SnowDrifter
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You have access to a scan tool? What are your fuel trims?
IAC command?
Commanded idle speed?
IAC command?
Commanded idle speed?
2004 Tahoe 5.3 1000rpm idle and harsh 1st to 2nd
- Thread starter Clarko88
- Start date
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I dont believe this truck has a iac does it??
SnowDrifter
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I thought it had them, just not replaceable as a separate unit. Pop the intake boot off and take a peek in there, see if you can see the pintle where the hole is. If there's nothing, then I'm mistaken
bottomline2000
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Seems the computer is seeing normal idle rpm..does it sound like its idling high? Fuel trims look good..
Sent from my SM-G975U using Tapatalk
Does not seem to be only symptoms I'm having is rough shifts in 1st to 2nd.. that there seems to be slight stumble in idle here and there
SnowDrifter
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Sounds like tach isn't reading accurately. Idle speed on the scanner shows as normal. It's possible someone pulled off the needles to replace a bulb/stepper and didn't put it back in the right spot when they were done. What does it read key off? 0rpm? Or is it offset?
If 0 rpm - likely bad stepper
If >0rpm - needle offset. Either adjust the needle or get access to a programmer to zero out the gauge
As far as the hard 1-2 shift, do you have a tune? Rather, do you know you DON'T have a tune? Does it occur all the time or only under a specific temperature/throttle condition?
Disconnect battery, touch terminal ends together, let sit overnight, then reconnect. ECU's computers have their own internal capacitors and what not and take quite a while to reset. Don't remember how long hence overnight.
Reconnect, does problem still exist?
If so, clean MAF. Check TPS w/ scanner.
If it's still there, drop the trans pan and inspect the accumulator + spring. They sometimes break and will cause a hard shift at all speeds
If 0 rpm - likely bad stepper
If >0rpm - needle offset. Either adjust the needle or get access to a programmer to zero out the gauge
As far as the hard 1-2 shift, do you have a tune? Rather, do you know you DON'T have a tune? Does it occur all the time or only under a specific temperature/throttle condition?
Disconnect battery, touch terminal ends together, let sit overnight, then reconnect. ECU's computers have their own internal capacitors and what not and take quite a while to reset. Don't remember how long hence overnight.
Reconnect, does problem still exist?
If so, clean MAF. Check TPS w/ scanner.
If it's still there, drop the trans pan and inspect the accumulator + spring. They sometimes break and will cause a hard shift at all speeds
