78 280z idle problem

[Jack Pearcy]

Well I got the pressure gauge but I can’t find a t connector anywhere, this really sucks I’ll have to look online I guess.

[Jack Pearcy]

1 hour ago, Dave WM said:

The wiring of the CTS and the CSV can get mixed up, bullet connectors and sensor plugs that can interchange. That's why its important to check at the 36 pin connector, it will account for any mixups. My guess is that pin 13 to ground will be wide open.

What is the 36 pin connector? This is probably a stupid question but I am unfamiliar with it

[EuroDat]

That is the connector on the ECU down next to the drivers left foot.

[Dave WM]

18 minutes ago, Jack Pearcy said:

Well I got the pressure gauge but I can’t find a t connector anywhere, this really sucks I’ll have to look online I guess.

just plug into the line that goes to the CSV, you don't need it anyway during summer months and it removes one more variable (a bad CSV) from the equation.

[Dave WM]

if your are reading how to do the test you will already know this, but just in case you missed it. Before disconnecting the 36 pin connector turn off the ignition, and disconnect the battery. Its a bit of over kill doing both but you don't want any possible voltage spikes from connecting and disconnecting the ECU with voltages present.

Exercise care when probing the 36 pin connector, you don't want to deform any of the sockets by sticking a prob in forcibly.

if you have not already don't forget the importance of making sure the connections under the hood are clean. Corrosion is a big problem, You may seen green corrosion on a plug end, it often will creep up a wire. Take pics of anything that looks like  that so we can see. We are depending on you to be the eyes and ears. its very hard to diagnose things remotely with out using your senses (no OBD with these old cars).

Edited June 28, 2019 by Dave WM

[Jack Pearcy]

22 minutes ago, Dave WM said:

if your are reading how to do the test you will already know this, but just in case you missed it. Before disconnecting the 36 pin connector turn off the ignition, and disconnect the battery. Its a bit of over kill doing both but you don't want any possible voltage spikes from connecting and disconnecting the ECU with voltages present.

Exercise care when probing the 36 pin connector, you don't want to deform any of the sockets by sticking a prob in forcibly.

if you have not already don't forget the importance of making sure the connections under the hood are clean. Corrosion is a big problem, You may seen green corrosion on a plug end, it often will creep up a wire. Take pics of anything that looks like  that so we can see. We are depending on you to be the eyes and ears. its very hard to diagnose things remotely with out using your senses (no OBD with these old cars).

Thanks Dave, all of my engine bay connectors are green so that may be part of the issue. I’ll document them as best I can and post the results

[Jack Pearcy]

[Dave WM]

Yep, start with cleaning those up. Use some fine sandpaper like 220 grit, rolled into flat, or better still some paint gun spiral brushes, some deoxit, and clean clean clean both the male and female parts of all those connectors. Don't forget bullets on the thermotime and CTS sub harness.

You really should replace them, but for now a cleaning will suffice to at least resolve the issues. the dried up rubber seals will just let them corrode again soon.

there are kits you can buy that will replace the connectors, you needs some solder skills and be sure to do neat work with proper solder technique.

Edited June 28, 2019 by Dave WM

[Jack Pearcy]

48 minutes ago, Dave WM said:

Yep, start with cleaning those up. Use some fine sandpaper like 220 grit, rolled into flat, or better still some paint gun spiral brushes, some deoxit, and clean clean clean both the male and female parts of all those connectors. Don't forget bullets on the thermotime and CTS sub harness.

You really should replace them, but for now a cleaning will suffice to at least resolve the issues. the dried up rubber seals will just let them corrode again soon.

there are kits you can buy that will replace the connectors, you needs some solder skills and be sure to do neat work with proper solder technique.

Oh man those used to be rubber? Haha thanks Dave I’ll give it a shot and tell ya how it turns out, most of those were fuel injector connectors so hopefully that’s why they’re staying open too long. I bought some di electric cleaner so hopefully that’ll help with cleaning them up 

[Dave WM]

54 minutes ago, Jack Pearcy said:

Oh man those used to be rubber? Haha thanks Dave I’ll give it a shot and tell ya how it turns out, most of those were fuel injector connectors so hopefully that’s why they’re staying open too long. I bought some di electric cleaner so hopefully that’ll help with cleaning them up 

the FI's are prob ok, as long as they are clicking. the problem will be on the CTS, corrosion equals resistance, resistance in that circuit increases on time for the injectors. I still bet you get an open reading (infinite resistance).

[siteunseen]

Those look like the Capitol's Dome. 

[Jack Pearcy]

4 hours ago, Dave WM said:

the FI's are prob ok, as long as they are clicking. the problem will be on the CTS, corrosion equals resistance, resistance in that circuit increases on time for the injectors. I still bet you get an open reading (infinite resistance).

Actually I neglected to mention that’s I already replaced the CTS connector because I tried to disconnect it once and the wires tore clean off of it so I went to autozone and bought a new one. I haven’t had the chance to run any electrical tests yet I had to take off right after I took those pictures, I’ll try and find a spare moment tomorrow and I’ll post my findings