Cold-start sputter, Dakota
- Thread starter Jarlaxle
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My '96 does that sometimes and I attribute it to a leaking injector fouling a plug.
You may have low fuel pressure at start up. Your injectors need a sufficient amount of pressure to properly mist your fuel, this may be what causes the sputter. there should be a threaded bleeder valve on your fuel rail that is designed to have a temporary fuel pressure gauge attached if you wish to check. Try turning your key to the on position until the audible fuel pump cut out, than crank the starter this might help.
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A dirty throttle body can cause funny start issues too .
Originally Posted By: CurtisB
You may have low fuel pressure at start up. Your injectors need a sufficient amount of pressure to properly mist your fuel, this may be what causes the sputter. there should be a threaded bleeder valve on your fuel rail that is designed to have a temporary fuel pressure gauge attached if you wish to check. Try turning your key to the on position until the audible fuel pump cut out, than crank the starter this might help.
Good suggestion. Look for a fuel pressure drop overnight. If cycling the key a few times to bring the gauge back to full pressure makes it start smoothly, then the fuel pump module needs replacing. If it still chugs, then I'd look for a bad injector.
You may have low fuel pressure at start up. Your injectors need a sufficient amount of pressure to properly mist your fuel, this may be what causes the sputter. there should be a threaded bleeder valve on your fuel rail that is designed to have a temporary fuel pressure gauge attached if you wish to check. Try turning your key to the on position until the audible fuel pump cut out, than crank the starter this might help.
Good suggestion. Look for a fuel pressure drop overnight. If cycling the key a few times to bring the gauge back to full pressure makes it start smoothly, then the fuel pump module needs replacing. If it still chugs, then I'd look for a bad injector.
Sounds more like a dirty idle air control valve. It is mounted on the back side of the throttle body and if it has never been cleaned or is dirty it can cause bad idle problems and eventually if it gets dirty enough it will stall the engine at idle.
You can remove the TB and remove the IAC from it and clean the pintle end with a shop rag soaked in throttle body cleaner. You need to be gentle with it, do not drop it or handle it roughly or else you will be buying a new one. You want to clean the black crusty crud off the pintle end of it. Spray the shaft with TB cleaner and work it in and out a few times to clean inside the bore, and when done try to re-position it at the same extension length as it was when you removed it.
Also clean the IAC orifice in the TB itself and lube the o-ring with a clean motor oil when you reinstall the IAC. Remove the MAP and throttle position sensors and clean the TB. Clean inside the bores the very best you can, use old tooth brushes or q-tips if needed. Lube the pivot points for the butterfly linkage and throttle linkage with spray silicone. If this does not help it may be time to replace the IAC and also check your throttle position sensor. The Haynes book for your truck has instructions on testing the TPS with a volt meter.
You can remove the TB and remove the IAC from it and clean the pintle end with a shop rag soaked in throttle body cleaner. You need to be gentle with it, do not drop it or handle it roughly or else you will be buying a new one. You want to clean the black crusty crud off the pintle end of it. Spray the shaft with TB cleaner and work it in and out a few times to clean inside the bore, and when done try to re-position it at the same extension length as it was when you removed it.
Also clean the IAC orifice in the TB itself and lube the o-ring with a clean motor oil when you reinstall the IAC. Remove the MAP and throttle position sensors and clean the TB. Clean inside the bores the very best you can, use old tooth brushes or q-tips if needed. Lube the pivot points for the butterfly linkage and throttle linkage with spray silicone. If this does not help it may be time to replace the IAC and also check your throttle position sensor. The Haynes book for your truck has instructions on testing the TPS with a volt meter.
Originally Posted By: Jimmy9190
Sounds more like a dirty idle air control valve. It is mounted on the back side of the throttle body and if it has never been cleaned or is dirty it can cause bad idle problems and eventually if it gets dirty enough it will stall the engine at idle.
I have had numerous experiences with bad Idle air valves and they always exert a start than immediate stall of the engine. At least in my experience. You can override the Idle bypass valve by applying some pressure to the accelerator pedal after the engine starts. The OP mentions that it sputters than resumes a fast idle which would not be normal for an Idle air bypass valve failure, it should most likely stall or give a consistent rough idle if it is malfunctioned or constricted. You could be onto something with the throttle position sensor though.
Sounds more like a dirty idle air control valve. It is mounted on the back side of the throttle body and if it has never been cleaned or is dirty it can cause bad idle problems and eventually if it gets dirty enough it will stall the engine at idle.
I have had numerous experiences with bad Idle air valves and they always exert a start than immediate stall of the engine. At least in my experience. You can override the Idle bypass valve by applying some pressure to the accelerator pedal after the engine starts. The OP mentions that it sputters than resumes a fast idle which would not be normal for an Idle air bypass valve failure, it should most likely stall or give a consistent rough idle if it is malfunctioned or constricted. You could be onto something with the throttle position sensor though.
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I had a 92 dakota 3.9 that "needed" 45 PSI (?) per the FSM but a failing fuel pump sometimes supplied 5-10... measured it myself. It ran... I can't believe it. Check the pressure.
Also the famed "auto shutdown relay" powers the fuel pump, switch it with a horn relay or something.
Also the famed "auto shutdown relay" powers the fuel pump, switch it with a horn relay or something.
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