theformula

Tim (or anyone else who's done this), Willie told me over the phone there is a procedure for doing this that you have done on your Z. Can you please explain?
Thanks

------------------
91 Formula
305 TPI 5speed
1LE/G92/WS6

Paxton SN92 polished kit, SLP airfoil, ported/polished plenum, March pulleys, Crane AFPR(43psi),Crane Gold 1.6rrs,MSD coil,MSD6AL (5275rpm limit),Holley 9mm wires,Ac delco R43ts plugs,fastchip,Ford SVO 24# injectors,Bosch O2sensor,SLP 1 5/8" headers,SLP catback,shortened shifter,3:73s w/Auburn posi,170* t-stat,JET 195* fan switch, Macewen white face gauges, Autometer gauges, Zoom hi-performance clutch.

Tim Burgess

You may bypass the knock sensor by disconnecting it from the harness. To keep the ECM from setting a code, first, measure the resistance from the output pin on the knock sensor the ground. Then, install a resistor of that approximate resistance from the wire that used to be connected to the knock sensor to ground.

I had disconnected mine for a short period of time after installing a gear drive - before I had a scanner - to see if the gear drive was causing a false detonation signal - it was not. I would not recommend leaving your knock sensor disconnected, permanently. Just out of curiosity, why are you disconnecting the sensor?

Tim

[This message has been edited by Tim Burgess (edited March 02, 2001).]

Willie

iTrader: (1)

Tim,

Ryan (theformula) installed a Paxton on his '91 Formula 1LE last month. He's getting a tremendous amount of knock retard (about 8 degrees or more across the board). I suspected it was because of detonation caused by an extremely lean condition, 611mV O2. I suggested to Ryan to disconnect the blower, which would result in a richened air/fuel ratio. This should have caused his knock sensor not to retard as much, if at all. This didn't seem to happen, so I suspect it could be a faulty knock sensor.

The problem is Ryan is not getting any audible knock and the sensor seems to retard timing an exaggerated amount. So in trying to diagnose a super lean condition, we may have discovered a bad knock sensor. Ryan wants to experiment by temporarily disconnecting the knock sensor to see if there's a difference in the way his car runs.

Willie

[This message has been edited by Willie (edited March 02, 2001).]

theformula

Thanks Willie.

I did another naturally aspirated run today and noticed I got no more than 1 degree of knock retard. Last night when I did a NA run i got 11degrees of knock retard. I don't know if the scanner I'm using is faulty or what. I bought it used. I'm not sure if it is true detonation or not. I was getting as much as 8 degrees with the blower connected. But the car ran extremely well. Very good mpg, and tremendous acceleration.

Also, is it normal for the 02 sensor voltage to fluncuate between 0 and 863 rapidly?
Should I replace the knock sensor? It has never been replaced.
Thanks guys

------------------
91 Formula
305 TPI 5speed
1LE/G92/WS6

Paxton SN92 polished kit, SLP airfoil, ported/polished plenum, March pulleys, Crane AFPR(43psi),Crane Gold 1.6rrs,MSD coil,MSD6AL (5275rpm limit),Holley 9mm wires,Ac delco R43ts plugs,fastchip,Ford SVO 24# injectors,Bosch O2sensor,SLP 1 5/8" headers,SLP catback,shortened shifter,3:73s w/Auburn posi,170* t-stat,JET 195* fan switch, Macewen white face gauges, Autometer gauges, Zoom hi-performance clutch.

Willie

iTrader: (1)

Ryan,

It sounds like your knock sensor is giving you erratic results. I'd definitely replace it, considering it is original. It would be good to know that it screws into a coolant cavity, so make sure you wear your rubber shower cap!!

It is normal for the O2 sensor voltage to oscillate back and forth (from rich to lean and back again) when in closed loop. So the data you're recording on the Xray is normal. It is at WOT that it stabilizes. For boost conditions, I like to see it at least 900mV and holding.

Willie

[This message has been edited by Willie (edited March 02, 2001).]

theformula

Well I had my girlfriends sister in the car with me today and she was viewing the auto xray under WOT. With the blower I got 16degrees of knock....

Tim Burgess

If replacing the knock sensor does not fix the problem when running normally aspirated, and the total ignition timing is less than 40 degrees, you may consider changing the electronic spark control (ESC) module - it processes the output signal from the knock sensor & passes the signal on to the ECM.

Tim

theformula

Hey man, I've been getting code 42 lately electronic spark timing (EST). Then code 51 came up (prom error) and code 32 EGR. I think the EST module needs to be replaced. YOu may be right. My car has been stalling out and I'm stuck in jersey . Any ideas guys?

Its on a 91 lb9


------------------
91 Formula
305 TPI 5speed
1LE/G92/WS6

Paxton SN92 polished kit, SLP airfoil, ported/polished plenum, March pulleys, Crane AFPR(43psi),Crane Gold 1.6rrs,MSD coil,MSD6AL (5275rpm limit),Holley 9mm wires,Ac delco R43ts plugs,fastchip,Ford SVO 24# injectors,Bosch O2sensor,SLP 1 5/8" headers,SLP catback,shortened shifter,3:73s w/Auburn posi,170* t-stat,JET 195* fan switch, Macewen white face gauges, Autometer gauges, Zoom hi-performance clutch.

[This message has been edited by theformula (edited March 04, 2001).]

Tim Burgess

If you are getting a PROM error, I'd look toward the PROM or ECM, or faulty power / ground to the ECM. Have you changed the PROM, recently? If so, try reverting back to the previous PROM.

Tim