5 replies to this topic

[Todd Tagget]

Ok ,

Semi new build from a crashed 1.6.. Re-tubed

 

Running pig rich ,, Here's what we've done:

replaced fuel pressure regulator

replaced AFM

replaced throttle body

replaced temp sensor on back of motor

pretty sure there's no vacuum leaks ( that would cause it to run lean anyway right ? )

confirmed fuel lines are correct ( wont run when switched )

 

 

All ideas are welcome!!

 

[LarryKing]

Adjust A/F ratio via fuel pressure while on a dyno. AFM meter clockspring can also be adjusted. Some experts recommend rotating the AFM so that lateral Gs do not effect 'door' position.

[Todd Tagget]

Adjust A/F ratio via fuel pressure while on a dyno. AFM meter clockspring can also be adjusted. Some experts recommend rotating the AFM so that lateral Gs do not effect 'door' position.

I"m well aware of all of those options, but am trying to get to the root cause of it running so rich.. The engine ran fine when it was pulled from the crashed tub. 

[LarryKing]

My money is on a vacuum leak, post MAF. The ECU is possibly compensating for increased oxygen detected by the O2 sensor. Just a guess.

[luvin_the_rings]

How do you know it's running rich?  Do you have an Lambda/AFR gauge?  Does it Idol fine but run really rich when you open the throttle? Or is it idling rich?  Our engine will fluctuate between 11.0 and 14.0 during idol. 

 

We had an issue with the engine idling rich and rough and it turned out that the flapper door on the AFM was getting stuck one notch before it closed, making the ECU think that it had like 20% throttle, but the throttle plate was completely closed. 

 

FYI, there is no MAF sensor on this 1.6 engines.  The engine only runs in closed loop during idol.  Once you get up off the idol control, its open loop.   So, off of idol, it's only looking at cam position and AFM meter readings.  It will adjust the ignition timing and possibly the injector duty near redline if the engine temp sensor is reading above ~200F, but this is a minor adjustment and shouldn't effect the Lambda too much during open loop revving. 

[Todd Tagget]

Just an update.. looks like the FPR was bad as was the replacement.. Put an adjustable one in and seems to bring the AFR's back into a reasonable range.