Lance Hohimer
Banned
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This and, check your base timing too.plug wires, cap 'n' rotor, fuel pressure. Make sure the coil can fire a spark tester calibrated for HEI
CO is not low. It's near the limit, way above "average". This indicates rich mixture.It looks kind of like a lean misfire to me. O2 is a little high, CO is low and HC is high. The low NOx numbers give me pause because if it's too lean the chamber will heat up and drive NOx up.
I'm not sure there's a difference in the EGR valves. Maybe yes...maybe no. But at least it "worked", even if it might be incorrect.The results posted are with old plugs, old FPR(blown), EGR valve off my 93 k3500, old CTS, dirty K&N air filter.
Installing a failed EGR valve increased the peak combustion chamber temperature; and it may be that the fresh plugs and repaired fuel pressure regulator have made some or all of the cylinders run better. NOx increases, CO reduces...but I still think there's a misfire (or the catalyst has failed.)I changed the plugs, FPR, put the Yukon's original EGR valve back on, new air filter and took for a retest...NOx went up to 900! CO came down to around 20 and HC was still around 200.
So I ordered a Denso O2 sensor, tested my MAP, EGR solenoid, both tested good. I do not know my fuel pressure. I also rigged up a vacuum tester for my 'tests' above and for the egr valve. The egr valve bleeds down slowly. So I am ordering a new Delphi from rockauto.
Yeah upon review I was looking at the average CO numbers, not the actual. Hard to read sideways I guess. I agree he is rich.CO is not low. It's near the limit, way above "average". This indicates rich mixture.
NOx is low because the engine is running rich, and the EGR is functional--therefore the burn is of moderate temperature, not enough to create oxides of nitrogen.
Sorry about the sideways picture, my camera SUCKS and that was the only way I could get a 'clear' pic.
I am getting a new cap/rotor/ wires today. May even put my spare distributor in. The one that is in there is from the 93 k3500. Timing is dead on '0' and does not bounce around. I did hook up a vacuum gauge and it read steady at 16"..no bouncing or fluctuations. When I revved it up, it shot straight to 20/21 and right back to 16.
Also sending my injectors to Mr Injector to be cleaned and inspected. For 18 ea I cant complain.