Rough Idle/Hesitation/Backfire - ZR-1 Net Registry Forums

tomtom72 · 07-25-2009

Gary, I have a 90 and I know for sure that my TPS is adjustable...to what degree I don't know, but the screws that hold it in place are in slotted holes, therefore I conclude it's adjustable.

You may want to look closely at those screws as you maybe able to make an adjustment. If you say that the needle on the VOM moves thru it's sweep at a smooth progression then maybe an adjustment is in order.

Just a fwiw, try it, in the end you can always go spend the money if the adjustment don't work.

Tom

secondchance · 07-25-2009

Quote:

Originally Posted by tomtom72

Gary, I have a 90 and I know for sure that my TPS is adjustable...to what degree I don't know, but the screws that hold it in place are in slotted holes, therefore I conclude it's adjustable.

You may want to look closely at those screws as you maybe able to make an adjustment. If you say that the needle on the VOM moves thru it's sweep at a smooth progression then maybe an adjustment is in order.

Just a fwiw, try it, in the end you can always go spend the money if the adjustment don't work.

Tom

It is adjustable. Loosen up both screws just enough to be able to rotate TPS and rotate until you get .54 volts. FSM gives you an acceptable range but gurus tell me .54 is optimal.

tomtom72 · 07-25-2009

Stupid of me not to include this. When I scan my 90 at idle, in closed loop, the TPS does read .54v on my scanner. So jsut make your adjustment at idle and make sure you are up normal operating temp.

Sorry I type faster than I think.....

Tom

XfireZ51 · 07-25-2009

Quote:

Originally Posted by tomtom72

Gary, I have a 90 and I know for sure that my TPS is adjustable...to what degree I don't know, but the screws that hold it in place are in slotted holes, therefore I conclude it's adjustable.

You may want to look closely at those screws as you maybe able to make an adjustment. If you say that the needle on the VOM moves thru it's sweep at a smooth progression then maybe an adjustment is in order.

Just a fwiw, try it, in the end you can always go spend the money if the adjustment don't work.

Tom

Gary

As TT has said, loosen the TWO bolts on the side of the TPS and adjust with IGN ON so the DVM reads about .54v. Then tighten bolts
and check WOT TPS signal. Should be at 4.5v or higher. If not,
swap in new TPS.

secondchance · 07-25-2009

When you say back fire, do you send detonation in the plenum or hear it at the tail pipe?

I never had this situation with fuel injected cars but way back when cars had carburators, cracked ign. wire would make gas vapor explode into the air filter housing.

If it is coming through the tailpipe, its coming from uncombusted fuel detonating when it his catalytic converter.

I very much doubt TPS, even if off a little, would do this.

Lastly, I struggled with a similar symptom a few years ago. In my case it was hairline crack on one plug (very difficult to see). Cracked plug wire will behave in similar manner.

07-25-2009	#1
tomtom72 Join Date: Dec 2004 Location: Jacksonville, FL USA Posts: 4,609	Re: Rough Idle/Hesitation/Backfire Gary, I have a 90 and I know for sure that my TPS is adjustable...to what degree I don't know, but the screws that hold it in place are in slotted holes, therefore I conclude it's adjustable. You may want to look closely at those screws as you maybe able to make an adjustment. If you say that the needle on the VOM moves thru it's sweep at a smooth progression then maybe an adjustment is in order. Just a fwiw, try it, in the end you can always go spend the money if the adjustment don't work. Tom __________________ 1990 ZR-1, Black/grey, #2233, stock. ZR-1 Net Reg Founding Member #316 & NCM member

07-25-2009	#3
tomtom72 Join Date: Dec 2004 Location: Jacksonville, FL USA Posts: 4,609	Re: Rough Idle/Hesitation/Backfire Stupid of me not to include this. When I scan my 90 at idle, in closed loop, the TPS does read .54v on my scanner. So jsut make your adjustment at idle and make sure you are up normal operating temp. Sorry I type faster than I think..... Tom __________________ 1990 ZR-1, Black/grey, #2233, stock. ZR-1 Net Reg Founding Member #316 & NCM member

07-25-2009	#5
secondchance Join Date: Aug 2006 Location: McLean, VA Posts: 3,730	Re: Rough Idle/Hesitation/Backfire When you say back fire, do you send detonation in the plenum or hear it at the tail pipe? I never had this situation with fuel injected cars but way back when cars had carburators, cracked ign. wire would make gas vapor explode into the air filter housing. If it is coming through the tailpipe, its coming from uncombusted fuel detonating when it his catalytic converter. I very much doubt TPS, even if off a little, would do this. Lastly, I struggled with a similar symptom a few years ago. In my case it was hairline crack on one plug (very difficult to see). Cracked plug wire will behave in similar manner.