JJHof525

OK so i have a low post count, and im guessing this has probably been answered before, but i swear i searched and i just cant find the answer. Im sure its common though.

I have a 1989 Mazda Rx-7 convertible 13b NA, Aboutr 120,000 miles.

OK so heres the issue. The car will run fine for a short while after starting it. After driving it for a short amount of time the check engine light will come on and the cars loses the ability to accelerate. Not entirely though, i still have almost half of the peddle to use but once i push it beyond that the car will bog and sputter and if i press the peddle down even further its as if i were giving it no gas at all. Theres not really a better way to describe this, but i can say that turning the car off and than back on will reset something, and the check engine light will go off and than start the whole process over again. I have replaced the O2 sensor, the map sensor, the fuel filter, and now finally the fuel pump (last night for $200 and about an hour of my time).

Im going nuts here people. Im not mechanically dumb here, but i cant seem to put my finger on this problem. Please help, its getting to be expensive replacing all this stuff that doesnt need to be replced.

I have heard it may be the cat, or possible the fuel pressure regulator. '

Thanks in advance for all your help. My mechanic and mazda basically want a kidney just to diagnose this since they claim the car has no memory and their diagnostic would not pick it up.

Tessai

My car has this EXACT same problem. 1990 GXL. It happens after about 10 minutes of the car being on, and again roughly every 10 minutes after I restart it.

Only thing I can tell you is that the problem is not the cat, since I don't have one.

JerryLH3

iTrader: (11)

All you need is a wire with a spade and an alligator clip on the end and you can check the error codes. It does have a memory, but I guess they're referring to their OBDII tool won't pick it up.

There is a green one pin connector near the leading coil and the battery. Attach a small spade terminal on the end of a wire and plug it in. Put a clip on the other end of the wire and ground it to the body.

Go in the car and turn the key to ON. Look at the check engine light. It will begin flashing the codes. A long flash is a "10", a short flash is a "1". So, say there were two long flashes followed by seven short flashes, that would be Code Number 27.

It will flash any stored codes and then repeat. Once you get the codes, download the factory service manual (the link should be in the FAQ at the top of this section) and figure out what codes you have.

From what you describe, the ECU is probably going into "limp" mode. It only allows partial throttle.

uRizen

iTrader: (2)

It does sound like limp mode. I'd check your OMP immediatly. That's probably the scariest thing that could be throwing a code that would cause it.

ilike2eatricers

Yea you will have to check the codes. I'm guessing omp, waterthermosensor and/or TPS.

JJHof525

Thanks jerry. Appreciate the quick response. I will have to try this tonight. Until than, any ideas on what this might be? off the top of your head i mean. It looks like we eliminated the cat since tessai is having the same problem and doesnt even have one.

bingoboy

drive it until it spits the check light at you. stop driving, do NOT turn off the car. plug in the checker, check the codes. most likely its an OMP code. find a used OMP from a forum member and install it, or just plug it in, stash it on the side of your engine bay, and start premixing.

bingoboy

if the OMP fails, the ECU sets the car to limp mode by running it in super lean condition. you get that no power/bogging after it initiates that. there is no way around having a working OMP hooked up. the factory ECU will not run correctly without it.

briandrennon

My 89 vert did the same thing. It was a bad Oil Metering Pump, I bought a used one from someone on here for 50 bucks and changed it out in about an hour. Mazda wants 1100 for a new one.

Tessai

If it is the OMP, why does my car continue to use the same amount of oil as it always has? ~1qt / 3k miles.

JJHof525

OMP...not to sound too dumb here, but i dont know what that stands for.

EDIT: sorry got my answer

briandrennon

Mine did the same thing and it was a bad connection, bule-ish green stuff all over the omp conection itself.

briandrennon

Mine did the same thing and it was a bad connection, bule-ish green stuff all over the omp conection itself. So it would work sometimes and not work others.

JerryLH3

iTrader: (11)

Have you checked the error codes to eliminate that possibility? Limp mode happens for other reasons, but the MOP is the one we hear the most about.

My old N/A went into limp mode once. It wasn't the MOP, but the throttle sensor would be completely stuck in place (about halfway out). After the throttle sensor was switched, it worked fine again.

bingoboy

so since you think that it's not it you won't check it out? the OMP doesn't have to actually stop flowing oil to be broken. it is a stepping motor that routes different amounts of oil into your engine based on which position it is in. it doesn't actually pump anything itself. it can still be doing this and "fail" from the ECU's perspective. the position sensor in it will tell the ECU that it is not working correctly. heck, if the OMP worked perfectly and the position sensor wire to the ECU was fried it would probably throw the same code and put you im limp mode while the OMP motor might actually be capable of working correctly.

Tessai

I edited my above post, Brian's reply was submitted shortly before mine, I hadn't seen it.

Yes, of course I will check it out. I was merely trying to find information like you supplied, stating that the OMP can "fail" and still work. Was also trying to find the next-most common things wrong.

Sheesh this forum is getting even worse... people jump all over you for everything.

JerryLH3

iTrader: (11)

Not jumping, just seeing if you had eliminated the possibility.

JJHof525

Thanks everybody for the help, you have no idea how much of a pain this has been, i seriosly thought about just selling this thing just cause i was getting so frustrated. Also id anyone knows anywhere to get an OMP, like a cheap site, or if someones selling one please let me know. Im guessing since the general opinion is thats what it is, i will probably be needing one, but i will check the codes tonight and see.


Thanks Again!

JerryLH3

iTrader: (11)

Check the Parts for Sale section of the forum. If you can't find one for sale, post a thread with "WTB: S5 MOP (or OMP, depending on which term you prefer)" and I'm sure someone will let you know if they have one for sale.

bingoboy

yeah...i learned...from experience .

didn't mean to jump. my stupid error light would reset so i couldn't check the codes. finally got Ted to take a look at it one day, we drive around the block, the error and limp mode comes in. he jumps out and hooks up the checker without turning off the car and *bam*...error code. i've been premixing since, with a good OMP ziptied to my strut tower brace (yeah ghetto), but i figure with heat and engine vibration it will last longer up there, since its basically just an electrical part with holes in it.