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Engine Specific Info and Questions => IDI Engine => Topic started by: honda_vtec2 on July 26, 2008, 11:50:17 pm

Title: What is the best mpg i can't expect from a 1997 jetta td AAZ
Post by: honda_vtec2 on July 26, 2008, 11:50:17 pm
Hi everyone, what is the absolute best mileage i can expect from a 1997 1.9 TD AAZ?

What are the best tweaks, mods to use to achieve the best power/mpg ratio while driving this car. I've read most of the posts on here and noticed that 1 individual is getting up to 1000km by placing a k24 turbo on the car instead of using a stock ko3.

I'm just looking for the cheapest/easiest mods to obtain better mpg on this car.

Thanks
Title: What is the best mpg i can't expect from a 1997 jetta td AAZ
Post by: homerj1 on July 27, 2008, 04:48:10 am
I'm driving a 94 & 95 Jetta both have aaz motors and are high mileage cars,  ( 453,000  & 335,000 kilometers) with no mods - except the 94 is missing its mufflers :)

My in town fuel economy is about 37-39 mpg consistently.

I hope helps?
Title: What is the best mpg i can't expect from a 1997 jetta td AAZ
Post by: Infinitrium on July 27, 2008, 09:48:52 am
I had a 93 Jetta with an AAZ and the CHD tranny. No matter how hard I drove it, my fuel mileage never went below 40 mpg.
Title: What is the best mpg i can't expect from a 1997 jetta td AAZ
Post by: honda_vtec2 on July 27, 2008, 02:34:19 pm
This 97 Jetta has the AAZ engine and i believe the ATH tranny. I'd really like info on what the best mods are to improve the mpg to around 50 or more.

Thanks
Title: What is the best mpg i can't expect from a 1997 jetta td AAZ
Post by: James8485 on July 27, 2008, 03:17:07 pm
i know i had a K03 turbo on my rebuilt AAZ and i got around 750 per tank of highway 115 km/h around 2800-3000 RPM i did the pin from the 1.6TD and then i did the pump mod where you join the 2 wires together and removed the switch on top the IP....reached around 800 k's now my last mod was putting a K24 turbo on instead of the K03 and i reach 950-1000k's now of strickly highway driving doing no more than 2800 RPMs

when driving with the K03 doing this my boost was 10 PSI
when driving with the K24 my boost is 4-5 PSI so my pin isnt out as far pumping in the fuel is what i recken. but ya 750 ----> 1000 with the bigger turbo

alittle more laggy but wow when it hits its like driving a new car!! more MPG and More POWER!!!! cant go wrong!
Title: What is the best mpg i can't expect from a 1997 jetta td AAZ
Post by: Dirtrag2 on July 27, 2008, 06:38:30 pm
X2

my '97 AAZ on fresh engine got 750 per 50 liters, now with a T3 and 1.6pin 800-900km on windy, up and down country roads.  about 41mpg US or 48 mgp imperial.
Title: What is the best mpg i can't expect from a 1997 jetta td AAZ
Post by: stewardc on July 28, 2008, 04:19:33 am
My AAZ has a Giles pump, T3 turbo with 2.5" downpipe and exhaust, ported head, etc, etc, etc. I regularly get 55 mpg (Canadian gallon). However, it is in an 800kg Rabbit pickup.
Title: What is the best mpg i can't expect from a 1997 jetta td AAZ
Post by: slorimer on July 28, 2008, 07:30:14 am
In my 94, I am regularly getting 900-950Km per 51-53L, which comes out around 49-51 Imp MPG.  The only thing I've done is pumped up the tires to over 40 PSI, and slowed cruising speed down to 110km/h.  I disabled the daytime running lights, but any improvement is in the noise cause I just found out my voltage regulator is gone.  Also my wastegate is stuck closed so I see 25 PSI with anything more than very slow acceleration.
Anyone know where I can get a used alternator for the 94 1.9L for under $100?
Title: What is the best mpg i can't expect from a 1997 jetta td AAZ
Post by: numbnuts on July 28, 2008, 01:25:49 pm
i have been driving my 96 golf aaz with k03 for the last 3 months mainly to get me to and from work. This consists of about 5 miles in the suburbs so not too busy and then a 10 mile blast down the motorway at about 80mph. I am running 1.1bar boost a rover fuel pin and also the fuel screw turned in a touch, it needs more to really get it going but i haven't plumbed in the egt yet :shock:
Anyway i am getting an overall 41 mpg and i don't hang about in it taking it easy. I do think the cth? 5 speed is a little to under geared as its revving too high in the motorway. I also have a t3 to go on when i get the time to rebuild it. I do think that if u run a bigger laggyer turbo and are not on boost as much, you will not be using as much fuel as before. With the ko3 i mostly seem to be 0.8bar and over :)
Title: What is the best mpg i can't expect from a 1997 jetta td AAZ
Post by: honda_vtec2 on July 29, 2008, 04:11:41 pm
The guys with the mods, is your car smoking at all or does it smell like diesel and stuff. Thanks

