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Old 07-29-2007, 07:17 PM   #1
pilfflip
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Join Date: Jul 2003
Chapter/Region: NWIC
Location: Salem, OR
Vehicle:
'02 Murdered WRX
'02 Silver Legacy

Default Is it a MAF or an O2 sensor?

These were the Symptoms while my car ran (at this time it won't start);

1. Rough idle - Occasionally when I start my car is idles high, anywhere between 1,800RPM and 3,300RPM. Usually this can lost anywhere from 40 seconds to 10 minutes, I know that they sometimes are known to do that becuase of EGR but this was a little excessive.

2. INCREDIBLY rich - My exhaust gas smells like gas. My sparks plugs and plug wires also went out in just a few hundred miles.

3. Trouble starting - When it was running some times it was really finicky about starting. (this was very hit or miss) Sometimes it would start immediately and others it would take it anywhere from 10 seconds to 30 seconds of engine turn over before it would start. During this time it would reek of gas and when it would finally start it would pour out smoke from the engine bay and the exhaust that smelled of gas.

4. CEL - Although I didn't have the chance to get the codes pulled recently, when I cleared out my CAT it threw a code and it was an O2 sensor, but that was more than 2 years ago.

Now, my car won't start at all. It turns over but nothing after that. It sounds like it wants to start and if I turn it over long enough it'll sputter and start but that'll only last between 4 to 6 seconds and it'll slowly die. Then it'll start from square one again. It smells of gas in the engine bay when I'm trying to start it. I checked all of the vacuum lines-nothing.

I was thinking that this may be a MAF sensor, but I don't get the feeling from my searches that a MAF could keep a car from starting/running but I could totally be wrong. What I did come up with though is that it could be an O2 sensor, but none of the posts that I read could really put a definitive finger on which.


Any ideas?



~Mike
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Old 07-29-2007, 07:20 PM   #2
Mulder
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We can't tell you with just the information you gave. At the very least you MUST get the code read to find out what it really is.
One thing for certain though, an 02 problem will have nothing to do with starting troubles since the ECU does not look at the 02 signal until the engine is running and at operating temperature. So your problem would have to lie elsewhere. That doesn't mean it's a MAF issue though, there are a lot of other things it could be. The code may point you in the right direction, but it might still have to go to a shop for further troubleshooting.
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Old 07-29-2007, 07:28 PM   #3
pilfflip
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That's what I was afraid of...

It's hard to get my car to a shop or a nearby Auto zone when it won't start. But you think I can rule out an O2 sensor?




~Mike
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Old 07-29-2007, 07:48 PM   #4
Mulder
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While it's possible you have a bad 02 (and it may be contaminated from all the extra fuel that seems to be getting dumped), that alone won't be the cause of a no-start.
You might try pulling the plugs, they may be too fouled at this point for the car to run. A fresh set could allow it to run at least for the time being. You could pull the 02 and look at it as well, if it's all carboned-up it will have to be replaced.
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Old 07-30-2007, 09:00 AM   #5
BeeGee
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Quote:
Originally Posted by pilfflip View Post
That's what I was afraid of...

It's hard to get my car to a shop or a nearby Auto zone when it won't start. But you think I can rule out an O2 sensor?




~Mike
Autozone will check out tools for a deposit, so they might loan you a CEL scanner.
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Old 07-31-2007, 05:32 AM   #6
pilfflip
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'02 Silver Legacy

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Really now!?!....hmm.



~Mike
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Old 07-31-2007, 07:32 AM   #7
munkis
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disconnect the MAF sensor and see if it starts. It should start and run in fail safe.
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Old 07-31-2007, 02:16 PM   #8
pilfflip
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'02 Silver Legacy

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Now, that's what i thought but I had a friend who said that it wouldn't run at all without the MAF plugged in.



~Mike
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Old 08-01-2007, 09:17 PM   #9
pilfflip
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'02 Murdered WRX
'02 Silver Legacy

Default

Went to Autozone and rented one of teh OBDII readers, the an "Actron CP9135" and pulled the codes:

P0115 Engine coolant temp malfunction
P0120 TPS/Pedal position sensor A Circuit Malfunction
P0125 Closed Loop Fuel Control, insufficient coolent temp
P1700 Manufacturer Control Transmission
P0121 TPS/Pedal position Sensor A CKT Range/Perf.

And a couple of those codes came up a second time with a "pd" on the far right of the screen, anyone know what that means?

My brother checked his '98 and came up with:

P0133 02 Sensor CKT slow response bank 1 sensor 1
P1443 Manufacturer control Aux. emission controls



~Mike

P.S. Gonna go Search...
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Old 08-01-2007, 09:51 PM   #10
Mulder
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The "pd" means they are "pending codes". That indicates they have been detected once, but have to be detected again before being set as hard codes and turning on the CEL.
The 0115 together with the 0125 is a hint that you may have a bad coolant temp sensor. This would also explain the extreme rich running, if the sensor is out of range and always reporting an abnormally low coolant temp to the ECU. The result will be an overly rich mixture all the time.
If you still have the scanner, and it can monitor live data as well as read codes, check the value of the coolant temp. If the car has been sitting for at least several hours, it should read within a few degrees of ambient. If it's a lot lower you've found your problem.
The 0120 and 0121 may be indicating a bad TPS, or a problem with the wiring.
Not sure about the transmission code but it could be related to the others, the TCU depends on proper coolant temp and TPS signals to operate normally.
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Old 08-02-2007, 01:08 AM   #11
pilfflip
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'02 Murdered WRX
'02 Silver Legacy

Default

I tweaked my thermostat a little bit and have been running irregularily low since I did my HGs.

I was thinking that My rich running was due to that and I knew that my TPS sensor had thrown a code, it's been acting up as well but not to an extreme and i have been unable to find a replacement for it...thanks Mulder


~Mike
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