can a slight tune up change the idle?

[87blackroxi]

Before the tune up the car idled at a steady 600 rpms smoothly. I pulled out the plugs and they were pretty bad. I had 7 very worn bosch plugs and one severely bad plug that had something like nst671 on it. It looked like an original plug they left in because it was in a tough place to get out. Took me 20 minutes to get it out myself ad .
Anyway, new plugs, then wires, distributor cap and rotor all went in. Now it still idles at around 600rpms but it is not steady, and A bit choppy. It has sort of the muscle sound choppy idle. Does this make sense? Would these changes change the idle?
The car is definately a whole new animal now with the tune up. It really has pepped it up. But the idle is alot different.
Any thoughts?

 

[wishuwerehere82]

I have always felt that it takes new plugs a while to break in.

 

[tlong]

Perhaps the computer needs some miles to rethink fuel air mixtures with new efficiency. The L98 isn't my bag baby. Folks will assume you've cammed her....

 

[74bigblock]

Sounds like what Hib told me mine would sound like if the plugs were gapped too far out. Do you have seperators on your plug wires?

 

[87blackroxi]

Sounds like what Hib told me mine would sound like if the plugs were gapped too far out. Do you have seperators on your plug wires?

Seperators? Do you mean the plastic spacers that the wires lock into to keep them away from the engine? Then yes I have them, but there are 3 wires that are touching. Would that create a problem?

 

[Edmond]

Now is also a good time to check the timing of the car. That will change idle quite noticeably.

 

[87blackroxi]

Is the timing something I would have to bring to a mechanic? or something i could do?

 

[Vettefan87]

You can do it yourself. You just need to unplug the EST wire I think? Then check the base timing. You need a timing light to do this. I am pretty sure you can run somewhere around ten degrees advanced with no problems, as long as you run premium fuels. I need to find out where this wire is myself so I can check the timing on mine. I think it is set to low, because the car isn't running like what it should be.

 

[74bigblock]

Seperators? Do you mean the plastic spacers that the wires lock into to keep them away from the engine? Then yes I have them, but there are 3 wires that are touching. Would that create a problem?

Yes... make sure the wires are not touching (use some clear plastic zip ties if you have to). Touching wires can cause the current to arc from wire to wire instead of traveling to the plug... causing a miss (rough idle), although if you have new wires it is prob not the case. Also be sure to double check all the plug wires are snug on the plug heads and distributor (or ignition coils).

 

[Edmond]

You can do it yourself. You just need to unplug the EST wire I think? Then check the base timing. You need a timing light to do this. I am pretty sure you can run somewhere around ten degrees advanced with no problems, as long as you run premium fuels. I need to find out where this wire is myself so I can check the timing on mine. I think it is set to low, because the car isn't running like what it should be.

Don't quote me but I think it's the brown wire going into the distributor.

The distributor nut is a 3/8 and you'll need a wrench that has a special angle to get in there.

Check your local auto stores to see if they have a tool loaner program for the timing light. I was fortunate enough that my neighbor has one.

 

[vetteboy86]

This job is much easier for two people, that way one person can turn the dist, and the other can check the timing. If not though it can be done by yourself. Make sure that area is clean, so you can see the numbers on the metal tab that you use to time the car, some white out on the balancer where the groove is helps to.

What kind of plug wires did you install? I agree that touching plug wires is not a good thing, but if the wires are new, it shoudln't matter. Although with heat the resistance of the wire outer coating could break down, as does most things with heat.

Craig

 

[87blackroxi]

I got MSD wires and ac/delco plugs. I went in and made sure no wires were touching and some were. After correcting that I still get the rough idle.

 

[AdvancedAutoCC]

Timing is already set...

your timing is at 9 degrees BTDC (remember?) unless of course, you moved the distributor around to replace the cap/rotor.

FYI, it's the tan with black stripe wire that breaks out of the harness below the master cylinder.

 

[87blackroxi]

I didn't move the distributor at all and I won't have any time this week to look at the timing. I will have to wait until the weekend after the headers go on.

(Robert, I forgot to tell you, the headers are on their way)
shane

 

[AdvancedAutoCC]

Replied in another thread for another of your problems, but did you use suppression core or solid core wires? Solid cores are a no-no on ANY computer controlled vehicle...8:30 Saturday morning.... don't be late! If you are, I'll be on my hawg instead...

 

[87blackroxi]

They are suppression core.

And I plan on dropping the car friday evening so the pipes are cool for the morning. and hide the keys somewhere. I'll call ayou and let you know.