Wideband AFR lean spike and TPS behavior

[Dougal]

Hey all,

I've been reviewing a recent log I did about a month ago as I will be doing further logs today to compare these too.

Something interesting that has been worried was a massive lean spike and some strange TPS signal data recorded.

So ive attached a view of the log data in Megalog viewer.

Basically if im reading this correctly of the three rev increases I performed the 2nd one shows that even though I pushed the accel pedal further than the others that the RPMs were less and that the lean spike occurred.
AFR of 18+ (over what the AEM Uego can show in its gauge!)
No counts of knock recorded.

If there was an issue with my TPS not providing a correct signal to the ECU then could this cause this condition.

From my understanding the MAF should be recording Air flow/Air mass data to tell the ECU how much is entering and then allow correct fueling required.

If needed I can put the other log data up also.
Megalog viewer log review Spike WB and TPS Fault.jpg

Any input you guys can shed on this is helpful.

[DocWalt]

Does it happen when you're driving or only free revving?

I'm running Megasquirt and see the same leaner than expected spike when I free rev it. In my case my accel enrichment is very aggressive and in normal driving is richer than ideal, so my lean spike isn't 18+ but still.

[Dougal]

Free reving when parked. After warmup.
Its a fairly new install of chrome ecu.
Just wanting to make sure its not going to die when I do take it out for more 3rd gear pulls soon. Been 6 weeks since I took it out and this log was done in between my new baby sons feeding times.

Driving accel behavior seemed mostly normal no spikes but has hesitation at 2500rpm for a split second. AFR were under 15 all of that drive.

Sent from my HUAWEI U8950N-51 using Tapatalk

[Greg E]

If your TPS signal is cutting out, yes that will cause your lean spikes. The code takes away IPW as you let off the throttle. If the sensor or wiring is faulty, the signal cut out will be interpreted by the code as you back off the throttle.

[Dougal]

From the log graphs I posted the TPS is recorded in full so I'm now thinking that this is actually something else.

I'll still test the TPS anyway though.

Maybe MAF sensor signal?
Or I have a giant intake leak after the MAF that is only causing Lean out conditions when throttle position is over a certain amount?

Will see what the new logs show me today and adjust according to the new logs versus the old logs.
MAP sensor installed since last logs and today's new logs that I'll do.


Sent from my HUAWEI U8950N-51 using Tapatalk