Bucking or detonation?

stephens89sc

Registered User
ok guys... last night was the first night i could drive again after a 6 months suspension...... anyways during my suspension time i did alot fo work to my car.... but theres a problem now.... under high boost or lots of throttle the car bucks and detonates or something... its definitally not a smooth pull when ur over 8 lbs of boost.


what i did to the car:

1 solid motor mounts
2 autolite double platinums
3 fuel filter
4 cold air intake

WHY IS THIS HAPPENING IT DIDNT DO THIS BEFORE

BTW I GAPPED THE SPARKPLUGS TO .45 I WAS TOLD TO DO THAT BY ANOTHER SC OWNER.

thx for all the help guys
 
Odd....

I had a sort of similar problem when I "upgraded" to my jacob's wires. I ran Motorcraft (same as autolight) Double plats and threw the jacob's wires on. It bucked heavily when I got into heavy boost (like 8lbs.).

The acceleration was rapidly cutting in and out.
It was like the whole engine in the car wanted to fall out.

Detonation would sound like a really loud Knocking noise.

Now, when I put the stock motorcraft wires back on, the bucking disappeared. After another set of jacob's wires and talking with jacob's tech representitives, I found that re-gapping the plugs to .035" did the trick and all bucking disappeared. Although I'm not happy with this undergapping situation, it has solved my problem.

I would suspect that the cold air intake you did, has something to do with the bucking. Did you replace the spark plug wires? Made sure that all the terminals were seated (with a nice click)? I know it's a pain, but you might want to try and undergap the plugs.
 
i didnt put wires in just plugs... the weird thing is my freind had it out wit me before i did motor mounts and spark plugs and it didnt do it....... what does that mean?


spark plugs?


theyre autolite double platinums
 
I am having the same problem with detonation. Actaully, if you go to page 2 or 3 on the this forum, I posted a thread titled "detonation" there is lots of good info there. Biggest thing, run the highest octane you can get and some octane boster will help. Detonation sounds like a knocking or a pinging. If you have a 5-10% OD pulley, go back to stock.
Now, I don't know what's up, but I just changed my spark plugs because of my detonation, thought they would be screwed up but they were fine, now with the new plugs the car idles rough and is undriveable. So I ordered some new wires hopefully that will fix it. If not, I have no idea what I am going to do.
 
If you didn't change your wires then chances are that you damaged them wether you know it or not. Change wires.

Jeff
 
I agree with Jeff...

If you didn't replace those wires, there is a good chance that one of the wires broke internally (after being disturbed for the first time in god knows how long). This can lead to a smooth running engine when at idle but when boost hits the voltage leak causes reduced energy at the plug gap and thus get's "blown out" under boost.

Change the wires and report back.
 
I was having a similier problem. When going into boost it would start with some bucking BUT after 5-10 miles it would run OK when going into boost. Solution was plug wires.

Most likely when I started out in the morning it was cold and damp then as the engine compartment heated up it also dried up and the wires would not leak. I had replaced the plugs and valve covers about 2 weeks earlier and had the wires off, so most likey damaged them then.

Have 180,000 miles on the car and these appeared to be orginal wires. Soooo, guess it was about time.
 
I had that same problem an dit ended up being the plugs..WHen you regapped them..perhaps you didnt do it properly?
 
The break in your wires...

Expands with heat. Therefore no bucking when cold, but when the broken wire heats up, the internal break expands and causes the voltage leaks.
 
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