HarlemLegend

I have a BEAUTIFUL '91 Convertible sitting in my garage. I purchased it from a friend who moved to Thailand. It's in needs some attention

2 questions:

1. A enthusuaist suggested that I bypass the omp and run it 2 cycle? I kinda knew what he meant after he described it to me, and it's a common thing to do. But, my Vert is bone stock, and I'd like to keep it as original as possible (for now). Is this bypass the way to go? And why?

2. .................................................. ....NOT allowed..(MOD MESSAGE..deleted)

misterstyx69

iTrader: (142)

Your Second question was deleted..
WHY? you can look for parts in a section called the Classifieds.

This section pertains to any tech questions ONLY.

back to question #1.
NO you can't "bypass the OMP" on your S5 (that is 1989-1991 by the way).
It is electrically connected to the ECU and IF disconnected will throw the car into "limp mode".
You can hang it off to the side and block it off at the engine(and run 2 stroke in the gas at one ounce per gallon of gas) but that is like Wiping before you poop..it doesn't make much sense.

There is a Way to defeat the "limp mode" and that is a aftermarket Ecu Modification.
They call the ECU an RTEK. ( digital tuning, inc.)
That way you can take the OMP right off and run Premixed gas/
Either way the internals need lubrication so it needs oil delivered into the housings somehow..either by Premix or by the OMP.

FdFrog

Depends on who you ask from what I have read.. Some say its dumb to remove it, and some say it's fine to.. If your worried or running big rpm leave it and premix also.. And read everything from guys who have been in the rotary game for a long time.. Good luck

HarlemLegend

Thanks for the insight on posting properly. Shortly after I posted this, I found the answer on a permanent thread.

Thanks for the OMP lesson. I'm a firm believer of "They build things for a reason". I think when I'm ready for this rebuild/repair, I'm going to keep the OMP funtioning as it should.

Evil Aviator

Sometimes time and modern technology will provide better solutions. However, in this case, the car has been running fine for over 23 years as-is, so I see no evidence that pre-mixing is worth the trouble.

Street cars do not necessarily benefit from the same modifications that are used on race cars.

Sgtblue

iTrader: (16)

My recommendations for a new owner...
*Get a copy of the Factory Service Manual if you don't already have one. Downloadable versions are everywhere. Every time you see something under the hood you can't identify, open the FSM and read until you can.
*Continue to search and check stickys when you have a question. Wonderful source of info here, but know there are few universal answers.
*Replace ALL fluids, coolant, oil, brake, transmission and differential. Doesn't have to be done overnight, but soon. Gives you a good baseline for maintenance.
*Spend the rest of the first year of ownership properly fixing stuff that needs fixing and regular maintenance....plugs, fuel filter, brake pads etc.
*Do the above BEFORE making any modifications, especially performance mods.

You'll be surprised on how much you know about the car after a year.

misterstyx69

iTrader: (142)

The switch from Mechanical OMP on the S4 to the electrical OMP on the S5 was one of the stupidest moves that Mazda ever made when they decided that it was an "upgrade".
The mechanical omp is pretty well bullet proof but the Electrical omp will Make the engine go into limp mode and drive like ****.
Try taking the linkage off the mechanical OMP..the engine will still run.
Disconnect the electric OMP and you are calling BOB the Tow Truck driver to pick you up.
If you research even further and take a look at the internals of some engines that have Premixed the Oil and gas verses using the OMP you will see some variations of wear.

I am an S4 Guy,and I hate the S5 OMP..plain and simple it is unreliable.
I do however believe that If the fuel has lubrication in it then it will hit more surface area internally than that of a Oil injector spraying a miniscule amount in one area of the engine.

So,Now I Premix and I don't worry about mechanical parts or the unreliable "Mazda Squirt gun" to dispense oil to my engine.

HarlemLegend

This is interesting info. I'm literally writing this stuff down. I'm doing as much research as I can. My vert is in beautiful condition. It stood the test of time and is completely stock. I can't wait to get her up and running again.

Evil Aviator

The S5 OMP uses less oil by only providing maximum output when needed, improving economy and emissions. The S4 OMP is always at max. Given that, I like the S4 OMP better, lol.

The much more stupid S5 "upgrades" would included the added weight, softer suspension bushings, and the lesser-performing VLSD. The only thing I REALLY like about the S5s is the far superior rubberized stereo surround bezel and vents, but fortunately we S4-lovers can use these on our cars too.

Be sure to write down the things mentioned by Sgtblue.

If you need a new top, the Robbins brand is top of the line and is the closest pattern to the original. I found that I could order it off the internet for less money than my local shops could buy it (due to the middle-men that they are required to go through). Unless you are a good seamstress, you will NOT be able to install it yourself, so you will need to take it to a professional convertible top or marine top installer. I found a high-quality local shop that only charged $400 for labor, while other shops wanted to charge as much as $700.

Use Raggtop or 303 protectants and cleaners to keep your top from ripping prematurely. You can order them from Amazon and other online stores, or you may be able to find them at select auto parts stores, marine stores, or sporting goods stores (in the boat section).
www.wolfsteins.com
303 Protectants and Cleaners is the premium choice for car enthusiasts, avid boaters and home owners since 1980

If your top has a slight leak at the top of the driver side window, rain can drip into your power window switch. A towel, sponge, or tray over the switch can help keep it dry if the car is parked outside in the rain. A car cover is best, but sometimes it isn't very practical.

HarlemLegend

Thanks. The top is in beautiful shape, as well as the interior, and the rubberized stereo bezel. I'm in search of an auto transmission. I was wanting to do a 5spd conversion, but I'll stick with the auto until I need to do a complete engine rebuild.

doanuts

Nice info i have an 83 and just started my rebuild. Broke the two hoses that go to this omp while taking off the water pump and housing. Didnt know what it even was till last night. This gave me a little more info thanks :-)