Intermittent Miss???

[SHO_ROLLER_2]

Ok, been working on my SHO on the weekends and so far have replaced the following:

Plugs, Valve Cover Gaskets, and Water Pump.

It had a slight miss before, but now it's worse. Checked for vac leaks, none. It runs smooth when I first start it but when I get on the road and give it some gas, it runs like crap.

Fuel pump and filter next?

Thanks!

 

[qiksho]

If you can get it to miss bad enough to trigger a CEL then you can read which cylinder is causing the issue with a code reader. I just purchased a 97 a few months ago and within the first 1,000 mils have had to replace a coil on both the front and back banks. They both would miss the worst when the car was warm and I was coasting to a stop with the car idling. When I was on the gas the car wouldn't miss very often. I was able to use a cheap Harbor Freight code reader ($50) to determine which cylinder both times.

 

[jimtash]

Last year I replaced the original plugs that had 70K miles on them. A few months later a coil on the rear bank went out. The experience for some has been the same. For some odd reason new plugs often overload a weak coil to the point they stop working. Those on the rear bank bear a lot of heat and will usually be the one's to breakdown first.

 

[rubydist]

there can be codes without the cel being illuminated, so you always want to start by pulling codes.

 

[stephen newberg]

The most common cause of missing in this engine seems to be a faulty or intermittently faulty COP. As noted above by another post, the rears seem to fail more often than the fronts, likely due to more heat build up back there.

If it is not missing at idle, it can be a real hassle to figure out which coil it is, and if it is intermittent, it often will not set a code. Sometimes you just have to wait for it to get constantly bad. Or you can do what I did a year or two ago, just say the **** with it and replace them all.

pax, smn

 

[SHO_ROLLER_2]

I'm going to get the codes run today. I'll let ya know what I find. Thanks!

 

[SHO_ROLLER_2]

Well, looks like a bad coil on #7.

How are those coils off of eBay for $30-$40 a piece?

 

[My_Silver_SHO]

Well, looks like a bad coil on #7.

How are those coils off of eBay for $30-$40 a piece?

I bought a full set from ebay seller "AlanIsDeals", they work great.

 

[stephen newberg]

I bought a full set from ebay seller "AlanIsDeals", they work great.

As did I and I also have had zero problems with them. Replacing the entire set gave the old girl back some pep I thought had been lost simply due to age and miles. The COPs degrade slowly, and it seems even before there are apparent misses, there is a general bogging down from them not working as well as when they are newer.

pax, smn

 

[SHO_ROLLER_2]

Awesome, just looked up that seller and will be (hopefully) getting a new set. If not, just one.

 

[stephen newberg]

I strongly suggest getting 8 and doing them all. Normally if one is starting to fail, so are others.

pax, smn