GA Smog question.....it failed AGAIN.

[Pick]

I've been away awhile (work shake-ups and other stuff put the T-Type on a back burner again.) sorry to return with yet another smog question.

OK...since the last failure......TPS changed, new MAP (still questionable), various vacuum lines replaced, computer SEEMED happy according to the scan tool. (O2 cross was still slow though.)

Here are the results - 1st test.

25/25 test
HC ppm 14 (152 allowed) PASS
CO% 1.47 (0.97 allowed) FAIL
NOx ppm 68 (1082 allowed) PASS
CO+CO2 15.6 (6.0 min.)

50/15 test
HC ppm 43 (157 allowed) PASS
CO% 3.13 (.088 allowed) FAIL
NOx ppm 66 (1184 allowed) PASS
CO+CO2 15.9 (6.0 min)

SO...........it wasn't that bad, but it still failed. I hadn't changed the cat yet, so I bit the bullet and had a new cat installed and new duals welded up last week, changed the oil again, checked it with the scan tool yesterday, and went back for a re-test today.

Here are the results - 2nd test (just completed this afternoon).

25/25 test
HC ppm 185 (152 allowed) FAIL
CO% 7.56 (0.97 allowed) FAIL
NOx ppm 130 (1082 allowed) PASS
CO+CO2 17.9 (6.0 min.)

50/15 test
HC ppm 176 (157 allowed) FAIL
CO% 7.59 (.088 allowed) FAIL
NOx ppm 66 (1184 allowed) PASS
CO+CO2 17.9 (6.0 min)

So..........it failed miserably with the new cat. (maybe rust and gook flying out of the previous exhaust system reduced emissions?)

Even though I've spent more than the limit, since it GOT WORSE rather than better I'm not sure if it qualifies for the exemption.

Since the only thing left was the O2 sensor, it got a new one just now..........but the O2 cross doesn't appear to be any different, and it actually gives me a LEAN indication more of the time after changing it. (but it does go RICH if I "wing it" or just jump out of the throttle abruptly.)

They didn't have a MAP sensor, so I have to try it if it comes in tomorrow. (the current one is reading, but with VERY little change in voltage or inHg............even if I'm on the brake, in gear........or just idle.....1 inHg is the max total change from atmospheric.) (29 atmoshperic, 28 shown on the MAP if/when it differs from atmoshperic)

I'm now so incredibly lost that I don't know where to look next if the MAP isn't it............and I still can't figure out how on earth the thing went THAT bad with new cat.

Sorry for the long post after a long layoff..........but what am I missing?

 

[b4black]

If you remove the hose at the MAP, do you feel engine vacuum? Can you put a gauge on it and see what it reads?

Does the new converter have an AIR tube?

 

[gofstbuick]

The air pump should only be active during warm up to light the cat off. But from your readings, It looks rich. If the O2 is lean at idle, can you introduce some propane in through the air cleaner snorkel and make it go rich? If so, you may have a vacuum leak somewhere that is causing the fuel metering system to open the flood gates.

 

[b4black]

From my observation the AIR pump does two things. The first is as you mentioned is during warm up (open loop). This is when it's pumping to the heads via the intake manifold. The second is during closed loop cruising. Then the air is pumped to the middle of the two-part converter. The first half is for reduction of NOx. The second half oxidizes unburnt hydrocarbons. The second part requires oxygen (air) to work. If the new cat uses an AIR tube, but it is not connected/operating, then the catalyst cannot oxidize the hydrocarbons. The low oxygen also prevents CO from becoming CO2.

I believe that some newer converters are efficient enough to not need the AIR injection. If so, do they still need the AIR pump to light off the catalyst? It would be great if they didn't, because with a new AIR-less converter, the AIR pump would not be needed.


The MAP has a big impact on A/F. That needs to be addressed. Figureing out whether it's the sensor or the vacuum source is step one.

 

[gofstbuick]

Oops my mistake. I was under the impression that when the engine was in closed loop, the air dumped. I had to go back to a really old mitchell manual and read some. But I still wonder if you can drive the O2 rich. Since he did say that the sensor always showed lean.

 

[Pick]

OK, some of the answers to some of the questions:

The new cat does have the air fitting on it, but it isn't connected to anything. I didn't think the original one had an air fitting on it..........but I really didn't pay much attention to the exhaust since it was OEM. ???

With the car cold and idling there isn't any vacuum or pressure on the map sensor hose, but it isn't obstructed between the MAP and the source. When I went to warm the car up just now, when it made the 1-2 shift it "popped" under the hood.................and wouldn't idle at all.............when I started hunting for the source, the vacuum hose running to the solenoid attached to the back of the carb.........some type of vacuum over electrical switch? (sorry for the technical term, but I don't have a clue what it does.).........was apparently blown off...........with it connected the obvious vacuum noise was gone, but the car still won't idle.

 

[b4black]

Originally posted by Pick
The new cat does have the air fitting on it, but it isn't connected to anything. I didn't think the original one had an air fitting on it..........but I really didn't pay much attention to the exhaust since it was OEM. ???.

You're gonna have to get air to it. Do you still have the smog pump, the diverter valves (near the distributor) and the ½" pipes?

I just went thru this with a Ford 5.0. One side was OK, but the other was rich (true dual exhaust). The AIR tube to the rich side was plugged. High HC and high CO.

With the car cold and idling there isn't any vacuum or pressure on the map sensor hose, but it isn't obstructed between the MAP and the source. When I went to warm the car up just now, when it made the 1-2 shift it "popped" under the hood......

I think you backfired and blew that hose off. Keep checking the hose to the MAP. I suspect there is a BIG leak somewhere (those hoses get roasted by the turbine). That vacuum "circuit" starts at the turbo compressor foot, goes under-behind the turbo mad and T's twice. Once to the wastegate actuator, and then again to the MAP and turbo power light switch.

 

[Pick]

The air pump and diverter valves are still in place.............I'll see if I can find out what was removed when they did the exhaust.

And I'll keep hunting the vacuum leak(s).........I've found many of them, but I certainly wouldn't be shocked to find more..... <sigh>

Thanks!

 

[Ttype83]

hmm... I think that I can help with the map, mines sitting in the garage right now and you can try it on yours to see if it's working or not.
You can also attach another hose to it and suck on it to see if the idle changes. Don't forget to plug the other hose.

The Air tube to the cat runs right beside the trans dip stick, I have a pic for it some where???

Check your headers for cracks, leaks around up pipe and at the turbo down pipe. This also will make it run lean. (more than likely this isn't it)

Give me a call and we see if we can get it going....or you can go down to troupe county and plate it
Jim