Rough Idle, Sloppy Shifter

[Geo31]

I could use some experienced help here.

I'm a long-time enthusiast and have been working on my own cars for oh, hell, longer than some of you have been alive. I've build engines, done swaps (even wrote an article for Sport Compact Car covering an SR20DET swap in a G20). Anyway, just wanted to give a little background - I'm not a noob.

OK, down to cases. My GF has a 97 with 100k miles in pretty good shape - well taken care of. It recently developed a problem and she is giving it to her niece in the next few days so I need to work fast.

Specifically, it developes a rough idle, but only when fully warmed up AND the AC is on. I've driven it cold and it doesn't exhibit the problem, does does it with the AC off, or at least it's unnoticeable.

I've searched the archives and have seen posts about the intake boot and the TPS. I seriously doubt it's the intake boot or other vacuum leak as the problem doesn't occur all the time like it would with a vacuum leak.

I am pretty certian it's a sensor issue since it appears that it only presents itself when fully warmed up and under load at idle (no real problems with steady-state driving or acceleration). The TPS has some merit, although again, I would think it would be a more consistent issue if it were the TPS.

So, I'm asking for some help here. I don't have an FSM and since she's giving the car away it doesn't make sense to buy one. I'm hoping this is something someone here as experienced before.

One other issue....

The shifter (manual gearbox) is VERY sloppy side to side. I have a hard time believing that something isn't amiss here. Any ideas on this?

George Roffe
Kingwood, TX (N Houston)

[Beerizfood]

Well George first thing I would do if it were me is to set the base idle and check ign timing.You have to warm it up ,all loads off and round the ten-pin under in the under hood DIAG connector located on the left of the engine compartment.Once warmed connect a ground lead to the ten-pin.This will take idle control away from the PCM.If it
dies or stumbles when you connect the ground wire you must turn the idle screw out on the the throttle body ans if it revs high when ground connected you must turn the idle screw in.This is the air bypass screw NOT the throttle stop screw.Its the #2 phillips.
I like to see no change in idle when connecting/disconnecting the lead then you know your close enough.At correct idle with the jumper in check IGN timing specs are 9-11 degrees BTDC at 650-750.
I trust the IGN system is good ,a bad wire can cause this issue as well.They leak inside the valve cover out the side of the hard plastic boot.

[Beerizfood]

As for the shifter check the shifter bushings underneath.There are 3 sets.
A left and right at the shifter bottom,A left and right near the tranny,and a top and bottom near the tranny.

[95dx]

i'm interested in seeing how this turns out. my gf's 95 sentra has the same problem with the AC, its got me stumped, and the two mechanics i paid to get it fixed failed miserably and insisted it was fixed.

can you post if you figure it out?

[Henchman]

As for the shifter check the shifter bushings underneath.There are 3 sets.
A left and right at the shifter bottom,A left and right near the tranny,and a top and bottom near the tranny.

I agree with this, it will most likely be a bushing issue.

Edit*

No CEL right?

[Geo31]

i'm interested in seeing how this turns out. my gf's 95 sentra has the same problem with the AC, its got me stumped, and the two mechanics i paid to get it fixed failed miserably and insisted it was fixed.

can you post if you figure it out?

You're in a bit of luck there. I'm pretty well connected in the Nissan community. I'm the original owner of a 91 SE-R, have been prominent on the SE-R mailing list and SE-R.net and have excellent connections there. I'm not as familiar with the GA16DE that you have, but I should be able to help some.

Thanks everyone else for the help. Will report back when I have a little time.

[Geo31]

I agree with this, it will most likely be a bushing issue.

Edit*

No CEL right?

Correct. Nothing seems out of the ordinary except when it warms up the idle gets bad with the AC on. It probably has a little problem without the AC on, but the load of the AC "challenges" the idle.

[95dx]

You're in a bit of luck there. I'm pretty well connected in the Nissan community. I'm the original owner of a 91 SE-R, have been prominent on the SE-R mailing list and SE-R.net and have excellent connections there. I'm not as familiar with the GA16DE that you have, but I should be able to help some.

Thanks everyone else for the help. Will report back when I have a little time.

Well we'll get along great then! i used to own a 91 se-r too. i wish i never sold it i'm currently in the market to buy another b13. i thought i might be the only nissan fanboy on here but i guess not lol.

as far as the problem, i may have found it. the cv boot is broken flinging grease everywhere and possibly causing the accessory belt to slip. the belt chirps ever so slightly. with the ac on, the car loses wayyy too much power(i know they always lose a little), and the car wont even get out of 1st gear without flooring the gas and slamming it in. i'm gonna put a whole new alxe in and replace the belt and see what happens.

[Beerizfood]

How are you making out witht the idle issue?
Does the IAC respond to other loads such as P/S ,headlamps etc?