Okay so i went to go checkout a 180sx today fitted with a 94 Sr20det black top. When the guy started it, it ran fine no knocking very smooth then about 30 seconds later i started hearing this abrupt noise coming from the oem recirc valve.
He told me this was the EGR acting up and its nothing to be worried about. He unplugged the vacuum line and blocked it from air passing and the noise went away. My question to you is, is this normal?
Let me know.
what kinda sound? and was the idle a little low?
I’m sure you know how the EGR works and if it is stuck open or the plunger spring is really weak it will start to stall the engine. Sometimes this cause weird engine noises almost as if it was about to die on you. Carefule though cause most EGR’s are expensive and can be a real headache to track down. One way to check forsure if it is infact the EGR is to remove it and place a metal plate over the opening. If the sound goes away than its the EGR most likely.
Hope that helps!
and if that is the problem just block it period no need for egr 
^^ except that is illegal and would never be done by such law abiding citezens such as ourselves. wink wink
It also won’t help emissions so be mindful of that. But it will give supposedly better power as now you aren’t burning crappy exhaust gasses a second time.
The sound i was hearing was kinda like a pumping sound. The idle was normal at 900rpm. The engine didnt stall out or didnt seem like it wanted to. I mean either way i will be removing the egr ive done it on the last 2 sr20’s ive owned. I just wanted to get a little backround check to make sure this is what it is.
If its any help its a 92 180sx fitted with a 94 s13 blacktop sr.