Code 23

[Peer81]

Where to begin...

First my engine was running fine (for a L81 without an exhaust) you could clearly hear and see the ECM kicking in as the engine was idling much smoother. I had some problem with a broken idle mixture screw so changed the throttle plate for another E4ME base plate, altered it just like mine and back on the engine. When trying to set the idle with the dwell meter, the meter was pointing to some inlogical positions (rich when running lean, backing off at strange moments (going into lean etc etc). The engine is idling like a sick horse and I can't hear the ECM kicking in. The check engine light was comming on when the engine was still warming up but also going out, serveral times during a run (cold or hot).

Second thing, with the first throttle plate the lowest rpm I could get was 600 (with the idle screw not touching anything, now I can't get the rpm lower then 1200 with the choke off and the idle screw backed out. Yesterday I checked the ALDL connector but didn't get anything not even a 12 check code. Looking at it again, when rebuilding I flipped the connector so terminal number 4 and 5 are 1 and 2. In other words, I shorted terminal 1 and 2. Could this be a problem?
Today I found the problem to shorted the correct terminal 4 and 5, and yes, code 12, 12, 12, 23, 23, 23, 12, 12, 12 etc.

So I have a code 23. M/C solenoid trouble. Now for me this is a conformation for the other symptoms. So in short this is a bad M/C solenoid or a bad ECM. I have to work myself through the code 23 chart to see what is what. If somebody has some other ideas please feel free to jump in.

Groeten Peter

 

[Peer81]

Btw. I also looked at the other topics an know to first check if the M/C solenoid is working (clicking) like it should. With the engine noise (without an exhaust) there is really nothing else to hear but the exhaust but with some extra tools I should be fine, but I'll first begin checking the voltage etc etc.

Groeten Peter

 

[Sensei]

You can test your MC solenoid by touching a 9v battery to the terminals for an instant (just a flick) and see if the bobber moves (just set a thin allen wrench down on it through a vent hole).

Are you sure you have the correct throttle plate, and are you sure it is all working correctly. A wrong gasket or a minor difference in throttle plate design (and there were endless variations) can cause the problems you describe (including code 23).

God bless, Cris

 

[Peer81]

Yes it is the same throttle plate, but I do need to take it apart again. Cold it is perfect but when hot one primairy throttle plate is binding when using the cruise control to open the plates. Still used the same gasket but I'll recheck and look if the M/C solenoid is responding. I also have an extra M/C solenoid from the spare carb so I'll check that one to.

Groeten Peter

 

[evariste]

Check (also) the cables...

Well, ECM error codes nearly got me crazy. :Silly

I think I had almost every error code. Some of them were real, and most of them made me think that a gremlin had established inside my Vette. hnoes
I checked and treated every connector, even those that are hidden under the console.
Every time, it corrected the problem, and every time some new codes appeared some weeks later.

I suspected even the alternator, and some day (last summer), I discovered something : The ECM grounding is located on the engine and nowhere else. So, if you have bad contacts in the large connectors under the bonnet, the ECM looses power and is lost.

I looked at many solutions to give the ECM a reliable ground. After having completely dismantled the console...
... I discovered that a very short strap between the ground of the TEST connector and the radio ground would do it. :duh

Since I did it, no more "ghost" codes. :W
I had a long trip form Paris to the Cote d'Azur (about 2000 miles) without having any trouble.

My 2 cents.

 

[Peer81]

Thanks for the advise, I'll be looking into the problem tomorrow

Groeten Peter

 

[Peer81]

Great idea Cris!

My second MC solenoid launched the plunger so that one is oke but the one in the carb was "dead in the water"! So to make a long story short, changed the MC solenoid and she runs alot better then before, still need to adjust the mixture needles to obtain the 25 > 30 < 35 dwell but that is something for next time. At this moment I'm around 5 to 10 dwell in park..
Thanks for all the idea's

Groeten Peter

 

[Peer81]

Today was another "dwell day". First warmed up the engine. Then took all the 4 wheels from the ground. In drive (1st) the dwell was around 7 to 10 degrees. First begun with a 1/4 turn for both mixture screws, waited a while and pushed the throttle a little, no big change, again 1/4 turn, very little change. Then took the change to give them a 1/2 turn, the dwell rised to 20 - 22 degrees. After that I turned them 1/3 and then the dwell was around 28 degrees. Adjusted the final steps with the idle air screw, first a 1/2 turn. Dwell jumped up to 35 - 40 degrees, backed it off 1/4 turn and then another 1/4 turn (where I started) and the dwell was back around 30 degrees. The dwell needle jumpes around over and under 30 degrees and sometimes with some bigger increments. I left it this way, checked the TPS voltage, it was at 0.55v to I changed it to 0.56v.

Still idles very rough but what can be expected without an exhaust and in drive or reverse the engine want so die. Not a very big problem, net time bump up the idle a little. More important thing is to get the exhaust installed.
Till next update!

Groeten Peter

 

[dskopp]

Peter,
If you do niot mind I would like to give this information to the person who works on my vette. I just had the carb rebuilt and it is running like newe. Yes, I have a computer on my vette. Send me your e-mail address to my aol address.
Dan

 

[Peer81]

Hello Dan,

No problem!

Groeten Peter