'82 L28et running/idling rough

[CAMarten]

I have recently acquired a 78 280z with a l28et swap from an '82 280zx. Right now it takes forever to start, and when it does it will not idle at the normal 7-800, but has to be at 1000 at least, it also runs rough and climbs rpm's hesitantly at times. I'm thinking timing, but was also going to check the cylinder compression- but I can't find what the compression numbers should be... anybody know? Also any other ideas about whats wrong would be appreciated.

[MJLamberson]

Have you given it a chance to warm up? def check the timing and compression, another thing that might have to do with the hard start things is there is a wire that provides more power to the injectors while cranking, that might not be wired in.

[hughdogz]

1) Make sure the air filter isn't plugged and check for vacuum leaks. Cracked hoses and boots...

 

2) There is an idle air regulator that allows air to bypass the throttle body when warming up. Make sure that is hooked up. This may be why it won't idle until warm...there is an idle adjustment screw on the manifold

 

3) The hesitation to accelerate might be poor spark (make sure the coil is throwing a decent spark), airflow meter out of adjustment (too rich / lean) or bad ECU connections. Make sure all the connectors are clean at the ECU, AFM, injectors, etc. Spray them with electronics cleaner and blow with compressed air. Sometimes they get so corroded with green oxidation you have to sand or scrape it off. This is the classic problem with older Bosch L-jetronic EFI. Then, push them on and off a bunch of times to get the surfaces nice and conductive before you finally connect them.

 

Make sure you check the timing, and the compression ratio (turbos are lower compression) should be 120-150? but all cylinders should be about the same. Be sure to get a Haynes manual and read as much as you can.

 

Hope this helps! Welcome to HBZ

 

[Edit: for an '82 Turbo, timing is 20 degrees BTDC +/- 3 degrees @ 700 RPM for manual, and 650 for an auto (+/- 50 RPM)

 

Minimum compression is 100 psi, 142 psi is normal pressure]

[thetremendoustim]

I dont mean to :hijack:but is there a way to test the ECU if the connections are all good but its still running like a pumpkin pie shitcan?

[CAMarten]

Thanks alot for the help, sadly after checking pretty much everything else- i found the #3 cyl. to be only 80-85 psi. I'm thinking a bad valve- and to take the head in to have a valve job- any other ideas other than valves?

[Guest flaflamif]

Then, push them on and off a bunch of times to get the surfaces nice and conductive

[stravi757]

Thanks alot for the help, sadly after checking pretty much everything else- i found the #3 cyl. to be only 80-85 psi. I'm thinking a bad valve- and to take the head in to have a valve job- any other ideas other than valves?

 

If you think it could be a worn ring you could try putting some oil in the cylinder and then do a comp test to see if it reads different. Sounds like the valves though.