IQ changed to 5 but no mileage improvement..

Hi Gurus,

I used to have IQ setting of 1.4 and it was shuddering for a long time and good amount of smoke during acceleration, start-up and cold running. A tank ago, I changed IQ to 5, significant reduction in smoke and I thought that should equate to +5 mileage improvement but didn't see any improvement. Does it take at least few tanks for the ECU to optimize? I also observed little bit more engine sound and pickup has gone down after IQ to 5. Any thoughts please..

IQ - 1.4 - 48-50 MPG - Shuddering and smoke
IQ - 5 - 50 MPG - No shuddering, very less smoke, more engine sound, less pickup

02 jetta 02M transmission, Mobile diesel

Thank you Gurus. Have a good day!!

Why were you expecting +5 mpg? Was there a particular thread that lead you to believe this? I've never heard of an IQ adjustment giving +5 mpg.

I guess then my bad. Thank you for keeping me on my toes

Hey I could be wrong, but you'd have to point me to the information that indicated this sort of FE change. I've seen no change in FE when changing IQ from 3 to 5.

I thought I read some of DBW postings. But it was a while ago. I am getting old so my memory is fading

I retimed an A3 AHU that was getting around 40 mpg, timing wasn't even on the graph, hard starts, lots of smoke, etc. After timing it the owner reports over 50 mpg all the time, great power, no smoke. I also timed a 1Z B4 and the owner is now getting over 50 mpg whereas he never did before.

So I suppose it's possible, but that was a complete timing revamp, not just an IQ change. I have also not noticed much difference from an IQ adjustment other than smoke output. Power and MPG seems the same.

My 2000 golf is running an IQ of about 8 just to reduce smoke. Running Titan 520 nozzles and a Malone stage 2 tune. Even had mark dial back the fueling but 13 percent. Still get a little smoke but not enough to bother...but man, does that car move! The car was an auto trans car so it has an 11mm pump too.
Mileage, about 50 on the freeway.

Abacus said:

I retimed an A3 AHU that was getting around 40 mpg, timing wasn't even on the graph, hard starts, lots of smoke, etc. After timing it the owner reports over 50 mpg all the time, great power, no smoke. I also timed a 1Z B4 and the owner is now getting over 50 mpg whereas he never did before.

So I suppose it's possible, but that was a complete timing revamp, not just an IQ change. I have also not noticed much difference from an IQ adjustment other than smoke output. Power and MPG seems the same.

Click to expand...

What did you set the timing at?

Advanced, near the upper green line but not over it. Also put the injection pump pressure regulator back in since it had popped out a little.

op have you tried setting your iq back to stock value (32768) then using the hammer mod to set iq at 5.0. This helped my mileage tremendously and car runs much more smoothly (probably because it was reading 1.4 at stock value to begin with). As a caution if you do this with engine running you just barely want to crack loose the bolts not 180 degrees as this will spray diesel fuel everywhere. http://forums.tdiclub.com/showthread.php?t=258297