Help!! 91 missing/underpower issue - ZR-1 Net Registry Forums

tomtom72 · 09-02-2007

The clattering may be a loose heat shield....I have one & at the right rpms I hear it & then it quiets down once I pass the resonance spot.

Miss....all the time or no? Checked the whole ignition system; plugs, wires, coils all are good. Did you pull any plugs to see how they are burning? Did you scan it to look at the fuel numbers? Did you scan to check the CCM for any history codes?

Gas milage going south + a miss; I say you will find something on a scan, JMHO. Are the injectors the OEM set? Remember 90 & 91 are not ethanol proof. When you get to the secondaries the miss goes away? Does she smell lean or rich out the exhaust at idle? Forgot this, how's the fuel system; pumps, regulator & filter?

FSM, section 6E, drivability & emissions is a place to start looking up your symptoms. There is also a page there with scan data for a normal LT5 in closed loop.

Tom

09-02-2007	#3
tomtom72 Join Date: Dec 2004 Location: Jacksonville, FL USA Posts: 4,609	Re: Help!! 91 missing/underpower issue The clattering may be a loose heat shield....I have one & at the right rpms I hear it & then it quiets down once I pass the resonance spot. Miss....all the time or no? Checked the whole ignition system; plugs, wires, coils all are good. Did you pull any plugs to see how they are burning? Did you scan it to look at the fuel numbers? Did you scan to check the CCM for any history codes? Gas milage going south + a miss; I say you will find something on a scan, JMHO. Are the injectors the OEM set? Remember 90 & 91 are not ethanol proof. When you get to the secondaries the miss goes away? Does she smell lean or rich out the exhaust at idle? Forgot this, how's the fuel system; pumps, regulator & filter? FSM, section 6E, drivability & emissions is a place to start looking up your symptoms. There is also a page there with scan data for a normal LT5 in closed loop. Tom __________________ 1990 ZR-1, Black/grey, #2233, stock. ZR-1 Net Reg Founding Member #316 & NCM member Last edited by tomtom72; 09-02-2007 at 08:26 AM.