Uh oh . . .

[anupaum]

Yesterday I had some time to recalibrate my O2 sensor. It's a bit of a pain because of everything I've got under the hood, but I managed to pull it out. The "momentary switch" on the LC-1 doesn't seem to be working very well. I REALLY have to hold it down in order to calibrate according to instructions.

As soon as I did that, the truck fired out without complaint. It went through warm-up enrichment without trouble, and when fully warm, behaved just as it should. However, the O2 correction is now giving me a lot of fluctuation, as if my fuel tables are "off" somehow.

I don't like the idea of having to tune the fuel tables again . . . One thing that nobody seems to talk about with respect to the wideband O2 sensor is the continuing need to recalibrate the thing. I'm hoping this isn't going to be an ongoing issue . . .

Now, it's become considerably warmer since the truck first starting giving me this starting trouble. I can't get a pressure reading on my fuel line because my pressure gauge doesn't fit onto the Schraeder valve. Have any of you done this? Do you have any suggestions?

robert

 

[TireIron]

glad to hear that helped, I've been so busy I haven't been by here in like a month but I had thought to mention pulling the O2 to recalibrate it.

I don't know what to say about the schrader valve though, ive never bothered or needed to use a pressure gauge.

 

[anupaum]

glad to hear that helped, I've been so busy I haven't been by here in like a month but I had thought to mention pulling the O2 to recalibrate it.

Why should the O2 sensor have anything to do with starting? It wasn't firing over, as if it wasn't getting any fuel, and that's why I initially suspected a problem with my fueling system.

Now there's a definite misfire of some kind at certain rpms and the O2 correction bounces all over the place. I'm going to have to re-tune the VE tables, which makes me wonder about the condition of the sensor . . .

After all, why should I have to re-tune at this point?

I don't know what to say about the schrader valve though, ive never bothered or needed to use a pressure gauge.

I wish someone who had experience with this would post something. I'd really LIKE to check that out before I return the FPR that I bought and didn't use . . .

robert

 

[jdm90]

This is really a good one. Any new info ?

 

[anupaum]

This is really a good one. Any new info ?

I haven't had a lot of time to re-tune the truck--and the fuel tables HAVE to be adjusted because they're just not right--but it's starting without any difficulty now. Of course, it's also significantly warmer than three or four weeks ago at the peak of the problem. What's particularly strange about this, though, is that I had NO trouble starting it through the worst of this winter . . .

What I'm wondering, is why does the O2 sensor have anything at all to do with starting? It should be in open loop mode through warm up, as it takes 30 seconds or so for the O2 sensor to heat up to operating temperature.

A friend of mine who works as a heavy-duty mechanic suspects I may have a vacuum leak. It's VERY frustrating to hear this, as vacuum leaks and air leaks have PLAGUED my experience with this truck ever since I first started messing with it!

robert