On Sat, 13 Apr 2002, Dennis Haynes wrote: > With readings that high, the catalyst is not your only problem. The cat > is a clean up device, not gross pollution prevention device. You don't > state what the CO (carbon monoxide) reading is. This would be very > helpful to help with a diagnosis. You need to check for the following;
The C02 readings are: idle (978rpm): 9.38 2500rpm (2636rpm): 11.52 02 readings: idle (978rpm): 7.5 2500rpm (2636rpm): 4.1 C0 readings: idle (978rpm): 0.35 2500rpm (2636rpm): 0.82
> 1) Engine condition. Good compression. Intake and exhaust valves sealing > properly. Leak down test would be best indicator. > 2) Ignition, make sure there is no intermittent miss fire. Have shop > test with a scope if needed. > 3) Vacuum leaks, bad injectors. Either condition can cause 1 cylinder to > miss fire, (lean-miss). This will cause high HC.
I'll have these three looked at.
> 4) Fuel mixture, what is the CO reading? Should be between .2 and 1.0%, > before or without the CAT. > 5) Basic engine settings. Make sure the timing is set to spec. Over > advancing the timing can cause high CO readings, particularly at idle.
It looks like these two are no an issue, correct?
> You need to get that HC reading down to at least 1/2 of what you have > before replacing the Cat. Otherwise you will burn up the new one. > > Good luck, > Dennis
So, it sounds like I'll definitely need a new cat, but not until the other work is done first...? Good info. Thanks! -Graham |
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