I'm sorry, I'm stumped. You seem to have done everything that you could that
applies to the problem. Try plugging your question into a a good search
engine and finding a forum where you can talk directly to pro mechanics. I
know there are several free ones around.
Your EGR should not be the cause, and no, 11 to 15k is well within it's
operating life. But if you can get ahold of a vacuum pump, test it anyway.
Do the one test with the engine running, 3 to 5 in. maximum to affect engine
speed. Then with the engine stopped, put 15 in. on the EGR. See how long it
holds that, it must not begin leaking down immediately. If there is
something wrong with it, it was likely defective to begin with.
I agree you should to the CAT temp test. And yes, Kalifornia has been
"adjusting" the pass values for years. I had proof of that back in 1988. But
try to get CARB to admit to that.
One thing a good smog mechanic will do first is to pull the codes. They
don't all set the light, but if they have occured in the last fifty key
cycles, they are stored in memory. One other thing is to prod the O2S with
the Snap-On meter. It gives him the values right on the screen that it's
returning. Should be 0.2 to 0.8 volts constantly varying back and forth. And
it should pass the 0.5 volt line so many times a second. I put one on my 95
a few years back and it just plain shorted out. It was returning almost line
voltage to the PCM.
By the way, I've been told that you should consider maximum service life on
both EGR's and four wire O2S's to be around 80K. Keep us informed, there's
lots more of us who could end up in the same boat in the near future. We
don't all just recycle our Dak's every 60K. Biff
----- Original Message -----
From: "rws" <rwsam2002@yahoo.com>
To: "DakotaTruck DML" <dakota-truck@dakota-truck.net>
Sent: Thursday, September 27, 2007 2:36 PM
Subject: DML: Re: 94 Dak 5.2L Cat Converter Air Pump or Air Switch Valve?
>
> Biff,
>
> Oil and filter was changed. Using oil branded for "older" vehicles. I
> think they put some copper in the oil to keep it running quieter, but need
> to verify.
>
> New O2S.
> New ECT sensor.
>
> Used Chevron's injector cleaner just prior to test, about a month ago. a
> BMW dealer says its the best they found to keep injectors running clean
> not dripping and remove the built up carbon on pistons and valves.
>
> PCV valve cleaned and checked and I can hear it making noise with engine
> running. Shop manual says this is a good sign.
>
> The EGR valve was replace 2-3 yrs or 11-15k miles ago. Maybe low oct.
> fuel can make it dirty again? I don't know. I tried to clean the EGR
> with solvents befor getting a new one. They are hard to clean so that
> they shut completly and smoothly, that's why I just got a new one. How
> long should they last?
>
> If I give up and take it to a CA certified smog mechanic, what will he do?
> Anyone here in California? Have you noticed the smog test criteria for
> the three elements gets lower the older the vehicle is?
>
> Ron
> -----------------------------
> Re: 94 Dak 5.2L Cat Converter Air Pump or Air Switch Valve?
> From: Biff Byrum (bbyrum9@foothill.net)
> Date: Thu Sep 27 2007 - 16:54:30 EDT
>
> Yeah, I had about the same results. Just passed by one. It's said that
> leaky injectors and the O2S are the leading causes of HC failure.
>
> Excess carbon buildup in the chambers can cause this reading. Someone
> sugested B-12 Total Combustion Chamber Cleaner. Also suggested was
> changing the oil so the new oil can absorb more HC. Remember that you do
> have that silly, prone to fail EGR on that engine. Also, new PCV valve?
> Biff
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