Hey everyone I just picked up an 87 z31 2+2 n/a. Owned a z a while back and loved it so ive been wanting another for a while. When I test drove it the car did just fine, 5 days later im having a problem. When I start the car it tries idling at 500 very roughly then dies, unless a give it a little gas, once the car warms up it idles near perfect at about 750 rpm and runs great. I noticed the vac lines to the avi and fpr solenoid were disconnected, I reconnected them correctly according to a diagram I found online. Started the car and it just died. Wont hold any kind of idle. So theyre currently disconnected again. I was thinking maybe one or both of the solenoids is bad, or possibly the maf sensor? Any thoughts?

 

Welcome to ZDriver! Sounds like you found a great Z.

You have your factory service manual, right? It's free and can be downloaded at XenonZ31 Reference Got lots of great inspection and troubleshooting pages that are easy to follow.

Your idle problem could have a number of causes. If you have a good multimeter, you can check your solenoids easy enough. On the air regulator, they are idle-up and fuel idle control. MAF? Your manual tells you how to check it with your meter - but I will let our MAF experts here give you their input on that. Fuel pressure could be a factor. Can you check that accurately?

I would also check your vacuum system for leaks or disconnects. If your hoses are original, they are most probably leaking. If replacing, you can use thumper's guide at Vacuum Lines for correct hose inside diameters and locations. You could also check the pressure of your vacuum system. FSM shows how.

Post some photos of that Z when you get a chance!

You are catching up on basic maintenance that was not done by the previous owner. That Z is worth your time.

Thanks and welcome.

 

temp related running issues generally come from a bad chts. I took all that idle crap off my engine because it usually causes nothing but problems. CAr runs just as good.

 

Where'd you buy the metal plate to seal the idle port?

 

used a piece of 3/16" aluminum bar I had laying around (but sold at Home Depot etc). use what you take off for a pattern. AL works easiy. make a gasket out of sheet material you can get at any auto store. Use some flat washers under the bolts to spread the stress.

 

Intake Manifold Block-Off Plate Kit - 1984-89 Nissan 300ZX & Turbo | Acadiana Sports Car Orphanage - Official Store They even sell them on ebay.

 

Sorry for late reply, ill check what I can with my multimeter when I get some time to go through it all, ive also been considering the avi delete. As an update, the cars started running sluggish until it warms up. After warm still idling fine at 750ish in drive and reverse, but in park it wants to idle at 1500.

https://www.zdriver.com/forums/album...0&ref=gnr-prev

Thats her, and no I didnt primer it lol, was the previous owner.

 

Question...

I am also new to my 88Z31, and I am new to working on cars. The part you recommend (Manifold block off) can you tell me what it does? Also what is CHTS stand for. Again, I am new to working on cars...

 

Chts= cylinder head temperature sensor.

What darcy posted are block off plates for if you want to start removing unnecessary components of the engine like idle controls and emissions junk.

 

here is a good writeup that really helps tidy up the engine bay

https://www.zdriver.com/forum/240z-2...anifold-19937/