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flooding; 3,5 floods after warm
Topic Started: Nov 21 2011, 09:00 PM (821 Views)
pawdad
New Member
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hey all, i have a 96 metro with 3cyl,5spd, starts fine when cold,drive 5 miles seems to flood, mash throttle starts, runs fine till stop,then same. had o2 senser code, replaced,now p420, could this be related ?,24000,on rebuild,comp good, sugestions?
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Memphis metro


PO420 is still oxygen sensor and catalytic converter issues. Did you replace both upstream and downstream sensors? Take a look at the after converter sensor and check its wiring. Welcome to the forum.
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mwebb
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FOG

pawdad
Nov 21 2011, 09:00 PM
hey all, i have a 96 metro with 3cyl,5spd, starts fine when cold,drive 5 miles seems to flood, mash throttle starts, runs fine till stop,then same. had o2 senser code, replaced,now p420, could this be related ?,24000,on rebuild,comp good, sugestions?
when your system had the front 02 sensor DTC
testing for the cat converter (and other things) was suspended

after you replaced the front 02 sensor , and cleared DTCs or drove the car and the system ran and passed the
Mode 6 testing for the front then the rear 02 sensor
the system ENABLED testing for the cat converter , which then failed to pass it's test .

do not frak with the rear 02 sensor it is not and can not be the source of your problem , your system does not trim on the rear 02 sensor .
be aware that the rear 02 sensor heater does not get powered up until the car hits 50mph
the rear 02 sensor signal will be flatlined at 1.2 volts until the heater is switched on using scan data on OBD2 generic scan tools.

the heater on the front 02 sensor , (white wires) must be powered up if the engine is running ... is it ? one wire will be positive the other negative , does not matter which is which

**********************
i would focus on things that could make the system rich
start with the vacuum line to the MAP sensor and the grounds that are located at the rear of the intake manifold .

post
long term fuel trim at idle
and
long term fuel trim at 2k rpm after holding at 2k rpm for 1 minute
hot engine

your cat is probably bad , but
do not consider replacing it until you have resolved the rich condition and put a few highway miles on the car , the cat may recover
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Memphis metro


It could be the rear sensor. Below is some more information on your current code. The rear sensor does play a major role along with the front sensor with the pcm. If the rear sensor is defective it could cause you problems. Your current code points to checking the wiring as well as the sensor after the converter, if that is good it points towards the converter as suspect. To make a statement that the rear sensor cannot be the problem is inaccurate because it very well can be the cause of your current code.

PO420 code will set when,
HO2S2 activity is more than a specified value.
or HO2S2 voltage is within a certain percetage of HO2S1

A defective sensor could cause either circumstance above and thus inducing code PO420 in the system. This being said, this does not mean your sensor is bad. I just say it can be and I would start by inspecting it as well as inspecting the complete exhaust system for leaks. If good, suspect converter. Before I condemned the converter I would in your case remove the battery cable for a minute and reconnect and drive the vehicle and let all the parameters reset and see if your code comes back again. If so proceed on with converter inspection. Also as stated above, it could be a fault in another system causing the rich condition. After driving the car for the five minutes, does it reach operating temp on the temp guage?

http://www.obd-codes.com/p0420
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pawdad
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yes gets up to operating temp, starts fine cold,runs fine untill you stop 1 mile or 100 miles, then acts like flooded smell gas, spins and spins, mash throtle,fires rite up then same.clear codes and po420 keeps coming back no vac leaks that i can find
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Memphis metro


You say acts like it is flooded. Are you seeing black smoke out of the tailpipe? Have you checked to see if by chance your converter is restricted?
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Bad Bent
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Facetious Educated Donkey

And how do the spark plugs appear when you take them out? They would be black or wet.

How about the two coolant hoses on the Throttle Body, above the alternator? Are they as hot as radiator hoses when the engine is warm. http://i404.photobucket.com/albums/pp123/BadBent/Repair%20Pics/CoolantHoses.jpg If clogged then you will run rich.
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