Canadian '94 1.8L Gas - HORRID mileage

[vanbcguy]

Yeah, this isn't a diesel, but there aren't too many places out there with lots of us Canadian folks!!

In addition to the diesel we've got a '94 1.8L monomotronic, it is an automatic.  Fuel mileage is absolutely crap - 16.5L/100km or so.  I replaced a bad thermostat a few weeks ago hoping the issue was related to it not warming up completely but no dice - still burning through fuel like no tomorrow.

I know it's never going to get single-digit numbers but I was hoping to at least get it in below the teens.  All the "usual" stuff like fuel filter, etc has been checked.  Plugs and wires are basically new.

Any thoughts?

[R.O.R-2.0]

coil any good?

is the trans in good working order? its never going to get awesome mileage, being a 1.8/slushomatic..

[vanbcguy]

Haven't checked the coil... The car starts fine even when dead cold so I think it is throwing a good spark.  No apparent misfires or anything, it drives fine.

The transmission seems to be fine, it shifts nicely enough, there's no weird noises or anything.  It does sometimes hold on to a higher gear than I'd want it to unless I give it a good shot of the go-pedal but I don't consider that "unusual" for an auto.

I haven't gotten in to the vacuum lines or anything yet.  There aren't too many on this vehicle really.  Hrmmm... EGR? Haven't checked that either...

[TylerDurden]

Dragging brakes?

[vanbcguy]

Just serviced the rears a few weeks ago, they spin freely.  Wheel bearings are in great shape.  No change in mileage before/after.  The fronts appear to be fine - they are not getting hot or anything like that.

Anyone else out here have a 1.8 monomotronic with an auto?  I don't really know what to expect mileage-wise.  My 2.0ABA manual could get 475+km to a tank, my diesel gets 650km around town unless I'm really beating on her, and closer to 800km on the highway.  The 1.8 auto is getting more like 275km.  I'd be happy with 350!

[8v-of-fury]

That is worse than my 84 1.7 with the CIS (Constantly Injecting Stuff) Mechanical injection and a super close gear box! .90 5th! I could get minimum 10L/100km out of it, which netted near 400-425 to a tank.

Something has gotta be wrong.. they produced this setup as an economy option. TBI and an auto, yeah! they were going for base price economy. LOL. I have never had the misfortune of driving one, hows the power?

[vanbcguy]

Power is... Well, I haven't managed to find it yet.  I'm sure it's in there somewhere...

It accelerates from a stop about the same as my TD..... before the turbo spools.  I always expect it to start increasing power as the revs go up.  Not so much!!  It can get out of its own way though.  Not the quickest vehicle I have driven by any means!!

The ACC engine was rated at 90HP at 5500 RPM and 107 ft-lbs at 2500 RPM.  So it claims to have more power than the AAZ, but the same peak torque.  I know it doesn't come anywhere close to where Jezebel is with her 1.6L @ 25 intercooled PSI and stick shift in exactly the same body.

[8v-of-fury]

Well with that horrid mileage, probably safe to say she isn't running right. As you say those power numbers would put it on par with an AAZ, they have some balls.

[vanbcguy]

I think I'm going to start by checking out the EGR valve and going from there.  The other thing to note is it passed emissions fine not too long ago so it isn't running rich and it doesn't have high NOx levels, but excessive EGR "air" would cause lean running without NOx which the emissions test wouldn't care about.

[R.O.R-2.0]

I think I'm going to start by checking out the EGR valve and going from there.  The other thing to note is it passed emissions fine not too long ago so it isn't running rich and it doesn't have high NOx levels, but excessive EGR "air" would cause lean running without NOx which the emissions test wouldn't care about.

take it off, check your mileage..

[bajacalal]

Sounds like you may have a clogged cat.

I thought this was common on the MK3. The oxygen sensor goes, which makes it run rich, which clogs up the cat.

You said it passed emissions, but then again I've passed cars here in California with NO cat (or at least a hollowed out one). Some engines run really clean, clean enough to pass emissions tests if the standards are loose enough, and others well... they don't.

[8v-of-fury]

Canada is really cracking down on emissions, so I dunno if his car fooled the test or not.

[nwcali6]

Could be the O2 sensor, clogged cat. 

  Last time pluggs were changed?

  How do these time themselves?  Can it be changed by the user?  I have a 2.0 that was given to me that I'm going to sell, it seems the timing could be off even if there is a crank positioning sensor.  I've not looked in the book yet to check it out...

  A good tuneup, followed with checking the cat and a new O2 sensor.  If it is still getting that bad after all of that a compression check maybe?  Maybe a bad, but still running MAP/intake sensor?

[R.O.R-2.0]

Could be the O2 sensor, clogged cat. 

  Last time pluggs were changed?

  How do these time themselves?  Can it be changed by the user?  I have a 2.0 that was given to me that I'm going to sell, it seems the timing could be off even if there is a crank positioning sensor.  I've not looked in the book yet to check it out...

  A good tuneup, followed with checking the cat and a new O2 sensor.  If it is still getting that bad after all of that a compression check maybe?  Maybe a bad, but still running MAP/intake sensor?

being that these cars (1.8 digifant, 1.8 TBI, and 2.0) all have computer controlled timing.. the timing is supposed to be set to 0*..

if the timing is not right, the computer just compensates it.. so, even if you adjust the timing, the ECU will just compensate, and bring it back to where it wants it..

moral of this story, dont adjust the timing, it just pisses the engine off..

i would try looking at the cat, hollow it out, and try again..

[nwcali6]

Could be the O2 sensor, clogged cat. 

  Last time pluggs were changed?

  How do these time themselves?  Can it be changed by the user?  I have a 2.0 that was given to me that I'm going to sell, it seems the timing could be off even if there is a crank positioning sensor.  I've not looked in the book yet to check it out...

  A good tuneup, followed with checking the cat and a new O2 sensor.  If it is still getting that bad after all of that a compression check maybe?  Maybe a bad, but still running MAP/intake sensor?

being that these cars (1.8 digifant, 1.8 TBI, and 2.0) all have computer controlled timing.. the timing is supposed to be set to 0*..

  But it still has a physical position that can be changed and the computer can only compensate so much?  I'd imagine it would (should) put up a CEL if its off too much..  =

if the timing is not right, the computer just compensates it.. so, even if you adjust the timing, the ECU will just compensate, and bring it back to where it wants it..

moral of this story, dont adjust the timing, it just pisses the engine off..

i would try looking at the cat, hollow it out, and try again..