MX-3.com

Hello, ladies and gentlemen. I’d like to share my experiences with you on rebuilding a sorry old ’93 MX-3 1.6 SOHC, to turn it into an amateur rally car. I’ve been around for a while but haven’t bought a car solely as a hobby project until now. Life got in the way. But I do have some other toys, so I’ve learned a few things through the years that I wanted to use before it got too late. So here we go…

I bought the car cheaply in January 2006, knowing that it needed some work, including the repair/replacement of a couple of rusted panels. The main appeal was that is was local, it had only 160,000 km on it and it had no unnecessary accessories (AC, electric windows, etc.) I repaired the items which the owner identified – no emergency brake, stiff shifter and left drive axle. Then I fixed other things which I discovered, such as no back-up lights, other burned-out bulbs and wiper blades. I also replaced the plugs, oil & filter, PCV valve and fuel filter. I took the car to a shop for a safety check and got a bit of a surprise.

The list included brake rotors, rear shoes, e-brake mechanisms, catalytic converter, timing belt, oxygen sensor, camshaft and (front) crankshaft seals, exhaust pipe gasket and a 12-inch long hole in the floor in front of the left rear wheel. So I’ve been busy since then.

While I was at it, I wanted to increase the power and decrease the weight, so I’ve fabricated a short air intake with 6” K&N filter and custom aluminum air pipe and installed a high flow cat and 2-1/4” Pacesetter cat-back system. I’ve also removed all of the possible weight aft of the B pillar – about 100 lbs - and moved the battery back there. Because it’s a rally car, I installed a full-size spare instead of the temp, as well as a fire extinguisher and tow strap. I also fabricated an extension for the accelerator and a simple black plate around the shifter. I have not only repaired everything listed above, but I’ve also replaced the auxiliary belts, coolant by-pass pipe, thermostat, coolant thermo sensor and installed a remote starter switch (under the hood, for diagnostics) and a master power breaker on the dash. By the way, if anyone’s missing either plastic splash shield under the engine, replace it! This is the best $32 investment you can make in a cold-weather climate where they use salt on the roads.

The motor runs great and all the mechanicals work really well. Compression is within spec in all cylinders, although #3 is a bit weaker than the rest. Maybe next winter will see new rings and a suspension upgrade. For now, I’m looking forward to some good driving.

Unfortunately, I can’t finish the necessary body repairs yet because it’s too cold for fiberglas and paint here in Ottawa. But I’ve acquired a replacement door, instead of repairing a large rust hole, so I’ll have it painted and get it installed while the temperature continues to rise. I have many, many pictures of the challenges I faced and the work that’s been completed, but I’ll only post a small number here. But first, I guess I need to find a web site where I can post them! Maybe later...

If anyone has questions or suggestions, I’d be happy to respond to your e-mails.

http://www.nexmatech.ca/car_pix.htm

After a couple of weeks of decent weather, much progress has been made. The new door has been painted and installed; the two main areas of rust damage have been fiberglassed, bondo’d and painted and mud flaps have been installed. Overall, I’m pleased with my handiwork.

Under the hood, I had to disassemble the belts and timing belt covers to find the timing mark. I’m amazed that the factory would rely on a notch that’s only 1/32“ deep, highlighted by an orange stripe which is invisible with the covers installed. We now have a proper 3/32” notch and white mark. I’ve also fabricated a second lateral support for the CAI to prevent any movement or vibration.

The engine has shown an inclination to stumble on acceleration and I’ve noticed some arcing at the distributor wire on the coil. Although I’ve cleaned out the corrosion of the main terminal of the coil, it may still be malfunctioning and the wire shows signs of decay. Also, I tested it and found the primary circuit slightly out of spec. So I’m replacing both the coil and wires. Unfortunately, I couldn’t find a high output coil, so the standard output will have to do.

My plan to use a high flow catalytic converter backfired, since there is no EGR valve to help reduce NOx emissions. The car passed its safety inspection (after replacing a leaky exhaust flex pipe) and all emissions tests except NOx. So I have to install a standard 3-way cat to pass that critical test.

I’m still showing a Check Engine condition, even though I’ve replaced the O2 and coolant temperatures sensors, and tested OK the Throttle Position and Air Flow sensors. Sure enough, that leaves the Idle Speed Control valve, which was outside spec on its resistance test. It may also account for the stumbling problem. When I opened it up, it was obviously not working properly. That’s a tough one, because these things are $700! When I’m done with that, this thing should purr.

Next step will be a good washing and the application of body graphics for rallying. New pictures have been posted for those who are interested.

IMO instead of spending $700 on an IAC valve for the 88HP SOHC - you can probably swap in a good 125HP BP engine for the same cost or maybe even a 180HP BPT for a bit more $$. From what i hear - those engines are pretty much plug n play for your model.

Thanks for the suggestion, but I’ve already invested in all the same OEM replacements on this motor as you have, plus a few more. It’s been a great winter project and I’m not planning to drag race. So I think I’ll be content for now with the 100 or so BHP I’ve gotten out of better breathing, plus the weight reduction of about 100 lbs. In addition, I think the existing gear ratios would be bit low if I introduced a 180 BHP motor. For navigational rallying, it should be good enough. For performance rallying, it’s not the right car. But that’s another winter project!

We are on the road as of last week, after installing an OEM equivalent cat. The NOx reading was 564 against a standard of 576 – about 1/3 of the high flow level. I’ll keep the high flow version – for “off-road use only”.

I’ve been fighting a sputtering problem on hard acceleration when the motor’s hot, but I think I’ve traced it to hose clamps on the CAI. The rubber connector I used between the air flow meter and the aluminum pipe tends to soften and leave an air gap, I think. I tightened it when it was hot and everything seems fine now.

I’ve posted some new pictures showing the graphics and the results of some back road running. The power is really good and the car handles very well. I may need a brake upgrade soon – those small discs and rear drums are a little scary at speed!


http://www.nexmatech.ca/car_pix.htm

Your site doesnt work.

Its pointing @ Pics on your local PC.

Thanks Custommx3 - let's call it a brain fart. I've fixed the link so you can actually see the pictures now. Much appreciated.

http://www.nexmatech.ca/car_pix.htm

By the way, the so-called sputtering problem was caused by excessive fuel pressure - a too-rich mixture at low rpm occured because the pressure regulator solenoid was sticking open after it had been heated up. I think. The give-away was black soot deposits on the plugs built up in 24 hours, combined with memories of the symptoms of old carburated cars with a too-rich condition. Thanks to my brother for that one.

Actually, the misfire/sputtering was caused by a faulty thermo sensor in the intake manifold. Thanks to the MX-3.com members who identified it!