Kyrasis6

Ok, I have finally got my first rotary, actually got it about 8 months ago and now have it registered, tagged, and made enough repairs to it so that it is drivable (since my other vehicle is currently a death trap). I've been reading this and that and downloaded all the manual stuff but I can't seem to find enough information and there are some things I would rather have an experienced oppinion on. This post is probably going to be kind of long.

Baught the car after it had been sitting for about a year without being started very often. The last owner was a car guy but the 7 was just a driver, he didn't pay much attention to it other then what it needed and he told me everything that was wrong with it. Engine has 158k and it is the original engine, hasn't been rebuilt. I think when we did the first compression check it came up at 60 psi solid accross both rotors. I squirted a little oil in each leading plug hole and checked again and got same results. After checking out other things on the engine and chassis I put about 2 oz of 2 stroke oil in the gas tank and put 5 gallons in it (it had been sitting on just about E). We had to start it on starter fluid because it wouldn't fire over. We then let it warm up and drove it around the block for about 30 minutes and checked compression again. Check came up about 80 psi accross the board and my test drive confirmed most of the things he said was wrong (although his diagnosis was off on most). I had it for 8 months starting it about every 2 weeks to a month and letting it run until it atleast warmed up. Got a new job and started making repairs on it.

The chassis stuff I'm not really worried about, all of that is about typical with any car and I know what I need to do to fix the stuff I havn't gotten to yet.

What conserns me the most is the engine. It starts up fine, does its rev up thing and warms up. Every now and then it will fire rev up then slowly idle down until it dies. If I give it a little gas at about 500 rpm when it does this it will stumble then rev up and start warming up like normal. If it doesn't do that it warms up just fine. As soon as the engine completly warms up I had a hunting idle between about 500-1000 rpm but it would never stumble and die at that point. After driving a half hour on the interstate when I come to stop and go traffic it refuses to idle. All of this remained the same after replacing, oil, plugs, wires, fluids, and fuel filter, did not chang air filter because it was already brand new. Plugs came out blackish brown with light amounts of brown deposits on them. Owner said he just gave it a full tune up but the electrodes where rounded down to small nubs so he lied about that.

I don't drive the car until it warms up completly. It doesn't seem to burn a lot of oil or smell rich. I tried checking the O2 but it was too much of a pain to try to back probe it. I know on the mazda trucks of that era it was safe to disconnect the O2 sensor to check it, is that safe to do on the 7s? Checked the TPS, terminals where corroded pretty badly so I cleaned them the best I could and on terminals A-B got 1.6K Ohms at idle and 5.8K ohms at WOT. Resistance increased linearly as it should while opening the throttle and decreased the same when releasing. From A-C it had 5.8k Ohms at idle and dropped to 1.6k at WOT and from terminals B-C it had 5.8k Ohms all the time. Checked it later and had 2.2k Ohms at idle accross A-B so I adjusted it down to 1.9k. I didn't adjust it all the way down because I figured some of the high resistance was due to corrosion and I plan to replace the connectors with weatherpack type soon. Test drove it and the hunting reduced to between 600-800 rpm most of the time sometimes doesn't hunt at all, sometimes will hunt between 600-1000 once or twice then either stops hunting or hunts a little like stated above.

The past couple times I've drove it for test drive it has sounded rougher at warm up and idle. It has an occational miss during warm up which reduces after at operating temperature and the engine feels a little rough at idle when warming up. Driving down the road has no hesitation at all, the sucker scoots although I have not dared to rev it past 5k. I'm not entirely sure about oil pressure since the sensor is caked full of crap. Average reading seems to be about 20 psi at idle about 30 psi at light throttle and about 60 at cruising speeds. Past time or two the gauge would not read above 30 psi. Since yesterday it was reading about 60 psi on the interstate revving 3k I'm guessing it is just the sending unit.

So what do you guys think about the engine? I plan on replacing it in about 12-18 months. Do you guys think it will hold out until then? I havn't done another compression check since I've been test driving it more often. Right now I'll be replacing all of the two pin and 4 pin connectors related to the engine and will be ordering more weatherpack connectors to do the rest, mainly 1 and 3 pin. I'm hoping replacing the TPS connectors and readjusting will help solve the rest of the idle issues. What could be causing the idle problems after long driving? Anything else I should be concerned about that I havn't mentioned?

Thanks,
K6

Syncro

iTrader: (1)

If your reading is right, 80 is pretty low. Engine could go any minute.

It also sounds like you have VAC leaks.

And finnally... the engine lasts depending on how it's been cared for
I'm on my original block with 105/100 compression.

Kyrasis6

I've checked double check and tripple checked for vac leaks. I only found one which was the source of it not wanting to run until warmed up which I forgot to mention.

I went up to Rotor Sports Racing and he said that for the engine having that many miles on it 80 psi even accross both rotors was pretty good although the engine was nearing the end of its life before require a rebuild.

Syncro

iTrader: (1)

I completely dissagree with him. Non-turbo rotaries can last for a *long* time. If you think *my* engine has good compression for it's age then you should see this guy in California with 400k on his original engine (unless he was lying )

eriksseven

iTrader: (6)

Check again for vac. leaks by spraying a thorough amount of 'carb-cleaner' or 'brake-cleaner' around the engine bay--especially behind the UIM and under it. If there is any idle variance while you're spraying, then you've found a vac. leak and will need to narrow it down from there. Also, you need to set your TPS to 1 Ohm at idle and just make sure it doesn't go off into infinity when you do the throttle 'sweep' test.

Also, set your timing. That should help smooth things out a little. Also, see if your variable resistor and BAC work--as they can help with idle adjustment.

Check fc3spro.com for how to properly set your TPS, and search if you need help with setting your timing.

How did you do your compression test? You could've gotten it wrong. 80psi is low for 158k miles. Do you have any problems doing hot-starts?

MaxRX7

dammit I hate people with this mentality. just drive the ******* car.