Poor performance and Detonation
Poor performance and Detonation I have a 98Z with a lid, K&N filter, free mods, and blowmaster cat back exhaust (changing soon). I have noticed here lately that my car isnt performing like it was. Once I find them (moved into new house), I have MSD wires and some NGK plugs to go on the car. I have noticed that under acceleration, you can hear detonation (valve chatter). You dont have to give it that much gas sometimes and it just sounds like crap. I know the car needs a tune but funds right now are tight. Will the tune get rid of this??? I just need some help from some of you to get this thing back the way it was. It has 83,500 miles on it now. Last time at the track, it was hot, humid, and had 75K miles. Ran 14.01 at 99mph with these mods... and crap tires.
Thanks!
Mike
Thanks!
Mike
Plugs and wires are a good start.... after that you might want to run some injector cleaner thru a tank of gas.
You shouldn't need a tune (helps but not necessary). Find someone who has AutoTap and have it scanned.
As for the 1/4 mile times..... too many unknown variables but does sound high.
You shouldn't need a tune (helps but not necessary). Find someone who has AutoTap and have it scanned.
As for the 1/4 mile times..... too many unknown variables but does sound high.
I know the SES light came on about 2 weeks ago and hasnt come on since. It stated that my EGR valve was sticking and one other code said I had low voltage to another sensor. I have the codes at home but dont know if thats a cause. I would love to just rip the emissions garbage off of it because there the laws for emissions tesitng are now gone. 
TECH Apprentice
Joined: Jan 2005
Posts: 396
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Your detonation could also be from oil contamination through the PCV. LS1's are known for sucking oil through the PCV and spitting it down the intake. You could foul out your plugs, build up carbon...all kinds of stuff. Do a search for a PCV catch can and that might help your problems. I had this same problem with my old '00 Formula.
TECH Fanatic
Joined: Jun 2002
Posts: 1,654
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From: Ga
I have a 98 Z also. IIRC there is a recall on our 98 with the EGR system. It caused My SES light to come on and I took it in and it was replaced. Also when plugs go bad your car will run awful. I thought mine were bad so I had them changed and when I got the car back it felt like a new car. Plugs and wires could be the culprit.
Do you recall if the sticking EGR was stuck open or closed. If stuck open then that is an obvious vacuum leak. Also the low voltage sensor sounds, with you driveability issues, like a bad O2. That will cause the computer to see false Air/Fuel info and could be causing your lean, detonating condition. But these are all just assumptions without more exact info.
I have a new pcv valve as well in the garage that I need to throw onto it....I will try this coming weekend to get this done and see where it stands.
Thanks for the info ZR2877, I will check into that.
DWill, yes the EGR code was that I had a low voltage to it and it was hung open and wouldnt close when it was supposed to. I was thinking of yanking the EGR and getting the SES turned off and a good tune after I throw the valve, wires, and plugs into it.
Thanks for the help guys!
Mike
Thanks for the info ZR2877, I will check into that.
DWill, yes the EGR code was that I had a low voltage to it and it was hung open and wouldnt close when it was supposed to. I was thinking of yanking the EGR and getting the SES turned off and a good tune after I throw the valve, wires, and plugs into it.
Thanks for the help guys!
Mike
