient cars on the road- even compared to brand new models. It's the smallest direct injection, non turbo diesel engine on the market. Ever. 👍🏻 Oh so good... Oh so good. Yay. Yay... 😀

[decvalts]

I had a (much newer!) 1.2 TDI Polo Bluemotion for a while a few years back, and I could never get anywhere near the 83mpg (combined!) figure it claimed. (I did manage mid seventies ish once with it, but it was an effort...). The SDI hits its combined/mixed-driving figure (64mpg) with ease, and I'm managing to regularly beat the "open road/highways" figure of 78mpg now. I think you are right about it it being one of the most efficient combustion-engine cars on the road in the UK (aside from imported 3Ls). I can't think of any others that better it?...and I've looked

[mk2]

I've found that with the TDI flavour engine (1.2/1.4), the torsion number (in VCDS) seems to affect the economy. But I don't know why. It also affects the emissions. I'm convinced it works in the same way as the timing position of the injection pump on the SDI (and other style VE pump diesel engines). I guess that the start of injection is in effect fixed by the position of the cam lobe (on TDI) and the pump cam lobes in the VE pump. But the timing is "variable" as set by the ECU... I get how it works, kinda, but can't explain why changing it has such an effect. 🤷🏻‍♀️

[ObjectiveAway]

Remaped 1.4tdi Lupo can get around 85 mpg if you drive 35mph on road to save fuel.

[tigcraft]

I’m running on an old ‘piggy back’ style  £15 eBay chip on mine from years ago and it produces ave 52mpg although loadsa fun in return. It does stink rich when I start it.  Would it do more mpg if it had a ‘real’ remap? 

[Sarahs Lupo]

i have never gotten more than 60 odd in my SDI - i cant seem to fill it with enough fuel lol. 350 miles to a tank is my normal i know we had this discussion on a previous thread about poking the air button thing in the petrol cap but i couldnt seem to understand what to do 

[tigcraft]

There’s a tab right at the top and the cap hits it when you put it back on. 

[mk2]

11 hours ago, Sarahs Lupo said:

i have never gotten more than 60 odd in my SDI 

I reckon that either your injection timing is out or the EGR is not working right.

The exhaust "smell" should be slightly sweet, never smokey, acrid or diesel tainted (unburnt fuel). A while back, one of mine was a bit smelly, like an old diesel truck, but still passed emissions. On VCDS everything checked out just fine. But my other SDIs had a much sweeter smelling exhaust aroma. So I messed with everything, and thing that sorted it was advancing the pump "very" slightly- by perhaps only 1/2-1 degree. Now all my SDIs run and smell the same. And quieter and more economical too. Tweaking the cam timing on a TDI (3 bolts) has the exact same effect, but you can measure it on that engine.

The official way to set up the injection timing on an SDI is by measuring the variable power value (PWM) to the advance solenoid that's mounted on the side of the pump. Use VCDS- Crap method. The old way where you insert a micrometer dial gauge into the distibution pump plunger port is way more accurate. I need to measure all of mine and get an average reading. I'll post on here the mm value at TDC if I ever get round to doing it.

 

[ObjectiveAway]

On 8/16/2022 at 11:15 PM, tigcraft said:

I’m running on an old ‘piggy back’ style  £15 eBay chip on mine from years ago and it produces ave 52mpg although loadsa fun in return. It does stink rich when I start it.  Would it do more mpg if it had a ‘real’ remap? 

Yes, remaping can increase mpg and power at same time, ebay chip is very low improvement.

[Sarahs Lupo]

On 8/17/2022 at 8:48 PM, mk2 said:

I reckon that either your injection timing is out or the EGR is not working right.

The exhaust "smell" should be slightly sweet, never smokey, acrid or diesel tainted (unburnt fuel). A while back, one of mine was a bit smelly, like an old diesel truck, but still passed emissions. On VCDS everything checked out just fine. But my other SDIs had a much sweeter smelling exhaust aroma. So I messed with everything, and thing that sorted it was advancing the pump "very" slightly- by perhaps only 1/2-1 degree. Now all my SDIs run and smell the same. And quieter and more economical too. Tweaking the cam timing on a TDI (3 bolts) has the exact same effect, but you can measure it on that engine.

The official way to set up the injection timing on an SDI is by measuring the variable power value (PWM) to the advance solenoid that's mounted on the side of the pump. Use VCDS- Crap method. The old way where you insert a micrometer dial gauge into the distibution pump plunger port is way more accurate. I need to measure all of mine and get an average reading. I'll post on here the mm value at TDC if I ever get round to doing it.

 

perhaps your right about the EGR - i wouldnt even know how to check.. pretty sure it was new or cleaned a few years back before i got the car 

 

[mk2]

Try pulling off the vacuum hose from the EGR valve (and block it so nothing gets sucked in). That's a quick an easy disabler, but if it's jammed open, it'll still bleed exhaust gas back into the clean air inlet.

[Sarahs Lupo]

On 8/20/2022 at 1:18 PM, mk2 said:

Try pulling off the vacuum hose from the EGR valve (and block it so nothing gets sucked in). That's a quick an easy disabler, but if it's jammed open, it'll still bleed exhaust gas back into the clean air inlet.

Got a pic ?

[decvalts]

4 hours ago, Sarahs Lupo said:

Got a pic ?

Not the best pics - but a small screw or bolt will go inside the ends of the vacuum hoses here:

Edited September 5, 2022 by decvalts

[Sarahs Lupo]

On 9/5/2022 at 4:41 PM, decvalts said:

Not the best pics - but a small screw or bolt will go inside the ends of the vacuum hoses here:

Amazing thanks 

[Sarahs Lupo]

On 8/20/2022 at 1:18 PM, mk2 said:

Try pulling off the vacuum hose from the EGR valve (and block it so nothing gets sucked in). That's a quick an easy disabler, but if it's jammed open, it'll still bleed exhaust gas back into the clean air inlet.

I tell ya what though. Found the little air bleed nipple thing.  Poked it with the petrol pump the last time I filled up. Might make it to 400 miles on this tank.  Which is more than I ever have 

[tigcraft]

Yippee 👏🏻 

[mk2]

I'd still give the EGR delete a go... but timing is probably more likely slightly out? 

[Sarahs Lupo]

15 hours ago, mk2 said:

I'd still give the EGR delete a go... but timing is probably more likely slightly out? 

I will have to check when im in the new house. i still have VCDS lite and the little cable so i could check with your help im sure. 

i managed 400 miles until the petrol light has come on. currently on 420 so i need to fill up now i am very impressed