Adjusted throttle stop -- bad idea?

So in my ongoing quest to fix the high idle on my 1999 Altima, I decided to back out the throttle stop screw a little bit and see what happened. It says right in the service manual, "Never Adjust!" but I decided this was one of those times where you have to ignore the warnings and give it a go. It looked like it may have been messed with before, anyway.

About 1/2 turn was all that it took to get my idle down to exactly where it's supposed to be, around 750 rpm. Any further turning didn't do anything, because the throttle was then resting on the fast idle cam. I went for a test drive, and everything seemed to work fine, the car felt noticeably smoother when getting onto the gas lightly and when letting off and coasting. It also behaves like my '94 when putting in the clutch now, coming to a stop, whereas before it would rev up to 2500 rpm when I'd come to stops.

The only problem I ran into was the throttle was sticking occasionally, but a quick wipe of the throttle plate and body with a rag and some cleaner seems to have fixed that.

I checked the throttle position sensor and closed throttle sensor, and they both seem to be within spec.

So, is there any reason I couldn't or shouldn't leave things as is? When I unscrewed the stop screw, it and the lock nut came out together, so they're still fused to each other, which means I could put things back as they were just by screwing it back in. I also marked everything with a marker before I started. But the way things are now, I can't see why I couldn't just thread the screw in until it's against but not actuating the throttle at all, snug down the locknut, and call it a problem solved.

Reply to
JM
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Not that I can think of unless you enjoy making things more complicated than they have to be! :-)

Reply to
Steve T

Reply to
john smith

Agreed, but I have tried and been unable to get the idle air screw to turn.. and made a mess of it in the process. I stumbled on this as being the problem by cleaning the throttle plate/body in the first place and suddenly having an even higher idle than before. After scratching my head for a while, I pulled off the aux air hose and plugged it, and the car kept running, which it wouldn't do before -- I had used this "technique" to test for vacuum leaks in the aux air system in the past. So by cleaning the grime out of the T/B I allowed a bit more air to squeeze around the throttle plate at the "closed" position and aggravated the problem.

I think it was a case of that screw being off a bit in the first place, which explains the weird idle that I was getting, so I'll leave it as is and see how it goes. It's only about 1/2 turn out anyway so if it does end up to not work, it's easily returned to the way it was.

Thanks for the replies :)

Reply to
JM

Heh, nope, I can't argue with that logic! :)

Reply to
JM

Well, as it turns out, adjusting the throttle stop wasn't quite the perfect fix it first seemed to be at first -- the idle is still too high at startup and until the car warms up, the engine still wants to race a few seconds when I put in the clutch. I guess this makes sense because what I did to solve the problem (adjusting the throttle stop screw) doesn't come into play until the fast idle cam lets the throttle rest against the stop, and that won't happen until the car warms up.

It does seem though that if I could actually get the idle adjust screw to turn, I would be able to solve the problem in both conditions... is the idle adjust screw normally sealed or secured in any way? Mine definitely does NOT want to turn in either direction.

Reply to
JM

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