Hesitation from Spark Plug Change

T

turbohye

Nuclear Reactor
Joined
Apr 19, 2003
Fresh tank of 93 premium, fresh clean air filter, fuel filter and everything else. Car still pulls timing at 13 psi whether i roll into it or floor it..So i decided to change the plugs today. Picked up 6 AC delco 23s, matched the gap to .035 as the previous ones in the car.... go to start the car, and its smoking a little more than usual, i check everything including vac lines etc. etc. But nothing is wrong. I go for a spin...i hit 13 psi but no knock-- and the car is feeling slow and feels heavy with very slow spoolup characteristics. I can even feel the pinging in the pedal..eventually i made another pull and about 2.5 degrees of timing is being pulled showing up on the scan master. I go back home and pull the plugs, none are soaked in oil, all are at the same gap as the previous ones...
So i regap at .30...
Start the car, and it idles like garbage and doesnt even spool up so i dont waste my time flooring it. Engine only has about 35k since the rebuild so i want to keep it safe. I pull the plugs, regap to .035 and now the car is idling better. I take it out for a spin to test it out, and its REALLY hesitating and finally knock comes through on the scan master.....not only that, but i also brake boost it, and it starts to hesitate around 1psi..so i let off and go back in the garage...
i pull all the plugs YET again, and regap to .033 (i have a feeler guage) and this time it idles and misses a little but still doesnt boost after i tried....i didnt touch any cables or vac lines when i did this...I usually never mess these things up, but the car was running alot better when i left those old 23's plugs in....Im completely lost. I searched through the posts but im completely burnt from this... I dont even know if its worth regapping or am i just dealing with bad luck...bad plugs...or something else...
I rechecked vaccum lines and even the ones i didnt even get near and everything is nice and tight... I dont know how i could have messed this up worse....car will drive but now even hesitates a bit in neutral..
 
Just an FYI - this engine has never seen anything over 15 psi...The engine was rebuilt very well by Steve V on this forum many years ago and only has 35k on it...It sat in my garage for a long time due to funds and since its freshly painted, i have gotten it back on the road.. Turbo spool sounds good and clean but this newfound hesitation is really frustrating considering these are the same plugs.
Please help guys...
 
First, what are AC Delco 23's?

Second, I quit using Delco plugs years ago as I had too many problems similar to yours here.
 
Nick Micale said:
Just another wild guess, could the gas you just put in be bad?
Click to expand...

Well this is the second fillup this month. i got this tank last week and with the old plugs it was doing the same thing. I wish i could see which cylinder was causing this. All of the plugs are clean when i pull them and the wires are a month old. 8mm MSDs and never had a problem with that brand before.
 
Could be a MAF crappin out,coil,module. I would put the orginal autolite or even NGK UR5's in it.
 
Thanks guys, ordered a new set of plugs and wires from Summitt today. While the engine was running nice and hot i could see the engine shaking very bad and when i put my head closer to the engine, i could hear spark arcing..i moved every spark plug wire a bit and it turned out to be the wire on the far back cylinder by the firewall right beside the condensor..shocked my hand when i touched it actually. I will install the wires when i get them, then post my findings.. Sounds like the car may need quite a tune afterwards but at least i have a good starting point. Thanks again. Updates to come this weekend.
 
Thanks to all your help guys, today was a revelation. Started out with starting issues *fixed*
but when i finally got around to the plugs, i pulled each SOB out, and saw that one of them was split right down the side. Spark couldnt have been insulated. Replaced all 6 with the NGK's that Steve V mentioned (thanks steve) from Summit racing and some brand new 8mm silicone Taylor wires.. gapped at .034
I warmed her up, took her out slowly and slowly accelerated without a downshift. 0 knock, 0 hesitation, 02s were showing 777 on part throttle at 10 psi. After a good 10 minutes of hot driving, i got on her just a few times with boost set to 12 psi. OMG 12 PSI and 0 knock. 02s were showing 800-804 and not an ounce of knock. Car pulled amazingly smooth and never felt any trembling in the pedal...The exhaust note was even much cleaner on WOT. Took the car on the freeway, locked the TC above 65 and slowly got into her.. again 0 knock at 12 psi and got up to 85 without a problem..
Thanks again for all your help guys, again, yall never let me down.
Next up...I will see how this goes for a while and will slowly get the boost up to 15. If all is well-- then i might decide to run an alky kit and see how well this baby can do on the stock turbo :)
 
I use ac delcos 42 and gap at 28 it made a huge difference on my car and for further info the ac delcos I bought are from the 1980's old style box and plug not the mexico or china crap the parts store had 12 boxes of the old school plugs he was blowing the dust of them I bought all 12 boxes at 9 bucks a box!!!
 
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