Revs staying high until complete stop
Thread Starter
Burning Brakes
Joined: Nov 2018
Posts: 980
Likes: 118
Revs staying high until complete stop
Noticed something on my first drive in my new to me 01 Z... When slowing down the revs will not drop below about 1800 until fully stopped for a few seconds. This means there's basically no engine braking at low speed and the car won't even slow down below a certain point.
I swapped batteries and this was the first drive. Could it be a learning procedure issue with the throttle? I've read people attributing this to vacuum leaks as well but that doesn't make much sense to me considering the circumstances.
Thoughts?
I swapped batteries and this was the first drive. Could it be a learning procedure issue with the throttle? I've read people attributing this to vacuum leaks as well but that doesn't make much sense to me considering the circumstances.
Thoughts?
Moderator, Tech Contributor
Joined: Sep 2013
Posts: 15,342
Likes: 3,936
From: Cape Coral, Florida
Anytime the battery is disconnected or swapped out in your case you will have to do an idle "relearn"...basically...
1) turn off AC
2) trans in neutral and set e brake
3) start engine
4) make sure coolant temp is more than 176 degrees
5) allow engine to idle for 5 minutes
6) turn off engine for 30 seconds
7) YOU'RE DONE !!!
1) turn off AC
2) trans in neutral and set e brake
3) start engine
4) make sure coolant temp is more than 176 degrees
5) allow engine to idle for 5 minutes
6) turn off engine for 30 seconds
7) YOU'RE DONE !!!
Last edited by C5 Diag; Apr 8, 2019 at 03:55 PM.
Burning Brakes
Joined: Jan 2006
Posts: 788
Likes: 105
From: Olathe Kansas
If the relearn does not work.. You could have a good old fashioned vacuum leak.. A bad Idle Air Control Valve or
even a Mass AirFlow Sensor issue.
Do the easy stuff first !! Good Luck.
BTW, the idle is supposed to be a little higher until you are at 0 mph.. The PCM does this so it's easier to shift (rev match)
But, 1800 is too high
even a Mass AirFlow Sensor issue.
Do the easy stuff first !! Good Luck.
BTW, the idle is supposed to be a little higher until you are at 0 mph.. The PCM does this so it's easier to shift (rev match)
But, 1800 is too high
Moderator, Tech Contributor
Joined: Sep 2013
Posts: 15,342
Likes: 3,936
From: Cape Coral, Florida
If the relearn does not work.. You could have a good old fashioned vacuum leak.. A bad Idle Air Control Valve or
even a Mass AirFlow Sensor issue.
Do the easy stuff first !! Good Luck.
BTW, the idle is supposed to be a little higher until you are at 0 mph.. The PCM does this so it's easier to shift (rev match)
But, 1800 is too high
even a Mass AirFlow Sensor issue.
Do the easy stuff first !! Good Luck.
BTW, the idle is supposed to be a little higher until you are at 0 mph.. The PCM does this so it's easier to shift (rev match)
But, 1800 is too high
Thread Starter
Burning Brakes
Joined: Nov 2018
Posts: 980
Likes: 118
Anytime the battery is disconnected or swapped out in your case you will have to do an idle "relearn"...basically...
1) turn off AC
2) trans in neutral and set e brake
3) start engine
4) make sure coolant temp is more than 176 degrees
5) allow engine to idle for 5 minutes
6) turn off engine for 30 seconds
7) YOU'RE DONE !!!
1) turn off AC
2) trans in neutral and set e brake
3) start engine
4) make sure coolant temp is more than 176 degrees
5) allow engine to idle for 5 minutes
6) turn off engine for 30 seconds
7) YOU'RE DONE !!!
I'll Chase leaks if it doesn't work. Though it's weird that a leak would prevent idle drop while moving but then be fine stopped?
Cheers
Moderator, Tech Contributor
Joined: Sep 2013
Posts: 15,342
Likes: 3,936
From: Cape Coral, Florida
A simple diagnostic test to possibly confirm it MAY be a vacuum leak is if car runs poorly at idle but runs fine at higher RPM !!
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Burning Brakes
Joined: Jul 2018
Posts: 1,113
Likes: 144
From: Miami
Noticed something on my first drive in my new to me 01 Z... When slowing down the revs will not drop below about 1800 until fully stopped for a few seconds. This means there's basically no engine braking at low speed and the car won't even slow down below a certain point.
I swapped batteries and this was the first drive. Could it be a learning procedure issue with the throttle? I've read people attributing this to vacuum leaks as well but that doesn't make much sense to me considering the circumstances.
Thoughts?
I swapped batteries and this was the first drive. Could it be a learning procedure issue with the throttle? I've read people attributing this to vacuum leaks as well but that doesn't make much sense to me considering the circumstances.
Thoughts?
Thread Starter
Burning Brakes
Joined: Nov 2018
Posts: 980
Likes: 118
Not stock, and unknown tuning history unfortunately. I'm just getting to know it. From what I can tell it has the vararam intake, an aftermarket cam, and headers + full exhaust. Pulls strong and doesn't exhibit any funniness besides this idle thing. But again, I've only had limited time with it.
Last edited by Jackie N; Apr 9, 2019 at 10:39 AM.
Burning Brakes
Joined: Jul 2018
Posts: 1,113
Likes: 144
From: Miami
Not stock, and unknown tuning history unfortunately. I'm just getting to know it. From what I can tell it has the vararam intake, an aftermarket cam, and headers + full exhaust. Pulls strong and doesn't exhibit any funniness besides this idle thing. But again, I've only had limited time with it.
Thread Starter
Burning Brakes
Joined: Nov 2018
Posts: 980
Likes: 118
Thread Starter
Burning Brakes
Joined: Nov 2018
Posts: 980
Likes: 118
Problem resolved itself after driving the car another 20 mins today. I guess it learned what it needed to learn lol. Previous drive was short after swapping the battery, probably didn't even reach operating temps.
Thanks guys
Thanks guys
Last edited by Jackie N; Apr 10, 2019 at 03:30 PM.
Burning Brakes
Joined: Jul 2018
Posts: 1,113
Likes: 144
From: Miami
Interesting. Yes, if you're engine is still running on a warmup table on open loop, it can definitely hang the RPM higher until 0MPH. I know mine does too, but settles once warm. Glad it's resolved.