Rich Running Falcon- Just After Opinions

[AngryRB]

Have a Au XR6 falcon ute and trying to figure out whats doing with it. Its using like 22L/100km and can actually see it puff out black smoke when free reving it.

It runs ok with an intermittent roughness like its trying to stall on me and a few times has cut out completely on me while driving, usually as I come to a stop at a traffic lights it will get rought and the revs come down to 400-500rpm. 90% of the time she'll run perfect though.

This weekend I removed the manifold and found the intake manifold flooded with what looks like fuel, so ive installed new injectors and tightened all intake manifold bolts and resealed the plenum. Took it for a drive and still doing the intermittent wanting to stall and coughing black smoke, no engine warning lights on and will idle perfect most of the time. so got me stumped.

Have read the falcon forums and I think people on here might have more knowledge.

Just looking for sensible idea's, suggestions and not smart ass comments. Apart from this issue its a good vehicle, dual fuel and just got a paint job.

Edited April 27, 2014 by AngryRB

[Ben C34]

Oxygen sensor?

Dirty maf, if it has one.

[Ben C34]

Actually I doubt O2 sensor would make economy that bad, but would contribute.

[AngryRB]

I have a second shitbox falcon same model so I can try swapping sensors but a few mechanics said if theres no engine warning lights on then the sensors should be fine

would a blocked cat cause rich fuel mixture?

Edited April 27, 2014 by AngryRB

[blind_elk]

Running that rich has possibly fouled the plugs.

Try replacing the temp sensor - ECU might be thinking the engine is always cold.

Clean air filter. Replace fuel filter.

[Ben C34]

True. Replacing fuel filter is just general maintenence though, could never make a car run rich.

Not all issues light up check engine light. The ecu isn't that smart....

[AngryRB]

tomorrow Im gonna take it to exhaust shop and have the cat and front muffler replaced with a straight thru pipe, then replace the coolant temp sensor, 02 and map sensor with the other falcons that runs

perfect..

thanks for the help so far ..

Edited April 27, 2014 by AngryRB

[r32-25t]

Check the inlet manifold gasket where it bolts to the head normally around number 6, usually cracks and draws air causing the map sensor to read high

[Trex]

The 4l doesn't have a maf. You've already replaced the inj so I'd check the reg. you're about 13l too rich, that's a lot for a few dud sensors.

[Cowboy1600]

Try an ecu reset. Disconnect the battery, hold your foot on the brake for 30 seconds, reconnect battery. If it's getting stuck on the cold map this should probably fix it. If not then hunt elsewhere.

[gtr jet]

I take it you've checked or replaced plugs and leads? Coil?

I'd think the car would run pretty rough if they were playing up though. Not just rich.

[r32-25t]

The 4l doesn't have a maf. You've already replaced the inj so I'd check the reg. you're about 13l too rich, that's a lot for a few dud sensors.

this is correct, it has a map sensor which a vacuum leak will cause the car to run rich

[Trex]

Where's the sensor?

[r32-25t]

On the fire wall

[Trex]

If there is a leak before the map it would run lean. Engine > leak > map.

[Ben C34]

Nope. Rich as it thinks there is more load on engine.

Less vacuum, more load

[r32-25t]

What Ben said

[Trex]

Do you guys have anything I could read on how it works? I always believed unmetered air would make it lean. It's been a long day, I'm probably not reading this thread right.

[r32-25t]

It's a maP sensor not a maF sensor so it measures vacuum in the inlet manifold, the more you open the throttle (more load) the less vacuum is in the manifold.

So if you have a vacuum leak the maP sensor believes there is more load on the engine and injects more fuel

MAF= Mass Air Flow

MAP Manifold Absolute Pressure

[mad082]

Wouldn't a vacuum leak also cause higher revs on a map sensor engine?

What about a dodgy tps? Or even a dodgy injector or fuel pressure reg?