Missfire - 75 1.8 turbo
 

Hi guys,

Noticed when flooring the car in fourth gear the other day, the car missfired briefly. Any idea what would caused this?
Thanks.

My 1.8T has done this for years!
I've replaced plugs, leads, coil packs and even had a new turbo💨 over the years but it still persists. I have learned to drive it accordingly and don't get tempted to floor it in too high a gear. The bonus being a much improved mpg!

I await suggestions on how to to solve this.🙂
Chris.

Plugs or leads breaking down under load would be my best bet, assuming that you don't have any smoke, noises etc.

No noises and no smoke as far as I know. Might change the plugs and see if it makes a difference.

Could it be hitting the rev limit?

The boost control valve on the airbox is also a possible known cause of missfire when they get (tired).

Have you tried a reduced spark gap for the plugs? Usual suggestion is to set the gap at 0.7 - 0.5mm depending on who you ask. Try 0.6mm.


TC

Do you mean boost cut? Didn’t think of this but I guess it could be....

I’ve not checked the gaps but the car was bought from a well known genius on the forum. I’d be very surprised if they weren’t gapped correctly.

A spray of WD40 (water displacer) over the leads may help in the wet weather but new leads would probably cure it if the plugs don't.

Yes,they are a known weak point.Not too expensive to replace and see if it cures it.I would re-gap the plugs first though as TC suggests if you haven't already done so.

Perhaps he'll know what's up?


TC