CTZCC.COM
http://forums.ctzcc.com/

Cold Engine/Transmission "Bucks"/hesitates until warmed up
http://forums.ctzcc.com/viewtopic.php?f=4&t=8968		 Page 2 of 5
Author:  Filipe [ Fri Apr 22, 2016 11:34 am ]
Post subject:  Re: Cold Engine/Transmission "Bucks" until warmed up
Alright, we may be on to something here. If (when?) I'm wrong, I'll admit it. Looks like I'm closer to being wrong every minute that passes. :P

Take a looksie here as well.
http://www.nissanforums.com/z31-300zx-t ... -when.html

Might be time to check out that IACV.
Author:  HowardJ [ Fri Apr 22, 2016 5:59 pm ]
Post subject:  Re: Cold Engine/Transmission "Bucks" until warmed up
When I have the opportunity I am going to see how difficult it is to test the EGR valve, then the PCV valve (which should just involve removing one hose) and then the fuel temperature sensor(or not so much?). The PCV is the simplest and most overlooked so "stupid" will check it soon. I haven't read about anyone checking or changing any of these hard working parts. There's a common bond between the EGR and PCV valve. They both have been sucking fumes for years and have moving parts that might be sluggish from years in the environment. Gee, that sounds like me. :shock: Anyway, I'm just saying that pollutants could be slowing down these cold(1st start of the day) carbon or oil coated internal parts. Maybe? For me, I think it's probably a little arthritis.Lol. :lol:
Author:  Frank T [ Fri Apr 22, 2016 9:57 pm ]
Post subject:  Re: Cold Engine/Transmission "Bucks" until warmed up
"Gee, that sounds like me".

:lol: HAHA! :lol: You guyZ are killin' me.
Author:  HowardJ [ Sat Apr 23, 2016 4:10 pm ]
Post subject:  Re: Cold Engine/Transmission "Bucks" until warmed up
So here's the latest. I removed a total of 4 vacuum hoses/connections. The first was the PCV Valve vacuum hose. I checked the valve by pushing in on the spring with the back of a 10 penny nail. The spring action seemed fine but I sprayed the internals with some WD40 anyway and put the hose and clamp back on. Next, I disconnected the one vacuum line that's between the EGR valve and EGR solenoid. Using a spare length of vacuum hose I connected it to the EGR valve and did a suck and blow on it. I was able to hear the valve opening and closing. :thumbs_up: Next... I did a suck and blow on the EGR Solenoid. It "held" both vacuum and "blow" pressure, but I gave it a short shot of WD40 anyway and put the vacuum hose back on them. Lastly I connected the spare vacuum line to the Fuel Pressure regulator and did a S&B to it also. It held, both pressure and vacuum but.... there was a hint of gas fumes in my mouth (understandable and reminiscent of the days siphoning gas out of gas tanks). I gave it a shot of WD40 and replaced the vacuum hose.Closed the hood. Started the cold engine and pulled off the driveway and went down the road...... SHAZAM!!!!!

It went like a bat out of.... with no hesitation or stumbling. What had I done? Did I work something loose? I just followed the "Keep it simple, Stupid" method. Now I can't wait until tomorrow morning to make sure that the "stumble" is gone. I'll let you know.
Author:  Frank T [ Sat Apr 23, 2016 4:15 pm ]
Post subject:  Re: Cold Engine/Transmission "Bucks" until warmed up
heyyyyyy......... :thumbs_up: 8) :thumbs_up:
Author:  Filipe [ Sat Apr 23, 2016 10:34 pm ]
Post subject:  Re: Cold Engine/Transmission "Bucks" until warmed up
We need a "guy on knees praising" emoticon. I was wrong. Nice job. Tisk tisk to me! Let us know when you have confirmed.
Author:  HowardJ [ Sun Apr 24, 2016 9:23 am ]
Post subject:  Re: Cold Engine/Transmission "Bucks" until warmed up
Filipe wrote:
We need a "guy on knees praising" emoticon. I was wrong. Nice job. Tisk tisk to me! Let us know when you have confirmed.


