20V suddenly started to misfire

[Alf6]

Hi, My recently purchased 1989 Corolla hatch has a Silvertop fitted to it. Last night it developed a horrible miss. It starts and idles well, but when you go above about 2500 - 3000 revs (guessing) it starts to backfire and miss very badly. Back off the revs, and the car seems okay again. Checked this morning and still happening. I will not have a chance until tomorrow (earliest) to look at anything. Just hoping someone can point me in the right direction in which to start.

Thanks in anticipation. Alf.

[retiredat44]

while in the dark, very dark garage fire it up and look to see if the wires are shorting around the cap and plugs... chances are the distributor,, inside/outsode is shorting... and bad, and/or bad coils... you may get away with just cap rother wires, plugs, etc.. but if you need a dizzy too, get as high quality lifetime warranty brand...

[Alf6]

I have looked for any sparks, etc, and can see nothing. I will have to wait until the weekend to look a bit deeper.

[ayang951]

is it the MAF? i once had a problem similar to that with my 01 corolla S... it was doing something liek what you were doing, but wouldnt go pass 3000rpm and itll start misfiring and etc etc... i plugged my OBD2 reader on it, and it said MAF and i changed it out and it drove fine again.

[Alf6]

I now know what - but don't know why.

Finally had time to pull the distributor cap off and ..oops. Two of the 4 contacts on the inside have almost melted away. No cracking of the cap, just the badly corroded, rapidly disappearing contacts. Help me - why did this happen??

[sam333]

The contacts in the cap wear out, its common .I replace mine every couple of years.

[Alf6]

I put a new dizzie cap on - unfortunately nothing solved.

Could it be a blown head gasket?

[eage8]

did you replace the rotor inside the cap too? and the spark plug wires?

[canadianae92]

would be good to check the timing

rev it where it missfires and start pulling spark plug wires out, one cylinder at a time until the miss stops(hard to tell) or pulling the plug wire has no/little effect

before you pull the next put back the one you pulled, dont just pull all of them, hope you know what i mean