Ben Liang

two days ago I was driving home, the check engine light came on and I felt a sudden lose of power. I got scared and pulled over to the side and stoped the engine. Since I was 3 blocks away from home, so I fire up the engine and check engine light was NOT on, so I drove it home. On the way home, the car run normal again, was able to rev past 3000rpm. ( the power seem normal, maybe I didn't wanted to accelerate too hard on the way home). Right before I got home the check engine light came on again, but this time the engine did not hasitated on me, so I thought maybe that was not big deal, I left it along overnight. Next morning, I start up the engine and there is no check engine light, so I thought it was OK and drove it to school and back home, and the engine felt pretty normal. later that day I check with the FSM and found out it is the code 27/MOP, f@$%! right the way, I checked this forum, I got really scared. I ran to Canadian Tire and bought some 2 cycle oil, mixed with some gasline into the tank.(so I can drive it at least). Later that day, I tried to clear the code by disconnect the battery for over 5 seconds, but the code remained, but the check engine light didn't come on when I drove it back to garage. I also tried to look at the 4 plastic oil lines coming out of the MOP: they seem to have oil inside because when I rev the engine, I can see some air with oil moving back and fore slowly inside one of those lines. The oil was pretty clear inside the lines.

Now today, while I was driving it to school, the check engine light keep fashing. the engine can rev past 4000 rpm but felt slight/abit low on torque and power.

OK, Questions:
Did I done lots of damage to the engine?
how safe it is to run on pre-mix compare to a working MOP? 1oz to 1 Gallon of gasline right?
what's up with the fashing check engine light? why it is keep flashing on me and I am not in the lume-home mode?
I have a track day coming up in two weeks, I had paid for it already, I don't want to miss it. what can I do?
Please help me out guys, I did search the forum and I am still confused.
Man this is Sucks, new MOP is over $1000!

Ben

Rotary Racer

Running Premix is better for your motor than the OMP. But the bummer about the series 5 cars 1989-1991 is the OMP has an electrical motor that runs it and if the computer shows it is not working properly it will run in the limp home mode. This will bring up the code, light, and make your car run like ****/safe. You did the right thing to put in the premix after you found out what the code was. I will say you probably did not do any damage to your car (don’t stress you have a NA ). You have to find out why you OMP is not working correctly if it is not major problem then you might be able to mod it. Do a search on the forum people have successfully moded the series 5 OMP not to work and not bring up a code. This way you can disconnect your OMP lines and plug the holes (I believe the bolt needs to be 10mm x 1.0 don’t quote me on that ). Us GTUs guys need to stick together hehe Peace

Silkworm

Rotary Racer,

WHERE? I've yet to see anyone get the S5 ECU to run properly without a working S5 OMP hooked up to it.

Ben, you're forked, better start hunting down junkyards for an 89-91 OMP, the car is not going to run properly (i.e. at full power) without a working OMP, premix or not.

PaulC

Ben Liang

I did search the forum and I can't seem to find how to make the damn check engine light quite flashing on me. I am going to try my best to follow the FSM and try to find out what exact is the cause. I know it flashs for a reason and I know I have to fix the problem, not try to avoid it. of all the posts here I read, no one has solution to by-pass the MOP succesivefully yet.

Scott 89t2

track day in vancouver?? at mission?? how much, how did you get in?

anyways the ecu's arn't too smart. the engine light sometimes will come on and sometimes won't.. but if the code is stored. the car isn't going to run at all... you'll need to get it fixed. pre mix will stop if from damaging the engine. but there is no way around getting the ecu to run normal with out the MOP working.

ebay7

Have you checked for any loose connections like the white connectors on top of the alternator. Now there are 2 connectors for the mop, having code 27 suggest that you look at the one behind it.

Ben Liang

Scott, it is at Mission Raceway, Oct 6, I pay $150 for their(510 Club) pre-registration, you still get in if you still interested, check out www.vcmc.ca and look under race event. It is likely that I am going to need a good MOP, prefer used, got any contacts Scott?

My bad, I just find out what causes the check engine light to flashing at me, I forgot to disconnect the grounding wire at the single green plug/diagnosis plug, I disconnected it. check engine light gone while I was just driving home. Another note, the car felt quite normal as I drove back home, however; I have yet to rev it past 5000rpm to find out how it is at higher rpm. I am too chicken to try I guess, it is a GTUs for God sake, enough on it , don't want to bore you guys out.
my gut feeling is telling me the ECU is an concervtive mode, like cut back on ignition timing etc...

I will check some connecters as Ebay7 suggested, see if it is just a loose connection, I am hopeing it is. thanks everyone, I will keep posting.

Ben

Rotary Racer

Paul, Mazdaspeed7 did this mod. I am still not 100% sure how he did it but he tore apart most of the internals of the OMP and the comp still thinks it works fine. I have yet to do it but I am probably going to carbs so I might never find out PM Mazdaspeed7. Peace

Silkworm

cool, I'll search for that.. thx

PaulC

Silkworm

Quoting from Mazdaspeed7:

I agree completely with rx7_ragtop. I tried that too, but to no avail. The circuit would have to be too complex for it to work right. Its not just a matter or wiring in some resistors.

Heres what I did. I pulled my OMP off, gutted it(took all of the gears and such out), blocked off the 4 outlets with solid bolts, and then put it back on, like it was. No codes for a year, runs great. I havent had any problems with it. But for this to work, the motor and sensor have to be working properly.

------------
So it has to work in the beginning for you to do this mod..

Good luck Ben!

PaulC

Ben Liang

Quote Silkworm:
"------------
So it has to work in the beginning for you to do this mod..

Good luck Ben! "

doh!

Now, lets say the problem is caused by a bad sensor OR a bad motor, can we just fixed that part instead of buy a new MOP which costs most people an arm and two legs. Has anyone try this before and worked?