MVD - Montreal Vdubbing

[akrallysport]

To Dan and/or Chris...

Alright, here goes nothing... my fuel consumption even with the recent warm/humid weather is downright dreadful. The fuel light turns on like clockwork after 375-380km on a full tank and the last time I had similar mileage was with my 1990 Integra that had a rusted out tank. The only difference is that the Acura smelled like fuel 24/7, so it was a no brainer.

Here are the main symptoms:
- On startup, it idles slightly higher, but rough and RICH. A quick blip usually produces a cloud of unburnt fuel out back. 99% of the time, idle smooths out once warmed up.

- While driving partially warm, clutching and easing off the gas, revs drop to 400-500, struggles but eventually returns to 800. Logic indicates a vacuum leak or throttle body issue, but again it's intermittent.

- But then, every blue moon it decides to run rough at a stoplight and die. It happened today, barely getting it started with lots of throttle (and the a**hole who blasted the horn when the light turned green got a cloud of fuel in his grille... stayed waaaaaayyy back after that).

- No CEL.

Any suggestions? Coolant temp sensor? O2 sensor? Can a leaky downpipe affect the O2 sensor that much?

I'm just trying to maybe justify $130 worth of parts for an engine that will be pulled in June/July or put that towards the TD replacement engine rebuild.

Me thinks a vag-com will be on my b-day gift request.

[MK3NORTH]

OBDI or II?

A leaky downpipe can cause all sorts of havoc on an 02 sensor reading.

[SilverBullet006]

Deffective coolant temp sensor.


Can not run fuel management on closed loop, thus thinking engine is coldand running rich = poor economy.

Also, this will affect warm engine start-ups. Either long cranking or flooding....

[akrallysport]

I'll admit, the downpipe leak has gone from non-existent to worse, but hasn't changed the symptoms... and no warm-engine starting problems either.

It's a 97, with an OBD-II plug, but the wiring matches the OBD-I wiring diagrams in my Bentley manual.

Gah! I think I'll be placing a large parts order to accelerate the TD rebuild and include a coolant temp sender for $30. I really can't justify an O2 sensor when I know the ABA will be receiving a Megasquirt or other programmable EFI setup which will not require it.

[akrallysport]

Dunno whether it's the humidity, but it just developped a massive missfire on the way to school. My guess is that the plugs are fouled. Again, no CEL. Looks like it's going to be parked for a while until I can do the engine swap.

[Mech2]

I would start by disconnecting the oxygen sensor,drive the car and see if the problem disappears.OBD1 cars would follow whatever the sensor tells them to the point of stalling with no codes.If the O2 sensor is defective disconnecting it will show an immediate result.If not the next in line is the temperature sensor or circuit.Ceck the circuit and if ok replace the sensor.They are not expensive.Last would be MAF sensor.Check readings with VAG Com and see what shows.Normal is 2.6 to 2.9 gps at idle,engine hot.
_________________
Chris Linstead
CB Garage
1000 Blvd. Decarie
Montreal,QC H4A 3H9
514-481-9208
www.cbgarage.com
cbg@total.net

You never know who your true friends are until a time of crisis.

[Broke4speed]

Coolant temp sensor IMO.
_________________
SMR 1974-2004
=======================
My apartment smells of rich mahogany, and I have many leather-bound books. I'm quite a big deal.

[akrallysport]

I am completely baffled... it ran fine on the way home. Rich but no hesitation and loads of power at the top end.

[Mech2]

Your symptoms are variable because the problem is variable.Solve the rich running and the rest should be ok.Temp sensors can give variable erratic signals which the computer follows,same for the O2 sensor.
_________________
Chris Linstead
CB Garage
1000 Blvd. Decarie
Montreal,QC H4A 3H9
514-481-9208
www.cbgarage.com
cbg@total.net

You never know who your true friends are until a time of crisis.

[akrallysport]

It's officially parked... there's a new worrisome knocking noise in the valvetrain. Teardown of the turbo diesel starts tonight... now aiming to have it ready in May.