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Discussion Starter · #1 · (Edited)
1968 Camaro Ls2 6 speed. The car was parked for about a month while I was working on my interior. Last night, I finally got the chance to move it. Turned it on multiple times.. all good. Turned it on this morning to go for an oil, coolant, radiator change etc.. everything was normal no idle jumps.

After replacing all the fluids.. turned the car on and the RPM started slowly increasing to 1.5k , and then goes faster up to 2k and 3k for about 30 seconds.. then drops back down steady to 1k. I've never had this before (video below).

Back to work with the car parked. I'll drive around more today and see if this happens again..


UPDATE: as I’m driving back to work and coming to a stop and press the clutch full in.. rpm stays on about 1.2k (as if like im stopped and lightly pressing at the gas pedal) then drops down normal.
 

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I notice your temperature gauge jumped a bit while idling up? Maybe not related, but you may have some air trapped in there, or an electrical connection issue. You mentioned gauge lights not working in your other post so there might be a common theme there - bad ground maybe?
 

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Discussion Starter · #3 ·
I notice your temperature gauge jumped a bit while idling up? Maybe not related, but you may have some air trapped in there, or an electrical connection issue. You mentioned gauge lights not working in your other post so there might be a common theme there - bad ground maybe?
could that be related to the battery replacement? anything hazardous i should be worried about.. or where to start looking? thanks
 

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Check the ground wire to the body at the battery is a good starting point.
 

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Discussion Starter · #5 ·
UPDATE:

as I’m driving back to work and coming to a stop and press the clutch full in.. rpm stays on about 1.2k (as if like im stopped and lightly pressing at the gas pedal) then drops down normal.


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Discussion Starter · #6 ·
Check the ground wire to the body at the battery is a good starting point.
That’s what i wanted to know... if the sudden issue is related to “new battery” or “new fluids”

So battery / wiring can affect?


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Discussion Starter · #8 ·
Bad grounds do all kinds of weird things
I’ll check the grounds now.. could a bad alternator also cause this?

I ask this because i jump started the car last night, about 15 seconds later unplugged the cables and it shut off... I didn’t try again. Just got a new battery .. but got me thinking.


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When the battery goes dead and is replaced the ECM loses its learned fuel trims.

This may be the case with yours.

Did it do the 3000 rpm thing again?

Possible it will recalibrate on its own after a few driving cycles.

When your battery goes dead or you disconnect it to work on your vehicle, the PCM “forgets” the adapative home position. . If you don’t do a relearn procedure, the PCM will “hunt” for a new baseline idle. It will eventually learn it on its own, but it may take over a week of driving, during which time you will experience high and low idle speeds and possibly rough idle.

Here’s the throttle body relearn procedure
1) Start the engine and let it idle in park for 3 minutes. During that period the idle may be higher idle than normal.
2) After 3 minutes, turn the engine off and leave it off for 60- seconds.
3) Start the engine again and let it idle in park for 3 minutes one more time. During these run periods you may see a check engine light. Scan for codes and if you get throttle body related codes, clear them.
4) If the idle speed is still off, drive the vehicle at speeds above 44-mph and operate several acceleration and deceleration cycles. Then repeat step #3 one last time.


The idle should now be normal
 

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As Vega$$ notes it may be your IAC (idle air control) sensor needs to reset. Not sure if the procedure is as he notes for your ECU or which ECU you have so look up the procedure in whatever manual you may have for it or if its a donor ECU/motor look up for whatever that car model/year is

Your IAC could just need cleaning if the car has sat for a long time. Don't push the printle in, just use throttle body to clean it and the oriface it is in.

vacuum leaks also cause high idle...confirm you don't have one and your air intake duct to throttle body is on tight
 

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Discussion Starter · #11 ·
When the battery goes dead and is replaced the ECM loses its learned fuel trims.

This may be the case with yours.

Did it do the 3000 rpm thing again?

Possible it will recalibrate on its own after a few driving cycles.

When your battery goes dead or you disconnect it to work on your vehicle, the PCM “forgets” the adapative home position. . If you don’t do a relearn procedure, the PCM will “hunt” for a new baseline idle. It will eventually learn it on its own, but it may take over a week of driving, during which time you will experience high and low idle speeds and possibly rough idle.

Here’s the throttle body relearn procedure
1) Start the engine and let it idle in park for 3 minutes. During that period the idle may be higher idle than normal.
2) After 3 minutes, turn the engine off and leave it off for 60- seconds.
3) Start the engine again and let it idle in park for 3 minutes one more time. During these run periods you may see a check engine light. Scan for codes and if you get throttle body related codes, clear them.
4) If the idle speed is still off, drive the vehicle at speeds above 44-mph and operate several acceleration and deceleration cycles. Then repeat step #3 one last time.


