changed spark plugs, now hesitates

so yeah, I changed the plugs and wires, I gapped them at .060, me and dad made sure to tighten them up good, and the wires are definitely in, we heard them "snap" into place. Now it hesitates and you can tell something's wrong with it when I give it more than about 30% throttle. I have a 2000 SS A4 by the way. Any help would be appreciated.

so yeah, I changed the plugs and wires, I gapped them at .060, me and dad made sure to tighten them up good, and the wires are definitely in, we heard them "snap" into place. Now it hesitates and you can tell something's wrong with it when I give it more than about 30% throttle. I have a 2000 SS A4 by the way. Any help would be appreciated.

Are you getting an SES? Did it start hesitating immediately? the test drive right after the tuneup? Or did it develop over time after the tuneup? Check and make sure your wires are also plugged into the coils. When you disconnected them from the plugs you might have yanked them loose from the coil aswell. Just double check your connections and make sure your plugs are tightened and not barely hanging. If that all fails, it is possible that a gap was blown wider than needed.

Could be a bad plug. Every once in a while a bad new plug gets out.

What kind of plugs did you put in?

im not sure about the SES light, because mine's been on for about 2 years now because of the clogged cats (ive been meaning to change those), but it started hesitating after we changed the plugs and wires. we know they're in tight, and we know the wires are plugged in correctly. i guess i'll just check each spark plug again. ac delco plugs.

btw, i hate doing plugs in this car. there's NO room to work with.

Just to be sure - you're aware stock cats are covered if you're less than 80K under the federal emissions warranty? With the light on for years have the codes read anyway - did you damage/forget to reinstall the ECT sensor connector by #1 maybe?

well, im almost at 100k miles now, but i didnt really think that the cats would be a problem since it ran 100k miles on stock plugs. i plugged everything back in where it belonged (ECT sensor - driver's side front?). I'll just have to get out there and undo them tomorrow one by one and see if any of them are messed up.

Possibly yanked to hard on one of the plug wires and broke or damaged it. Try changing the wires.

btw, i hate doing plugs in this car. there's NO room to work with.

That's unfortunate, because you need to do it again. .060" gap is too big. LS1's like between .045" and .050" Chances are while replacing the plugs you will find your problem - most likely a wire.

That's unfortunate, because you need to do it again. .060" gap is too big. LS1's like between .045" and .050" Chances are while replacing the plugs you will find your problem - most likely a wire.

Not true, Some of the NGK's come pre gapped at .060, not sure which ones my are the iridiums I believe they are pre gapped at .050.

Well, at Oreilly's they told me .060, so that's what I did. I just found my problem: the ceramic coating on one of my plugs was cracked on both sides. I changed that one, and it drives excellent. I've only got 3 left to check, but I doubt they're bad, seeing as it drives so good. The 3 are the ones in the back on the passenger side, and if I notice any bad changes, I'll check those. I appreciate the help.

thought it might be them plug wires. Happened to a buddy. Glad you found your problem and got it fixed.

Not true, Some of the NGK's come pre gapped at .060, not sure which ones my are the iridiums I believe they are pre gapped at .050.

Just because they're gapped at .060" out of the box DOES NOT mean it's correct. Again, .060" is too big. I've run into dozens of LS1 Corvettes bought at my dealer where the customer brings the car back for a rough idle. Installing a set of NGK TR55's closed down to .045" always fixes the problem.

Could be a bad plug. Every once in a while a bad new plug gets out.


score

Just because they're gapped at .060" out of the box DOES NOT mean it's correct. Again, .060" is too big. I've run into dozens of LS1 Corvettes bought at my dealer where the customer brings the car back for a rough idle. Installing a set of NGK TR55's closed down to .045" always fixes the problem.

I believe the plugs with a .060" gap is intended for a FI or No2 set up. Some buy them because they believe the plug is better since its intended for higher horse set up but dont know that there is a difference in the gap or why. Therefore .060" pregapped is not incorrect. Just not intended for all cars.

just food for thought ! under the hood of my Z28 it says .60 gap for the plugs . my car has a little rough idle , maybe that the problem ? i also have tr55 plugs gaped at .60

I believe the plugs with a .060" gap is intended for a FI or No2 set up. Some buy them because they believe the plug is better since its intended for higher horse set up but dont know that there is a difference in the gap or why. Therefore .060" pregapped is not incorrect. Just not intended for all cars.

You've got it backwards. Nitrous and boosted cars have much higher cylinder pressures which often "blow out the spark" on plugs. To combat this, you CLOSE the gap, often to around .035"

Actually now that you say that...that does sound right. I stand corrected. So why does NGK pre gap a spark plug that is specific to our engine with the wrong gap for different plugs?

That spark plug is not specific to the LS1. It is used in other engines. And although the manufacturer may recommend a .060" gap, the LS1 runs better on a smaller gap. It's been proven time and time again.

See that's the thing. The factory recommended gap is .060 so the spark plug manufacturers when building a replacement plug spec out a .060 gap.

Many years ago some industrious hotrodders tried NGK copper plugs in their LS1s and found out that they work just a little better than stock for high performance applications. During their research they found that tr55 were the right heat range and depth but with a .050 gap and it worked well so now most that run their cars hard or at the track use the copper plugs and the smaller gap for more consistant spark under extreme conditions. Tr6s are one step colder and many use them for FI and NO2.
For a daily driver that isn't going to get beat on much I'd stick with a quality Platinum or Iridium and tighten the gap to .050-.055. Why put in a copper plug that will need to be changed every 10-30k (depending upon tune and usage) when you can use a plug that will go 50k or more?

what is the ect sensor?? will it make a car miss or run rough if it is unplugged or broken?


thanks bobby

ect = engine coolant temperature.