Hey guys I have a bit of a problem here with my engine lately. Recently I replaced the plugs with Bosch Platinum (which I did not gap) and MSD wires because the engine was misfiring from a worn wire. After doing this my car ran great for a day or two then I took a drive about half hour both ways somewhere and the performance just crapped out. At first I thought it was a vaccuum leak due to the rough idling and the rough engine when I drove at a steady speed. However I hear no vaccuum leak under the hood and also I smell exhaust all the time up near the engine. Some mechanically inclined friends of mine said it could be the EGR Valve or Fuel injectors just to name a few. Just wondering if anyone else has any advice to offer on what to check for and what they think it is.

Symptoms: ('87 Z28 305 TPI)

- Idle is fine for a little bit then gets rough
- Engine shakes a lot
- Strong Exhaust Smell coming from under the hood
- Performance dropped heavily to the point where if I am at a stand still and floor it my tires don't spin the car just slowly picks up speed
- Engine gives a tug-like shake frequently while I'm driving at normal speeds

 

try unplugging the egr and see if this corrects your problem. mine is unplugged since i got the car. i noticed it unpluged one day and since i am a fim believer in the egr system i plugged it in and it idled like *** so i unplugged it and the idle went back to normal. it could just be stuck open.

 

Not saying this is the problem but I had problems with the Bosch Plugs doing that in my camaro. I'd check them out. I'm running the stock AC R45TS plugs gaped at 35...NO problems... Just an Idea! Goodluck.

 

I'll put money on this one:

I hate to say it, but I think you might have burnt through a wire again. When you did your spark plugs, you might have re-routed the wires poorly and left one resting against a header. When the header gets hot, it burnt a hole through one of the plugs again.

Wait for your engine to cool and inspect all the wires for any parts that may be severed. Also, wait until it is dark out and see if you see any blue sparks arcing from your plug wires while the engine is running.

What I believe is happening is if you DO have a hole in a plug wire, then that spark is never making it to the plug...so you are essentially running with a dead cylinder (or two, or three, lol). It's the same symptoms I had when it happened to me.

The fact that the car was fine for a few days and THEN this happened re-inforces my belief. Who wants to put 20$ down?

 

Whats your engine temp when this is happening? When I bought my car, the engine would get up to the prescribed 220* and it would act like a slug. Then I hotwired the secondary fan to run at all times and got it to run much cooler, in the 180-195* range depending on how warm it was outside, and the car picked up performancewise.

 

i'm going with lespaulgoth on this one, i think you probably didnt route your wires away from the exhaust manifolds, and the hot exhaust burnt the wire

 

LesPaulGoth for the win...discovered this problem yesterday and just snipped the bad part of the wires and then re-routed them. It turns out 2 of them were resting right on the headers which burnt right into them. Thanks for all those who posted -- live and learn lol

 

Who was the bookee? lespaulgoth is gonna want his $20

 

Haha, hell yeah I want my 20$.

But seriously, it all goes back to starting at the simplest probable issue and working up. Just sit down for a few seconds and think as to what the most probable cause could be.

New wires, and the problem occured 3 days later. Well, it is 90% likely that it is something to do with the wires/plugs. Symptoms of a missing cylinder? Since we are working with a 90% chance it is the plug wires/plugs, it's time to check to see if they are all plugged in right. One might have fallen out, you know? Few days, one might have jiggled loose. Uh oh, all are in snugly...well were they routed properly, or routed so that they were touching a header?...ahaaaaa.

So, twenty dollars was it?

 

you should look into getting a set of spark plug wire boots. i bought a set for mine when i was putting my headers in and those were a godsend. they are basically a 6 in long, 2 layer kevlar boot that slips over the spark plug wire at the plug. I had them on my car for at least 2 years and never had to worry about a burn plug wire. They started off black but you could see shiny white places where it had touched the header and saved me from having to buy a new wire.

kinda of a pita to put on the first time, but i would much rather deal with that than having to replace plug wires all the time. They can sit directly on the headers and your plug wire will not melt.