RE: Idle problems

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RE: Idle problems

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Corvette Forums >> Corvette Models >> Corvette C4 Forum >> RE: Idle problems

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RE: Idle problems - 7/28/2007 9:18:51 AM

cwb

Posts: 1508
Joined: 5/13/2007
From: eastern NC
Status: offline

quote:

ORIGINAL: lbelew

Old gaskets looked to be in good shape with no areas compromised. I'll hit it with the propane again. How do I troubleshoot the computer if the whole thing has been the computer from the start. thanks.

The parts retailer will usually plug in their scanner for free. If you do that, ask them if anything in the computer, and only in the computer, can get by their scanner.

Do not ask them about a vacuum leak; they'll say if you can't hear it, there ain't one. And that ain't the case with a TPI. I know ya' don't wanna' hear it after all the intake re-workin', but I think you didn't get two parts seated properly.

Was there any part you weren't sure of when re-installin'? At all?

The gasoline delivery process, and the ignition (spark) process, by themselves, will not cause the lopin' idle - only airflow process can do this.

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Don''t know nuthin''; ain''t never got paid for wrenchin''...
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(in reply to lbelew)

Post #: 21

RE: Idle problems - 7/28/2007 12:31:21 PM

lbelew

Posts: 54
Joined: 7/10/2007
Status: offline

I have a code 43 and a code 44. The 44 more than likely is due to the 43. I can read these myself by jumping the appropriate ports in the diagnostics port. First I'll try the propane and if no joy I'll have to replace the ECM BASED ON THE CODE 43. THANKS.

(in reply to cwb)

Post #: 22

RE: Idle problems - 7/28/2007 3:00:51 PM

cwb

Posts: 1508
Joined: 5/13/2007
From: eastern NC
Status: offline

quote:

ORIGINAL: lbelew

I have a code 43 and a code 44. The 44 more than likely is due to the 43. I can read these myself by jumping the appropriate ports in the diagnostics port. First I'll try the propane and if no joy I'll have to replace the ECM BASED ON THE CODE 43. THANKS.

I do NOT think they are related.

As far as the 43 code, I would NOT spring for a new ECM, until testing for a signal for timing retard. The 43 code says retard has been on too long (which would mean there IS a signal) OR ignition retard system failure (no signal). TEST FOR SIGNAL FIRST!!!

If 44 can mean vacuum leak, I'd go that way first. Since both codes COULD be because of ECM connections, and not necessarily a bad ECM, check all the leads with a probe.

Even if there's some short circuits to the ECM, you still got the loping idle.

Check the service manual for both codes, to see if it says go after one of the two codes first. Or did you already do that?

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Don''t know nuthin''; ain''t never got paid for wrenchin''...
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(in reply to lbelew)

Post #: 23

RE: Idle problems - 7/28/2007 4:11:33 PM

lbelew

Posts: 54
Joined: 7/10/2007
Status: offline

Just checked it with the propane with no evidence of a vacuum leak. I think I'll pull the ecm and reboot it. Thanks.

(in reply to cwb)

Post #: 24

RE: Idle problems - 7/29/2007 4:54:08 AM

mech259

Posts: 1759
Joined: 1/22/2006
From: Lumberton, Texas
Status: offline

Code 43 can be caused by bad knock sensor or broken wire to the knock sensor which is just in front of your starter.

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L.B.
ASE Master Certified
L1 Emissions Certified
1986 C4
1969 RS Z28 Camaro
1970 Chevelle SS 396 (under construction)

(in reply to lbelew)

Post #: 25

RE: Idle problems - 7/29/2007 6:28:39 AM

lbelew

Posts: 54
Joined: 7/10/2007
Status: offline

The knock sensor wouldn't affect my idle, would it. I rebooted the ecm last night and that didn't do anything for me. I think I'll pick up an ECM today to at least use as a trouble shooting tool. Thanks for the help.

(in reply to mech259)

Post #: 26

RE: Idle problems - 7/29/2007 10:32:21 AM

mech259

Posts: 1759
Joined: 1/22/2006
From: Lumberton, Texas
Status: offline

Knock sensor won't affect idle. It is used by spark timing control to retard timing when detonation is picked up by sensor. Code 44 is a lean code and maybe the result, not the cause of poor idle problems. What kind of O2 readings do you have at idle and cruising speed?

_____________________________

L.B.
ASE Master Certified
L1 Emissions Certified
1986 C4
1969 RS Z28 Camaro
1970 Chevelle SS 396 (under construction)

(in reply to lbelew)

Post #: 27

RE: Idle problems - 7/29/2007 11:22:00 AM

cwb

Posts: 1508
Joined: 5/13/2007
From: eastern NC
Status: offline

quote:

ORIGINAL: cwb

As far as the 43 code, I would NOT spring for a new ECM, until testing for a signal for timing retard. The 43 code says retard has been on too long (which would mean there IS a signal) OR ignition retard system failure (no signal). TEST FOR SIGNAL FIRST!!!

Here's your ESC signal test:

Take the idle speed up a couple of hundred rev's over idle - 900 - 1000. Hit the block quickly on the passenger side a couple of times with a screwdriver. If the idle drops, your ESC system works (or at least has a signal complete circuit.

If there's no drop, there's no signal gettin' to the computer to retard the timimg.

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Don''t know nuthin''; ain''t never got paid for wrenchin''...
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(in reply to cwb)

Post #: 28

RE: Idle problems - 8/5/2007 6:27:33 PM

84corvetteC4

Posts: 173
Joined: 8/5/2007
Status: offline

sounds to me like your running lean, I also wouldnt give up on the vacuum leak possibilty until I was 100% sure it was not the problem

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1984 corvette ls1, 650 holley(high rise), custom intake, cam, full exhaust, 373's, bug catcher, 425rwhp/ 498ft/lbs is finally achieved Thank God!!!(new intake need to re-dyno;)

(in reply to cwb)

Post #: 29

RE: Idle problems - 8/5/2007 7:17:57 PM

lbelew

Posts: 54
Joined: 7/10/2007
Status: offline

Tearing the intake apart again insearch of a possible leak. Thanks.

(in reply to 84corvetteC4)

Post #: 30