Still struggling with car at idle after 8 years

[siteunseen]

Your numbers look good to me. My first thinking was lower spark on #4 but you've tried everything. The valve clearance on #4 may be off. The locking nut could be bad or something with that one valve?

When I fouled plugs all the time on a 2 stroke dirt bike I had we put an anti foulet on and helped from what I remember. It was a 1982 motorcycle too.

I do not know if they work on cars? Maybe someone else can explain?

https://www.google.com/search?q=spark+anti+fouler&source=lmns&bih=449&biw=320&client=ms-android-americamovil-us-revc&hl=en&sa=X&ved=2ahUKEwiu6ZqO08X9AhUFrIkEHfBMAxcQ0pQJKAB6BAgAEAU

 

 

Edited March 5, 2023 by siteunseen

[Mark Maras]

 The numbers look OK. Lets try heading down another path momentarily. Something I don't remember discussing in the past is oil usage. How many miles do you drive before it needs a quart of oil and are there any oil leaks?

[Patcon]

Those numbers look a lot better. Maybe a little low but that doesn't appear to be compression rings

[jalexquijano]

4 hours ago, Mark Maras said:

 The numbers look OK. Lets try heading down another path momentarily. Something I don't remember discussing in the past is oil usage. How many miles do you drive before it needs a quart of oil and are there any oil leaks?

No oil leaks whatsoever

[Mark Maras]

What about oil usage? Miles per quart or how often do you top it up?

[jalexquijano]

I normally drive the car 1 or 2 hours per week only on weekends when there is no traffic to avoid engine misfire

[Mark Maras]

So, not enough miles driven to determine oil usage?

[siteunseen]

Make sure your dipstick numbers on the side start with an E. That's the right length for the 240. The 280s start with P.

Oh yeah! Back to the first.

Do you add oil before an oil change? If so it's using oil. Fill it to the FULL line at the top and check it every week to see if it's lower.

Edited March 6, 2023 by siteunseen

[dutchzcarguy]

19 hours ago, jalexquijano said:

I normally drive the car 1 or 2 hours per week only on weekends when there is no traffic to avoid engine misfire

Take all.. i mean ALL the aftermarket junk off the car.. (Ignition) get yourself some original parts and i say: you will have NO LONGER a PROBLEM..  yes..it will not be easy but do-able..

When people start about a ignitor induction coil from "ignitor" with twice the power or so, i instantly get a headache! 

Same with those stupid aftermarket distributors.. YES YES i know some of you have one that works well but only some do..  I drive my 240z for 20+ years, summer and winter, most winter.. and never had a problem with normal contacts in the ignition. (Last year i renewed the contacts for the first time in 20 years+ and around 20-25000km or something like that..)

[jalexquijano]

3 hours ago, dutchzcarguy said:

Take all.. i mean ALL the aftermarket junk off the car.. (Ignition) get yourself some original parts and i say: you will have NO LONGER a PROBLEM..  yes..it will not be easy but do-able..

When people start about a ignitor induction coil from "ignitor" with twice the power or so, i instantly get a headache! 

Same with those stupid aftermarket distributors.. YES YES i know some of you have one that works well but only some do..  I drive my 240z for 20+ years, summer and winter, most winter.. and never had a problem with normal contacts in the ignition. (Last year i renewed the contacts for the first time in 20 years+ and around 20-25000km or something like that..)

Sorry im not taking the distributor and pertronix ignitor from the engine. This is the original distributor and it does work. 

[AK260]

Take all.. i mean ALL the aftermarket junk off the car.. (Ignition) get yourself some original parts and i say: you will have NO LONGER a PROBLEM..  yes..it will not be easy but do-able..
When people start about a ignitor induction coil from "ignitor" with twice the power or so, i instantly get a headache! 
Same with those stupid aftermarket distributors.. YES YES i know some of you have one that works well but only some do..  I drive my 240z for 20+ years, summer and winter, most winter.. and never had a problem with normal contacts in the ignition. (Last year i renewed the contacts for the first time in 20 years+ and around 20-25000km or something like that..)

I’m not sure that would help much in this situation as only plug 4 is consistently fouling, not others. Unless there is an ignition lead problem on 4 (which I seem to recall was eliminated with new leads or a swap with another OK lead?) then there is something other than electrical happening there. I am of course assuming Jalex is running a healthy distributor with a new cap and rotor + little to no play in the shaft.

Glad you’ve found points to work well for you. They were shockingly bad at high revs on mine and the 280zx (12-80) distributor out gunned it on my L26 with better engine behaviours above 4.5k rpm and pushed keenly another 700 revs towards the red line.

As for coils, I have to agree with you. I’ve had a number of different output coils and frankly, on the road, it’s impossible to tell the difference between a flamethrower and a stock coil - with my hairy butt dyno at least!

[jonbill]

i think the 8 years show that guesses from the forum isn't going fix it.

Can you not just get another engine?