YELLAHEEP
NAXJA Forum User
- Location
- Littleton, Colorado
Ok, I've been trying to get my rig to pass Colorado emissions since last November and I'm getting nowhere fast. It's high on all readings - Hc, Co, and NoX. Basically, it's running hot and rich.
Subject vehicle stats: '93 H0 with 5 sp (133K miles), non A/C, 4:56's, 35" tires.
Driveability is fine - runs good at high rpm's and has only a hint of a misfire at idle. No check engine light.
Terrible strong rich smell from the exhaust at all times. No visible smoke, no black bursts on acceleration. Good throttle response.
Replaced:
O2 sensor, MAP sensor, TPS, Coolant temp sensors (both), spark plugs, Oil pressure sensor, antifreeze, oil, thermostat, fresh tank of gas.
Recently replaced:
radiator (checked for calcium deposits and restrictions in fins just today) and I've had an aux. A/C fan hooked up and working for a year now.
Symptoms:
operating temperature with highway driving never lower than 220, under load goes into the red and boils. Trail use - I can keep it at 220, no boiling. Rich exhaust smell, slight misfire at idle, some backfiring on decelleration between shifts. Paper over the tailpipe test does show some occasional suction at idle.
Shadetree diagnostics done to this point:
-I've replaced the above sensors and parts which got it to just squeek by on Hc and Co, but NoX is still high.
-Using a strobe timing light with plug wire pickup, I see an inconsistant flashing of the light indicating a misfire condition to cyls 3,4,&5. Cyls 1, 2 & 6 are good.
-Plugs were pulled, look very clean, no unusual residues, smell like unburned fuel.
-Wires ohm checked and are fine.
-Compression test shows all cylinders in good shape: #1=120lbs, #2=125lbs, #3=125lbs, #4=125lbs, #5=125lbs, #6=120lbs.
-Cat converter appears fine as far as flow, but is OEM unit.
-I can't check actual timing since I don't have a magnetic pickup timing tool. I can't locate a notch on the balancer and the timing scale on the timing cover only has dashes on it - no numbers.
-I've replaced the fan clutch and discovered the old one was just fine.
-I've inspected the cap and rotor for cracks and loose contacts, and cleaned the contacts.
There you have it. I am at my wits end with this problem. I must be missing something. I don't suspect a head gasket problem since it doesn't use any coolant, and the coolant is clean, no oil or bubbling.
My only thoughts at this point are possible a low-functioning water pump and a wornout cat converter.
Would a bad water pump and bad cat be able to peg the emissions readings?
Another thing, emissions testing out here uses a dyno-based system where the vehicle is tested under "real time operation". The safety requirements for the dyno equipment limit tire size to 34". When I went for my tests, I borrowed a pair of 33" tires. I imagine this certainly raised my RPM's a bit at 60mph - which is the speed they take them to. I'm gonna try to find some 34's for the next attempt to help keep engine speed down.
They also have a large electric fan that they place at the front of the car during the test, I had the tech put the fan right under the bumper and aim it up to get max flow - but this didn't keep the engine from boiling over.
Thanks in advance fellas!
Subject vehicle stats: '93 H0 with 5 sp (133K miles), non A/C, 4:56's, 35" tires.
Driveability is fine - runs good at high rpm's and has only a hint of a misfire at idle. No check engine light.
Terrible strong rich smell from the exhaust at all times. No visible smoke, no black bursts on acceleration. Good throttle response.
Replaced:
O2 sensor, MAP sensor, TPS, Coolant temp sensors (both), spark plugs, Oil pressure sensor, antifreeze, oil, thermostat, fresh tank of gas.
Recently replaced:
radiator (checked for calcium deposits and restrictions in fins just today) and I've had an aux. A/C fan hooked up and working for a year now.
Symptoms:
operating temperature with highway driving never lower than 220, under load goes into the red and boils. Trail use - I can keep it at 220, no boiling. Rich exhaust smell, slight misfire at idle, some backfiring on decelleration between shifts. Paper over the tailpipe test does show some occasional suction at idle.
Shadetree diagnostics done to this point:
-I've replaced the above sensors and parts which got it to just squeek by on Hc and Co, but NoX is still high.
-Using a strobe timing light with plug wire pickup, I see an inconsistant flashing of the light indicating a misfire condition to cyls 3,4,&5. Cyls 1, 2 & 6 are good.
-Plugs were pulled, look very clean, no unusual residues, smell like unburned fuel.
-Wires ohm checked and are fine.
-Compression test shows all cylinders in good shape: #1=120lbs, #2=125lbs, #3=125lbs, #4=125lbs, #5=125lbs, #6=120lbs.
-Cat converter appears fine as far as flow, but is OEM unit.
-I can't check actual timing since I don't have a magnetic pickup timing tool. I can't locate a notch on the balancer and the timing scale on the timing cover only has dashes on it - no numbers.
-I've replaced the fan clutch and discovered the old one was just fine.
-I've inspected the cap and rotor for cracks and loose contacts, and cleaned the contacts.
There you have it. I am at my wits end with this problem. I must be missing something. I don't suspect a head gasket problem since it doesn't use any coolant, and the coolant is clean, no oil or bubbling.
My only thoughts at this point are possible a low-functioning water pump and a wornout cat converter.
Would a bad water pump and bad cat be able to peg the emissions readings?
Another thing, emissions testing out here uses a dyno-based system where the vehicle is tested under "real time operation". The safety requirements for the dyno equipment limit tire size to 34". When I went for my tests, I borrowed a pair of 33" tires. I imagine this certainly raised my RPM's a bit at 60mph - which is the speed they take them to. I'm gonna try to find some 34's for the next attempt to help keep engine speed down.
They also have a large electric fan that they place at the front of the car during the test, I had the tech put the fan right under the bumper and aim it up to get max flow - but this didn't keep the engine from boiling over.
Thanks in advance fellas!