Changed the O2 sensors out today and filled up with a fuel system cleaner and fresh tank of gas. Once I burn through the tank I'm going to go get retested.

 

I'm still failing emissions and it's not getting much better. I've taken it in 3 times now for the test and each time I come back with near exact results. Here is the results from the latest test today.

HC Cruise Limit: 400 HC Emissions: 837 FAIL (2389 RPM)
HC Idle Limit: 400 HC Idle Emissions: 230 PASS (814 RPM)
CO(%) Cruise Limit: 3.00 CO Cruise Emissions: 0.14 PASS
CO(%) Idle Limit: 3.00 CO Idle Emissions: 0.11 PASS
O2 Cruise Emissions 3.4
O2 Idle Emissions 3.1
CO + CO2(%) Cruise Emissions: 13.43
CO + CO2(%) Idle Emissions: 13.70


I've changed out the O2 Sensors, Spark Plugs, and changed the oil and nothing has helped. What else could be causing the problem? It looks like I pass the CO test with flying colors.

 

When we're the plugs last changed? What about air filter?

 

A high HC reading is the result of poor combustion. The most typical cause is a poor ignition system. HC is nothing more than fuel that makes it out the tailpipe without being burned. This points to a misfire, which is why you still need to get the truck scanned for PENDING codes.

 

Just took it in and the number 10 cylinder is not firing most of the time. He did a compression test and it came back very low. I'm hoping at worst its a broken valve spring.

 

Wasn't a broken Valve spring, not really for sure what the problem is. The mechanic is saying its losing compression on the intake side. He recommended to "R&R the head to further inspect" and quoted me $4,000. I do not want to drop that kind of money on this. Is there anything else I can do? Would a carbon build up cause this? I bought a can of Sea Foam and was looking to run some through a vacuum line to see if it helped.

 

Did he check the compression dry and wet?

You can do the test wet and dry. Check the lbs. dry and then give a little shot of oil in the plug hole and check the lbs.

If the pressure goes up wet, then the rings are losing the pressure. If the pressure is the same wet or dry, then it's a good chance that it needs a valve job.

Hope this helps...


biz

 

He did a wet test and the pressure stayed the same. I ended up taking it in, I should find out exactly what the problem was sometime next week.

 

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