Rough Idle

[jdeangelis]

Here's the situation:
*Replaced oil cooler line o-rings. (BTW-If you go to the GM dealer be sure that you get the "reinforced" o-rings detailed on the relacement drawing. A couple of trips back and looking at HIS screen fixed this.) (no problem noticed)
*Changed oil and filter.
*Decided it was a good time to replace plugs.
*All plugs replaced with CR42TS gapped at 0.035". Had to replace one wire. Replaced with an Accell 9000 custom cut.

After all was done I've been having a rough idle. After accelerating/coming to a stop, it;'s ok for about 5 seconds and then the RPMs drop and then pick up again. It seems to settle and then start all over again.

I proceeded to replace one of the vaccuum hoses.(It looked old.) No help.
I pulled all of the spark plugs and rechecked. (Seems ok)
I pulled the two PCV valves just to check. The one closest to the firewall has a lot of vaccuum, the other has no vaccuum(Should it?)

Not sure what to do outside of replacing all of the vaccuum hosing.

Also, my truck has historically "smoked" at startup. It does seem to be smoking a lot more now.

Ideas? I'm kind of at a loss.

 

[gmcturbo]

i would take a shot in the dark and say you either cracked some porcelin on a plug or the a wire is bad or not fully seated. if i were you i would just bite the bullet and buy a new cap and rotor, some new ngk plugs, and some taylor wires and put them all on at the same time. i also recommend some plug "booties" for the right bank.

 

[TYRODD]

Re: Rough Idle

Here's the situation:
*Replaced oil cooler line o-rings. (BTW-If you go to the GM dealer be sure that you get the "reinforced" o-rings detailed on the relacement drawing. A couple of trips back and looking at HIS screen fixed this.) (no problem noticed)
*Changed oil and filter.
*Decided it was a good time to replace plugs.
*All plugs replaced with CR42TS gapped at 0.035". Had to replace one wire. Replaced with an Accell 9000 custom cut.

After all was done I've been having a rough idle. After accelerating/coming to a stop, it;'s ok for about 5 seconds and then the RPMs drop and then pick up again. It seems to settle and then start all over again.

I proceeded to replace one of the vaccuum hoses.(It looked old.) No help.
I pulled all of the spark plugs and rechecked. (Seems ok)
I pulled the two PCV valves just to check. The one closest to the firewall has a lot of vaccuum, the other has no vaccuum(Should it?)

Not sure what to do outside of replacing all of the vaccuum hosing.

Also, my truck has historically "smoked" at startup. It does seem to be smoking a lot more now.

Ideas? I'm kind of at a loss.

Well, if the vac lines are all the same age, replace them all, it cant hurt, be sure to zip tie ALL connections. If their is even a little leak at the MAP sensor, it will throw things WAY off, I had a little leak from a vac plug, made the Ty idle and startup like horse$hit, not to mention hurt my fuel economy bad.

The CR42TS plugs are notorious for their "popping" idle, try some NGK UR-5s, they make my Ty purr

Try pulling your oil fill cap off while the truck is idling, if you feel any air blowing out, you could have blowby (bad valve seals), this would cause your smoke at startup.

Replace the PCVs with the correct SyTy specific GM#, very important, and it can throw your idle off.

Ive found that cleaning out the intake manifold will smooth things out as well.

One more, is your air filter clean?

HTH!

 

[Merk]

To follow through my "lacking communications", couple of things to consider:

1) bad plugs ( I've had brand new GM plugs be crap)
2) ECM reset ( changing engine parameters, the computer needs to relearn)
3) bad wires (replaced just one?)

Solution:

1) try the NGK series - UR5 or UR6; iridium series if you can pocket it
2) Unplug the ECM-B fuse for a 5 min period. After, restart so the computer can re-learn the fuel and idle curves. Wouldnt hurt to step the RPMs.
3) Replace all wires; some boots get damaged in plug change. ATR make good ones.

 

[#2875]

ATR does NOT make good plug wires. they arc everywhere and the crimps are not tight. i have replaced 3 wires in the past 3 months. it doesn't seem to matter where on the boot you pull they come apart. i like the msd wires; they are durable, snap over the ngk plugs well, and are just a better all around wire.

 

[odium]

I agree about the ATR. After pulling plugs in and out the last few weeks, I've had to recrimp the damned things every other pull or so. It is especially bad with plug #1 and #6.

