Runs like crap after spark plug change Options

[Con99vert]

99 Celica GT, Automatic. I wasn't sure how long it had been since the spark plugs had been changed so I decided to pick some up while I was at the store today. I picked up a set of Bosch Platinum +2 (4303) and installed them once I got home. The old plugs didn't look too bad except 2 of them that had some oil on the porcelain from when I spilled some a few weeks earlier. The platinum 2's do not require any gapping so I just pulled the old ones and installed the new plugs in about 10 minutes. Then I changed the air filter and started the car. It was idling kind of rough, and stumbling very low, maybe as low as 300 rpm. I revved it up slowly a couple times and it felt like the throttle response was lagging until the rpms got higher and then it would smooth out. I drove it from one side of my parkinglot to the other, maybe 300 feet, and it was really stumbling and gutless. It stumbled less as it accelerated. Does the Celica not like the Bosch Platinum 2 plugs, or did I maybe get a bad batch? Any help I can get would be appreciated. Thanks

[Johnnyny]

could not be properly tighten or wires loose check dat first and alos preggaped plugs are a lie

[Spider77]

Although Ive never run Bosh on mine, I do hear that they dont go so well with the Celica. And your going to hear about using Denso or NGK. Did you perhaps mix up the wires?

[Con99vert]

The wires are not mixed up, I swapped them one at a time, plus they are all different lengths so it would be difficult to mix up unless disconnected completely. I double checked that they were tight before installing the wires, but did triple check the torque and the wires after it ran like crap. I also just pulled the ECU, hazard and EFI fuses to reset the ECU thinking maybe the ECu needed to relearn after changing the plugs and air filter.

Also, if pregapped plugs are a lie then how do you gap a dual electrode plug, and what would I gap it to?

[Spider77]

Spark Plug Gap: 0.043 inches (1.1 mm)
After some reading, you'll notice that some (and I mean that.....some) owners have had problems with Bosh, almost to the same point that you are describing.

This post has been edited by Spider77: Nov 2, 2010 - 4:41 PM

[d3ath2009]

if u replaced plugs, u may wanna go ahead and replace distributor and rotor button... otherwise u've only got a half a new ignition system and ur still possibly lacking there.. as far as the idle and running issue, sounds like at least one, if not more, cylinder is not getting fire.. try the dist cap and rotor button, if that doesnt do it, add in new plug wires.. if still not fixed. talk to somebody with more knowledge... im assuming it was running fine b4 u replaced the plugs

[Con99vert]

Everything was fine before changing the plugs and air filter so I highly doubt that it is the dizzy or wires. I am just going to swap the old plugs back in for the time being to see if the problem goes away.

[Spider77]

I agree, Unless your filter was solid.....

[d3ath2009]

it could easily be the wires... my dad changed the plugs in my brother's civic and damaged one of the wires w/o even noticing. it make the car start to miss... better idea, try pulling one plug at a time while its running and see what happens. if the idle drops, then that cylinder isnt missing. if the idle doesnt change, uve found the location of ur problem. then u could just try an old spark plug that u know works and if it still misses, u have a bad plug wire; if it runs fine, u have a bad plug. also, check the connections of the wires to the dist ( make sure and have the car OFF when doing this, otherwise u will probly get shocked)

[Con99vert]

Yes, it is true that you can easily damage the wires when pulling them, but that is why I use a boot puller. I took a few minutes to clean up the old plugs, regap and reinstall them and it runs great now. Infact, it runs better than before. So I am going to return the Bosch plugs and get some Denzos.

[Johnnyny]

get ngk they are great

[Con99vert]

Denzos are what I pulled out and they worked fine so i will be sticking with them.

[Johnnyny]

yup densos are them oem

[SleekCelica]

but NGK is better. Just saying.

[Spider77]

Stick with what works, although Im sure you wont have any problems with NGK's, but given your last experience I cant blame you for sticking OEM.

[Celica94ST]

I had the same issue on a car a long time ago, ended up being one of the spark plugs had a fine crack in it...so recheck the plugs, make sure they are busted or cracked

[Bitter]

return bosch, install denso or NGK, update thread.

[tjblacrosse]

I can not help myself but laugh at the many people who buy platinum and iridium sparkplugs for a car that has an ignition system set up for OEM plugs. Do your research people, those kinds of sparkplugs have too much resistance from the higher grade metals used, causing them to have a weaker spark (although they say to have a better and stronger spark). If you aren't sure what spark plugs to get, look in the freaking manual it's there for a reason!

[Smaay]

something about toyota ignitions, they just do not like platinum plugs! stick with plain copper or iriduim. i use IK22 in my stock car and IK27's in my turbo cars. those got a little pricey so i switched back to NGK BKR7ES copper plugs. much cheaper and work just fine. they only wear out faster. especially on teh turbo cars.

[Remy]

According to toyota all 96-99 Celicas came with platinum plugs from factory. I never had any problems with copper,platinum, or iridium plugs in my car I've used all three I only use NGK or Denso plugs though with copper plugs you pretty much gotta change them out every time you change your oil.