1977 280z EFI Nightmare

[Captain Obvious]

Awesome! Glad you got to the root of the issue!     

You said "They wondered if it was the injectors so they did full spray tests into graduated cylinders for fuel flow, consistency, and volume, and it looked totally fine."

Did they run that injector flow test on the car, or on the bench? I'm wondering if they used the 's ECU to drive the injectors, or a stand-alone injector tester rig designed to check things like that.

[Zed Head]

Sakura Garage is @cgsheen1 and his son, I believe.  No surprise that they figured things out.  

Might be that the problem was an opening and closing issue.  The flow test was probably just wide open.  The rig for pulsed testing is kind of spendy and more complex.  I wonder if the "bad" injectors were original or aftermarket.  

[ckurtz2]

3 hours ago, Captain Obvious said:

Awesome! Glad you got to the root of the issue!     

You said "They wondered if it was the injectors so they did full spray tests into graduated cylinders for fuel flow, consistency, and volume, and it looked totally fine."

Did they run that injector flow test on the car, or on the bench? I'm wondering if they used the 's ECU to drive the injectors, or a stand-alone injector tester rig designed to check things like that.

Honestly, I don't know, I will have to ask. However, I think their final conclusion was that the injectors were undersized for the car. 

[cgsheen1]

1 hour ago, Zed Head said:

Sakura Garage is @cgsheen1 and his son, I believe.  No surprise that they figured things out.  

Might be that the problem was an opening and closing issue.  The flow test was probably just wide open.  The rig for pulsed testing is kind of spendy and more complex.  I wonder if the "bad" injectors were original or aftermarket.  

Ya, we pulled the injectors and fuel rail and used the ECU. I suspected a few clogged injectors (I knew that they were all opening or at least "clicking") but when they all fired properly and filled the graduated cylinders equally, it obviously wasn't that. The injectors on his engine look relatively new - green top hose type - but they need to be flow tested on a real bench and perhaps resized. The ultra lean condition immediately disappeared when I installed some "known value" injectors.

Young Kurtz has done an great job with help and advice from you guys! His undercarriage looks amazing and he has accomplished a great deal. We're going to finish up a little engine work for him and he'll have a nice 280Z to cruise around in. 

Edited November 11, 2021 by cgsheen1

[ckurtz2]

There you have it! Thanks Chuck for the kind words, didn't realize you were on this forum🙂 You all have been a great deal of help. Can't wait to rip the Z around town!

[Captain Obvious]

8 hours ago, cgsheen1 said:

Ya, we pulled the injectors and fuel rail and used the ECU. I suspected a few clogged injectors (I knew that they were all opening or at least "clicking") but when they all fired properly and filled the graduated cylinders equally, it obviously wasn't that. The injectors on his engine look relatively new - green top hose type - but they need to be flow tested on a real bench and perhaps resized.

Gotcha. Out of curiosity, did you run the same test (using the ECU) to drive the replacement injectors before you stuck them in? Or was it just faster and easier to toss the replacements in and give it a whirl?

Glad you were able to get his car running better!

[cgsheen1]

12 hours ago, Captain Obvious said:

Gotcha. Out of curiosity, did you run the same test (using the ECU) to drive the replacement injectors before you stuck them in? Or was it just faster and easier to toss the replacements in and give it a whirl?

Nope, just stuck in the replacements (I felt I'd gone through all other options), fired it up, and watched the AFR's. AFR came back inline immediately so I heaved a huge sigh of relief. We had already checked every other part of the EFI. With the injectors all looking new(ish) and the nasty end of the plugs all looking the same, I didn't suspect injectors.

[kickstand80]

I that an open ended "T".

[Captain Obvious]

1 hour ago, kickstand80 said:

I that an open ended "T".

No, it's fine. They sealed off the other end (the end you can't get a good look at) with a brazed on cap. Not sure why they felt like it needed to be that complex, but that's what they did.

[Captain Obvious]

11 hours ago, cgsheen1 said:

Nope, just stuck in the replacements (I felt I'd gone through all other options), fired it up, and watched the AFR's. AFR came back inline immediately so I heaved a huge sigh of relief.

Understood. I was just thinking maybe you had some measured flow numbers from the two you could compare. I was thinking that could be a data point for someone looking to verify if their injectors are the right ones or not. No biggie.

Again, glad you were able to help the OP get back on track!