ECM CODE 61

[gorgeousgeorge]

I finally got the ECM CODE 61 with the method once Bob Saveland shown me(ALDL diagnostic port jumping) and my LT5 engine speed is limited to just 3000 rpm.

I have read the shop manual and now I understand that the CODE 61 refers to "Secondary Port Throttle Valve System". NOT a tiny work to fix..

I am suspecting "Secondary Port Throttle Valve Solenoid" failure or "Electric Vacuum Pump" failure. How would you think about this trouble? Is there any other cause concerning CODE 61?

Thanks in advance.

Yoshifumi Honda
91 Z
Nagoya, Japan

[XfireZ51]

GG,

The ECM is getting a vacuum signal that is below operational for the secondaries to either open or stay open. Turn the ignition ON and see if the secondary vacuum pump is operating. If it contnues to run, then you have a vacuum leak likely under the plenum. You are limited to 3000rpm when secondaries throttle is not operating because ECM will not allow secondary injectors to turn ON.

[gorgeousgeorge]

Z51JEFF, XfireZ51,

Thank you for your replies.
I inspected my car this morning with the ignition ON and engine OFF. The electric vacuum pump (located under the passenger side headlight) were winding loudly, and IT NEVER STOP until ignition key being off.

It is most likely I have some vacuum leakage under the plenum. Removing prenum is not easy for me but I have to go ahead with this issue.. I will keep reporting about this trouble.

By the way Z51JEFF, what is P.M.?

Yoshifumi Honda
91Z
Nagoya, Japan

[VetteMed]

P.M. is Private Message.

[gorgeousgeorge]

VetteMed,

Thanks

Yoshifumi Honda
91Z
Nagoya, Japan

[Demps]

Trace the hose with a flashlight under the plenum from the pump. You may see it off.

Another trick is to turn the key again. With the pump running, pull the drivers vacuum line in plenum between 3/5 and Plug with your finger. Does pump stop? Yes check valve is bad. Put vacuum check valve in the connection and a small piece of gas hose to mate to the plenum nipple until you can get under plenum.
Ted

[gorgeousgeorge]

Ted,

Thank you for your reply. I will look for lose vacuum hose connection.

About another trick you told to "pull the drivers vacuum line in plenum between 3/5...".



Does 3/5 mean cylinder#? Is the hose you mean the red circled hose in the picture above?
Does the check valve exist behind the nipple of a plenum?
Does your trick means that add another check valve in line if the original check valve is bad, so that I can fix this problem without removing plenum?

Sorry for disturbing you. I am relatively new to the ZR-1 world and I sometimes do misread English. That?s why I ask this to you



By the way, do I have to check the line of RH, between 4 and 6?

Thank you.

Yoshifumi Honda
91Z
Nagoya, Japan

[Paul Workman]

Originally Posted by gorgeousgeorge

Ted,

Thank you for your reply. I will look for lose vacuum hose connection.

About another trick you told to "pull the drivers vacuum line in plenum between 3/5...".



Does 3/5 mean cylinder#? Is the hose you mean the red circled hose in the picture above?
Does the check valve exist behind the nipple of a plenum?
Does your trick means that add another check valve in line if the original check valve is bad, so that I can fix this problem without removing plenum?

Sorry for disturbing you. I am relatively new to the ZR-1 world and I sometimes do misread English. That?s why I ask this to you



By the way, do I have to check the line of RH, between 4 and 6?

Thank you.

Yoshifumi Honda
91Z
Nagoya, Japan

Here is a picture to show the secondary vacuum system. From the picture you will see that the vacuum line between #4 and #6 on the passenger side is not part of the secondary system.



I would start by checking the vacuum pump first by pulling apart the vacuum connection on the line between the vacuum pump and the plenum. With the pump running, place your thumb over the end of the line and see if the pump stops. If it does, then the pump is working correctly.
Next step is what Demps suggested. If, as he said, the pump continues to run, then there is a check valve problem, or maybe a connection loose? At that point, removing the plenum is your only option. (Removing the plenum sounds a lot more difficult than it is! It is really quite easy.)

Let us know what you find, and we'll continue to troubleshoot.

P.

[Demps]

Paul's picture and explanation are great.

If you plug the drivers hose (one you circled) and the pump stops, the check valve is bad. You can put one in-line at that location until you can remove the plenum.

This may help the code 61 and can keep vacuum in the system if the check valve is the only thing bad.
Ted

[HAWAIIZR-1]

Yoshifumi-san,

I have my household goods arriving tomorrow with all my tools. We can pull your plenum and do the work with no problems. I have everything from all the gaskets, etc. that are need with addtional spare parts. I'm not sure if you can drive to Yokohama, but depending on how soon you need to fix this I can make the 2 1/2 (according to google anyway?) hour trip to Nagoya. I go to Korea in a few weeks so I'll send you and email and we can talk about this over the weekend on Sunday. On Friday and Saturday I will be at the Navy base in Yokosuka to install all the emissions back on my Z.

Matane.

Craig