So i recently deleted the EGR system on my 1977 Datsun 280z. The car sputters and loses power at higher RPMS only under load (as if it doesnt get enough air)

My theory is:

The egr system is ment to suck air from the exhaust system and push it back into the intake system. So the car is designed to have that 'extra' air coming in. So if i delete the EGR and leave the MAF as it is the car will lack air because the MAF does not know that the car is no longer getting the recycled air and is not compensating for it. And if i buy a new MAF then it might have the same problem because that MAF is designed to be on a car that is getting that extra ait from the EGR system.

 

so my question is does that make any sense? Do i need to adjust the MAF sensor if i delete the EGR system?

I'm going to guess the MAF you're talking about is the AFM (air flow meter) but I didn't when I deleted all that stuff from my '77.

Removed the egr and blocked off that hole, removed the BPT valve and two vacuum lines, one line went to a vacuum switch on top of the warming plate, removed all that.  Plugged the coolant line that comes off the warming plate and goes around the front of the head to the suction side of the radiator by the alternator and the other one at the thermostat housing.  The other vacuum line went to the bottom of the BCDD I think, plugged that too.

the yellow circle in this picture

 

Here's something I did when I removed that stuff.  It sucks air like you wouldn't believe, stock air filter. 

I think you should also put a vacuum gauge on the intake and see what you're pulling.  I'm thinking "under load" could be an air problem too.

Read over this link real quick, courtesy of @240260280

http://atlanticz.ca/zclub/techtips/vacuum/

EDIT: scatter brains here to explain why I said what I did above. While I was working on the 280, about 6 months worth, Alvin and the chipmunks that live nearby made a food storage facility out of my air cleaner. It would rev up fine in the garage but didn't have any power under load. Damn chipmunks.

Edited April 19, 20178 yr by siteunseen

It's not air, it's exhaust gas.  Essentially inert, the oxygen has been burned up.  You shouldn't need to adjust any air-fuel ratio components.

Might just be coincidental.  Did it run perfectly before the EGR system removal?  Has it had a tuneup recently, including lash adjustment?

Maybe you're sucking air at one of your delete area's, like at the egr plate, etc?

 Spray some stater fluid at those spots, being careful, to see if you get a rpm spike. 

And then what ZH said, how was it running before the delete?

10 minutes ago, rcb280z said:

Maybe you're sucking air at one of your delete area's, like at the egr plate, etc?

 Spray some stater fluid at those spots, being careful, to see if you get a rpm spike. 

And then what ZH said, how was it running before the delete?

i never got to drive it before the EGR delete. the motor sounded fine but it sounds fine now as well until im actually under load

so you say try starter fluid around the delete plate?

Edited April 19, 20178 yr by Senor Grizzly

11 hours ago, Senor Grizzly said:

 The car sputters and loses power at higher RPMS only under load

This sounds more like an ignition problem.  Electrical.  The EFI system runs pretty rich at high RPM under load (the system just dumps an extra 27% of fuel in when the TPS shows full throttle), so any vacuum leaks would probably be compensated.  Plus, vacuum leaks are more significant at low air flow levels.  At high RPM there's so much more air coming through the normal pathways that the leaks don't really matter.

9 hours ago, Zed Head said:

This sounds more like an ignition problem.

It does actually. I was thinking more of idle. Clearly Senor Grizzly mentioned higher rpm's. Don't know why I went that direction.

At what rpm's does the sputtering happen? Does it clear up as soon as you let off the throttle? 

14 hours ago, rcb280z said:

It does actually. I was thinking more of idle. Clearly Senor Grizzly mentioned higher rpm's. Don't know why I went that direction.

At what rpm's does the sputtering happen? Does it clear up as soon as you let off the throttle? 

it starts to sputter around 3000 rpms and if im in neutral the car is fine. i can rev it wherever i want and yes it stops when i let off the throttle

"Sputter" can mean a lot of things.  Does it stall and buck, or pop back through the intake, or is it popping out the back end?  Does it fell like it's running out of fuel?

Could be a fuel supply problem too.  I said electrical but I had a vision in my own head of sputtering.  Might not be the right one.  Just guessing right now.  

Lacks power after 3000 RPM under load.  Sputters (makes me think of misfiring) as it loses power.  Never actually tested under load before.  That's what I get so far.

Sounds like mine before I put the CTS tweak on but opposite. Mine spit and sputtered bucked like crazy until 2500 or 3000 rpm then pulled good.

Could your wires be reversed where the CTS and thermotine plugs are, the thermostat housing and the other place about a foot towards the windshield? 

You could try clamping the return hose to build more fuel pressure and see if that makes it run better. 

If you deleted the EGR, then you removed the intake/exhaust manifolds to plug the exhaust port? If so, did you replace the intake/exhaust manifold gasket? Did you remove the Throttle Valve Switch for any reason?,