Running Rich After Headers and new Exhaust installed

[Zed Head]

5 hours ago, RRR007280Z said:

Mechanic says they looked fine last time I was there, after the exhaust installation, I had my fan motor replaced and since I had already mentioned it to him I mentioned it to him again and asked that he check out the plugs to see if they were fouled, so he said he pulled one of the plugs and it looked fine.

This looks more like you've just noticed something that has always been happening.  Your tail pipe is probably in a different position and the new position allows the residue to deposit.  It's not looking like something that happened during the installation.

Cars without catalytic converters have dirtier exhaust fumes than those with.  These cars will spit black water when they're cold.

[RRR007280Z]

My feeling is either the plug for the CTS may be corroded or dirty or the connection itself maybe loose on the sensor.  If the the thermotime plug and CTS were crossed I'm not sure how it would run, if at all.
Here is the link to the 77 PDF you can give your mechanic. It has all the checkout procedures for the EFI. The CTS or WTS is on page 95. There is much more diagnosis in the EF section. Here is a snipet of page 95. These cars are notorious for running rich if the CTS doesn't have a good connection to the sensor or ECU. Plus the plug gets old over time. I put a pic of the plug at the bottom. Clean it good with Emory board and electrical cleaner.  Do the sensor too.
http://www.nicoclub.com/FSM/280z/1977/

Thanks, I will definitely bring these things to his attention, hope to get to the root of the problem soon, my mileage is suffering and I don't want the back of my car to be stained. Not to mention that for the first time in 20 years I wonder it it would pass inspection for emissions. Thanks again.


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[RRR007280Z]

This looks more like you've just noticed something that has always been happening.  Your tail pipe is probably in a different position and the new position allows the residue to deposit.  It's not looking like something that happened during the installation.
Cars without catalytic converters have dirtier exhaust fumes than those with.  These cars will spit black water when they're cold.

I wish it were but it's definitely different and I had the same exhaust system without the header before. Only reason I got the header is because it was faster to get than the stock manifold. The outside of my exhaust pipe, inside too, is covered in black soot. Never had that before. Thanks I'll keep looking around and reading what I can.


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[Zed Head]

Can you smell the extra fuel?  What are your mileage numbers?

Just looking for something concrete to work with.

[RRR007280Z]

Can you smell the extra fuel?  What are your mileage numbers?
Just looking for something concrete to work with.

Mileage is noticeably lower but can't quantify. I don't smell anything either. I'm trying to research so I can make educated suggestions when I bring it in next time for inspection and annual check up in May. It's making me nuts and staining the left rear of the car, brake light lens etc... it can't be good for the engine either I would imagine. Thanks for your help feel free to reach out if you think of anything.


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[Dave WM]

again to confirm all this, start with a new set of spark plugs, drive around for a day, then pull the plugs and post up some pics.

It would be nice to confirm the rich condition and the plugs.

If rich, then next up is a series of test starting with (as mentioned before) sensor readings at the ECU, primary of which would be the temp sensor.

CSV is a suspect, and of course fuel pressure. there is an throttle pos switch and of course the AFM.

Did the old manifold have a O2 sensor (think its too early for that) and what about EGR?

 

[Chickenman]

Here's a picture of the CTS and Thermo Time Bullet connectors. It's easy to swap these around. Car will run pig rich.

Bullet connectors must be clean. No corrosion, as must connections at the sensors them selves. Some De-oxit works wonders. 

 

[RRR007280Z]

Here's a picture of the CTS and Thermo Time Bullet connectors. It's easy to swap these around. Car will run pig rich.
Bullet connectors must be clean. No corrosion, as must connections at the sensors them selves. Some De-oxit works wonders. 

 

Thanks for all the info, I have a lot to digest. I'll post updates.


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[Reptoid Overlords]

Almost sounds like the EGR is stuck open, if equipped.

[the_tool_man]

I think EGR stuck open would be a big vacuum leak and cause severe drivability issues. When my car had a similar leak around a single injector, it was undrivable.

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