Twofer

I've got an '87 NA with 135k mi and people have been telling me that it smokes and stinks like a bastard. I did some back roads with my S2000 buddy and he said that his eyes were burning trying to follow me. At the last club meet one of the guys following me complained of the same thing. I've also noticed that the general public seems to keep their following distance behind me. (No tailgaters is nice.) Anyhow, I'm starting to get worried about it.

Symptoms / Notes

- Smokes and stinks at high RPM (4k+, I think it's worse before the engine gets to operating temperature.)

- Changed oil about a month ago, put in 1.5 qts yesterday. (No puddles of oil underneath, but wouldn't rule out a small leak.)

- Last tank of gas was about 14.5 mpg. (195 mi / 13.5 gal, mostly short trips)

- Compression tested it today and front was just under ~120 and rear was a bit less. 3 good pulses. Piston engine compression tester with valve removed.

- Seems to have full power. Starts fine. Pulls fine. Redlines fine. Hicups after 4k if not up to operating temperature, then starts to stink badly.

- Replaced spark plugs and O2 sensor (Bosch universal, soldered in) last smog, which I guess was Nov of last year.

- Spark plugs now look kinda bad (see picture).

- Replaced main cat a couple months ago with a Bosal universal-ish cat I got from a RX7 mechanic. (Note on the Split air pipe, the rubber hose got pushed back into engine compartment, because the fitting on the cat is too far forward.)

- Gutted #1 precat, #2 precat intact.

I read up a bit and I'm thinking the Oil Control Rings are on their way out. Right now the car is my daily driver and I take it out for the club cruises and the occasional auto-cross. My daily commute is short, maybe 10mi per day. I'm thinking about riding it until it dies and saving up for another car in the meantime.

If you have any ideas on stuff that I could check for a diagnosis, or have any thoughts on what I should do, please let me know. I don't know about a full rebuild, since the rest of the car is in "ok" shape, not spectacular.

Spark plugs, about 9 months old. In their respective positions. T - Top, L - Lower.


And the old O2 sensor and plugs. (Premix + working OMP = nasty)

hurleysurf24

iTrader: (3)

nevermind

Twofer

I guess the question is, what would you do in my situation?

I've been thinking about saving up for a newer car, probably a late 90's Miata. I'd love to get a Turbo II, but it's damned near impossible to find a decent one in Socal.

Maybe get a clean roller, junk J-spec motor and start from scratch?

classicauto

iTrader: (3)

I'd start by ditching the OMP. If you're pre-mixing, then you're just building carbon up in the engine for no good reason.

Next, get it on a wideband and see where its at. May have a sticky injector thats dumping in more then it needs to. Add that to the fact that they run too rich from the get-go and you have yourself an eye watering gas guzzler

After that you should have some improvment without a crap-tonne of investment/work. The excess oil burning may continue if the oil control rings are wearing out, but you'll need to assess that afterwards.

Turbo II Rotor

iTrader: (2)

Are you serious??? Try finding one in the north east.

Twofer

I'm no longer running Premix. I thought that the OMP lines were dry and therefore the OMP had stopped working. After failing smog pulling the spark plugs, I realized the OMP probably was working and ditched the premix.

Picture of OMP lines. Kinda dry looking?



Since I've changed to the current set of plugs, I haven't been running premix. Also I haven't had time to properly test the OMP function.

I hadn't thought about the sticky injector, but figured it would be running alot worse if that was the case. Also the car starts like a charm. (Except every once in a while, if it's a hot day and trying to hot start it, then it floods a little, though it's rare.)

classicauto

iTrader: (3)

Actually, they look like typical aged MOP lines to me...but, no way to be sure without actually testing them. I'd say its working though...

Choice is up to you on the premixing/ditching it though. It can be a little bit of a PITA on a DD car.

I'd definetly throw a wideband on it and see where its though. My last DD N/A RX-7 got terrible mileage and made horrible emissions, but a little e-manage tuning....well, fuel removing ....got it right back up to snuff. There weren't any driveability or starting issues with it before the changes either.

FWIW though, I've had lots of bikers give negative comments about my tailpipe's breathe on the cleanest/best running 7 I've had....take it with a grain of salt.