50+MPG on the AAZ sounds fantastic! I hope i'll be able to hit that and more with an old engine...lol
Title: What is the best mpg i can't expect from a 1997 jetta td AAZ
Post by: honda_vtec2 on July 29, 2008, 06:38:57 pm
Quote from: "James8485"
i know i had a K03 turbo on my rebuilt AAZ and i got around 750 per tank of highway 115 km/h around 2800-3000 RPM i did the pin from the 1.6TD and then i did the pump mod where you join the 2 wires together and removed the switch on top the IP....reached around 800 k's now my last mod was putting a K24 turbo on instead of the K03 and i reach 950-1000k's now of strickly highway driving doing no more than 2800 RPMs

when driving with the K03 doing this my boost was 10 PSI
when driving with the K24 my boost is 4-5 PSI so my pin isnt out as far pumping in the fuel is what i recken. but ya 750 ----> 1000 with the bigger turbo

alittle more laggy but wow when it hits its like driving a new car!! more MPG and More POWER!!!! cant go wrong!


James, I live in the Toronto area. I'd like to run a setup like yours, where is the best place to get the parts that you are using?
Title: What is the best mpg i can't expect from a 1997 jetta td AAZ
Post by: dieselweasel on August 03, 2008, 06:11:07 pm
These 1.9s tend to not be as good on fuel as the 1.6s are.  Perhaps its because the mk3 bodies are heavier than those of the mk1 and mk2s...not sure.  

I've had two 1.9s...my first was '93 Golf which always averaged around 37 mpg US.  Could never get any better no matter what I did, although got about 45 mpg US on it ONCE, driving 50-70 km/h through New England.  My second and current car is a '94 Jetta, so far it consistently gets 42-44 mpg US (50-52 mpg imperial).  

On both cars I did the following mods and the fuel mileage definitely got better:

-advanced inj pump timing to .039" ( most guys do this to their VW IDIs...I believe the stock setting of ~.033" was to meet emissions...more NOx produced as inj timing advances, but better power and fuel economy)

-there is a valve with a solenoid on it right on the front bottom of the pump...it effectively prevents the dynamic timing advance in the pump from working below 3000 RPMs which is no good, so run a wire to it from the fuel shutoff solenoid which will keep fuel flowing to the advance mechanism all the time

-keep tires inflated on the high side
-rarely use A/C
-rarely go over 100 kmh
Title: What is the best mpg i can't expect from a 1997 jetta td AAZ
Post by: mattbondy on August 03, 2008, 07:24:37 pm
I would suggest checking out the www.vwdieselparts.com/forum general diesel forum. There is a sticky post regarding internal pump pressure. Most users on this forum are running vehicles with the 1.6 or 1.5 so Im not sure if their is any difference in the pump on the 1.9. (Someone above mentioned something about a solenoid controlling timing advance?)
I think this is basically what Giles must do (adjust the timing advance mechanism) among other things. There is a systematic method of going about this in this post:
http://www.vwdieselparts.com/forum/viewtopic.php?t=5936&sid=b42978438754b51e5cbb58d4ba6d78cf
I just adjusted the timing advance piston and have been playing it by ear/ odometer but that is probably not the best way of going about this. There are holes that you want to avoid obstructing completely at the very least.
Title: What is the best mpg i can't expect from a 1997 jetta td AAZ
Post by: honda_vtec2 on August 03, 2008, 09:24:40 pm
Thanks so far for the info and tips guys, please keep em coming.
Title: What is the best mpg i can't expect from a 1997 jetta td AAZ
Post by: jtanguay on August 03, 2008, 09:37:00 pm
Quote from: "slorimer"
In my 94, I am regularly getting 900-950Km per 51-53L, which comes out around 49-51 Imp MPG.  The only thing I've done is pumped up the tires to over 40 PSI, and slowed cruising speed down to 110km/h.  I disabled the daytime running lights, but any improvement is in the noise cause I just found out my voltage regulator is gone.  Also my wastegate is stuck closed so I see 25 PSI with anything more than very slow acceleration.
Anyone know where I can get a used alternator for the 94 1.9L for under $100?


25 psi? stock turbo??!!!! unless that is a K24 or T3 that is wayyy past the efficiency range  :lol: better get an egt gauge
Title: What is the best mpg i can't expect from a 1997 jetta td AAZ
Post by: IainS on September 03, 2008, 11:54:58 am
My last check in my 1997 1.9 TD was 6.85 L/100 KM or 41.24 Miles per Imperial Gallon or 34.34 Miles per US Gallon.  The only thing I can really suggest for improvement is a 5th gear swap or a ring and pinion swap to get the rpm range down into a more fuel efficient range. (or find a good TDI donor)