dubyayoung

I posted another thread about my 22R not running right when the timing is set right, and this is a follow up to that thread.

That thread started because my '85 truck failed it's smog test at a CA test only station (required for my registration this year). Even though it passed all of the numbers, it failed because the timing was off 40 degrees (and two other minor issues). It turned out that the harmonic balancer had slipped and once I replaced it, I was able to get it running right. The problem was that it then failed it smog test.

So I am posting photos of my three tests, giving a description of what was done each time, in hopes of gaining some understanding of what the heck is going on, and maybe myself and others can avoid these problems in the future!

What may or may not bring any bearing on this is that they had entered the wrong engine on the first two tests, entering a 2.0L engine, when it is in fact a 2.4L.

Test 1:

This test was failed because they smelled fuel in the engine compartment, the gas cap failed it's test, and the timing was off 40 degrees.
I cleaned up the engine, bought a new gas cap, replaced the harmonic balancer, and timed the engine correctly.

Test 2:

Now, with the timing dead on, my NOx readings are too high!

I took the truck to another shop to have them check it out and see what needed to be done to get it to pass smog. Supposedly they just retarded the timing a couple of degrees.

Test 3:

The correct engine is entered, which oddly enough lowered my max allowable NOx levels, but I wasn't even close this time! The tester said the timing was off a couple of degrees, not enough to fail it, but everything else was fine.

So can the timing really lower the readings this much? Is there some other explanation?

I was originally thinking I may just barely pass, but will need to start looking for some other fix to really lower my numbers. But by these numbers I don't think I will mess with a thing!

Any thoughts?

smogman

It looks like the smog machine is having some issues. See the o2 readings? They are changing a lot between the last two test. The last test shows 2 different 02 levels and co2 has a far spread. Even though the smog machine has some issues, the bench in the machine has a separate sensor to read NOX. Your different readings are dramatic. NOX will not change that much by adjusting NOX a few degrees. It could lower it to pass but not that much. It looks like you have or had a egr problem. They might have found some vacuum lines messed up and fixed that. Either way, it looks good now so don't worry about it until you have to smog it again.

dubyayoung

One thing I noticed during the test was that the probe in the exhaust pipe started slipping out, and it probably had 4-5 inches of the spiral probe at the tip not in the pipe throughout the last half of the test. Could this have made any difference? The guy doing the test didn't seem to be concerned when he removed it after the test, so I figured it was no big deal.

smogman

That is why there is a difference on the last test between 15 and 25 mph. That makes sense. Now the difference between the 2nd and third test looks like a new converter was installed and the egr fixed. Here is why. The difference between the co2 levels between test 2 and 3 is significant. the o2 is high on the second test and co2 low shows the cat was not working 100%. the third test shows low o2 at 15 mph and really high co2 this shows the converter is working really good. Its not because the guy didn't warm it up for the 2nd test because you would see a difference on the co2 between 15 and 25. it would increase. Either way this does not effect NOX very much. Your egr was not working for the second test and the third test it was.

sbhern89

I been keeping up w/ ur post (even the previous).. would all this info apply to the 85 efi???

sbhern89

I been keeping up w/ ur post (even the previous).. would all this info apply to the 85 efi???