malharmemon

so ive been having some problems with my for a while now.
i had two codes before, (dont remember them), basically for rear o2 sensor reading too lean, and cylinder 2 misfire
i ignored them for a while but then i noticed one day when i was driving hard my temp needle moved towards the hotter side. as soon as i saw it move i shut the car off. It didnt go more than 70% hot. (if that makes sense)

i suspected the cat, got a shop to remove it. they broke my o2 sensor so i didnt have anything for that rear sensor.
still same symptoms.

IT got worse earlier of nov. when my car 'jerks' between 3k and 4k rpms. Even if im just building revs to overtake someone, or getting up a ramp, i have to downshift so i can get higher rpms and do so, it just jerks alot and its almost imposible to get past these unless you downshift.

ive stopped driving it hard and rarely take it to redline, but i noticed that if the car is stationary, and u rev it to spit flames ,it doesnt over heat, only the CEL blinks. Yes ive stopped doing that too. just saying...

i got a compression test done last week, the numbers were good, all identical around the 95-100 range.

• for overheating im guessing i should just replace the thermostat and waterpump -($200 fix i guess)
• and try sea-foaming it and see if that helps. If not any advice for what to look for?

current codes are p0037 and p0302.

keep in mind the car doesnt have a rear o2 sensor. and i suspect that theres a leak in the exhaust too where they welded the pipe when they were doing the de-cat.

RIWWP

iTrader: (2)

1) If your coolant temp needle moves at all, you are already hotter than is safe. Coolant seals can fail at 220F, and the needle won't even start moving until 235F. The fact that it moved at all immediately makes a coolant seal failure likely. I'm rather surprised you didn't address your cooling system, as cat problems won't cause that kind of overheating and you don't have any coolant lines that run through or next to the cat. Thermostat is the usual culprit, but if you haven't replaced anything else in the last 4-5 years, then you should just go ahead and add the radiator ($150 from Mazmart), the coolant lines (varies), and the coolant bottle and cap ($130 from Mazmart). It's cheap insurance and those parts CAN fail too. If they aren't dead yet, they might be holding silt or rust that will re-clog your new thermostat.
To test for a coolant seal failure, send an oil sample for testing (blackstone labs) for coolant, test the coolant for combustion gases, and let the car sit overnight then crank without firing (pedal to the floor as if deflood) and then pull the plugs to test for coolant. Once you replace all the cooling system stuff, you can also pressure test the cooling system, though i wouldn't trust that with an unknown failure in the cooling system.

2) misfires need to be addressed immedately. They cause all sorts of cascading failures if ignored, including cat failure, O2 sensor failure, engine damage, and eventually car fires.

3) Stumbling in the 3k-4k range could be an SSV valve actuation problem where it's fluttering and disrupting the airflow into the engine, but it could also be any number of other things, including everything that can cause misfires, and coolant being pulled into the engine from a failed coolant seal.

4) spitting flame is typically when everything is hot and you are catless. If it's LOTS of flame, then you are probably misfiring like crazy and/or a failing compression engine, dumping lots of unburnt fuel into the exhaust system. And there is no correlation to flames out the back to coolant temp.

5) 95-100psi doesn't mean anything without the RPM. 95psi at 250rpm is on the failing line. 95PSI at 260rpm is below the failing line. 100psi is failing for 270rpm or higher. 100psi is great at 200rpm or lower. Even with the RPM values, a good compression test doesn't immediately rule out a coolant seal failure

malharmemon

makes sense. ill look into coolant seals.
what do mean "send an oil sample for testing for coolant..." do i actually send it to some place?
also reading up on SSV, from my understanding i should just clean it, but im still researching on that.
flames werent that much, very little.

and for the compression test, it was at a rxclub meet and the guys there told me i was good, im pretty sure they knew what they're talking about. but ill ask again how we did it. (i was just following instructions- plug that, crank this, stop etc.)

RIWWP

iTrader: (2)

Oil testing: Blackstone Labs
And our forum's thread on the results: https://www.rx8club.com/series-i-tec...m-here-184241/

If club members tested the compression then you are probably fine, because any member I can think of with a compression tester knows what they are talking about when it comes to compression scores.