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2003 Disco starving for fuel?

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  #51  
Old 08-19-2016, 07:45 PM
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Well, it's good there's no problem with it, but now what?
Have you looked at the MAF reading with the key on, engine off? With it plugged in, I mean? I wonder if the computer is actually using information from it, or using a substituted value?? If it still gives you the same reading with just the key on, I would suspect that the computer is ignoring the actual MAF reading.
Also, if you're still not hearing the fuel pump, did you check for power at the fuse and relay?
 
  #52  
Old 08-19-2016, 08:27 PM
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Is there a way to test the maf with my multimeter to see if it is bad?
 
  #53  
Old 08-19-2016, 08:29 PM
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I think when I had it plugged in with the key on, it read .73 without the engine running, and when I tried to start it it jumped to 64.something I believe.
 
  #54  
Old 08-19-2016, 11:40 PM
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A multi meter will do a lot of things... but if you want to see what your maf is actually doing... you need a scan tool that reads live data. The cheapest one I know of is the Ultragauge. It's a code reader... and it does log live data... you can see if your O2 sensors are working.. read engine temp... battery voltage.. current codes that are set... and codes that are pending. It will show you if your maf is working...

I'm not trying to sell you something... just saying that if you have more data... we can help you figure out your issue... Ultragauge is one of several tools that will help you diagnose your problems... I only mention it because it's the best for the price. Paid ~$69 for mine. Money well spent.

Don't Guess... Scan it.
 
  #55  
Old 08-20-2016, 01:33 AM
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I have a scanner with live data. I did post the scans from it, I posted I think 31 frames of data while it was running a couple of pages back in this thread. It is reading, but I am not sure what the normal parameters are for it.
 
  #56  
Old 08-20-2016, 01:37 AM
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I did, and wasn't able to get a reading. Also now, I don't think I can hear it while the engine is turning over either. I could hear it kick on for a second right as the engine almost started, and now I barely hear it doing anything.
 
  #57  
Old 08-20-2016, 05:47 AM
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If you have a multi meter with a frequency or MHz setting, you can use that. The problem you run into is that, no matter what, the sample rate is still too slow. An oscilloscope is really the only option to get full detailed signals like that.
I think there is a problem with your MAF. It shouldn't be reading .73 lb/min with the engine off. Then the spike up to 64?? That certainly doesn't seem right!
 
  #58  
Old 08-20-2016, 06:00 AM
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I just went back and looked, the MAF reading was .73 lb./min. Unplugged as well...
It looks like the intake air temperature did just what you'd expect, but I really don't know about the MAF reading. You would think it would be zero especially with it unplugged.
Assuming there's no problem with the wiring. The only other thing that would confuse the computer like this would be a MAP sensor that's stuck. But you saw no mention of one in the RAVE. They're also called 'boost' sensors sometimes. So that might be something to look for. Either that or maybe a 'baro' sensor could be stuck, making the computer think there's more, or less atmospheric pressure than there really is.
It has to have something like that because it needs to know how to get the air/fuel ratio to 14.7:1 so it has to use atmospheric pressure as part of the calculation.
 
  #59  
Old 08-20-2016, 12:58 PM
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What ranges should the frequencies be in? My multimeter will do that, and it has a max/min that reads even if the display hasn't refreshed quickly enough if that makes sense. I think I can use it, but I think we will be in the same boat. We are getting readings, just don't think they are accurate. I can get a reading with my mulitimeter, but unless we know the parameters, it isn't definitive.
 
  #60  
Old 08-20-2016, 02:19 PM
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If there is a glitch in the frequency and it happens regularly, you may be able to catch it with the 'max hold' function on the multi meter. It seems strange that it's backing fuel off though.
Is there any way it could have some plug wires mixed up? That can cause problems like this too.
 


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