Spark Plugs Fouled?

[Shaggy]

Today my car started to studder ("duh-duh-duh-duh-duh") and lose acceleration on the highway once it hit 10 psi, needle on boost gauge would bounce with studder by about 1-2 psi. At first I thought God hated me and decided to take it out on my turbo. But once I started driving in the city the same studder also occured when starting from a stop or accelerating in too low of a gear (no boost). The car is perfect when I'm just cruising. Are my spark plugs fouled? What other things can cause these symptoms. I have a data logger and checked for knock and such but there was none. I'm fairly new to MMcd so I don't know what all the abreviations are for. Is there something else I should look at, or a combination of things on the logger? I will be able to check it out tomorrow but I wanted a few opinions before I go tearing through the engine on my only car.

Car: 91 Talon TSi AWD 5spd
Mods: K&N, small 16g, Wahlboro 190lph fuel pump, AFPR, 2.5" TB exhaust. Stock boost control at ~13 psi.

[thebluesky]

is your car throwing a code? or does the check engine light not come on at all when it happens?

[TheJackal]

It could be several things,check your timing, I would make sure your balance shaft belt is still there, pull the plugs out and look at them, see if they are all gummed up or not. If you havent put new plugs in that are a step colder, you might try that you want NGK BP7RES but checker does not carry them... They carry the stock BP6RES though.

[Shaggy]

No CELs, It has NGK BP7RES in it already...Where would I find the 7's locally?

[Weston]

Running a cold plug like that could cause fouling if it's not running hot enough to need it. The whole point of plug heat ranges is to keep the combustion chamber temperature in the ideal range... too cold and you foul plugs; too hot and you detonate.

Check your ignition system too... a weak spark will encourage fouling. Could be worn plug wires or distributor cap and rotor. Or you could just have the spark plug gap set too wide... if you close it a little, the spark will be able to jump the gap easier and stronger, but it generally reduces engine power.

[TheJackal]

No CELs, It has NGK BP7RES in it already...Where would I find the 7's locally?

Dont know, I have been tryin to find a place for awhile, not all that motivated though..



Weston that is all assuming that his plugs ARE fouled, he hasnt pulled them yet..

[Shaggy]

I have an set of 6's I could throw in. The 6's should be pre-gapped since they are stock, and the 7's won't, correct?

[thebluesky]

yes. check your plugs first, then check your wires, and finally chech your ignition plugs. check ALL the plugs on the ignition, to include the one that supplies it power.

the 7's are special order usually, but sometimes you'll find them at a parts shop when someone changes thier mind.

[TheJackal]

I think napa carries them

[DSMxSteve]

Check for boost leaks. Are you blowing black smoke? Also previously mentioned, plug wires, how new?

[sbiggi]

Check for boost leaks. Are you blowing black smoke? Also previously mentioned, plug wires, how new?

Start with boost leaks. The try plugs. Then wires.

Check for boost leaks the correct way, just tightening clamps wonth do shit in most cases.
http://www.vfaq.com/mods/ICtester.html

bpr7es are not special order. Carquest and Napa carry them, and you should have no problem running a colder plug.

[Shaggy]

Start with boost leaks. The try plugs. Then wires.

Check for boost leaks the correct way, just tightening clamps wonth do shit in most cases.
http://www.vfaq.com/mods/ICtester.html

bpr7es are not special order. Carquest and Napa carry them, and you should have no problem running a colder plug.


Thanks for the link. How does the valve stem attach to the pvc though?

[chrisbarnett01]

The whole point of plug heat ranges is to keep the combustion chamber temperature in the ideal range... too cold and you foul plugs; too hot and you detonate.


Technically? Slightly incorrect. Too hot of a plug and you get preignition, not detonation.

Similar effects, two different issues. Just FWIW.

[sbiggi]

Thanks for the link. How does the valve stem attach to the pvc though?

You just pull it through. You can go bling and get the chrome valve stems to :D

[Skaterkid]

The NAPA warehouse has all sorts of NGK plugs.

[TheJackal]

The NAPA warehouse has all sorts of NGK plugs.

Yea but its also in the ghetto and 30 min from my house

[yrretvr4]

Check your ignition system too... a weak spark will encourage fouling. Could be worn plug wires or distributor cap and rotor. Or you could just have the spark plug gap set too wide... if you close it a little, the spark will be able to jump the gap easier and stronger, but it generally reduces engine power.:werd: Check your gap before you buy anything

[Bedlam]

Yea but its also in the ghetto and 30 min from my house

Well..there is a regional distribution center for NAPA in Billings, MT that my uncle runs..its in a very nice part of town there..and I get a discount! :) Its only a 7 hour drive...

-Bedlam