mdd

A while ago my car developed a slight miss during WOT at about 4K. I checked various sensors and hoses, tried different gas, changed the rotor and dist cap. The problem was still there. Over the last several months I've been noticing the misfire getting worse. I had bought spark plugs a while ago but didn't really think that the plugs were the problem since they had been changed about 15K miles earlier. I had some time today so I finally changed them. Well, I forgot how fast the car really was. The misfire is completely gone, the car runs noticably smoother on acceleration, and it is much faster. Here is a picture of the old plugs. They don't look bad to me but they obviously are.



Any opinions on why these plugs went bad so fast.

The plug change went pretty smooth except for one bolt. The allen head bolt that holds the #6 plug access cover in place was in too tight and it rounded out when I tried to remove it. I had to drill and grind the head off to remove the access cover. Due to the tight area, that was a real pain.

I noticed my 2 intercooler hoses were looking bad on the ends. I'll need to change those soon. Where's the best place to buy the good orange hoses and a set of the upgraded hose clamps?

Steve Weiner-Rennsport Systems

Mark:

Your situation was not unusual at all. Turbocharged engines (especially modified ones) are hard on plugs and frankly, they do not last as long as people think or wish they did.

My recommendation has been to change plugs every 10K for best performance although I do know people who have gone longer than that.

Operating conditions and gasolines both play a large role in how long each person's spark plugs will last before needing replacement.

About your hoses, we use the newest factory ones and a set of T-bolt clamps. That works very well,....

mdd

Thanks for the feedback Steve. I'm not looking forward to a plug changes every 10K. That's nearly as bad as a valve adjustment every 15K on the '91.