Thanks for the reply. It's 18 years old and 250K miles. The SES light is always on!
Seriously- it is always on because I have a p0300 "catalytic system below efficiency threshold" code all the time, and I live where there is no emissions testing so I have not fixed that yet due to lack of funds. I think I have 2 O2 sensors that are flaky (O21/2 and O22/2), they don't graph out the same as the other two during drives, not as consistent "up and down" on the graphs and the p0300 is intermittent, I can clear it and go a week before it comes back. It also might need a new cat on that side, maybe the sensors are right. IDK. Its been that way a long time and has never seemed to affect the driving.
That being said, I cleared it back out, and I get a P1406 code, which is the EGR valve. That code came back within 20 minutes of clearing it (I also drove it to make the hesitation/surging happen on purpose). I am beginning to wonder if the replacement EGR is flaky. The one I replaced was the original, it was really carboned up, cleaning it only lasted a couple days. It was getting stuck, the truck threw that same code and wouldn't idle worth a salt. After replacement it idles great, just the intermittent surging/hesitation at certain speeds/RPM.
I have not had a chance to put the fuel pressure gauge on it yet- I will try to get that done this afternoon. The fuel pump and filter are about a year or so old, @25K miles.
Saturday, April 5th, 2014 AT 9:00 AM