kensaysrawr

I have a Del sol d16z6 with 211,000 miles. Got a new clutch 10 miles ago (yesterday). I ran seafoam through about 100 miles before clutch replacement.

When I'm coasting in 5th gear (mostly) @ 60 mph @3k rpm, the rpm needle will drop down and back up and car will jerk. Seems like it is misfiring. Not sure if the cause is seafoam, i didn't get much smoke from doing it. But I'm not sure what is causing it. It could need a basic tune up (new rotor, plugs, wires) but could that fix it?
I had a silencer in my exhaust at time of seafoam and took it of and was all black (from carbon) also there was a dirty liquid on it as well. (un-burnt fuel?)
I also feel a loss of HP.

No check engine light

Edit: Hypothesis

1: Seafoam clogged up my cat which in return is building pressure and forcing air back into my engine.

2: O_rings- bad o rings on the injectors are sucking in air through the walls and so not all of the fuel in the cylinder is being burnt which is causing loss of HP.

3: Vacuum leak: Air getting sucked in engine bypassing O2 sensor and putting to much air in engine and I'm return not burning all fuel in cylinders.


Solved:
1. I pulled out my PCV valve and it was clogged like a ****. Replaced it.
2. Also replaced the distributor cap and rotor as they were worn down a lot compared to a new one.

beecee18

The way I look at high mileage cars is just let them be and dont fix unless broken, the seafoam has probably done more harm then good, Is you MIL illuminated and if so, what codes are present.

commercial airplanes rarely crash and fly daily because of their duty cycle.
An airplane mechanic told me once the thing that keeps them up in the air for so long is cause they are constantly being used. You would never want to introduce foreign items/fluids to something like an airplane. So with that said, keep driving brotha!
I have a ford truck with 200,000 miles and never have faults/problems cause it constantly and routinley drives, if it were to sit for a month, or I went outside and flushed it with seaform or some dorky injector cleaner/fuel additive I would be sure to get negative feedback from my vehicle.

First check for cels's
if non, just try to drive it off.
If you have a steady miss then I would troubleshoot that accordingly.