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General Dakota Board
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Billy
Dodge Dakota
JOIN HERE
8/31/2004
06:59:41
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 Subject: hard starting when cold
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Message:
My 94 3.9 has to crank over for about 10 seconds when the engine is cold.Has a rough idle but smooths out a little when warmed up. Starts instantly when engine is warm. Trucks seems to hesitate on the highway not the power it used to have. fuel pressure good,replaced injector,02 sensor,computer,distibutor pickup,temp sensor,plugs,wires,dis cap,rotor.Run out of money.I don't know how and what to check.
Please help
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Noltz
Dodge Dakota
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8/31/2004
09:50:21
|  RE: hard starting when cold
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Message:
Well, none of those things are a waste of money, c'ept the injector & computer. They're tune-up items. When it takes 10 seconds to to start in the morning, does it try to start at ALL, or just crank, crank, crank, vroom? Do you need to give it throttle at all?
Another thing to check is the throttle position sensor. If they're out of range, it can cause a whole mess of problems. Are you sure you changed the COMPUTER temp sensor? Some vehicles have two sensors, one for the computer, one for the gauge on the dash. Unplug the one you replaced & see if the dash gauge goes dead.
If I had your truck at my shop, I'd ask to keep it overnight. First thing in the morning, I'd hook up a scan tool and check all the values of the sensors; Intake air temperature, coolant temperature & crank position sensor specifically. I'd also have my fuel pressure gauge hooked up to make sure the prime pulse is activating when you key-on before cranking. While cranking, I'd have an inductive lead checking voltage in the ignition wire & datalog that. Once running, check the timing & injector spray pattern.
One of those isn't working to spec's.
A consistant poor cold-start condition is usually easy to diagnose when you have all the tools.
Good luck.
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?
Dodge Dakota
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8/31/2004
10:43:01
| RE: hard starting when cold
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Message:
You didn't mention the EGR valve /solenoid ??
Or the ' cat ' ?
Has either ever been replaced ?
And as above check the TPS sensor
( drivers side of thottle body )
key on only - centre pin to ground
should measure about 0.7 volts
then if you pull on throttle
should see the value increase Smoothly to about
4.5 volts
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billy
Dodge Dakota
JOIN HERE
9/05/2004
19:31:32
|  RE: hard starting when cold
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Message:
Thanks for your replies.To answer your questions I checked the egr valve,it's ok. About the cat,I didn't think it would make the truck hard to start just cause a loss of pawer.I did replace the computer temp sensor(when I unplug it fault code comes up for engine coolant temp sensor.This morning tryed cycling key back and forth a few times,heard fuel pump run for a few seconds each time.when fuel pump stopped kicking in by turning the key,tried a start and bang,instant start. Any Ideas.
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Kowalski
GenIII
9/06/2004
08:36:40
| RE: hard starting when cold
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Message:
Sounds like you're loosing fuel pressure as it sits - bad back check valve in fuel system or an injector could be leaking down the pressure.
Lead, follow, or get out of the way
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