Lucys500dollar87z24i

Hi all -

87 4cyl 5 speed manual

I am still struggling with my hardbody's rocketship idle. I need some advice.

I adjusted the fast idle cam/roller to specs in Haynes and Chilton. The idle is so high I am afraid to continue.

Quick history - bought it in Aug. idled fine but needed coils and starter. I added new plugs, cap and rotor. Passed emissions ok, failed for something non related.

installed new battery and immediately the idle shot up.

Failed for high CO.

A friend gave it to a mechanic. he replaced the vacuum hoses, and I don't know what else. I got it back with a lower but irratic idle - up and down. Changed O2 sensor and idle was a bit better. The upper radiator hose didn't get too warm so I changed water temp sensor and thermostat and new coolant.

got a 44 on computer - kewl

Changed PCV (it was really gunked up) and small hoses to the Thermo element.

As I said above, I used the haynes manual to make final adjustment to the idle.

The idle is now like a rocketship. No tach so I can't give RPM's but it is so high, I am afraid to idle it or even drive it to a real mechanic.

1 - Can someone shed some light on how aligning the marks on the fast idle cam and setting the proper "G" clearance can make the idle so high?

2 - What should I do next, and what should I not do?

3 - Is it safe to drive/idle?

4 - Are there any quick fixes to get the idle down long enough to get it to the shop?

Thanks

 

oramey

have you check the timing to see if it's too far advanced?
Retarding the timing might lower it to the point to where you can get it there.
A few other things I can think of are-
1.) Vacuum leak.
a.) check the brake assist (boost)
b.) PCV valve for leaking hose.
c.) all lines really.
2.) Idol adjustment. I'm sure you've checked that, but.....
a.) check the throttle cable. Make sure it's not too tight at the adjusting
screw. At the engine side and the pedal side.
3.) check for a vacuum leak around the intake manifold. A quick way to
see if it's leaking is to squirt a little WD40 next to where the
gasket meets head, and also squirt the carb mount to manifold
area. if the idol changes there is a vacuum leak

There are a bunch of other things to check as you know. I have had some luck with idol problems after doing the above checks.

I hope this helps a little.
Let me know and good luck buddy!!

Lucys500dollar87z24i

Thanks oramey!

If it stops raining, I will be outside shortly with my WD40 in hand.

BTW, with the idle so high, is it dangerous to drive/idle? I know it is a girly question :-) but I am a woman who is a bit intimidated by the rocket ship idle.

I sure do miss the boyfriends who knew how to "do stuff" - I grew up around men who could fix anything and were great troubleshooters. Men who weren't afraid of getting dirty hands! You are all a dying breed. I salute you all and I am sure you all make your women proud! And for the women reading this, you know what I mean :-)

Thanks again,

Lynn (Lucy)

oramey

Well, I know how it is . I have been married for 19 years now and my wife is my girlfriend still and she still depends on me to make all the car run . So I know where you are coming from .

It might not be a good idea to run the truck with the idol so high. But from your first post hare it sounds like you know a little about it .

Try the WD40 trick and all that I mentioned, and see what gives. It is definitely carburation and or vacuum from what I can tell. Have you tried the timing setting yet and the idol thingy??

well, let me know . I'll be around here for a while tonight to respond.

good luck girl!!

Will

Here's a relatively inexpensive trick that worked for me awhile ago to get my idle back to normal. Spray the throttle body area with some throttle body cleaner(while the motor is not running).

 

Lucys500dollar87z24i

I drove the rocketship to the gas station - kind of like the movie Speed - I had to keep turning off the key to slow it down enough to be able to shift at stop lights and signs. It must have been a good ride because the engine was really warmed up! I adjusted the idle and throttle again - was able to get the idle down somewhat. Did the spray/leak test and it appears there are no vacuum leaks. Even though the idle came down, it was still "loping".

I didn't clean the butterfly yet.

I checked continuity at the FICD solenoid and found none. I changed the part and the idle is now stable. Still high, but not rocketship.

I was told to use blue locktite to hold the idle adjustment screw in place. Everyone said it is non-permanent. I used too much. it won't budge. As this is the next step in reducing the idle, I will soak it in wd-40 and try to break the seal.

Timing is next. Maybe tomorrow if I get the screw loose!

