[Diy_efi] Need help from the experts diagnosing lean state upon

ralph granchelli rgranchelli at yahoo.com
Sat Feb 19 04:50:17 GMT 2005


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Adam,
 
Thanks for your inputs. I have been sick for a week so have not worked on the problem this week
 
This system is continuously looking at all the sensors and not only at start up. It continuously makes corrections based upon all sensor inputs
 
The heat soak theory makes sense, however this problem can occur when the system is cold like after sitting all night.
 
I suspect that I may have a sticking injector. I have a 4 channel TEK scope and plan to hook current probes to the injector trigger lines and look at their signatures. I don't have any experience trouble shooting injectors per say but have looked at some waveforms of good and bad injectors.
 
At least I should be able to tell if one looks any different from the others
 
TNX for the input
 
Rgds,
RG
AZ

Adam Wade <espresso_doppio at yahoo.com> wrote:
--- ralph granchelli wrote:

> The problem I am having is as follows. Sometimes
> when I start the engine either hot or cold it will
> go into a real lean state, around 22:1.It will stay
> this way until I restart.

Well, since you confirmed that it is reading from the
same load/speed map site either way, we can conclude
that the engine speed and engine load sensors (TPS,
MAF, MAP, whatever combination you are using) are
delivering correct readings, and the ECU is
interpreting them correctly. And you have it
programmed not to go into closed-loop mode, so it's
nothing to do with the O2 sensor. What does that
leave?

I don't know about your particular unit, but it used
to be standard practice for many automotive and some
motorcycle ECUs to check ambient air temp and density
at startup, and not again until the next key-on. 
Often this was done so that a pressure transducer
could be eliminated; for instance, the MAP sensor
could be used prior to cranking the motor. If your
setup reads like this, it could be getting a bad
signal from a pressure or temperature transducer (bad
harness, connector/connection, or sensor).

Another possibility is that one of the temp sensors
(ambient/intake or coolant) is situated somewhere
where it receives undue amounts of heat when parked
hot; perhaps the CTS is in a pocket on a head where
the coolant locally gets extremely hot when the water
pump is not turning, or (more likely) the ambient
sensor gets heat-soaked, perhaps from a hot exhaust or
something. Especially with the AAT sensor, reading
more than 150 deg. F would tend to make the ECU think
that air density was much, much lower than it actually
was, and to deliver a very lean mixture accordingly,
using the multiplier table for air density.

Note that I'm not familiar with the system under
discussion, and am offering general comments about
possible culprits. This may well be a "known issue"
with the unit itself, and my comments may not be
applicable. They're meant as general brainstorming
for troubleshooting the symptoms. Hopefully someone
who knows your specific system can chime in about
anything particular to the unit that might be helpful.

=====
| 82 Honda CX500 Turbo (Cassandra) 90 Kwak Zephyr 550 (Daphne) |
| "It was like an emergency ward after a great catastrophe; it |
| didn't matter what race or class the victims belonged to. |
| They were all given the same miracle drug, which was coffee. |
| The catastrophe in this case, of course, was that the sun |
| had come up again." -Kurt Vonnegut |
| M/C Fuel Inj. Hndbk. @ Amazon.com - http://tinyurl.com/6o3ze |

