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When cold 5.8 runs great, but when it gets to operating temperature it will idle rough run rich. Changed just about everything electronics. Any suggestions or advice please. Vacuum has been checked
When cold 5.8 runs great, but when it gets to operating temperature it will idle rough run rich. Changed just about everything electronics. Any suggestions or advice please. Vacuum has been checked
you changed things that werent bad, you screwed your diagnosis when you did the parts canon. no telling if those parts are all good
Very good point, he didnt say anything about that, I fear he just did that all without knowing about codes... oof
, I check the codes early on and had quite a few. I changed what the codes directed and checked sensorss as directed. Zeroed computer and check again according to OBD1 directions after each correction. Narrowed down to code 173 HEGO (HO2S) sensor fault/rich
334-EGR closed, voltage high. Manually checked movement changed EGR valve and EGRPOS, same systems?
So your truck runs good when it's cold but poorly when it's warm? As the truck warms up, the ecu logic switches from open loop (fixed injector values) to closed loop (adjustable injector values based on o2 sensors). There's a few things that can cause it to run rough. EGR leak will bleed non oxygenated air into the cylinders, which will cause the o2 sensors to pick up and record a rich running mixture. If your air injection system is malfunctioning or if you have a massive exhaust leak, it can leak oxygen rich air into your exhaust which the o2 sensors will detect and record a lean running engine, which it'll try to compensate by adding more fuel. If your pcv valve is defective or leaking, it'll dump fresh air into your intake manifold, bypassing your mass air flow meter, which will cause the engine to run rich.
So your truck runs good when it's cold but poorly when it's warm? As the truck warms up, the ecu logic switches from open loop (fixed injector values) to closed loop (adjustable injector values based on o2 sensors). There's a few things that can cause it to run rough. EGR leak will bleed non oxygenated air into the cylinders, which will cause the o2 sensors to pick up and record a rich running mixture. If your air injection system is malfunctioning or if you have a massive exhaust leak, it can leak oxygen rich air into your exhaust which the o2 sensors will detect and record a lean running engine, which it'll try to compensate by adding more fuel. If your pcv valve is defective or leaking, it'll dump fresh air into your intake manifold, bypassing your mass air flow meter, which will cause the engine to run rich.
I will do that and let you know. If the tube that goes from the EGR valve was leaking I would hear it, or would it be better to take it off and check it?
Do you still have code 173 or did you replace the 02 sensor.
yes I did, located at Y connector, it is still pulling same code. I pulled air box off and no maf sensor. Bit I did find the tub going to left valve cover was broken. Thank you much for your help.
So your truck runs good when it's cold but poorly when it's warm? As the truck warms up, the ecu logic switches from open loop (fixed injector values) to closed loop (adjustable injector values based on o2 sensors). There's a few things that can cause it to run rough. EGR leak will bleed non oxygenated air into the cylinders, which will cause the o2 sensors to pick up and record a rich running mixture. If your air injection system is malfunctioning or if you have a massive exhaust leak, it can leak oxygen rich air into your exhaust which the o2 sensors will detect and record a lean running engine, which it'll try to compensate by adding more fuel. If your pcv valve is defective or leaking, it'll dump fresh air into your intake manifold, bypassing your mass air flow meter, which will cause the engine to run rich.
Did you clear that code? If not it will not go away by itself without multiple restarts. If you want to check your EGR and the components associated with it, here they are. Much better to test them for accuracy. https://easyautodiagnostics.com/ford...e-egr-system-1
What parts did you replace as you posted on the first post? Specifically the ICM and the color of it. Grey or black?
I will do that and let you know. If the tube that goes from the EGR valve was leaking I would hear it, or would it be better to take it off and check it?
No. You won't hear if it's leaking. The normal engine noises will cover up a EGR leak. Easiest thing to do is remove the vacuum hose and unbolt the EGR valve from the intake manifold
and plug the hole in the intake manifold. Start it up and see if the you can feel or hear exhaust gases leaking out of the valve before it gets too hot to touch. As it warms up and goes into closed loop, see if it begins to run rough again. If you find the valve is leaking or if the engine runs well when it warms up, replace the EGR valve. If it begins to runs poorly when it's warm, reinstall the EGR valve because it's not causing your problem.
No. You won't hear if it's leaking. The normal engine noises will cover up a EGR leak. Easiest thing to do is remove the vacuum hose and unbolt the EGR valve from the intake manifold
and plug the hole in the intake manifold. Start it up and see if the you can feel or hear exhaust gases leaking out of the valve before it gets too hot to touch. As it warms up and goes into closed loop, see if it begins to run rough again. If you find the valve is leaking or if the engine runs well when it warms up, replace the EGR valve. If it begins to runs poorly when it's warm, reinstall the EGR valve because it's not causing your problem.
plug bottom or top of the tube and put a plate over the mount hole of egr?
plug bottom or top of the tube and put a plate over the mount hole of egr?
You can leave the metal tube connected to the valve since the tube should have alittle bit of flex to it, but be careful since it's ~30 years old and probably corroded internally, and you don't want to accidently crack the metal tube. As for the intake manifold side, you can put a few layer of duct tape over it since it's just a temporary thing. If you feel crafty, you can make a block off plate and a gasket. I've seen people use rubber corks... You just gotta make sure it's air tight and big enough that engine vacuum won't suck the plug into the intake manifold.
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