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Discussion Starter #1
I've had my REV400 kit installed for a few months and I love it. However, I've been wondering if my AFR readings and RPM are typical or not. They tend to wander around whether the car is idling or running at higher RPM.

Here's a link to a video of the AFR at idle: AFR at idle
Here's a link to a video of RPM at idle: RPM at idle

Here's the car running at about 2500 RPM: AFR at ~2500RPM

It's harder to tell if RPM is wandering at higher RPM since I can't hold my foot perfectly still. Any wandering is small enough that after you get through the reduction provided by the transmission, it doesn't cause any noticeable variation in speed/bucking. I've never gotten a check engine light related to this, so if there is something amiss, it's not severe enough to trip the light. I don't have any pending codes either.

I have noticed at times that when I am cruising at speed, and then clutch in and let off the accelerator, RPM will drop to idle, but bounce back up, and then down again. Sometimes this happens a few times before the idle settles out. The peak RPM is perhaps 1200 RPM.

Perhaps related, or not, before the REV400 install, the car would sometimes idle a bit high. Sometimes I could correct it by turning the car off and restarting. Other times it had to cool down, then be restarted before it went away.

What I don't know is if the RPM is wandering because of AFR changes, or if AFR is wandering because of RPM changes. What kind of variation do others see in their AFRs and RPM at idle or under load? Any other thoughts or troubleshooting tips are much appreciated!
 

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I think that's all pretty normal, my AFR is much the same as yours, can’t comment on RPM, my tach moves VERY little, but it always has.
 
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Have you asked the source, BOE???
 

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First of all is that a wideband O2 sensor? If not I wouldn't trust it much.

Stoichmetric is 14.7, so your idle and even 2500 rpm doesn't look to be a problem. It looks like your gauge moves around a lot, so not sure how much credence I put in the numbers shown.

San
 

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Discussion Starter #6
First of all is that a wideband O2 sensor? If not I wouldn't trust it much.

Stoichmetric is 14.7, so your idle and even 2500 rpm doesn't look to be a problem. It looks like your gauge moves around a lot, so not sure how much credence I put in the numbers shown.

San
Yes, it's a wideband AEM meter. AEM claims it's one of the fastest meters on the market. Perhaps it's reacting faster than the O2 sensor that's actually being used by the ECU to control AFR?

 

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I am pretty sure that is normal. Mine does the same as do the others I have seen. BOE also states that it is difficult to read an active guage unless you can hold your foot super still on the throttle (I cannot, it seems to always go straight to the floor)
 
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About 12 or so yrs ago, my friend Bob (sort of famous Toyota engineer), bought his 1st BMW motorcycle. (He learned to hate that bike.)

Bob had build a number of championship winning bikes and cars. BMW had some mixture issue; dealer said "They all do that."

Bob got out his digital voltmeter and found that the Bosch oxygen sensors were very ssllloooowww.

Replaced them with Denso (lighter and less expensive) and problem was solved. He sold a bunch of kits on the web, IIRC.
 

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For comparison, please watch this video. It’s an AEM gauge as well and shows much the same as mine. I don’t think you will ever get a read out like on oil pressure or water temperature gauges.
 
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