2002 Chevy Express 1500 Starting and Shifting issues
February 13th, 2018, 10:42 PM
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2002 Chevy Express 1500 Starting and Shifting issues
Hi all,
I just picked up a 2002 Chevy express 1500. It has the 4.3L V6. It has a hard time cranking (takes 3-4 times) and shifts hard right at 10 mph. Everything else seems fine. The Seller said he just had the fuel pump and transmission replaced.
I'm thinking the hard start might be a Fuel pressure regulator? Not sure. But I have no idea what would cause the hard shift only at 10 mph. Any ideas?
I just picked up a 2002 Chevy express 1500. It has the 4.3L V6. It has a hard time cranking (takes 3-4 times) and shifts hard right at 10 mph. Everything else seems fine. The Seller said he just had the fuel pump and transmission replaced.
I'm thinking the hard start might be a Fuel pressure regulator? Not sure. But I have no idea what would cause the hard shift only at 10 mph. Any ideas?
February 13th, 2018, 11:24 PM
#2
A hard shift form first to second when cold is not uncommon, does it do it warm? 3 to 4 cycles turning the key and cranking..? hard as it cranks over slowly, or its hard to fire up?
February 15th, 2018, 9:02 PM
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Hard as in it doesn't want to fire up. you can get it on the first try if you get the timing right to be exactly right after the fuel pump has ran when you put the key on start but too fast no start, too slow no start.
February 15th, 2018, 10:01 PM
#4
Fuel pressure dropping after the pump shuts off maybe.....Regulator, or the injector is bleeding fuel and its dripping out the poppet valves instead of the spray you need.....
Can you test your fuel system pressure?
Can you test your fuel system pressure?
February 15th, 2018, 11:02 PM
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I'd have to get some gauges, I don't have any. It looks like the lines are pretty burred in the Chevy Express.
February 16th, 2018, 11:15 AM
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im not sure if I can use OBD for the fuel pressure or not, some cars report it with it, but even so if it’s mostly an issue at starting it won’t help much since the OBD link doesn’t estiablish til the engine is on.
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February 16th, 2018, 2:48 PM
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Early shifting is a common fault response. TPS and VSS
faults, MAP faults, anything that corrupts the "load"
calculation.
You don't mention what those DTCs mean.
https://www.obd-codes.com/p0131
P0131 Oxygen Sensor Circuit Low Voltage (B1S1)
P0137 02 Sensor Circuit Low Voltage (Bank I Sensor 2)
P0151 O2 Sensor Circuit Low B2S1
Both banks bad together indicates a fuel pressure issue.
I had to replace my fuel pump and regulator, and still see
some pressure bleed-back. To get reliable starting I let
the key sit at IGN=on until the pump quits its precharge
whine, and then crank (~5 sec). Fires right up. But if I let
it sit for 15 sec or crank right off the bat, it struggles to
catch.
A fuel pressure gauge will set you back about $40. It is
complementary to any OBDII scan tool - there still exist
things that are not computerized yet matter a lot, that the
PCM simply makes assumptions about.
There are 3 ways to "kill codes" and one of them is "No
MIL" (malfunction indicator light"). The lack of SES light
(MIL) is not lack of fault,then.
Long term sensor faults can also drive gross fueling error
in closed loop, "false trimming".
Long term lean running, if real (e.g. fuel pump) will also
tend to cause a lot of "knock learning". On the V8s (where
I have experience) this will drive the Knock Learn Factor
to interpolate toward the "low octane table" and pull timing,
further aggravating starting "catch" as well as power and
economy.
First order of business is to determine whether the lean
fueling indication is real (fuel pump, vacuum leak, etc.)
or spurious (crusty sensors, times three - possible, maybe
even likely if these are untouched).
Putting new sensors into a whacked-fueling motor will
foul them in short order. So if you decide to debug by
throwing parts at it, return the suspect sensors to the
position once you've seen what a good one does.Before
all the soot finds a home.
P0131 Oxygen Sensor Circuit Low Voltage (B1S1)
Read more at: https://www.obd-codes.com/p0131
Copyright OBD-Codes.com
P0131 02 Sensor Circuit Low Voltage (Bank I Sensor I)
Read more at: https://www.obd-codes.com/p01-codes
Copyright OBD-Codes.com
P0131 02 Sensor Circuit Low Voltage (Bank I Sensor I)
Read more at: https://www.obd-codes.com/p01-codes
Copyright OBD-Codes.com
faults, MAP faults, anything that corrupts the "load"
calculation.
You don't mention what those DTCs mean.
https://www.obd-codes.com/p0131
P0131 Oxygen Sensor Circuit Low Voltage (B1S1)
P0137 02 Sensor Circuit Low Voltage (Bank I Sensor 2)
P0151 O2 Sensor Circuit Low B2S1
Both banks bad together indicates a fuel pressure issue.
I had to replace my fuel pump and regulator, and still see
some pressure bleed-back. To get reliable starting I let
the key sit at IGN=on until the pump quits its precharge
whine, and then crank (~5 sec). Fires right up. But if I let
it sit for 15 sec or crank right off the bat, it struggles to
catch.
A fuel pressure gauge will set you back about $40. It is
complementary to any OBDII scan tool - there still exist
things that are not computerized yet matter a lot, that the
PCM simply makes assumptions about.
There are 3 ways to "kill codes" and one of them is "No
MIL" (malfunction indicator light"). The lack of SES light
(MIL) is not lack of fault,then.
Long term sensor faults can also drive gross fueling error
in closed loop, "false trimming".
Long term lean running, if real (e.g. fuel pump) will also
tend to cause a lot of "knock learning". On the V8s (where
I have experience) this will drive the Knock Learn Factor
to interpolate toward the "low octane table" and pull timing,
further aggravating starting "catch" as well as power and
economy.
First order of business is to determine whether the lean
fueling indication is real (fuel pump, vacuum leak, etc.)
or spurious (crusty sensors, times three - possible, maybe
even likely if these are untouched).
Putting new sensors into a whacked-fueling motor will
foul them in short order. So if you decide to debug by
throwing parts at it, return the suspect sensors to the
position once you've seen what a good one does.Before
all the soot finds a home.
P0131 Oxygen Sensor Circuit Low Voltage (B1S1)
Read more at: https://www.obd-codes.com/p0131
Copyright OBD-Codes.com
P0131 02 Sensor Circuit Low Voltage (Bank I Sensor I)
Read more at: https://www.obd-codes.com/p01-codes
Copyright OBD-Codes.com
P0131 02 Sensor Circuit Low Voltage (Bank I Sensor I)
Read more at: https://www.obd-codes.com/p01-codes
Copyright OBD-Codes.com
February 25th, 2018, 7:02 PM
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It seems like all the issues basically went away on their own, It starts fine now and the shifting hard goes away once it's warmed up.
The van had mostly sat since 2015 until they (It was part of a fleet for a flooring company) had the tranmission, fuel pump, tires, and windshield replaced recently. It may have have just been some old fuel in the tank or something. No clue.
The van had mostly sat since 2015 until they (It was part of a fleet for a flooring company) had the tranmission, fuel pump, tires, and windshield replaced recently. It may have have just been some old fuel in the tank or something. No clue.
