midiwall

So I was out running around watching STFT, LTFT, temp, etc. and then... nothing. My reader just stop showing info.

I reset the reader - no luck, I reset the ECU - no luck, I tried another reader - no luck. The OBD fuse under the hood is fine (in fact, all of the fuses are fine), there's supply voltage across pins 1 & 9 at the OBD II connector...


Any ideas? The ECU is obviously okay since the truck runs...

DarylD

Hey Mark , Try unpluging a sensor one at a time and see if it will read a code , start with the Map sensor . I've seen this before were a bad sensor caused a problem with the diagnostics . Daryl

midiwall

Okay, now that was cool. THANK YOU DARYL!

Here's what I did...

- I pulled the MAF and the TPS connections
- Reset the ECU
- Plugged the MAF AND TPS back in
- OBD II connected

But, it's VERY clear that the ECU is VERY busy trying to deal with the flakey sensor. You can watch the OBD tool (a Palm based Auterra) updating it's display maybe one value every 20-30 seconds instead of its usual refresh of five values many times per second.

I had things torn apart yesterday and I cleaned the MAF and had oiled the TB butterfly and associated area. It's possible that there's just crud on one or the other and this'll work itself out.

I played a bit with various combinations of reseting the ECU with just the MAF off, or just the TPS off, and if I had to guess, I'd say it's the TPS. I say that 'cause if I had damaged the MAF, then I wouldn't expect the truck to run.

I can run with the TPS disconnected, but of course I don't expect to be able to run with the MAF disconnected. But, with the TPS disconnected, I still get the sloggy updates through OBD II. Hmmm, that would tend to say that it's the MAF.

Maybe I can find someone who'll let me swap a TPS and/or MAF with them for a test to be sure.


Interesting problem... It shows the multitasking/multiprocessor nature of the ECU.

Anyway... I've got a problem, but I have a process that can help figure out what's up.


Thanks Daryl!