Karman Vortex Testing

[CyFi6]

Well I am having an odd issue where my idle will drop very low when returning to idle. This is on a newly rebuilt engine with parts i have not used before, so their condition was unknown. I decided to test my AFM so I did some searching. The only specs i found werefrom JetJock. The tsrm makes no mention of testing the frequency output of the sensor. I tested the frequency output of the sensor and got around 27hz at idle, and nearly 87hz at 2500RPM. From what i got from searching, idle should be around 15-20HZ and 2500 rpm should be around 35-40HZ

Now i cant confirm these specs are correct because i dont know where the original poster got the information. but if these specs are correct i am assuming it means my AFM is junk. Any help?

 

[hvyman]

hows your isc, tps, and dash pot? a cleaned isc will make a world of difference and same with the tps and dash pot set to the correct position.

 

[jetjock]

Your AFM is fine...

 

[CyFi6]

ISC was fully disassembled and cleaned, TPS is checked and perfectly adjusted etc. Reason i wonder about the AFM is because when i pull the small cruise control vac line off and drive around with that off, the idle is perfect. In fact i forgot to put that line back on and drove around and thought i fixed the problem. If the AFM is putting out 87HZ when its supposed to be much lower, wouldn't that mean the computer thinks there is more air entering the engine than there is and would run very rich? Then when i remove a vac line, unmetered air enters and it runs smoother.
Care to explain further why my readings mean its good?

 

[Poodles]

Dashpot...

 

[jetjock]

Care to explain further why my readings mean its good?

You'll just have to take my word for it. Besides, why are you worried about the signal at 2500 when dealing with an idle problem? Is the signal at idle not close to what it should be? And wouldn't more fuel cause idle to be higher, not lower? And if you think the engine is rich why don't you confirm it? If you're without a wideband use the OX terminal. That's what it's for...

 

[CyFi6]

Haha that's one thing i wish i could do, but i don't have an analog meter or an oscilloscope. What do you mean take your word for it, is it some kind of secret?

I was thinking it could be rich because fuel in excess could also cause it to stumble, and when i made it leaner by removing a vac line it idled fine.

 

[jetjock]

No secret, just don't want to explain a bunch of stuff. Same as what would happen if I said you don't need a scope or analog meter to see what a NB sensor is doing. In fact the vast majority of analog meters wouldn't work.

Btw your profile, including pics, shows you aren't even using a Karman, let alone which one, or what mods you have. Might want to update it...