Running rich after cold starts. - Fuel Economy, Hypermiling, EcoModding News and Forum

sarguy01 · 09-29-2010, 08:59 PM

I have a 2006 Pacifica with 63k miles. The exhaust smells like gas after a cold start.

Anyone have any suggestions for what I should check? O2 Sensor? Leaking injector?

Maybe its normal? It makes me cringe knowing I am running rich and wasting gas.

gone-ot · 09-29-2010, 11:07 PM

..."how long" does the gasoline 'smell' persist after those cold starts? A couple of minutes or what?

sarguy01 · 09-29-2010, 11:11 PM

Quote:

Originally Posted by Old Tele man

..."how long" does the gasoline 'smell' persist after those cold starts? A couple of minutes or what?

1 minute, maybe 2? I will have to start it and then time it...

Is that normal?

gone-ot · 09-30-2010, 12:45 AM

...todays engines 'start' in "open-loop' (no computer control) which CAN be too rich, but should become "normal" as soon as the engine warms up enough for the computer to go into "closed-loop" control, usually within 1-3 minutes or sooner if being driven (loaded).

...is there a "puff" of black smoke during start-up, too? That, typically, should not occur.

Daox · 09-30-2010, 02:44 PM

Don't sit there and idle your car. Start and drive!

Mustang Dave · 10-01-2010, 12:23 AM

Quote:

Originally Posted by Daox

Don't sit there and idle your car. Start and drive!

Yeah, what Daox said. I can't believe how many co-workers will sit in their cars eating their lunch with the engine idling to power the air conditioning. And they complain about their bad fuel economy!

saand · 10-01-2010, 06:15 AM

If you are running rich (by design) at cold start you can "fix" this by putting an appropriate resistance on the MAF (mass air flow) sensor signal which will make your car leaner when the car isn't in open loop.

sarguy01 · 10-01-2010, 10:52 AM

I usually sit for 10-15 seconds and then go. I give it just enough time for the rpms to drop.

I am not sure I want to lean out the motor. I still owe money for this vehicle.

Ryland · 10-01-2010, 12:11 PM

putting a load on the engine is going to warm it up faster, so it will go in to closed loop sooner, idling your engine will put more wear on it, you should be ready to drive before you even start your vehicle, seat belt should be buckled, mirror adjusted.
I coast down my drive way and pop the clutch at the bottom so my car is moving before it ever starts, 208,000 miles and the engine is in perfect condition.