Filipe. I just took the car out for its first morning cold start run down the road. I'm happy and ecstatic to say that the "bucking","balking" "stumbling" or whatever else people want to call it, is GONE. It's my belief that, of the three things I did, I'd guess it was the shot of WD40 into the EGR Solenoid that freed up a slightly lazy/sluggish part BUT I'd ask that you try doing a "shot" into your solenoid (the cars) and then taking it for its cold engine run to see if it eliminates the "stumble". I'm very curious to hear Z results. :shock: :roll: :wink:

Good luck.
Howard
Author:  Frank T [ Sun Apr 24, 2016 9:29 am ]
Post subject:  Re: Cold Engine/Transmission "Bucks" until warmed up
I'm climbing out on a skinny limb here. I don't know the injector system very well, nor its intricate components. What I'm about to say will be theory only.

I suspect this:

1. These cars worked flawlessly when they were new. I reject the idea that Nissan would have foisted any system off on their primary market (USA) with an inherent stumble built-in from the factory. Nobody would sell a car which behaves as if it has a vacuum leak right off the showroom floor;

2. HAD Nissan been dumb enough to let such a glaring deficiency pass their QA and enter our market, the American buyers would not have been stupid enough to spend our hard-earned cash for a car which did that. Mustangs cost less and gave blistering straight-line performance without any hesitation at all. In other words, a stumble in *every* new 300ZX car would have made Mustang or Camaro buyers out of a lot of loyal Nissan fans. Further, every Datsun/Nissan fan would have known about it and it would have been black news throughout the Nissan community. I never heard about it back in the day. As it was, the 300zx cars were tremendously popular, scary-fast, and sold by the boatload. That simply wouldn't have happened if they had been faulty off the showroom floor;

3. Now that they have 30yrs on them, some parts are worn, dirty, sticky, etc. Normal wear and tear will cause any part to fail eventually, and it probably will stop doing its job efficiently before that happens;

4. My ignorance of your fuel systems prevents me from identifying which specific Widget is failing on both your cars, but SOMETHING is designed to open or close or adjust or somehow modify either your cold-engine fuel flow, your cold-engine ignition advance, or your intake airflow, and that Widget has become sticky or corroded or spring-weak or something, so it doesn't work normally. What both of you describe is racing your cold engines (which increases internal crankcase pressures), probably forcing some sticky piston to slide past the 30yr carbon or fuel resin buildup in the barrel it slides in. Maybe. Sounds logical to me. Higher revs = more pressure (or Filipe's boost), which forces sticky things to move when they should have slid easily under normal pressure;

5. By sticking his 10-penny nailhead into a few Widgets, Howie might have broken a sticky ring of carbon build-up or fuel resin and freed a sticky sliding piston (or something). The WD40 probably helped do the same thing. If that theory is correct, his car should run normally for awhile and then begin stumbling again when he builds up some more sticky carbon or fuel resin....maybe in another 30 years?

What'a'ya think?
Author:  Frank T [ Sun Apr 24, 2016 9:46 am ]
Post subject:  Re: Cold Engine/Transmission "Bucks" until warmed up
I also think Filipe has an opportunity to be a Z hero here. Because Howie blanket-bombed all his Widgets at once, there's no way to determine which one was faulty. If Filipe performs the same cures on each of his Widgets ONE AT A TIME and tests the car after each individual cure (a scientific approach), he might be able to actually identify the specific Widget which is causing everyone's problem.

Then you guys should consider carrying that news over to the other Z websites and sharing your experimentation results with them. Link this thread so they can follow the progress you both made and map the paths you each took. No ZX owner should have to live with a stumble in his/her great car.

