So propane leak checking didnt work

[JHZR2]

Hi,

In trying to fix my high HC and high NOx, I did a propane torch leak checkonmy car. Unfortunately I found nothing (and I did disconnect the IAC valve).

In no place did the idle speed change notably, when compared to when I jammed the torch into the intake and listened... There are a lot of air hoses on the intake of the car, all around, and I did a pretty good job of checking each one and just spraying propane generically over the area - no real luck.

Im hesitant to use carb cleaner... Ive tried that before and it is nasty... but are there any other tips to using propane to check for leaks?

If propane showed no leaks and my O2 sensor is good, this tells me that it has to be my cat, right???

Thanks!

JMH

 

[JustinH]

Did you get it retested without the chip in there?

You should disconnect the battery for about an hour after disconnecting the chip so that the ecu can relearn the factory software.

You shouldn't need anything else.

 

[DC84]

If your trying to correct high HC and Nox id be looking at your ignition system. Check the enigne for mechanical defects too such as compression and cylinder leak down. If all else fails it could be a convertor going out but if its an OBD II car there should be a code showing if its bad enough to fail emissions

 

[JHZR2]

OBDI car, no egr, runs great and 175 psi across all cyllinders, IIRC. Replaced the chip, disconnected battery, etc., and no luck.

JMH

 

[kc8adu]

something making it run lean?
if so hc from lean misfires and explains high nox.

 

[JHZR2]

Quote:

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something making it run lean?
if so hc from lean misfires and explains high nox.

---

That is why I was checking for leaks - figuring that an intake leak could allow the air in to cause the so-called lean misfire.

But, propane did not seem to do anything as far as pointing out leaks - I could sense an RPM change when sticking the line into the ctual intake duct at the airbox, and I could sense an RPM increase with an intake vacuum hose disconnected and the propane stuck in it.

local and global propane blanketing around the intake hoses did not help... and the ICV was disconnected so that the engine would not compensate.

So perhaps it is not a lean misfire??? What are the other signs of one of these?

Thanks!

JMH

 

[1sttruck]

I've had hoses that had cracks, where they would leak when deflected and/or under load, but weren't noticeable otherwise. One of the stethoscopes with a long probe and moving the hoses around will help to fins any.

The emissions on the older Taurus increased gradually over time, due to three injectors that were eventually replaced, and a spike in oil consumption that I kind of got under control but never eliminated. None of the diagnostics implicated the injectors, and I checked quite a few different systems per the troubleshooting guides for Ford fuel injection, and per an Alldata account (the factory manual for emissions is really expensive). The dealer was worthless too, as a few years earlier their $130 a session diagnostic tool couldn't even detect a bad O2 sensor that I eventually found.

If it's the CAT you could try 'cleaning' it. I drilled a small hole in the exhaust system in front of the cat and put a self tapping sheet metal screw in. After getting the car warmed up I'd open the hole, and have one of the kids keep the revs up while injected a commercial citric acid cleaner in the exhaust with a big syringe from a feed store. A better way to have done it would have been to inject while driving at highway speeds, using a tube of some sorts. I tried the citric acid as an article that I ran across was using such a solution to clean cats on heavy duty trucks. The car died before I needed another emissions test, so I don't know well it actually worked.