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Hi,
I picked up a Ford 1992 F-250 with the 4.9 Liter straight six – Automatic. The engine runs. It idles rough, but does run. Starts right up, and CEL comes on only after warm. When CEL is on, I have these codes: (OBD 1)
KOEO
553 – Air management circuit II failure.
KOER
Code – 116 – Coolant temp sensor
Code – 311 – Thermactor air system fault during engine running self test.
Code – 213 – SPOUT circuit open. (Verified SPOUT plug IS installed…)
Code – 332 – Insufficient EGR Flow Detected.
Code – 538 – Insufficient RPM change during KOER test. (Probably my fault – not hitting the throttle quick enough…)* I removed and replaced the coolant temp sensor – and this code is gone.
* I checked all the vacuum lines, and sprayed all around the intake with carb cleaner – no joy.
* I did find the vacuum lines rotted to the Evap PURGE Solenoid – so badly that the solenoid broke when I tried to remove them. Changed the lines and the solenoid out – no difference in codes.
* I have seen references to a “Rotted/Rusted” vacuum canister all over the web as a possibility, however this truck has a plastic reservoir mounted on the fender and it is intact. I pulled it off and checked it over, it appears to be good.
* I have read on-line as well that there are two switches mounted on the valve cover that control vacuum in some manner. But I cant find anything with some good directions on how to troubleshoot these. All the lines to them are connected and appear to be in good shape.
* Due to its age – there is nothing in the junkyard locally that I can rob from, any parts will be ordered. Since it cost me 80 bucks for that broken purge valve, I really want to ensure I complete some solid troubleshooting and not just throw parts at it. Cant afford it!Obviously this is an older truck, and it is hard to find any direct troubleshooting information on the web. It seems like people that keep this truck, remove all the emissions in some fashion. Delete the smog pump, delete the EGR, etc. I am not interested in that unless I can keep the CEL off. It wont pass inspection in my state if it is butchered or the CEL is on for emissions.
I am focused on the emissions issue at the moment. In my experience these seem to be the most expensive. If anybody out there has some old school 4.9L experience I could use a hand!
Thanks.
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Replies
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If the EGR valve or passages are clogged it will cause all kinds of hell on just about any engine. That’s where I would start if it were my truck. My dad had an old Ford with a bad EGR valve and it stalled and wouldn’t idle right. Replaced it and it was peachy.
I salute you for your Ford and for delving into OBDI codes. You are a trooper, sir.
Those two solenoids I mentioned are the TAB and TAD for the thermactor system. They both hold a vacuum until energized, then release it. So, they appear to be working. I also checked the EGR control valve and this appears to work as designed.
Wow that’s some real testing you’re doing there. My only other guess is gonna be a bad vacuum hose somewhere because of the age of the truck, but I am going to guess because you are so thorough you did that already.
Your right, everything I have read so far leads me to that. But I cant find it. The biggest problem is the way they are all routed. On this engine, they start on the drivers side valve cover, and then run all around the back of the engine, down under the intake manifold and then out the other side. Tomorrow I may try to plug each line where they come out and put the vacuum pump on them, maybe this will reveal that there is a crack in a vacuum tube that I missed. Beside pulling the intake off, I don’t see any easier way to do it. Visually, they look good. Nothing obviously broken or disconnected. They pass the carb cleaner check too.
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