Idle Hangs in neutral...
03-18-2007, 01:49 PM
#1
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Idle Hangs in neutral...
...Ok, I need some help from the "pros" in here.
1979 280zx Coupe, 5-speed, A/C converted to 134:
The car is idling at about 1,000 rpm after the car warms up and in between shifts the idle will sit at between 2,000 and 2,500 rpm and will drop finally when the car is almost stopped. This problem only occurs when the car is in motion. My question is, what is causing the idle to hang high and sometimes climb when the clutch is pressed down and I am shifting or in neutral while the car is in motion?
I cleaned the TPS connector.
I know someone out there has had a similar problem.
1979 280zx Coupe, 5-speed, A/C converted to 134:
The car is idling at about 1,000 rpm after the car warms up and in between shifts the idle will sit at between 2,000 and 2,500 rpm and will drop finally when the car is almost stopped. This problem only occurs when the car is in motion. My question is, what is causing the idle to hang high and sometimes climb when the clutch is pressed down and I am shifting or in neutral while the car is in motion?
I cleaned the TPS connector.
I know someone out there has had a similar problem.
03-18-2007, 04:59 PM
#4
Big Poppa
Join Date: Jan 2005
Location: Mission, British Columbia
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i had the exact to the point same problem. adjust your timing, cant remember which way, but check it. also the tps might need some minor adjustment. it can be clean but telling the ecu the wrong position. read haynes aboot that adjustment. its weird, and plaged me for some time. also if all that doesnt work, do the air fuel ratio, it makes a large diff, but it most likely is the timing
03-19-2007, 11:22 AM
#6
"Destroyer of Worlds"
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Hey THX,
Rod is correct. I dealt with this problem for a long, long, long time. It only took me three years to find out what it was.
Anyway, what you probably want to do is to take your whole throttle body assembly off, and pretty much soak it in penetrating oil, WD-40, pick your poison. If that doesnt work, i just ended up swapping mine out to one from a another motor of a 1978. Start with the the throttle spring on the side though, that could be 95% of your problem.
bob
Rod is correct. I dealt with this problem for a long, long, long time. It only took me three years to find out what it was.
Anyway, what you probably want to do is to take your whole throttle body assembly off, and pretty much soak it in penetrating oil, WD-40, pick your poison. If that doesnt work, i just ended up swapping mine out to one from a another motor of a 1978. Start with the the throttle spring on the side though, that could be 95% of your problem.
bob
03-19-2007, 12:19 PM
#7
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Originally Posted by Bob79280zx
Hey THX,
Rod is correct. I dealt with this problem for a long, long, long time. It only took me three years to find out what it was.
Anyway, what you probably want to do is to take your whole throttle body assembly off, and pretty much soak it in penetrating oil, WD-40, pick your poison. If that doesnt work, i just ended up swapping mine out to one from a another motor of a 1978. Start with the the throttle spring on the side though, that could be 95% of your problem.
bob
Rod is correct. I dealt with this problem for a long, long, long time. It only took me three years to find out what it was.
Anyway, what you probably want to do is to take your whole throttle body assembly off, and pretty much soak it in penetrating oil, WD-40, pick your poison. If that doesnt work, i just ended up swapping mine out to one from a another motor of a 1978. Start with the the throttle spring on the side though, that could be 95% of your problem.
bob
03-19-2007, 01:21 PM
#8
"Destroyer of Worlds"
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The only reason i would imagine it would not work is the differences in the TPS. It could fit weird. Also, some of the vaccum lines cub possibly be different. There may be another route they follow. You will just have to compare.
03-19-2007, 01:27 PM
#9
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Quite often this has nothing to do with the throttle body itself. It's usually the BCDD (Boost Controlled Deceleration Device) that's located under the throttle body. Easy way to determine is this is the problem is to disconnect the vacuum line that runs to it and plug it. If the problem persists then yes I'd agree with a dirty throttle body. Otherise it's just the BCDD and you can pull it, clean it and hook it up again, or just leave the vacuum line disconnected as I and many others have done.
03-19-2007, 05:00 PM
#11
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Well...I swapped the AFM for the one in the '82...slightly better throttle response but the idle is still hanging. I must have adjusted that AFM pretty good though cause it made a difference. I think I will mess with the timing when I get a timing light and tomorrow I will swap some more parts like the TB if it has all the right connections. My poor '82 must hate me right now....maybe I should do the 4bbl conversion on it....we will see. For the timing, what should it be if I want a little more pull than stock? 10*, 12*.....34* btdc? I did spray the entire throttle linkage with WD40 and it helped a little. Remember, it is not a Turbo. 
Last edited by thxone; 03-19-2007 at 05:03 PM.
03-19-2007, 05:12 PM
#12
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Originally Posted by Bob79280zx
The only reason i would imagine it would not work is the differences in the TPS. It could fit weird. Also, some of the vaccum lines cub possibly be different. There may be another route they follow. You will just have to compare.
03-20-2007, 01:45 PM
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F#$K F@#K F%^K!!!!!!!! Ok, so it's not the TPS. I do have some big thing hanging off the bottom of the TB and it has a 1 wire connection and 2 vacuum lines. Man, this is pissing me right the hell off!!! Ok, check this out, when I go over about 3,000 rpm I can here what sounds like "turbo whine" coming from under the hood and there is an ever so slight drop in power....could this be a vacuum leak?????? Please somebody come and fix my car 
03-20-2007, 02:06 PM
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Originally Posted by snwbrderphat540
oh sorry, let me refrase that, its probably ntohing at all, just let it go im sure nothing will catastrophically fail on you 
Well I got the car running like it was before I messed with anything....gonna do a couple more swaps with the ECU being the last thing.
Last edited by thxone; 03-21-2007 at 11:57 AM.
03-22-2007, 12:57 PM
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Ok, so I pulled all the spark plugs, they are all NGK's and are fairly new as well as the spark plug wires, also NGK's. None of the plugs were gaped but they are at .043 now...was .030, I also cleaned the electrodes with fine sandpaper. The plugs all looked fine as far as running condition, no wetness or bad colors. The cap and rotor button were also pretty new and I swapped them for the ones on my 82. The rotor button was identical but the cap was different. The car is still doing it own thing...it's baffling me. It's almost like there is a choke stuck on when the car warms up....when it is cold the idle is low and stays that way until the car warms up, then it does the jumping idle again up to 2,000rpm and there is some hesitation when driving spirited...if I shift right at 3,000 in every gear the car is super cool to drive....but I don't like driving like that all the time if you know what I mean.
I am thinking I will swap the Air regulator, Cold start valve and maybe the Thermotime switch....what do you all think? Can't adjust the timing yet as I do not have a timing light and I don't know what needs to be done in order to do it on a 1979 280zx N/A 5-speed or how it needs to be done on my car. I want to drive up to see my daughter Friday but I want the car to be cool first....though I will go either way.
I am thinking I will swap the Air regulator, Cold start valve and maybe the Thermotime switch....what do you all think? Can't adjust the timing yet as I do not have a timing light and I don't know what needs to be done in order to do it on a 1979 280zx N/A 5-speed or how it needs to be done on my car. I want to drive up to see my daughter Friday but I want the car to be cool first....though I will go either way.
03-22-2007, 01:04 PM
#23
Did you take off the BCDD & clean it?
Originally Posted by naviathan
Quite often this has nothing to do with the throttle body itself. It's usually the BCDD (Boost Controlled Deceleration Device) that's located under the throttle body.
03-22-2007, 01:06 PM
#24
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Originally Posted by NismoPick
Did you take off the BCDD & clean it?