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<DIV>Adam,</DIV>
<DIV>&nbsp;</DIV>
<DIV>Thanks for your inputs. I have been sick for a week so have not worked on the problem this week</DIV>
<DIV>&nbsp;</DIV>
<DIV>This system is continuously looking at all the sensors and not only at start up. It continuously makes corrections based upon all sensor inputs</DIV>
<DIV>&nbsp;</DIV>
<DIV>The heat soak theory makes sense, however this problem can occur when the system is cold like after sitting all night.</DIV>
<DIV>&nbsp;</DIV>
<DIV>I suspect that I may have a sticking injector. I have a 4 channel TEK scope and plan to hook current probes to the injector trigger lines and look at their signatures. I don't have any experience trouble shooting injectors per say but have looked at some waveforms of good and bad injectors.</DIV>
<DIV>&nbsp;</DIV>
<DIV>At least I should be able to tell if one looks any different from the others</DIV>
<DIV>&nbsp;</DIV>
<DIV>TNX for the input</DIV>
<DIV>&nbsp;</DIV>
<DIV>Rgds,</DIV>
<DIV>RG</DIV>
<DIV>AZ<BR><BR><B><I>Adam Wade &lt;espresso_doppio at yahoo.com&gt;</I></B> wrote:</DIV>
<BLOCKQUOTE class=replbq style="PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: #1010ff 2px solid">--- ralph granchelli <RGRANCHELLI at YAHOO.COM>wrote:<BR><BR>&gt; The problem I am having is as follows. Sometimes<BR>&gt; when I start the engine either hot or cold it will<BR>&gt; go into a real lean state, around 22:1.It will stay<BR>&gt; this way until I restart.<BR><BR>Well, since you confirmed that it is reading from the<BR>same load/speed map site either way, we can conclude<BR>that the engine speed and engine load sensors (TPS,<BR>MAF, MAP, whatever combination you are using) are<BR>delivering correct readings, and the ECU is<BR>interpreting them correctly. And you have it<BR>programmed not to go into closed-loop mode, so it's<BR>nothing to do with the O2 sensor. What does that<BR>leave?<BR><BR>I don't know about your particular unit, but it used<BR>to be standard practice for many automotive and some<BR>motorcycle ECUs to check ambient air temp and density<BR>at startup, and not
 again until the next key-on. <BR>Often this was done so that a pressure transducer<BR>could be eliminated; for instance, the MAP sensor<BR>could be used prior to cranking the motor. If your<BR>setup reads like this, it could be getting a bad<BR>signal from a pressure or temperature transducer (bad<BR>harness, connector/connection, or sensor).<BR><BR>Another possibility is that one of the temp sensors<BR>(ambient/intake or coolant) is situated somewhere<BR>where it receives undue amounts of heat when parked<BR>hot; perhaps the CTS is in a pocket on a head where<BR>the coolant locally gets extremely hot when the water<BR>pump is not turning, or (more likely) the ambient<BR>sensor gets heat-soaked, perhaps from a hot exhaust or<BR>something. Especially with the AAT sensor, reading<BR>more than 150 deg. F would tend to make the ECU think<BR>that air density was much, much lower than it actually<BR>was, and to deliver a very lean mixture accordingly,<BR>using the multiplier table for air
 density.<BR><BR>Note that I'm not familiar with the system under<BR>discussion, and am offering general comments about<BR>possible culprits. This may well be a "known issue"<BR>with the unit itself, and my comments may not be<BR>applicable. They're meant as general brainstorming<BR>for troubleshooting the symptoms. Hopefully someone<BR>who knows your specific system can chime in about<BR>anything particular to the unit that might be helpful.<BR><BR>=====<BR>| 82 Honda CX500 Turbo (Cassandra) 90 Kwak Zephyr 550 (Daphne) |<BR>| "It was like an emergency ward after a great catastrophe; it |<BR>| didn't matter what race or class the victims belonged to. |<BR>| They were all given the same miracle drug, which was coffee. |<BR>| The catastrophe in this case, of course, was that the sun |<BR>| had come up again." -Kurt Vonnegut |<BR>| M/C Fuel Inj. Hndbk. @ Amazon.com - http://tinyurl.com/6o3ze |<BR><BR>__________________________________________________<BR>Do You Yahoo!?<BR>Tired of spam?
 Yahoo! Mail has the best spam protection around <BR>http://mail.yahoo.com <BR>_______________________________________________<BR>diy_efi mailing list<BR>diy_efi at diy-efi.org<BR>http://lists.diy-efi.org/mailman/listinfo/diy_efi<BR></BLOCKQUOTE><p>
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