You get the plug pulled out only to find the connection crimp is still on the plug, even with a plug boot puller... I hate that.

 

[syclonekid43]

i notices the same thing with mine. all vac hoses are good. im gonna go with ngk plugs. i like the accel 9000 extreme heat wires.

i have had my syclone a little over 10 years. i never changed my pcv's. i dont even know if there the right ones.
anybody know the right part number they should be?

 

[jdeangelis]

Rough Idle

Thanks for the advice.

Answer to a couple of questions: I only replaced one wire becuase the wires are about 3 years old. May seem like a lot but the Accell 9000 are pretty durable. I replace one because I broke off the snap when I pulled it out. The CR42TS plugs are highly recommended by the massess. I've run with CR42s for about 5 years. I disconnected the battery for about 30 minutes to clear any programming.

Is there a way to check for a bad plug outside of replacing all of them again?

I got a tool that can read the firing on each wire. It's a little tough to see. Any ideas? Each wire reading kind of looks the same.

Do people have "hard" plastic tubing instead of hoses on most of there vac lines? It looks like most sensors have hoses that run to "hard" plastic tubing that is molded for the particular application.

The truck starts with no noticable miss. It then backs off on the idle and then starts to miss every couple of seconds.

Frustrated.

 

[jdeangelis]

Rough Idle

Thanks for the advice.

Answer to a couple of questions: I only replaced one wire becuase the wires are about 3 years old. May seem like a lot but the Accell 9000 are pretty durable. I replace one because I broke off the snap when I pulled it out. The CR42TS plugs are highly recommended by the massess. I've run with CR42s for about 5 years. I disconnected the battery for about 30 minutes to clear any programming.

Is there a way to check for a bad plug outside of replacing all of them again?

I got a tool that can read the firing on each wire. It's a little tough to see. Any ideas? Each wire reading kind of looks the same.

Do people have "hard" plastic tubing instead of hoses on most of there vac lines? It looks like most sensors have hoses that run to "hard" plastic tubing that is molded for the particular application.

The truck starts with no noticable miss. It then backs off on the idle and then starts to miss every couple of seconds.

Frustrated.

 

[InvisiBill]

Re: Rough Idle

Thanks for the advice.

Answer to a couple of questions: I only replaced one wire becuase the wires are about 3 years old. May seem like a lot but the Accell 9000 are pretty durable. I replace one because I broke off the snap when I pulled it out. The CR42TS plugs are highly recommended by the massess. I've run with CR42s for about 5 years. I disconnected the battery for about 30 minutes to clear any programming.

Is there a way to check for a bad plug outside of replacing all of them again?

I got a tool that can read the firing on each wire. It's a little tough to see. Any ideas? Each wire reading kind of looks the same.

Do people have "hard" plastic tubing instead of hoses on most of there vac lines? It looks like most sensors have hoses that run to "hard" plastic tubing that is molded for the particular application.

The truck starts with no noticable miss. It then backs off on the idle and then starts to miss every couple of seconds.

Frustrated.

The CR42TS is the right AC plug. Others (like CR42T or CR43TS) will not work well at all. However, many people have found that the NGK UR5s actually work better than the ACs. It's something small worth trying.

As for wires, it will depend some on how much you drive it, but there are other owners who change them every 10k. Our ignitions are horrible. They're known for having bad wires that look (and should be) fine. If you only changed one, and it's really been three years, it's probably worth doing a full change. I've only ever used Taylors, but I've never had any problems with them.

The hard plastic lines are stock too. They're known for getting brittle and cracking, giving all sorts of invisible vac leaks. It's best to just go through and replace everything with good silicone hose and zipties.

It sounds like you have a lot of little tuneup things that shouldn't be causing problems, but are known to. I'm not one to advocate just throwing money at problems, but simply replacing all of this stuff with good, brand new stuff will probably fix your problem with the least amount of trouble. And it's not too expensive (in the grand SyTy scheme) either.

 

[odium]

If you have an ohmmeter, the resistances should be ~.195 for the coil to rotor, ~0.6 for 5 of the plug wires, and ~ 0.8 for the #1 plug wire. Check them out and make sure they are still good, the heat usually increases resistance over time.

Thats what they are for my ATR black beauties at least, and they are working fine when the crimp doesn't fail... But that's another story.