Code question
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Freshman User
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Sorry brain fart, it did have heater circuit. I would start with basics mist water around intake and vacuum lines. The EGR allowed exhaust gas into the combustion chamber to reduce NOX by lowering combustion temp. This will cause a richer mixture in the cylinder. Check vacuum leaks, EGR for vacuum leaks and blockage. You can buy pads air injection by removing belt see if that make a difference,
Fleet Owner
Joined: Oct 2005
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From: Kentucky
The OP's truck is a 1990, the O2 sensor is before the converter.
Fleet Owner
Joined: Oct 2005
Posts: 20,784
Likes: 1,751
From: Kentucky
Wherever you found that listing it's wrong. Post converter O2 sensors were not used on this vintage truck until OBD-II was implemented. On gas engine trucks this is generally accepted as 1996.
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Freshman User
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Looks like its just one serpentine belt for the whole thing, not v belts. From what I can see when i was changing the o2 sensor is that there is just one, and its before the cat, on the H pipe.
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I would fix first what you have found wrong first. A lean code could be just about anything, vacuum leak, injector, air pump. Like I said the egr uses exhaust gas to lower box and combustion temp for NOX. It's makes the air fuel richer less air. For a lean code you have to have all component working. Did you mist some water to check for vacuum leaks. There are other products you can use but water is safer
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Freshman User
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I would fix first what you have found wrong first. A lean code could be just about anything, vacuum leak, injector, air pump. Like I said the egr uses exhaust gas to lower box and combustion temp for NOX. It's makes the air fuel richer less air. For a lean code you have to have all component working. Did you mist some water to check for vacuum leaks. There are other products you can use but water is safer
Junior User
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Water
If you use a spray bottle go around the intake the water will seal the vacuum leak of a couple of seconds. I also great at finding bad wires, if just find it easier to fix what you have found wrong with the truck. Then move on to the next step, it's hard finding problems on the older trucks with out live data. Spray around intake, vacuum lines, EGR, make sure iac is working.
Thread Starter
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Freshman User
Joined: Jun 2014
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If you use a spray bottle go around the intake the water will seal the vacuum leak of a couple of seconds. I also great at finding bad wires, if just find it easier to fix what you have found wrong with the truck. Then move on to the next step, it's hard finding problems on the older trucks with out live data. Spray around intake, vacuum lines, EGR, make sure iac is working.
Lead Driver
Joined: Aug 2006
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From: Sand Lake, MI
+1 with Conanski suggestion.
Disconnect the AIR hose from the AIR pump so that secondary air is bypassed to atmosphere during test, run the KOER test again see if code 41 disappears.
Should able to disconnect and plug the vac line to the diverter valve but that may be the sourse of the problem. Failure of the valve, its stuck, or someone rerouted vacuum lines as so it always has vac to it even when shouldn't have. Secondary air dumped to atmosphere = no vacuum supplied to the diverter valve.
Disconnecting the hose at the pump itself ensures that no air is delivered to the engine for accurate test result.
If code 41 disappears hose disconnected from pump the secondary air system is source of the problem know to look to it find fault.
If code 41 remains it is not the problem, reconnect hose move on.
Thread Starter
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Freshman User
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Oh yea sorry I did read that earlier on in the thread.
+1 with Conanski suggestion.
Disconnect the AIR hose from the AIR pump so that secondary air is bypassed to atmosphere during test, run the KOER test again see if code 41 disappears.
Should able to disconnect and plug the vac line to the diverter valve but that may be the sourse of the problem. Failure of the valve, its stuck, or someone rerouted vacuum lines as so it always has vac to it even when shouldn't have. Secondary air dumped to atmosphere = no vacuum supplied to the diverter valve.
Disconnecting the hose at the pump itself ensures that no air is delivered to the engine for accurate test result.
If code 41 disappears hose disconnected from pump the secondary air system is source of the problem know to look to it find fault.
If code 41 remains it is not the problem, reconnect hose move on.
+1 with Conanski suggestion.
Disconnect the AIR hose from the AIR pump so that secondary air is bypassed to atmosphere during test, run the KOER test again see if code 41 disappears.
Should able to disconnect and plug the vac line to the diverter valve but that may be the sourse of the problem. Failure of the valve, its stuck, or someone rerouted vacuum lines as so it always has vac to it even when shouldn't have. Secondary air dumped to atmosphere = no vacuum supplied to the diverter valve.
Disconnecting the hose at the pump itself ensures that no air is delivered to the engine for accurate test result.
If code 41 disappears hose disconnected from pump the secondary air system is source of the problem know to look to it find fault.
If code 41 remains it is not the problem, reconnect hose move on.
Makes allot of sense, thanks man! I will do that in the morning and post the results.
