# 87 D21 z24i Idle up/down and dies



## RobertBlevins (Nov 6, 2013)

California emissions are so much fun. Okay, not really. This 1987 D21 with the z24-i engine has been surging up and down with the idle for almost two years. Doesn't die at stop signs, though. And when you cruise it along it runs great with plenty of power to spare. 

Then recently it started falling on its face completely at stop signs, surging up and then down, then it dies. On the freeway or cruising, still runs great but there is a definite vacuum leak going. 

Any ideas?


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## Car guy (Mar 31, 2016)

Is yours the dual fuel injected throttle body with side-mounted TPS, MAF, fuel cut solenoid, and FPReg, and bottom mixture heater and dash pot configuration? Air-housing-situated temp-controlled vacuum motor, on air inlet top?

BPT-controlled EGR valve config?

Front-cover FP config?

Optical dizzy?

If so, there are 30-40 vacuum hoses on the: TVVs, BPT, EGR, AIV solenoid, EGR/canister solenoid, canister itself. Then, gaskets on TBI chambers, IM, and air housing.

Dang, would I love to tackle this one. Have 53 hoses on mine.

Can you post pics of the engine bay?


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## RobertBlevins (Nov 6, 2013)

Well, first I did get your PM but I can't answer until 15 posts, so I will quote it first here for you:



> 'Thanks. I also saw your post, and I will reply to that. Yeah, I've had some nice Datsuns over the years. B210 I got rid of quickly because the back end is too light. Once had a 610 sedan and found out it was one of the best Datsuns all around. (They cornered really well) I had a few of the trucks, the oldest being a 70, but mostly mid-70's on the others. On every one of them I dumped the 16 or the 18 motor and installed L20B's instead, one time with a Holley 2bbl carb and that sucker really flew. Ha. Good old days for sure. This current 87 isn't bad but I failed to notice it had California emissions or I probably would have said pass on it. The sticker was covered in grime and when I cleaned it that's when I found out. Mileage not bad for the age, though. Has 152K currently.
> 
> Sincerely, Robert'


I have to admit that even as a Datsun/Nissan guy, I didn't understand some of the terms you used there. Most of my previous Datsuns were a lot simpler of course. One thing I noticed about this vacuum problem is that today when I drove it, it was about 25 degrees outside and it no longer died at stop signs, although the surging was still there. I am going to look at it tomorrow. I will take some pictures then and post them up for you. Might snow tomorrow here in Seattle so if it does, I will do the pictures on Monday.


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## RobertBlevins (Nov 6, 2013)

Right now I'm considering buying a 1987 300ZX with leather, T-tops, 5-speed, original high-end stereo (it works), that has only 128K on it. It's owned by a rich family who happen to be customers of our cleaning business. (Gayla Prociv and I are the only couple in America who run both an upscale housecleaning business and are registered US trade publishers, no kidding.) 

Anyway....I can get this vehicle for $1,300 plus the tow. The only thing wrong with it is that it will start up every time, and run just great. For a few minutes...and then when it dies absolutely NOTHING works. I mean zero, zilch, nada, negatory. No lights, no dash lights, no starting, no fan motor with the key on, absolutely no power to anything. Maintanance on it has always been regular. Has the straight six engine, fuel injected, no turbo. 

He took it to a mechanic once and they couldn't figure it out. This is what I think is wrong: Something in the main fuseable link box is no good, or a connection is loose in there. That's the first stop after the battery. If it were another electrical problem, SOME things would still work on ACC, or with the key on, but on this one there is zip. 

After the car sits for a bit, it will restart and run fine. For a while.


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## RobertBlevins (Nov 6, 2013)

*UPDATE*

I figured out the problem with the truck. On the day it began falling on its face at stop signs and seeming like it had The Vacuum Leak from Hell, I had filled the tank to the brim at a Fred Meyer gas station. So...about the time the truck was just about out of gas again, I refilled it elsewhere. Within a couple of miles, the problem just vanished and 350 miles later, it hasn't returned. 

Still has a slight up and down fluctuation in the idle, but barely anything. Runs smooth now. I chalk it up to bad gasoline or something. Usually at that Fred Meyer I use regular. This time (when the engine went screwy on me) I filled it with supreme, and I guess I got a bad load of supreme there. 

Had to be the gas. Shortly before this all happened, Seattle was struck with a real tough cold snap. I figure maybe water in the gas or something.


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## RobertBlevins (Nov 6, 2013)

*UPDATE*

I figured out the problem with the truck. On the day it began falling on its face at stop signs and seeming like it had The Vacuum Leak from Hell, I had filled the tank to the brim at a Fred Meyer gas station. So...about the time the truck was just about out of gas again, I refilled it elsewhere. Within a couple of miles, the problem just vanished and 350 miles later, it hasn't returned. 

Still has a slight up and down fluctuation in the idle, but barely anything. (It's been doing that for years anyway, with no ill effects.) Runs smooth now. I chalk it up to bad gasoline or something. Usually at that Fred Meyer I used regular. This time (when the engine went screwy on me) I filled it with supreme, and I guess I got a bad load of supreme there. 

Had to be the gas. Shortly before this all happened, Seattle was struck with a real tough cold snap. I figure maybe water in the gas or something.


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## Car guy (Mar 31, 2016)

Thanks for letting us know. Glad to hear.


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