I decided to try to change my own spark plugs on my 1985 305 tpi trans am. Everything went fine, untill if hit the gas, it gave a poping sound,and the car shaked alot, the first thing I thought was "missifre" so I double checked the spark plug wires to make shure they all went to where they are suppost to, and they where correct. The only thing I can think of that went wrong was that I did tighten they down a little to much and I did not gap them, the guy at the auto parts store said they did not have to be gaped. What the hell did I do wrong? I can tell that I am missfireing, but what is making this happen, and also will I have to buy new spark plugs, or can I use the same ones I just put in. Any help would be life-saving. Thanks guys.

 

The guy at the auto parts store was wrong. Pull you plugs, and gap them correctly. The spec should be on the emissions label under your hood. Gap guages are dirt cheap, and some parts stores give them away.....

Also, verify you plug wires. I know you checked them, but, check 'em again, just for giggles.

 

Two more questions, have I messed up my car in anyway? It sounded ugly when it was poping, It was not that loud at all, it sounded more like popcorn.

Also does anyone know the gap size I should use on my 85 tpi trans am?

 

Probably no damage.

Look for your emissions label. That will tell you plug gap.

 

Normally for a street car, new plugs don't need to be gapped but checking them doesn't hurt. They're close enough to a factory spec that they will work fine unless the plug has been damaged and the gap is closed up.

Double check #5 and #7 plug wires. To me it sounds like you have those 2 mixed up which is a very common mistake.

 

I've never had to regap my plugs from the stores. They are all close. Your firing order like mentioned above is messed up.

 

Really? I have always regapped my plugs, and always find them not quite close. (some are way off) Given shipping, and other assorted handling, I would be surprised if the plugs were anything close to consistent.

 

Thanks for the help guys, I will not get a chance to work on my car till monday, but I really do apreciate the help, I really do.

I checked the wiring order like 5 times yesterday from a chart I found using the search method, I pretty sure it was right, are all the wiring charts the same for both camaro and firebird v-8's.

Do you think the engine is missfireing becase I tightened the spark plugs to much? Because I did tighten them really good.

I will pull the plugs on monday and gap them, are there any other suggestions you can tell me to make sure this does not happen again.

Again thanks for the help, you guys kick butt.

 

1-8-4-3-6-5-7-2

#1 can be where ever you want to put it depending on how the distributor is installed but since you never pulled the distributor, #1 should be roughly at the front driver side of the cap.

Rotation is clockwise. Just double check #5 and #7 plug wires to make sure they're going to the proper plugs.

It's possible you cracked a plug or 2 from over tightening or you just managed to buy some bad plugs. If you have some spare plugs, try swapping them to see if the miss goes away.

You could also use a timing light to see if the plugs are firing. With an inductive timing light, put the clamp over each plug wire. If the plug isn't firing, the timing light won't flash.

 

This is good advice. This is why I always keep a spare set of properly-firing plugs after I change them...to use as an 'emergency diagnostic' set. What you describe sounds very, very much like a crossed wire. A single cylinder drop will cause nasty bogging and a good shake, but doesn't usually cause backfiring and the such unless you're running rich and doing, say, a high rpm decel or something.....to get backfiring during normal driving it's usually dropping more than 1 cyl, at least in the cars I've worked on.

 

Here is the pic I used to make shure my spark plug wires where going to the right place, is this chart correct?

 

yep, I have a common practice of regapping my plugs too. I have gotten plugs anywhere from .35 to .50 . I have found that the engine runs best at a little over .40 (emissions says .45). And all it takes is one stinkin plug to not be gapped right to cause a problem. Happenes alot around here with the parts stores because they are always opening one box in the pack so the customer can "look at the plug to make sure it is the right one they need" After so many people one is bound to get knocked around.

 

Also, if is VERY possible that while you were changing all that you may have just simply removed a vac line and didnt realize it. Check all the vac connections real close to make sure. It is possible.

 

I just thought about something. If you tightened them real good and you think you may have over tightened them, you could have cracked the plug insulator. I have done that before when i was in to much of a hurry. That can cause quite a few problems as well.

 

Thanks for all the help guys, like I said before you guys kick butt, the problem was in one of the spark plugs, and the wires where mixed up #1 and 3, stupid me!!! Well thanks again.