I took my "1988" 5.0 liter Bronko through inspection and it is failing emissions.

I pullud the codes and with the KOER the codes are 44, 33, 13, and 52.

I set the timming, replaced the TAD/TAB solenoid and the EEGR valve and I continue to get the same trouble codes.

Can someone give me advice based on the above information?

Thanks,
JAB.

 

Did you remember to clear the codes either before or after the work was done?


Dennis https://www.ford-trucks.com/user_gallery/sizeimage.php?&photoid=1733&.jpg



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First I would disconnect the battery for a couple of minutes to clear the codes. Then go for a short test drive and check the codes again. NOX stands for oxides of Nitrate not Oxygen. NOX readings go up when combustion chamber temperatures go up. One of the biggest contributors to that is a faulty EGR valve.

code 13 engine running: RPM was wrong during low idle self test, check for vacuum leaks, idle air control operation and high minimum idle.

code 33 memory: EGR sensor signal did not change when the EGR was commanded to open. EGR intermittently did not open during normal operation

code 33 engine running: EGR does not open when the processor commands it to open. Check EGR vacuum line, solenoid operation and sensor operation.

What are your HC and co readings? Hope this helps a little
Randy..........

 

If your EGR system is working fine, check for timing (excessive timing advance increases NOx emissions) and also check for deposits on the piston or the combustion area (they increase CR which also increases NOx).

 

I took my truck back to the emissions station today. It failed again, the results are as follows.


Complete Test Second Phase
Standard Reading Result Standard Reading Result

1. HC grams/mile 3.2 2.86 Passed 2 2.62 Passed
2. CO grams/mile 80 23.69 Passed 64 24.39 Passed
3. NOx grams/mile 3.5 6.27 Failed 3.5 7.83 Failed

I removed the new EGR valve and found a large amount of carbon deposits at the inlet and the outlet of the valve. I cleaned it and removed the deposits.

I am now attempting to check the vaccum lines however, I do not know where I should see positive or negative pressure.

Any help in this matter would be greatly appreciated.

Thanks,
JAB.

 

Try this test. While idling, pull the vaccum line off of the EGR valve and apply vaccume to it using a vaccum pump. The engine should start to stumble or even die out if the EGR valve is good. How's the ignition timing?