Hi All,
OK I got an annoying intermittent problem here.
1995 T&C, 110,000 mi. When we bought the van 2.5 years ago, it would not pass emissions. No Check Engine Light displayed. High NoX readings.I replaced the EGR valve and transducer, and that fixed the problem. Van passed emissions very well. Because I'm a curious type I took the EGR transducer apart and discovered the red rubber diaphram had been cracked and was brittle. The selonoid tested OK with an ohmmeter. The valve appeared to work with a vacuum pump. I put both parts in the box and saved them.
About a year later, CEL comes on solid. Code 32 EGR. Turn off and on the van and immediately CEL. Same code.
I cuss crappy cheap emissions parts out, and assume the selonoid is bad. I take the new transducer off, take it apart, extract the good rubber diaphram, find the old transducer which I still had, replace it's brittle cracked diaphram with the new one, put the transducer back together and put it back on the van. CEL is now off, everything is fine. As a test I took the van through the emissions test, NoX is where it should be.
Needless to say, the old and new transducers appeared identical in construction. (and no, the new valve was not a Mopar part, and yes I know I'm an idiot since a few months after I bought it I happened to ask at a dealer parts counter and discovered the Mopar part was cheaper) And no, I didn't put the diaphram in upside down or anything dumb like that.
About 6 months ago, the CEL comes on again. But this time it is very strange, it only comes on every once in a while. Same code 32. After several months I finally figure out that the CEL only comes on when the van is driven at a sustained speed of 60Mph or higher, for at least 15 minutes. And it comes on when the throttle is barely on. That is, I get the van up to 70Mph, and put it on cruise control and nothing happens. 15 minutes later I take it off cruise, let it coast down to, say, 60Mph, and during the slow down the CEL comes on.
The CEL -never- comes on when my wife drives it. She does mainly city driving. (although I suppose that says something about me as a driver, heh heh)
The van still passes emissions with fine NoX readings.
I have done the EGR system test in the shop manual and it passes that. (abruptly accellerate a warm engine to approximately 2000 rpm and observe the EGR valve stem, it should move when accellerating the engine)
I have done the EGR gas flow test and it passes that (connect hand vacuum pump to valve, slowly apply vacuum at idle, engine should stall out)
The shop manual has no other EGR specific tests. I did replace the O2 sensor at 100,000 miles as a preventative maintainence, it didn't make any difference to this problem.
I am guessing that it's either partially clogged EGR passages, or possibly a flakey selonoid. I don't like guessing in this instance though, as getting at the passages to clean them out is a bitch and appears to be at least a 4-beer project (a beer an hour I reckon) and a new transducer/selonoid means buying a brand new valve which is $70. I'd rather not spend either the money or the time without being sure.
Any other suggestions, (other than ignore it) anyone ever see anything like this?
Ted