So I decided to take a 150 mile drive to Atlantic city for a friends bachelor party. And the ride down was smooth no problems. However, on the way back, I began to feel this almost pulsation like surge while holding a constant speed. And it happened no matter what the speed was. The only thing that stopped it was going hard on the gas. I didn't see the Tach change at all, but you can feel it, almost like an extra kick.

It is a 99 C70 LPT with just about 91K on it. The dealership did a software upgrade to remedy in idleling problem. But didn't replace the ETM module. Could this be related to that? Could I need new plugs and wires? Or is there another problem im missing?

 

Check your plugs, and wires, maybe the coil....

S.

 

That will probably be my plan for today, but I don't want to go out and spend 200 for plugs and wires to find out its just the ETM!

 

Just the ETM?? Plugs and wires are a drop in the bucket contrasted to the cost of an ETM.

r.

 

The cost is small for plugs, and wires. If you suspect they are the problem, you obiously dont know when they were done last. So they very well could be old and crappy enough to warrant new ones.

S.

 

Well I went to Autozone and bought the Bosch Platinum plus plugs, but since mine is a 99 there is no wires. Just coils. And at 70 a pop, I decided to try the plugs first.

What I found when I removed the plugs was as follows:

The first plug was a Champion plug, the rest were Autolite plugs. All had approx the same gap. The 2nd plug had a decent amount of oil on the top half of the plug and the inside of the recessed area (where the plugs drop down into) had some dark residue, while the rest were still quite shiny and clean!

I replaced each plug one at a time and started the engine and ran for 1 min each time to make sure there was no problems. After all were done, I replaced the covers and took it for a ride, pushed hard for a few straightaways and there was no problems, no CEL's....nothing! So im hoping that fixed it.

One more question though, there are those black corrugated plastic sheaths over the wires that run under the black cover leading to each coil and plug. These have become brittle and have been torn to shreds. Do I really need to replace these? Or were they just for looks?

 

The plastic 'tubes' protect the coil wires. Nothing to worry about until the two coil wires part company. A good tip when installing the Bosch platinum plugs is to gap them appx. .05 greater than what is called for. Two other tips include putting a dab of high temperature anti seize on the plug threads and also to dab some dielectric paste inside the rubber boot placed over the plug. The dissasembly in the future will be greatly inhanced!

r.

 

Well now im in a bind....

So I replaced the plugs and everything went well. The car drove like a champ for almost 3-400 miles. Went for an oil change, everything is still fine. Decided to go visit my sister, and as soon as I pull out of the garage the car starts to shudder and idle poorly, a block down the road, my CEL starts to flash. So I turn around and park the car. Decide to check it out in the morning.

Took it apart, nothing looked odd, so I tried to pull coils one at a time to see if the running got worse or stayed the same. Thought I had narrowed it down to cylinders 1 and 2. So I bought 2 new coils. Replaced them.....still running crappy.

Back to the dealer, and bought OEM plugs, installed all 5 of those.....still runs crappy.

Tech behind the counter said its possible my thermostat and ECT is causing my engine to run rich (he came to this hypothesis because the bosch plugs that were in cyliners 1-3 were an ugly black color over the tips). So I bought a thermostat and a new ECT sensor, flushed the coolant, swapped out the old for the new......still the same problem.

Am I missing something? I'm probably going to be going back to the dealer in the AM with the car this time so they can put it on vadis. I never got the codes read from the original incident, because with the CEL flashing, I really didnt want to drive it 30 miles to the closest autozone.
I really hope I don't get reamed at the dealer tomorrow!

 

ok, well 120 dollars at one dealer and 70 at another and the car is back to tip top shape. Turns out there was a permanent fault in cylinder 3, So my guess is that the first 2 coils went and while swapping around the other coils, I probably killed the 3rd. So I drove to another dealer (cuz yesterday I bought the last 2 coils at the 1st dealer) replaced and im golden again! Granted it was an expensive fix, at least its not a headgasket!

 

Thanks for the up-date. I am sure that will help other members in the future!

r.

 

Well all was well for 55 miles..... and then it started again! And of course I was to far from the dealership I used to make it there. So I spent an extra 30 for 2 more coils after a quick stop at autozone to confirm that cylinder 4 was misfiring.

So after all was said and done, replacing 1 coil, caused me 2 replace 4 more. So it may be worth it if u are doing this yourself, to just bite the bullet and replace all of them. So u don't get stuck somewhere!