Tolkmod Posted October 18, 2016 Report Share Posted October 18, 2016 Sooo... Over the past few weeks I've had some idle issues creep up again. It was getting close to my 3k oil change and tune up so i figured I'd just go a head and do that. Changed out all the plugs, cap, rotor, air filter...ect ect... Still, same issues. Dang thing does NOT want to hold an idle, and when it does, it barely keeps it. As seen below: FYI, no one is at the gas peddle, that's the engine doing that all on it's own. I have no idea what is going on. While doing my tune up I did notice that my fuel pump was squirting fuel out the bottom of it, so I went ahead and replaced that. Still, idle issues (the vid is after the pump was installed, but still acting the same way with the engine) at least I don't have fuel dripping out of my pump now. I've checked the timing, it's good... I double checked all the vac hoses and everything looks good. I'm at a loss as to what is going on. Anything else that wouldn't require a mechanic's shop or an ASE cert that I could try to check? Thanks! Quote Link to comment
Dguy210 Posted October 18, 2016 Report Share Posted October 18, 2016 Check the bolts at the bottom of the carb, they have a nasty tendency to loosen up and cause an air leak which causes low idle problems, 10mm wrench will be needed. 1 Quote Link to comment
Tolkmod Posted October 18, 2016 Author Report Share Posted October 18, 2016 Check the bolts at the bottom of the carb, they have a nasty tendency to loosen up and cause an air leak which causes low idle problems, 10mm wrench will be needed. humm... now that you mention that. I do remember having to tighten them down about a year ago when I was replacing 90% of the vac lines on it (and finding the 3 cracked leaking ones as well) When my bud squirted carb cleaner on the outside of the carb the engine would have a quick rpm boost, proving that there was a small leak somewhere around the seals. We replaced them and tightened it down. I'll have to check that out again, maybe try the same trick, see if there's a leak down there again. Thanks! Quote Link to comment
Tom1200 Posted October 18, 2016 Report Share Posted October 18, 2016 I was thinking some kind of air leak as well; it sounds rather like a leaky compressor. Double check the manifold nuts/bolts as well. Tom 1 Quote Link to comment
Tolkmod Posted October 18, 2016 Author Report Share Posted October 18, 2016 I was thinking some kind of air leak as well; it sounds rather like a leaky compressor. Double check the manifold nuts/bolts as well. Tom aren't there torque requirements for those bolts? Quote Link to comment
Tom1200 Posted October 20, 2016 Report Share Posted October 20, 2016 There is a torque spec, I'd have to look it up but you could check on the net. Tom Quote Link to comment
Tolkmod Posted October 20, 2016 Author Report Share Posted October 20, 2016 found it in my book, 6.5 to 10.1 ft-lb I'll probably be checking all this out this weekend. Time to break out that torque wrench I have only used twice since buying it lol Thanks for all the suggestions guys :) Quote Link to comment
Tolkmod Posted October 20, 2016 Author Report Share Posted October 20, 2016 just in case anyone else was curious about the 74' B210 Torque ratings Quote Link to comment
datzenmike Posted October 20, 2016 Report Share Posted October 20, 2016 Try adjusting the idle mixture screw in or out. See if the idle will improve and it revs up. If so turn the idle speed back down to normal and adjust the mixture screw in and out trying to find the position that has the smoothest fast idle. Again if it speeds up turn the idle speed back to normal. Keep adjusting until you cannot improve the idle quality and the idle speed is normal. The mix screw may have about one full turn where the idle quality is best and if turned in (lean) or out (rich) it drops off. Just set in the middle. You may need to do this 5-8 times. So don't worry. Quote Link to comment
Tolkmod Posted October 20, 2016 Author Report Share Posted October 20, 2016 Try adjusting the idle mixture screw in or out. See if the idle will improve and it revs up. If so turn the idle speed back down to normal and adjust the mixture screw in and out trying to find the position that has the smoothest fast idle. Again if it speeds up turn the idle speed back to normal. Keep adjusting until you cannot improve the idle quality and the idle speed is normal. The mix screw may have about one full turn where the idle quality is best and if turned in (lean) or out (rich) it drops off. Just set in the middle. You may need to do this 5-8 times. So don't worry. Ya know Mike, this was one of the first things I tried. I thought maybe the mixture was off, or the idle screw loosened up a bit. Weird thing is, NOTHING changes on it. The only change I noticed was when i screwed the mixture screw in almost all the way, then it pretty much died on me. That, I think, was the weirdest feeling for me. You'd expect the idle to increase if you screw the dang idle screw all the way, or for it to rev a little higher by opening up the mixture screw, but nope... just stayed the same and the engine bounced all over like it did in the video... I'll be dedicating some time to this issue this weekend, I have a nice 4 day weekend to either get it right, or completely screw it up lol Quote Link to comment
datzenmike Posted October 21, 2016 Report Share Posted October 21, 2016 Screw in, shuts off the idle mixture, out opens it. Same as the kitchen sink HOT tap. Quote Link to comment
Tolkmod Posted October 22, 2016 Author Report Share Posted October 22, 2016 So, I think I've found my issue, and have a temporary fix for now. I found it completely by mistake as well, so it's not like I'm some super mechanic who knows what he's doing lol I was working on tightening down the carb, as well as the manifold bolts, and so i removed the air cleaner to get better access and figured I might as well check things out while I had access. My hand brushed by this.... I noticed it was SUPER loose, like just wobbling around and barely attached. So I messed with it a little, and then realized that it was part of the vacuum system. Turns out it's called a "vacuum cutting solenoid" or something along those lines. At least from my mechanic's book anyways. So i took it apart, to check it out. Apparently there's a pin that goes down (similar to the anti-dieseling solenoid that cuts off the fuel flow to the carb when you turn the car off) When I tested it per the book's instructions it didn't pull the pin up at all. It should pull up the pin at after a certain amount of time with the engine on, and power going to it. I guess it heats a coil inside that pulls the pin up, allowing for the vacuum to continue through the hole. I found another website that a guy had the same problem with another car (not a nissan...) and he just pulled it, and put a screw on the top to allow the vacuum to open up. Said it made for a little higher idle than normal, but at least it didn't die on him while he was driving around. So I did the same. It ran rough for about 30 seconds (like it had been) then bam.. Idle smoothed out and seems to be pretty steady now. I had to adjust the idle screw a little to pull it back down cause it went up to around 1500 rpm, now I'm hovering around 1k to 900, and it is holding and running smoothly. Anyone know where I can find a new one of those? I'd like to get it replaced, not sure how big of a deal it is to have it open at all times like that. Thanks! Quote Link to comment
datzenmike Posted October 23, 2016 Report Share Posted October 23, 2016 Yes idling way too high. It isn't anything to do with the idle or mixture as it is only on the rear two cylinders. There would be no reason to compromise the intake vacuum with a leak. So that solenoid only opens and closes to send a vacuum signal somewhere. Where does that hose go to??? Quote Link to comment
Tolkmod Posted October 26, 2016 Author Report Share Posted October 26, 2016 ugh, sorry man donno why i never got the alert that there was a response. I'll take a more detailed look at it tonight and let ya know. Quote Link to comment
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.