4 Ecodiesel questions

[larry104]

1,2) I just had my '92 Eco emissions tested. In Ohio, they use what's called an opacity test. They hook up the instrument to the tailpipe and run the car to 28 mph and hold it there for about a minute. The opacity limit is 20%. Mine registered 0%! Even with rounding errors, that's less than 1%. My question is, I want to get rid of the cat and install a straight-through 2.5 in. exhaust. I've been told that the cats on these cars get plugged up. Anyone have any experience with this? I'd expect the car would pass even if the cat weren't installed.  Does anyone have the results of an opacity test from a healthy, straight-exhaust TD or Eco?

2) Airbox mods. The stock airbox inlet is about 1/2 the diameter of the ducting to the turbo. I'm thinking of tossing it in favor of a big, round K&N, or possibly perforating the stock box. Will the combination of a better breathing inlet and open exhaust make a noticable difference in performance?

3) Right now I think the car might hit 70 mph on level ground.   How fast will (should) a stock, healthyEcodiesel go flat out?

Thank you.

[Maarten]

Those mods won't help you much for more power, the ECO diesel does not have fuel enrichtment LDA so more air won't give you more fuel.

Do you have a mushroom on your injectionpump? if so, swap the lid and pin from a real TD else you have to swap the complete pump.

As far as you explained the emissiontest it seems to be easily fooled when you don't pass, just turn the pump down so it will inject less fuel..  :lol:

[zyewdall]

You can always pass the opacity test by turning the fuel screw down a half turn or so.  I did this on my turbodiesel truck, and reduced peak opacity from 48% to 9%.  Then you can turn it back up later if you want more power.  From the sounds of the opacity test, and your power description, it sort of sounds like it's already turned way down, and perhaps turning it up a quarter turn might help.

BTW, the fuel adjustment screw is supposed to be set at the factory, and never changed.....

[91 ECO]

My eco with close to 300,000 miles will cruise down the interstate at 70-75 mph no problem.  Sounds like you can turn up the fuel some, but you might want to have the cat off at that point.

[larry104]

Those mods won't help you much for more power, the ECO diesel does not have fuel enrichtment LDA so more air won't give you more fuel.

Do you have a mushroom on your injectionpump? if so, swap the lid and pin from a real TD else you have to swap the complete pump.

As far as you explained the emissiontest it seems to be easily fooled when you don't pass, just turn the pump down so it will inject less fuel..  :lol:

No mushroom -- a new pump is in order if I want way more power.  Actually, I'm more interested in fuel economy than performance with this car, but I'd like to squeeze more out of it without hurting economy, hence the proposed exhaust/intake mods. Yeah, the test seems pretty easy to sidestep. :wink:

[larry104]

If you can barely get 70 MPH, you gotta problem. My N/A Rabbit can whup 80 if pressed hard enough. Never tried for any more than that.

I'm hoping the cat is plugged. The car has only 126K and has been well maintained. Starts good, no smoke at all.

[larry104]

You can always pass the opacity test by turning the fuel screw down a half turn or so.  I did this on my turbodiesel truck, and reduced peak opacity from 48% to 9%.

Thanks for the numbers. That's good to know.

[larry104]

My eco with close to 300,000 miles will cruise down the interstate at 70-75 mph no problem.  Sounds like you can turn up the fuel some, but you might want to have the cat off at that point.

Thanks for the data point.  300K on the original motor?

[91 ECO]

Yep, it's all original.  Just normal maintenance.

[DieselMonkey]

Dont know anything about opacity readings, there is a value in the AutoData book for all my diesel VW's, but its not tested here.

I'm surprised you guys can only get 70 - 80 mph out of your Rabbits and Jetta's etc... Maybe I push mine too hard, but i've gotten my Eco (125,000 miles) to 105 mph, on motorway and down slight gradient. I'm pretty sure there was more in it.

[Rat407]

I know, my 91 ECO is fresh with a Giles pump and fresh K14 turbo, along with a 2.5" exhaust.  I ran it up to 100mph on level interstate and it had more pedal to go, just didn't want to get caught as it was and I was only pushing 10psi boost.  Just goes to show these little 1.6L engines will run.

[jtanguay]

If you can barely get 70 MPH, you gotta problem. My N/A Rabbit can whup 80 if pressed hard enough. Never tried for any more than that.

I'm hoping the cat is plugged. The car has only 126K and has been well maintained. Starts good, no smoke at all.

if the cat is plugged won't it damage the engine from back pressure??? or damage the turbo?

[larry104]

I know, my 91 ECO is fresh with a Giles pump and fresh K14 turbo, along with a 2.5" exhaust.  I ran it up to 100mph on level interstate and it had more pedal to go, just didn't want to get caught as it was and I was only pushing 10psi boost.  Just goes to show these little 1.6L engines will run.

Just curious. What about longevity with that setup? From my experience with tweaked-up motorcycles, you don't get something for nothing; great power = short life, usually.

[larry104]

If you can barely get 70 MPH, you gotta problem. My N/A Rabbit can whup 80 if pressed hard enough. Never tried for any more than that.

I'm hoping the cat is plugged. The car has only 126K and has been well maintained. Starts good, no smoke at all.

if the cat is plugged won't it damage the engine from back pressure??? or damage the turbo?

What I meant was, I hope the apparent lack of power is caused by something as simple as a plugged catalyst and nothing more serious.

[Rat407]

I know, my 91 ECO is fresh with a Giles pump and fresh K14 turbo, along with a 2.5" exhaust.  I ran it up to 100mph on level interstate and it had more pedal to go, just didn't want to get caught as it was and I was only pushing 10psi boost.  Just goes to show these little 1.6L engines will run.

Just curious. What about longevity with that setup? From my experience with tweaked-up motorcycles, you don't get something for nothing; great power = short life, usually.

Longevity with this set up is no different than any other, it is just how much you play.  If you play hard every day well then yea, it isn't going to last like a  standard stock set up.  Adding a modded IP, and letting the engine breath just opens up the engines potential. Keep the preventive maintenance going, like frequent oil and filter changes, running temps down, get and egt gage if you really want to play so you can monitor EGT's and you should be able to live a long happy life like any other diesel, I would think, abuse it and like most things it will not last.  I have to admit, abusing it is a ton of fun, considering my other vehicles are a mini van and a full size truck that doesn't handle well.  As for my 65 Impala SS, well gas is so expensive now that I can't afford 8mpg for much fun.