The idle should now be normal
Wow thanks a lot!! This does make sense I’ll try again shortly and see if it jumps again.

I was starting to worry it was an alternator issue because of the jump start- dead battery


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Discussion Starter · #12 · (Edited)
Great now what lol.. short drive, off. On back home off again.. then was about to do the relearn test and this happened.

3 times no start.. 15 sec wait then startind again . Wthhh .. alternator or leak or

Let me recap the issues that keep popping up every second post new battery and oil change:

- Rpm jump + high/fast idle

- Car suddenly doesn’t crank 3 times (all day it was turning on fine)

-waited about 2 mins. Turned back on, but with hesitation.

-left it on for about 6 mins running, and suddenly the car started dying out and about to shut off


So.. what could be the issue? Is it a leak? Alternator issue?

And sadly over here we don’t have any musclecar experts and neither am I

Video: no start


Video: hissing sound from the brake drum section

 

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you need to confirm your alternator is working to charge the battery. with a volt meter probe the + battery terminal and ground. You should have about 13.8-14.2 vdc with engine running and a good battery should read about 12.7 vdc engine off. video it appears your battery is dead. Jump starting will make it start but if alternator is not charging it is bad or you have a wiring issue preventing the alternator from charging

as noted when you disconnect the battery or it goes dead your ECU returns to its base settings until various sensors "learn" which may be why your idle is high after your battery died. In that case you may need to do the IAC "reset" procedure noted
 

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Discussion Starter · #14 ·
you need to confirm your alternator is working to charge the battery. with a volt meter probe the + battery terminal and ground. You should have about 13.8-14.2 vdc with engine running and a good battery should read about 12.7 vdc engine off. video it appears your battery is dead. Jump starting will make it start but if alternator is not charging it is bad or you have a wiring issue preventing the alternator from charging

as noted when you disconnect the battery or it goes dead your ECU returns to its base settings until various sensors "learn" which may be why your idle is high after your battery died. In that case you may need to do the IAC "reset" procedure noted
Sorry just updated the previous post with notes and videos.

The battery is brand new just replaced it last night. Hankook , same as the one i had on previously that died.


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Screen shot from your first video (with the engine running).
271469

It appears that your engine is at operating temp (aprox 200°), car is idling at aprox 1000 rpm,.... but your voltage is about 11 volts. That voltage is too low for a running engine. It should be about 13.8 - 14.2 as SoCal805 previously mentioned.
It seems like your engine is running off of battery voltage only and the alternator is not charging.
That could be the reason why your other battery went dead. At some point, the voltage drop in you battery will be low enough that your engine still runs... but will cause all kinds of other problems.
Do you know what type of alternator you have (1 wire, 3 wire). If your alternator is a 3 wire, it may need to be "excited" before it will begin to charge.

You mentioned in another post that a shop did some interior work to your dash.
  • Is it possible that the shop may have disconnected... or rewired something incorrectly?
  • Was your battery voltage higher (when the engine was running) before you took your car to the shop?
  • Did you do a battery current draw test to see if anything was drawing current with everything in the car off and all doors closed?
If so, you may want to take your car back to the shop that did the interior/dash work.
 
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Go to the 1st video the OP posted. You can see by looking at the volt meter that it is not charging.

LOL we were busy posting the same thing at the same time
 

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That "hiss" sound is likely a vacuum leak. It may be from that brake booster fitting which if plastic may be cracked. That results in high idle as its a huge vacuum leak if that is what is making that sound. Its a very cheap part to replace.

the no start, then start, then die then no start...sounds more electrical/ignition which could be several reasons why. lose grounds are suspect

have you metered the battery with a volt meter to see what the charging voltage is when the motor does run?
 

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I don't see a loose gound causing the ALT to not be charging the battery. Most likely needs to repair or replace ALT.
 
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Discussion Starter · #19 ·
Ok i think this is it! .. as im making my way to a shop now to check everything. Car starts bogging midway, and just completely DIED. I get out and it’s leaking like hell.

Towed it to the shop, turns out the side of the radiator/intercooler is leaking hard.. not sure why and why all of a sudden.
Does this seem likely? Overheating causing the leak/shutoff/high idle




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well your problems seem to be mounting. Cooling issue, possible electrical/charging...maybe a vacuum leak also unless that "hiss" sound you hear near brake booster is really from the radiator leaking steam although the video does sound like it comes from booster area.

Get the radiator replaced or fixed. Get car started and check the charging voltage. Don't know why you have yet to do that...it would IMMEDIATELY show if alternator is putting out enough voltage
 
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