Thanks for all advice!

oramey

When you sprayed the WD40 on it and the idol came down a little, this is an indication that there is a vacuum leak somewhere. The fluid fills the leak just for a second until it is all drawn in. Once it's drawn in, the leak is not sealed anymore and the idol will race back up again. There should be no variation in rpm if there are no leaks.

check that again and see what gives.

DanaCat

Ok Lucy, I am going through the EXACT same scenario you just spelled out! I have an 89 Nissan Z24i engine. Hopefully yours is solved by now, but just in case, I think SPEEDO is right, the problem may be the Thermo element. I am about to find out though on mine, if I can get the idle down far enough to drive mine to the dealership. Did your Thermo element have a green scaly color on it? This is an indication it is leaking. Even though I was able to get the fast idle cam aligned properly, that's when my engine really started racing. ( I look forward to the "Speed" scenario on the way to the shop!). I think even though the manual says to change the element if it is not alignable, I still think the Thermo element could be faulty enough to cause problems even if you can align it....

oramey

New idea!!

Have you removed the throttle body injectors? (If it has them) If so, is it possible that you might have nicked the orifice at the end of the injector?

That would make the fuel mist inconsistent and could cause a rich scenario that might cause it to idle high.

One more thing, If it sat for a while, a mud dobber (insect that loves to build nest in round holes... a southern US thing mostly.. ) might have tried to build a nest that might be clogging one of the vacuum lines or something else.

Just a thought.

DanaCat

Thanks, but I just found out (at least part of the problem) was that the fast idle cam roller arm was jammed (stuck). I followed the manual in adjusting the roller with the aligning mark, then tried to adjust the clearance between the cam plate with the alignmnet mark and the roller. The second adjustment wasn't working, and it was now stuck in super-high rocket idle. Following the manual, turning the screw to make the clearance adjustment didn't do anything until I figured out that I needed to loosen the center "lock nut" that holds the throttle lever and the adjusting screw together. Once I loosened that, I was able to turn the adjusting screw and was able to create the clearance between the roller and cam plate, thus dropping the idle back down to a safe idle. I had also sprayed the throttle body parts down with a cleaner/lubricant during this to help clean and unstick parts. I just replaced the thermo element last night. Personally I think the new element allowed me to make better adjustments than the old one did. The old one's plunger looked like it was not pushing right and was trying to throw the levers out of adjustment again. It now looks like a textbook adjusted assembly with the new thermo element instead of the sloppy apperance with the old one. Of course so many things were cleaned and moved around during this it may have been a combination of many things.
Anyway, thanks for your input. For everyone's knowledge, I did find out from a Nissan tech that was working on Nissan trucks back around the 80's(maybe 90's as well) that they were known to have weak throttle bodies. He said it wasn't uncommon to have a truck at 80,000 miles needing to have the throttle body replaced to solve rough idling problems. I heard the term "bad harmonic balancer" used. Maybe this is the cause of some of the rough idle issues posters have been reporting here. He said mine was bad as well (had him take mine apart and check it out), but it wasn't $1500.00 bad. I can live with the uneven idle for that kind of money (it's really not that bad anyway, I just wanted him to take it down and clean and re-adjust everything anyway). Anyway, he said even if I replaced it who's to say the new body wouldn't go bad in another 80,000 miles (I guess poor Nissan design). And of course that for obvious reasons leaves out junk yard used throttle bodies, not worth the time or money.

 

88pathoffroad

The main problem with the TBI setup is dealerships not knowing how to properly troubleshoot and fix things. They like to throw new $1000 parts at problems and say "See? It's fixed now! It needed a new TBI!" ...when all it needed was a new gasket, mixture heater or a single injector. Bastards, anyway.

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oramey

I'm glad you got it all figured out. Sounds like you have an uneven idle still though.
You might try and lower the idle a little . I found that when the idle is a little off the computer tries to slow it down to normal, and then the idle is forced back up again due to the MANUAL settings. So try this. Lower the idle just a 1/4 or an 1/8 turn. Then let it sit and see if it smooths out. I did have this problem and worked
with it and finally got it all smoothed out..

great thread. was fun !!

PEACE OUT..

DanaCat

You got a good point! I agree, stealership bastards!

DanaCat

Thanks Oramey, I'll give that a try......