Originally Posted by thornburg (Post 111094)

I've searched for this info on his site and on Google, and I haven't had much luck.

I replaced the plugs, wires, and distributor cap on my car this past Sunday, and everything seems fine, except that the idle is a little higher and causes a bit more vibration than it did before. At least it seems to.

The only thing I found in my search was about vacuum leaks, but I've checked, and I didn't bump any vacuum hoses in the process.

Note that I used Bosch Platinum +2 plugs, because they were only a few dollars more than the regular plugs (for a set of 4, not each), and I thought it would be worth a try.

Does anyone have any idea why my idle would change like that, and if it is a problem I should worry about?

Thanks in advance for your help.

Originally Posted by Ford Man (Post 111096)

If you were working in the area of any vacuum lines you should check them to make sure none of them are cracked and causing a vacuum leak. It could be they were brittle and cracked if you bumped it. Usually if you have a very bad vacuum leak it will make the idle much higher. I also wonder if it would help to disconnect the battery and let the computer reset, it may have something to do with the new type plugs. I have never used the +2 platinum plugs, so I don't know the effects of them.

Originally Posted by thornburg (Post 111104)

Thanks for the reply.

I had the battery disconnected when I did the job (and actually for about 36 hours beforehand as well), because it was recommended to disconnect it before doing the plug wires & cap, and it was necessary to remove it from the car to get the cap off anyway.

The idle isn't a lot higher, maybe 90RPM or so? I wish I had paid closer attention to what it was in various states before, so I would know exactly.

One thing I can say for sure is that idle in neutral with the AC on is almost exactly the same, before and after (about 1100RPM), it is the idle in neutral (no AC) and idle in gear w/foot on the brake that seems somewhat higher.

I'll try to remember to take a look at the vacuum lines for cracks before I leave work this afternoon. I'm not real engine-savvy (yet), so I've just been checking any small-ish hoses to when checking for vacuum lines. That is what they are, small hoses, right?

Originally Posted by mrmad (Post 111123)

Did you gap the plugs and adjust the timing when you were done?

Originally Posted by thornburg (Post 111126)

Bosch Platinum +2 are "gapless" and specifically say not to adjust the gap. I'm not even sure you could, those prongs look like they might break if you tried to bend them.

I did not adjust the timing. Is it necessary to adjust the timing when you replace the spark plugs & wires? I didn't see that in the Haynes manual or the Autozone online instructions...

Originally Posted by Jay2TheRescue (Post 111130)

Its not absolutely necessary, but its always a good idea to check the timing when replacing that stuff.

-Jay

Originally Posted by thornburg (Post 111132)

I suppose that in order to check the timing I need to take off the timing cover and have a timing light?

The only car I've even been remotely involved in the timing belt on was a VW TDI and we used a VAG-COM to monitor timing instead of a light...

Originally Posted by dkjones96 (Post 111136)

It's possible for this to happen. The more efficient combustion from the new parts can cause the engine to run a little higher at idle.

We get this at work all the time on older carbbed engines and notice that the IACV closes a little more at idle. If you have a EFI you should take a look at your IACV to make sure it's working correctly.

Originally Posted by thornburg (Post 111160)

There don't seem to be any directions relating to the IACV on autozone's onine manual... I haven't checked my Hanes yet. Where do I find it, and how do I check it?

Jay2TheRescue: Perhaps I'll see if I can borrow a timing light... I looked at the timing procedure, and it looks like I don't need to take off the timing cover. It mentions (if necessary) loosening the "pinch bolts" on the distributor and twisting it to adjust the timing... The pinch bolts aren't regular screws, are they? I'll have to figure out what those are... The stupid autozone manual only has pictures of what it wants to have pictures of, and the haynes book has only a few pictures and they are mostly of different engines than mine.

Originally Posted by thornburg (Post 111202)

I couldn't get any time to look at the car last night, but I did have an idea this morning...

The car was a little hard to start this morning (didn't take more than one try, but it cranked longer than usual before starting, and sounded a little different). Last night, I filled up at the gas station a little less than a mile from my house, so the car was started, and then not run for very long.

What if my battery is dying? If the battery is toast, that would cause the alternator to run more, right? Would that increase idle RPM? I'm building a house of cards here, since I know very little about cars/engines...

I have no idea how old the battery is. The positive terminal was all covered in crud, so I cleaned it & the connector with a wire brush while I had the battery out for the distributor cap.

Originally Posted by Ford Man (Post 111298)

Harder starting and/or rough idleing could be another sign of a vacuum leak. I don't think the battery would be an issue in this, but I guess anything is possible. Does your car have an idle speed control motor or idle air control valve? I have had them go bad before and the engine idle would change, but if that was the problem your ECU should be sending a code.

Originally Posted by suspendedhatch (Post 111354)

Those Bosch plugs are junk and will give you nothing but problems with a Toyota. Toyota's are known to be picky about spark plugs. I suggest getting the regular old NGK plugs or factory Denso.

Check ignition timing and reset the ECU. Make sure your throttle cable isn't binding.