4 hours of repair and $500 later ...
brett at cloud9.net
Sun Jun 5 14:14:14 EDT 2005
On Jun 5, 2005, at 12:41 PM, Cat ^. .^ ~ wrote:
> Okay, the fule pump works if he by passes the fuel pump relay . . .
> but now he cannot get spark, my hbby says.
You put a known-working relay into the car, so it's not the relay.
From bypassing the relay, you know it's not the wiring to the pump
or the pump itself. Now we learn there's no spark. Spark is
controlled by the ECU triggering the output stage.
[Addressing the list] Why didn't anybody ask her to check whether or
not the relay is getting power from the ECU, before sending her
shopping for a new relay? The mother of all $#@!ups is making
assumptions. You all haven't learned from your mistakes, either-
you're now assuming ignition problems because there's no spark. Stay
focused. Lack of ignition is useful information, but don't get
distracted from "why is there no fuel pump operation". See below.
> Does the fuel pump relay have anything to do with the spark ?
No, but if there's no spark (assumption is spark-testing procedure is
correct) and no power to the fuel pump relay, that means the ECU has
a sensor failure, or there is something very wrong with basic engine
function which it has detected (such as a snapped belt or broken
distributor gear. Rotating the engine by hand or cranking it with
the distributor off will tell you either, and I believe the gear is
metal on the 10v engines, so it's unlikely to be that?)
Wiring trouble is possible, but unlikely to be simultaneously
affecting both the ignition and fuel pump system(s); the simultaneous
'failure' is too coincidental, so I'm tempted to rule out a problem
with the coil, ignition stage, etc. However, both the fuel pump
relay and the ignition power output stage can be checked for proper
ground and power/signal if there is doubt.
Either the ECU:
-does not think the engine is spinning/cannot get timing (flywheel
sensor; I forget, is the MC-2 a "skip a tooth for TDC" or is there a
TDC pin and second sensor?)
-can't figure out the cycle (ie, distributor hall effect sensor. The
ECU may know where the crankshaft is, but it doesn't know which half
of the 4-cycle process it's on for that particular cylinder, ie intake
+compression or power+exhaust, until it knows cam position...which it
gets from the distributor.)
-thinks some other really important sensor is broken*
*the temperature sensor on the 20vt (I don't know about the MC-2)
will cause a no-start if it's determined by the ECU to be bad or
disconnected. I'm not sure whether failed knock sensors will result
in a no-start, but I'm fairly certain the intake air temp sensor will
not, and I can't think of any other engine sensors).
Crank the engine for 15 seconds, do NOT shut off the ignition...and
pull the codes. Most of the things that cause no-start conditions
are reported by the ECU if they're true.
Wastegates really don't fail. The membrane can, but there's a reason
the wastegate itself is NLA; nobody ever bought them, because they
don't fail. Regardless, it won't cause a no-start condition, so it
is irrelevant at the moment.
Faye, if your husband is troubleshooting this himself, he needs to
start on the "no start" troubleshooting chart in the Bentley, and NOT
IGNORE PREREQUISITES/CONDITIONS, OR STEPS! Obviously some things
like fuel pressure can't be checked by most people given that CIS
fuel pressure gauges are rare, the Bentley tends to be a little
"replace-happy", and if you're stuck with limited tools/light/time
like on the side of the road, you do what you can. Otherwise, you
really need to avoid skipping over steps or ignoring stated
prerequisite conditions. I've tried to avoid listing suggestions or
ideas without -my- assumptions, but the Bentley is obviously more
professional and thorough. My memory of the 10v engines is also
quite fuzzy, it's been 6-8 years since I owned one.
"They that give up essential liberty to obtain temporary
safety deserve neither liberty nor safety." - Ben Franklin
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