Does your Cobra go Pffffft at 2500-2750 rpm?

[rmoreau]

I have noticed this for a while now.

While driving with the windows up, AC on or off, in 3rd gear, driving normal on the freeway, my car lets out a soft quiet Pfffffft.

It sounds like air escaping.

I get the car to 2500, and normally roll on to 2750, right in between it goes Pffffft.

I do have the by-pass mod :rollseyes that may or may not be part of it.

Does your car do this??

Randy

 

[jhwalker]

Thats a pretty good description of a sound I get sporadically at the lower rpm levels -- dealer can't diagnose, and I usually can't make it do it at the dealer :bash:
Does the car react in any way (surge or lag)?
JW

 

[rmoreau]

no reaction from the car at all.....just the sound. at first I thought it was from the AC compressor, and really it was only today that I could nail down and repeat at that rpm range.

Randy

 

[jhwalker]

Originally posted by rmoreau
no reaction from the car at all.....just the sound. at first I thought it was from the AC compressor, and really it was only today that I could nail down and repeat at that rpm range.

Randy

Yeh, Mine is the AC compressor I think -- the car shudders along with the noise. So, a different pffffttt-maker for you.


JW

 

[RickSvt]

I had it today too going about 40 in 3rd gear....the car would surge a little bit when it did it though. I just thought it had something to do with the electric fans, not for sure.......I have my boost bypass mod as well.......

Rick

 

[stangin]

Originally posted by RickSvt
I had it today too going about 40 in 3rd gear....the car would surge a little bit when it did it though. I just thought it had something to do with the electric fans, not for sure.......I have my boost bypass mod as well.......

Rick

I suspect this is your boost valve releasing boost, my KB does this more so than the Eaton and is much more noticable. You do not want boost all the time or it will wear out the S/C so it releases boost, even with the boost mod. Only other thing I can think of is the A/C, but I think you said it did it with the A/C on or off so I would suspect the boost valve and is normal.

Hope this helps..

 

[RickSvt]

I had the A/C off, I heard it from the rear of the car it sounded like, but I also had the drivers window down, I dont know for sure what it is. The car was at full operating Temp, so thats why I thought it was the fans........felt like a slight power hick-up when ever it happened though.......

Rick

 

[03rocks]

I have the exact same symptoms. Sit in your drive way and let it idle you'll find that it does it even at idle. Now turn your defroster/AC off suddenly the symptoms go away.

Basically the noise and feel on the accelerator is from the compressor turning on and off.

 

[RickSvt]

Yeah, i just took a trip in the car, I saw that I had the Floor/Defroster on, I didnt think that it was using the A/C, I thought that Defroster only used the A/C.....well it was something to do with the A/C being on......

Rick

 

[rmoreau]

not mine, its defiitly from engine compartment, wont do it in first, or at least cant hear it. ac on or off...2500 thru 2750 ...pfffft

Randy

 

[stangin]

Yes, the A/C is on with the defrost. Turn off the A/C and defrost and then see if it does it. Normally the A/C compressor will turn on and off while in use depending on the temparature so the evaporator does not freeze up.

 

[03DOHC]

That's the boost bypass.

 

[rmoreau]

so long as its "normal"

Randy