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Rather than open a thread can I ask here how 'noisy' does you rpm indication in Rovergauge appear?

I have a slight lumpy idle when hot and am in the process of faulting sensors but I find the rpm is quite jumpy in rovergauge and wondering if the lack of a capacitor or diode in the rectifier on my highly budget looking alternator is giving the ecu 'noisy' rpm information. Which is making the ECU react. Have yet to set base idle and go through the afm and tps, lamda, air leaks, fuel pressure checks (you get the idea)

It isn't huge but seems to jump up and down +/- 75 rpm when the engine hunts very smoothly and slowly.

Any opinions? will post a video if it helps but car isn't outside this evening...
 

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Discussion Starter #22
Not 100% positive, but i don't think the ECU cares abour RPM information, it operates solely from the throttle potentiometer, MAF, temp sensor and O2 sensors. There is a relationship between the road speed transducer on the speedo cable and idle, but mostly just lets the rig know you are moving and regulates a high or lower idle, not surging.
Mine does a little of that "searching", but I just ignore it.
 

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Hi Reddog, maybe but I thought the IACV would need some reference especially when idle mode is active which I agree the road speed sensor and TPS will indicate to the ECU to activate.

I'm zoning in on my idle issue in that I'm going through the well worn path of sensor verification etc but it's a fair thought that if the rpm info is noisy then the feedback loop means it will continue to hunt.

Basically if others have rover gauge and too notice at idle the rpm does flicker around a notable amount then I'm probably barking up the wrong tree. I pondered if a diode in the rectifier was bad then some AC ripple might be introduced which would have some fun on other items in the system. In reality I'm probably trying to talk myself into changing a perfectly good alternator but I'm highly suspect of anything I didn't fit to this car. Alternator is a 'universal' and looks like the cheapest one might hope to buy!

Forth bridge for those of you who know the analogy!

Sent from my LG-H930DS using Tapatalk
 
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