1999 Ford Ranger won't run - codes listed

sox · 10-25-2009, 01:25 PM

Hello - it's a 1999 Ford Ranger 3.0 (4x) - it just wont start/run - just backfires...we think that it's getting too much gas...(?)

Codes:
PO0171 too lean bank 1
PO304 Cyl 4 misfire
PO306 Cyl 6 misfire
Fuel PSI between 50 & 70

So far we have checked for vacuum leaks etc and replaced the following: plugs and wires, crankshaft timing sensor (CKP), cam sensor (CMP), the timing chain, all oxygen sensors (O2s). mass air flow sensor (MAF)

Not sure what to do next - appreciate any advice.

bradrhale · 10-25-2009, 01:33 PM

do a compression test on the cylinders, all of them. the tester is relatively cheap and might can be rented free from autozone. this might shed some light as to why it is 1. backfiring, 2. measuring too lean meaning too much air and not enough fuel, and 3. why just those 2 cylinders.

sox · 10-25-2009, 06:22 PM

Hi - thank you for your response - we will do that compression test....do you have any idea why the code would indicate "too lean" however we could smell gas from the exhaust (before it quit running) and the spark plugs were soaked with gasoline when we replaced them. Again thanks for your help!

leolkfrm · 10-25-2009, 06:32 PM

does it have a timing belt?

sox · 10-25-2009, 06:36 PM

It has a timing chain...and we replaced it - - it was not bad and the timing marks lined up correctly so it had not jumped a tooth or anything.

bradrhale · 10-25-2009, 07:55 PM

if you turn out with lower compression in those 2 cylinders, do measure all of them, than you likely have a bad couple of exhaust valves which would not get a good burn in the cylinder, hence the misfire, and combustion out of the cylinder which would be backfiring and possibly lean condition a it is also igniting unburnt gas leaving the exhaust manifold.

anyone here think that sounds like BS??

crabtruck · 10-26-2009, 06:18 AM

Welcome to the forum sox.

You may want to disconnect battery for 10 min to force a re-learn for fuel.
On a truck with MAF, no real baro info is available so it is calc'd and stored.
You may be "holding" the rules for a problem you have already "fixed"

10-25-2009, 01:25 PM	#1
sox Junior Member Join Date: Oct 2009 Posts: 3	1999 Ford Ranger won't run - codes listed Hello - it's a 1999 Ford Ranger 3.0 (4x) - it just wont start/run - just backfires...we think that it's getting too much gas...(?) Codes: PO0171 too lean bank 1 PO304 Cyl 4 misfire PO306 Cyl 6 misfire Fuel PSI between 50 & 70 So far we have checked for vacuum leaks etc and replaced the following: plugs and wires, crankshaft timing sensor (CKP), cam sensor (CMP), the timing chain, all oxygen sensors (O2s). mass air flow sensor (MAF) Not sure what to do next - appreciate any advice.

10-25-2009, 06:32 PM	#4
leolkfrm Senior Member Join Date: Mar 2008 Location: N.Y. Posts: 4,300	does it have a timing belt? __________________ 4 wheels move the body 2 wheels move the soul B.W.A.I

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10-25-2009, 01:33 PM	#2
bradrhale Senior Moderator Join Date: Apr 2006 Location: Texas Posts: 8,024	do a compression test on the cylinders, all of them. the tester is relatively cheap and might can be rented free from autozone. this might shed some light as to why it is 1. backfiring, 2. measuring too lean meaning too much air and not enough fuel, and 3. why just those 2 cylinders.

10-25-2009, 06:22 PM	#3
sox Junior Member Join Date: Oct 2009 Posts: 3	Hi - thank you for your response - we will do that compression test....do you have any idea why the code would indicate "too lean" however we could smell gas from the exhaust (before it quit running) and the spark plugs were soaked with gasoline when we replaced them. Again thanks for your help!

10-25-2009, 06:36 PM	#5
sox Junior Member Join Date: Oct 2009 Posts: 3	It has a timing chain...and we replaced it - - it was not bad and the timing marks lined up correctly so it had not jumped a tooth or anything.

10-25-2009, 07:55 PM	#6
bradrhale Senior Moderator Join Date: Apr 2006 Location: Texas Posts: 8,024	if you turn out with lower compression in those 2 cylinders, do measure all of them, than you likely have a bad couple of exhaust valves which would not get a good burn in the cylinder, hence the misfire, and combustion out of the cylinder which would be backfiring and possibly lean condition a it is also igniting unburnt gas leaving the exhaust manifold. anyone here think that sounds like BS??

10-26-2009, 06:18 AM	#7
crabtruck Senior Member Join Date: Jul 2007 Location: on your 9 Posts: 3,364	Welcome to the forum sox. You may want to disconnect battery for 10 min to force a re-learn for fuel. On a truck with MAF, no real baro info is available so it is calc'd and stored. You may be "holding" the rules for a problem you have already "fixed"