While looking to solve the LTFT Low issue with cams and hard pipes I noticed that at idle the MAF Hz value will never hold steady. Occasionally it even spikes huge. I then looked to find other factors that could contribute to this. As it turns out Load also spikes at the exact same time and by huge amounts.

What could be causing this to happen?

I logged at cruise and both MAF Hz and Load remain relatively stable.

 

I have noticed the same thing. I'm not sure if it is related to changes in fueling and timing to compensate for idle stability, but the jumps are much more pronounced now that I have bigger injectors in.

I attributed it to low airflow with cams, but I also wanted to drop my non-cut airbox lid back on and see if that changed anything. It can also be related to sound (why I think I get idle dips when people rev by me) and the radiator fans.

 

Cooling fan turning on?

The MAF Frequency is an input, load is merely calcualted from MAF Frequency and if MAF frequency spikes, so will load. Thus, if the MAF frequency is spiking, then something in the intake pipe/inlet area is physically causing the spike and it is most likely not related to anything within the ECU.

 

The cooling can wouldn't matter since I built a heat shield around the filter to isolate it from any engine heat or airflow.

The fans were not coming on though.

What would cause the MAF spikes then? They are so random.

 

Vibration?

Physical or sonic...

 

Great....so how in the world can I isolate it????

 

This also could be a problem of resolution. Make sure what you are logging where it looks like a "spike" is not just the minimum difference between 2 values. That could make it look "spikier" than it actually is.

 

Yeah I realized this when I was looking at the graph. I assure you that a spike from 33Hz to 57Hz is far above the norm.

Any ideas how I can cure this?

 

I noticed when logging idle trims that the car cycles through a voltage drop about every 4 mins. Similar to when the routines recalculate. I would have a massive voltage dip like clockwork, on a repeatable timeline - regardless of the fan. The ECU is doing something that creates this...

 

I wish this were repeatable....the spikes are sparatic.