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Mitsumark · 08-11-2013

Thanks for the warm welcome guys..Ive been a car guy my whole life..However,this is my first Vette..I've been trying to do as much reading as possible to avoid asking what I'm sure has been answered a million times..It sure sucks being the new man in class..Anyway,yes..I do have a few drivability issues..For one,the car does have a stumble at low-mid throttle.It will break up a bit before it clears up and takes off..Also,even once it gets going,I can hear pre-ignition(pinging) and sometimes even slight detonation.I immediately take my foot out of it as I'm scared to hurt it..This happens with or without the power key on..Being this car was specifically Dyno tuned back in 93 right after the build,I figured it was tuned on old fashioned gas and could really benefit from a new tune..After reading about Marc H great rep,I spoke with him and I went with him..So far I've done his chip along with checking for any vac leaks.I have discovered that my secondary vac pump is innop as is will not cycle on.Ive confirmed this by connecting direct voltage.However from what I've read,this pump failure should have little or no effect on driveability,especially with the power key off..My problem occurs weather on or off.So although I have full documentation of a new Marc H chip,new NGK TR71X gapped at .50,new GM wires, and new FIC injectors.I have also checked for vac leaks and can't find any.Map sensor hose is new and attached at both ends.As stated earlier,this car sat on a used car dealer lot for a short span before I got it..Imcluded in the documents was full coil replacement from an outside source.I know they were changed as I can see the hand written #s on each coil from the previous installer.What I'm guessing is that non factory cheap coils were probably used.So my conclusion is I'm almost 100% positive I have a defective coil.Upon changing them I would love to rip out the secondary system as it seems to be a complex system with many fail able parts..Besides the miss,,I have a dyno sheet (vin specific) that says this car was making 423 rwhp..I know what 423 rwhp feels like and this car is not making anywhere near that now so something definitely isn't right.Im located in S.Plainfield NJ which is right in the middle of the state..Again if any knowledgable local members are close,provide me with a list of what parts I would need to fully remove my secondary system,plugs,seals,gaskets,ect and I will be happy to pay for your time.Im sure I can handle the plenum pull myself.What I'm a bit Leary of is removing all of the secondary parts and buttoning up all the loose ends..

08-11-2013	#8
Mitsumark Join Date: Aug 2013 Location: NJ Posts: 117	Re: New ZR1 owner Thanks for the warm welcome guys..Ive been a car guy my whole life..However,this is my first Vette..I've been trying to do as much reading as possible to avoid asking what I'm sure has been answered a million times..It sure sucks being the new man in class..Anyway,yes..I do have a few drivability issues..For one,the car does have a stumble at low-mid throttle.It will break up a bit before it clears up and takes off..Also,even once it gets going,I can hear pre-ignition(pinging) and sometimes even slight detonation.I immediately take my foot out of it as I'm scared to hurt it..This happens with or without the power key on..Being this car was specifically Dyno tuned back in 93 right after the build,I figured it was tuned on old fashioned gas and could really benefit from a new tune..After reading about Marc H great rep,I spoke with him and I went with him..So far I've done his chip along with checking for any vac leaks.I have discovered that my secondary vac pump is innop as is will not cycle on.Ive confirmed this by connecting direct voltage.However from what I've read,this pump failure should have little or no effect on driveability,especially with the power key off..My problem occurs weather on or off.So although I have full documentation of a new Marc H chip,new NGK TR71X gapped at .50,new GM wires, and new FIC injectors.I have also checked for vac leaks and can't find any.Map sensor hose is new and attached at both ends.As stated earlier,this car sat on a used car dealer lot for a short span before I got it..Imcluded in the documents was full coil replacement from an outside source.I know they were changed as I can see the hand written #s on each coil from the previous installer.What I'm guessing is that non factory cheap coils were probably used.So my conclusion is I'm almost 100% positive I have a defective coil.Upon changing them I would love to rip out the secondary system as it seems to be a complex system with many fail able parts..Besides the miss,,I have a dyno sheet (vin specific) that says this car was making 423 rwhp..I know what 423 rwhp feels like and this car is not making anywhere near that now so something definitely isn't right.Im located in S.Plainfield NJ which is right in the middle of the state..Again if any knowledgable local members are close,provide me with a list of what parts I would need to fully remove my secondary system,plugs,seals,gaskets,ect and I will be happy to pay for your time.Im sure I can handle the plenum pull myself.What I'm a bit Leary of is removing all of the secondary parts and buttoning up all the loose ends..