85' 308qv - I'm going to use my New "Gunson Gastester" to check my CO exhaust reading. My problem is , where do I insert the test probe for a pre-cat reading ? (PHOTO if possible please) (I changed injectors and want to check it- seems rich to me now) Steve
I have a Testarossa but hopefully the idea is the same for your car. On the TR there are sampling ports or tubes just before the cats. I would imagine that your car as a similar setup. Many times the original tubes are missing and the ports blocked off with a threaded plug. Look for something like this on your exhaust system.... I'm sure somebody will pop in and give you better information soon...
I'm aware of the individual exhaust taps but is there one place where they can be tested together ? (all 8 at once) Pre-cat , on a 308qv ? Or am I just supposed to just use 1 individual tap ?, I thought it might be better to use a mixture of all 8, if there is such a tap, where they all come together.
At the inlet side of the cat (the same side as where the O2 sensor is mounted), there should be another removable "inspection" hex plug. It's not a big opening, and you'd need some way to get hold the (plastic) sampling tube in the right place (and it may be too hot for the plastic tube in any case) but that's a place where you'd get exhaust gas from all 8 cylinders.
91tr- is this it ?- see photo- My exhaust tester has a metal pipe (at the end), so I hope it will be ok. (do you normally test here or only at the individual taps ? (they seem very hard to get to) Image Unavailable, Please Login
Yes -- that's the inspection plug. Having a metal test pipe does get around the "melting" problem, but be careful about hot exhaust gas coming out and contacting the nearby components. I don't have a 308QV with Lambda to care for so no experience on how/where the F professionals typically do the sampling - hopefully, they'll give a comment. Have you made the crude estimation of just measuring the output voltage from the unplugged O2 sensor single wire at warm idle? Is it currently pinned up at +1.0V (i.e., rich) at warm idle?
I think was between .8v and .9v , I don't remember the exact number. I thought I'd put the voltmeter on the O2 sensor, at the same time I test the exhaust with the analyzer. I don't think it is too far off but I want to check it to be sure. I removed the exhaust plug and looked inside the Cat- the opening is only about 1/8" (tiny compared to the 17mm plug size) so maybe it won't be too hot. I'll have to fabricate a new plug and tube coming out to reach the analyzer. (I don't want to modify the orig plug)- that's tomorrows chore.
