Christi@n

I've recently replaced stock wires with the bigger taylor spyro pro 8mm.

Is not a big deal cause a bigger clip retainer would be required, anyway at the moment i'm running with the stock clips. (Wires are a little bit squeeze in them)

Anyway Strange thing is happening since when i've replaced wires and ive never noticed it before...

Only in 6th gear when climbing hill with full throttle and low rpm, appears misfire (i think it's misfire car looks like turn off engine for an half of a second for one two three times)

Wondering 8mm wires could be culprit? A bigger coil would be reccomended? Or that little squeeze could be culprit?

Still just the same day ive replaced wires, ive made a full tank of mid grade gas...it is 95 octane european gas that should be like your u.s 89 mid grade gas...usually i run with 100 octane that is like u.s. premium 91 and never had trouble...

Problem is that i've already re-filled tank with premium gas again (about half tank of premium) and problem still there's

Joe C

FWIW, I can't see any reason why 8mm plug wires would be the culprit.

Christi@n

Would you see rather some reason in gas?

Joe C

possible - I have on occasion, got a bad tank of gas, but not often. i'm thinking only once or maybe twice in my lifetime - in fact, I can only recall one time. bad gas - a slim chance, but not likely.

since the issue seems to be related to the wires, zero in on that. if you can and if they are still good, swap out the originals. inspect each 8mm wire for any kind of damage - especially around the retaining clips.

c4cruiser

8mm performance plug wires like the Taylor wires you installed are not the problem. If anything, the lower resistance in performance wires should provide more electrical energy to the plugs.

How fast were you going in that 6th gear, going uphill at full throttle? You said "low RPM" and it sounds like you were lugging the engine and that would certainly cause the noise you heard. Probably pinging if not some sort of detonation. Using a gas that is effectively not premium fuel won't help. You should stay with that 100 octane (91 US) gas.

6th gear in a ZF trans is a .5:1 ratio. 6th is really designed for steady cruising on places like freeways/autobahn/autostrade where the speed limits would be at least 100KM or above. Manual trans-equipped cars like the C4 (and the C5) typically reached their advertised top speed in 5th gear, not 6th.

CMiller95

I had a low rpm misfire, only under load and only at a low rpm. It turned out to be a bad spark plug. It's ~$20 for a set of NGK's and its a cheap place to start

Christi@n

Yes for sure i was lugging the engine.. I was at about 40mi and at 1300rpm.... But i've never noticed it before... I usually to downshift gear yes....but just before downshift i've noticed this.

Also there was not any noise just a cut off of the engine power

Christi@n

Recently replaced with ngk iridium...still good think...they have ran 10k miles. Eventually i would correct the gap

Christi@n

Any obd code recorded would be available for my trouble?

vader86

No, highly unlikely any code set for this kind of problem.

I would check all wires and make sure none contact the pipes, make sure the firing order is correct (though that would almost definitely cause a backfire bang) on the wires. Might need to hook a scanner up and see what its reading when you get a miss.

Christi@n

Firing order is it correct for sure, just now you said about pipes, think that some wires contact no pipes but some bracket (like the asr cable box bracket or ac compressor bracket i had to check it)

Do you think can this contact make a bad ground?

Aren't cables isolated?

vader86

The wires are insulated yes, but if one has hit an exhaust pipe and burnt, even a little, it can cause this misfire. I've run into that many times, even when I thought none were in contact. Look at the boots too.

Touching another metal bracket should not cause it.

You may want to fire the engine in the dark and see if you see arcing.

Gibbles

While i doubt it's your problem, msd for one makes these little wire separator clips.
the idea is to keep an air gap between the wires, making sure they are not touching each other.
Or atleast limit the touching to a miminimum.

Also one time i had a rotor screw work it's way loose on my S10.
It idled fine, but on the freeway i got some weird surging.
One night as it got worse i opened the hood, and there it was.
Arching coming from the distributor cap area.

​​​​​​​For fun, take a good look in low light. Rev the engine etc and look for any light show...

dizwiz24

ive had misfires when gapping plugs to .030" (or less) on mine.
its highway low rpm. the experience seems like something out of balance.

gapped them to .036" and no issues

Christi@n

Do you run l98? Stock lt1 afair shuld be 0,050"

dizwiz24

supercharged - less gap so it lights under boost conditions

Christi@n

It is just a little bit curios why do you use in America .035 and we use in Italy ,035...

Also it looks like you usually use comma in this case 1,200,000.00 $ Mmmmm

I would write it this way 1.200.000,00 €

jmgtp

"Only in 6th gear when climbing hill with full throttle and low rpm, appears misfire"

Why on earth?! 6th, low rpm, climbing a hill, full throttle

Drop it down a gear, problem solved.