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So my S2 8 started idling rough. Kind of. And I know that is indicative of a blown Apex seal. But after about 10 ish seconds.. it’ll balance out and idle fine right around 900 like it normally does. It was driving weird this morning on my way to work and when I got there I scanned it and received the codes in the attached photo (Its straight piped btw, doesn’t have a cat). I took the MAF out and cleaned it. It’s also worth mentioning when I went to inspect the misfire code I noticed the last coil pack, the one closest to the firewall wasn’t even plugged in. I have no idea how long it was like that. I just plugged it back in, drove to the gas station and that’s when the idling problem happened. Like i said, it will balance out and idle properly. It just takes a second. Help me please!
Do you have a aftermarket intake or stock?
When was the last time you replaced your ignition coils, spark plug wires and spark plugs?
When was the last time you did a compression test and what were the results?
P0420 is because you are catless.
P0302 and P0300 are your misfires. Indicative of ignition issues, air fuel ratio issues, vacuum leaks, or compression issues.
P0101 Is MAF reading issues. What did you use to clean off your MAF? Did you allow it to dry COMPLETELY before using the car? And after you did everything you mentioned, did you reset your fuel trims by disconnecting your battery?
I have a stock intake. The exhaust is the only aftermarket part. I changed the plugs about 4K ish ago when I bought it and was told that the packs and wires were new. I did allow for the MAF to dry completely and I cleaned it with a CRC electronic cleaner. I did not unplug the battery at all... Is that a necessary step?
I haven’t ever done a compression test but I don’t have loss of power and other than this problem the car has been a dream
UPDATE:
I put a MAF in it and it significantly helped but didn’t fix it. The RPMs are still bouncing but not as hard or for as long.
There are a few things here. 1) blown apex seal is not a thing, it's what people who don't know anything about rotaries say about rotaries. Your car is still running so it's not that. Compression loss is a thing, but it doesn't just happen one day. 2) get a compression test so you know where you stand. Usually it's recommended to do that before putting money down for the car, but either way it's good to know what you arw working with. 3). if you haven't already, absorb every paragraph of the New Owners section of RX8help.com. 4) for the actual problem there are a few possible causes:
- coolant seal leak: if the low idle problem happens only on cold start up, it might be that- vacuum leak: car generally has trouble keeping stable idle- eccentric shaft sensor problem. Try resetting the computer memory by pulling the battery and, once the battery is hooked back up and key is in ON but not running, press the brake pedal 20 times in row.
- poor ignition: if you're not sure, replace the ignition coils with new or known good ones.
If nothing helps, hook up an OBD reader and get data on rpm, airflow g/sec, short and long term fuel trim, and afr while idling and fully warmed up.
If apex seals don’t “blow” what’s the correct term? I know they separate and seal the edges of the rotor and over time they can get brittle and break. I’ll try resetting the computer. Could the seal on the MAF be the problem? It didn’t idle odd until after I took it off to clean it. It will idle weird regardless of engine temp. I drove it home (about 20 miles) and it was doing it then too. It doesn’t have any loss of power, it’ll very easily accelerate and doesn’t feel like it’s lagging at all. Thank you for the website! I’ll for sure check it out! I can do a compression test Monday when I get to work. What are the numbers I want to see? And do I test leading or trailing plugs? Most importantly, is it safe to drive?
For the comp test you ideally need a rotary tester. You're looking for more than about 100psi on each face (that's 6 numbers) at 250rpm. Google "rx8 compression chart" to understand what you should see at other rpm.
Test the leading plugs. You can search google or youtube for the test procedure.
MAF seal could do it, if you have any opportunity for air to enter the intake after the MAF, the car will not work properly. The computer can compensate for minor leaks, but there is only so much it can do.
Apex and side seals wear over time and let gas get by them, leading to reduced compression at low rpm. When the engine is hot, the metal expands and gaps open up, which is why this wear usually manifests in difficulty starting the car while it's warmed up. Cases of apex seals actually breaking are pretty rare and usually result in an engine that stop running altogether.
Actually there was a guy on the forum with blown apex seals but that was a very isolated incident. And yeah, if it's blown, as in completely shattered, your engine won't run at all.
It's more of a problem to worry about when you are turbocharged(so mostly FC and FD RX-7) where the lean spikes and higher pressure can do a lot of damage. Since your car is mostly stock, it's very unlikely to happen in the first place.
If you aren't sure of the coils, there are tools you can pick up to test ignition coils. Generally it's a good idea to replace them if you just bought the car and the previous owner didn't have any concrete evidence of replacing it like a receipt.
Awesome! Thank you so much for the information! Resetting the computer did solve the problem. I reinspected the MAF just in case but it seems like it’s properly installed. You really did save me a lot of stress and anxiety. I probably will install new wires and packs just so I know how old they are. How often should one replace the ignition system?
Regarding the MAF - next time you take it out to clean replace the gasket. I had an idle issue on my S2 following cleaning the MAF. It was caused by reusing an old gasket that lost elasticity.
02-19-2021, 06:02 PM
