///// Will bigger injectors help fuel economy on NON computer controlled diesels (specifically 7.3 IDI). /////

Andyinchville1

Veteran Member
Joined
Apr 7, 2016
Location
Virginia
TDI
2003 Jetta TDI wagon, 5 sp, 226K miles
Hi All,

Been driving my cargo van (1993 E350 extended cargo van with 7.3 IDI) much more than my TDI lately and it has come to the point where I need to replace injectors (251K miles BUT idled alot by the previous owner so lots more hours on the engine than miles may indicate).

Anyways, in the TDI world (MKIV), bigger injectors and pumps can mean more MPGs IF you keep your foot out of it ...... I was wondering does the same apply to a mechanical diesel (i.e. would bigger injectors get better MPG's on a mechanical diesel OR does that only apply to computer controlled disesels like our TDIs ?).

Thanks in advance for any and all help on this

Andrew
 

Mozambiquer

Vendor , w/Business number
Joined
Mar 21, 2015
Location
Versailles Missouri
TDI
1998 VW Jetta TDI. 1982 VW Rabbit pickup, 2001 VW Jetta TDI, 2005 VW Passat wagon TDI X3, 2001 VW golf TDI, 1980 VW rabbit pickup,
Hi All,

Been driving my cargo van (1993 E350 extended cargo van with 7.3 IDI) much more than my TDI lately and it has come to the point where I need to replace injectors (251K miles BUT idled alot by the previous owner so lots more hours on the engine than miles may indicate).

Anyways, in the TDI world (MKIV), bigger injectors and pumps can mean more MPGs IF you keep your foot out of it ...... I was wondering does the same apply to a mechanical diesel (i.e. would bigger injectors get better MPG's on a mechanical diesel OR does that only apply to computer controlled disesels like our TDIs ?).

Thanks in advance for any and all help on this

Andrew
In my experience with idi diesels with bigger injectors, the fuel economy didn't go up with larger injectors. I put bigger injectors on a 6.5 diesel Chevy and on my idi VW. From what I understand, for better fuel economy on them, simply go with stock sized high quality nozzles set up correctly from a qualified injection shop.
You want the best atomization possible for them.
 

mech644

Veteran Member
Joined
Feb 7, 2007
Location
Blue Hill, Maine
TDI
'00 Golf, '14 Touareg
I’d go to ford-trucks.com and visits the pre-power stroke diesel forum. Lots of good info there, one of the few websites that I’ve found that comes close to tdiclub in terms of info and competency of the core members. https://www.ford-trucks.com/forums/forum117/

I’ve been rehabilitating an ‘07 super duty (not diesel though) and have found to a great resource.
 

Mongler98

Top Post Dawg
Joined
Mar 23, 2011
Location
COLORADO (SE of Denver)
TDI
98 Jetta TDI AHU 1.9L (944 TDI swap in progress) I moved so now i got nothing but an AHU in a garage on a pallet.
They might, but only if you put more crap around the title of your threads!
 

compu_85

Gadget Guy
Joined
Sep 29, 2003
Location
Springfield VA
TDI
... None :S
Making sure you have good atomization - which means good injectors, and a good injection pump making maximum pressure, is the way to restore MPGs on any diesel engine.

Like TurboABA's link says, go through the rest of the chassis and be sure it's in tip-top shape. Rolling resistance adds up!

A quick google search shows the 7.3 IDI uses the same type of prechamber as the VW 1.6, which don't suffer from soot buildup like the Mercedes style do.

You should also verify the start of injection timing is set properly, and if there's any timing control devices on that pump that they work correctly too.

-J
 
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