Frank T
Author:  HowardJ [ Sun Apr 24, 2016 10:08 am ]
Post subject:  Re: Cold Engine/Transmission "Bucks" until warmed up
Frank. That was why I followed "old school" thinking. We used to be able to "squeeze" on the EGR's diaphragm to see if it affected the engines rpm. If it did, it was good. With this engines EGR you can't do that. The solenoid next to it appears to be the source for its vacuum so.... if it were a little "tarnished" it might not be working as quickly as when it was a young whipper snapper. That's why I gave it some WD40. I'm trying to pinpoint which widget was/is the gremlin by asking Filipe to try my "fix" on just the EGR Solenoid. If he can do that, then we would know if it's the part that would need changing if/when the stumbling comes back.
Author:  HowardJ [ Sun Apr 24, 2016 10:53 am ]
Post subject:  Re: Cold Engine/Transmission "Bucks" until warmed up
There are a lot of smart people in this world who can make things work and function "just like new" when they slow down or stop functioning as intended. I've Rube Goldberg'd many things to get them up and running again when others might have thrown them away. The cures and "fixes" that I read about (swapping parts from other year cars, reprogramming this or that) was not cutting it for me, which is why I decided to try and find the cause of the Z31 stumbling issue. If it worked fine when the car was new then it should be able to be returned to its perfect running status once again! Why not? I was fully aware that once I came up with three possible engine parts that might be causing this cold engine "only" issue, it should be done ONE at a time. I elected not to do it this way because I didn't think that such a long time issue, spanning many years, could be resolved by such a simple fix. Who knew? Duh! "Keep it simple, Dummy" worked again for me. Yea!!! :D :thumbs_up:
Author:  Frank T [ Sun Apr 24, 2016 11:25 am ]
Post subject:  Re: Cold Engine/Transmission "Bucks" until warmed up
I agree. There was a time when I was a kid when the corner mechanic would remove a faulty part from your engine and REPAIR it, reinstall it, charge you a little bit of money and send you on your way for another 10,000 miles. One of the very first projects I was assigned at my corner-gas-station teenage job was the replacement of a fuel pump diaphragm. The boss tested it, approved it, and reinstalled it on the customer's car. I think I was 14 and I did that work in between washing cars and running to the pumps to fill customer cars, wash their windscreens and check their oil each time anyone drove over the bell hose.

Today that breed of men are retired or dead and the new mechanics remove and replace (R&R) various parts with expensive new replacements until the problem goes away. :?
Author:  HowardJ [ Sun Apr 24, 2016 2:01 pm ]
Post subject:  Re: Cold Engine/Transmission "Bucks" until warmed up
I guess it's all up to Filipe now to confirm whether or not my suspicions about the "cure" for the stumble being a lazy EGR Solenoid is correct.
Filipe where are you? Z final leg of the race/piece of the puzzle depends on you letting us know if WD40 worked for you too. :? :lol: :thumbs_up: :thumbs_up:

HowardJ
Author:  Frank T [ Sun Apr 24, 2016 2:34 pm ]
Post subject:  Re: Cold Engine/Transmission "Bucks" until warmed up
It's perfect Z weather. He's out blasting about.
Author:  Filipe [ Sun Apr 24, 2016 6:00 pm ]
Post subject:  Re: Cold Engine/Transmission "Bucks" until warmed up
Hi y'all. Sorry - I was a bit "caught up" with life yesterday and today! You're looking at Wentworth Institute of Technology's newest Masters of Architecture graduate!

The car isn't driving at the moment. Still need to fix my busted axle. It'll be a few weeks till I can drive it. Plus, I'm a bit busy Z'ing around in the other Z. :lol:

Attachments:
13096007_10206619907071851_5684364469073811026_n.jpg
13096007_10206619907071851_5684364469073811026_n.jpg [ 81.26 KiB | Viewed 8584 times ]
Page 2 of 5 All times are UTC - 5 hours
Powered by phpBB® Forum Software © phpBB Group
http://www.phpbb.com/