02s drop from 750-770 to 560-600 when fans come on?

[bpman1234]

have new alternator new battery new belt redid all my grounds added some for some reason when my fans come on I get that drop on my 02s when they go off it goes backup and when in boost it doesn't read past 600 .any ideas been trying track this down even raised my fuel pressure to see if I can get to the 700 with no luck.thanks

 

[Nick Micale]

I would check the voltage at the fuel pump before and after the fans turn on.

 

[pacecarta]

whose hotwire kit is on the fans

 

[mikestertwo]

When you say you "redid all the grounds" are all the grounds still in their original locations? What grounds did you add and to where? Where did you ground the fans? You have to make sure your signal grounds and power grounds are separate.

 

[Chuck Leeper]

Check for volt drop at the pump. [Fans on & off]. Also check integrity of the pump ground.

 

[bpman1234]

ok gonna do the voltage check at the pump before and after fans turn on and off . the grounds I added were grounds to firewall from the battery grounds to the intake bolt I think I also moved the block ground strap there to should I have done that ?gonna try and put it back just to see .also added and extra battery negative cable to the chassis I also took all those connections out and made sure they were clean of paint sanded surface and reconnected even the ones that go to the fender next to the battery .was thinking of adding a long ground from the battery to the fp.is there anywhere else I should look .

 

[bpman1234]

the old fan gave out so I just got a Darrel fan and went c for ground and a for high power.

 

[bpman1234]

don't know if it makes a difference but I have no ac and my fan delay relay is unplugged not getting any power from the low side relay b on the fan connecter.

 

[bpman1234]

checked the volts at the fuel pump 13.9 fan off 13.7 fan on .

 

[fastblackracing]

Does your engine have header gaskets on it or do the headers go directly to the head?

 

[bpman1234]

Yes headers have gaskets the stock type silver looking ones

 

[mikestertwo]

ok gonna do the voltage check at the pump before and after fans turn on and off . the grounds I added were grounds to firewall from the battery grounds to the intake bolt I think I also moved the block ground strap there to should I have done that ?gonna try and put it back just to see .also added and extra battery negative cable to the chassis I also took all those connections out and made sure they were clean of paint sanded surface and reconnected even the ones that go to the fender next to the battery .was thinking of adding a long ground from the battery to the fp.is there anywhere else I should look .

Remove all those extra grounds you added and put the original stock grounds back in there original locations. Adding and moving grounds can be detrimental to the signals going back to the computer. More grounds is not necessarily a good thing.

 

[Phoneguy]

If you used the factory ground to C it is not big enough for dual fans. The duals have a high amp draw when they turn on.

Bryan

 

[bpman1234]

Ok thanks gonna go back from what it looks like the guy that put the motor had extended those grounds that are supposed to be at the tranny dipstick to the battery also gonna ground the fan to chassie ground that I made coming from the battery

 

[TurboBob]

fan wash/turbulence can cause the idle to lean out.

or you may have ground issues with the O2 sensor.

What does the wideband do under these conditions?

Bob

 

[bpman1234]

I posted a log #1 but the wideband stays pretty much the same . I went out there and cut the extra 3ft of 12gauge wire X4 that previous owner connected to the fender next to the battery negative where the battery ground wire goes .had to connect ring connecters to them 1 alone and 3 had 2 wires going to them 7 wires in all .so I had an extra intake stud bolt and took out the passenger side rear intake bolt out and put the intake stud bolt there and installed all those 4 rings there (DID SOME SEARCHING ON THIS SITE ON THOSE WIRES AND ONE OF YOU FELLOS SAID THAT THATS THE WAY HE DOES HIS CARS WAS READING FAST SO FORGOT WHO SAID IT BUT THANKS AND IT SEAMS TO BE WORKING )and got a new flat ground strap at the parts store and put it where it goes driverside head and fire wall .seams to be right now but haven't drove the car yet will post soon thanks to all that helped been chasing this for some time .

 

[Chris McDade]

What is ground to C?


Posted from the TurboBuick.Com mobile app

 

[bpman1234]

My fan is ground to c on the fan plug harness side

 

[Chris McDade]

Any pictures? I'm still a little confused.

C a wire?


Posted from the TurboBuick.Com mobile app

 

[Phoneguy]

The plug connector is labeled A , B and C.