tie pilot

what happened:

suddenly, the check engine light came on and the car had bad acceleration except under very light throttle. I believe this is what you call "limp-mode" correct? checked error codes, got 27 (Metering Oil Pump). so my plan is to run premix (1oz of TCW-3 2stroke per gallon of gas) until I can get the car to a professional and have the MOP replaced or the circuits fixed.

my question is, is there any way to get the car out of limp mode in the meantime?

forgive me if this was covered once somewhere, but searches turn up spotty results and this IS my daily driver = )

ddub

Try this.

https://www.rx7club.com/showthread.p...t=OMP+blockoff


One person in that thread says that it builds up pressure over time and EVENTUALLY you'll have problems. But if this is a temporary fix and you'll only do it for a short time I don't see why it wouldn't be okay. According to that thread it doesn't cause a limp mode for s5's. So try that, premix, and get it fixed as soon as you can.

tie pilot

gave that a look...

seems like it wouldn't cause a limp mode if you didn't already have one, but I need to erase a limp mode that already exists. not sure if the above method would do that. hmmm...

ddub

Does unhooking the battery on s5's reset the ECU?

ajsuper7

you need to be careful, if the mop has failed then the ecu might be fried and trying to reset it wont work, you will have to replace both the mop and the ecu with working units, if you try a new mop with a fried ecu then the new mop gets fried and vice versa. i had this problem last year... however if it is just a clog and the electronics didn't fail you might be ok. don't drive it without premix the engine will wear very fast without oiling.

tie pilot

good to know. I would hate to replace everything twice (or more) = \

speaking of clogs... do you mean if the injectors or MOP was simply clogged then it would trigger this error code and limp mode? I thought that it did not, and that was the silent death for rotaries.

dDub, I haven't tried resetting the brain yet.

j9fd3s

iTrader: (3)

reset the ecu and keep driving, if the code comes back replace mop and recheck

Kenteth

Sigh mis information.

OMP errors will throw the S5 engine in limp mode. PERIOD. Theres been talk of a resistor that can be placed in the leads to trick the ECU, but no one ever researched it enough to find a safe way of doing it (OMP uses the ECU's 5V ref wire, if you **** that up, you fry your ECU)

That 5V reference is why S5 ECUS commonly fry when the OMP hits the fan. Best fix I can think of is to buy a cheap OMP, mount it to the firewall, remove the old OMP, blockoff hole and premix.

ddub

Then why did that one person in the thread say he did it and no limp mode? All I'm doing is relaying information posted on this board with someone that has tried it.

Kenteth

I guess I don't see anywhere in that thread that says removing the S5 OMP won't cause limp mode.? (or for that matter any temp fix to keep it from limp mode.)

In theory you could reset the ECU and it won't be in limp mode until the ECU realises the OMP is facking up. Then you're back in limp mode until you reset again. I'd imagine the more you do this, the close you are to frying the 5vref though. (not to mention kill the housings if you aren't premixing)

Furthermore, the guy in that thread had an S4 OMP anyway, not S5.

EDIT:

Ok I see what the *other* guy did.

Basicaly, with a WORKING S5 OMP, you can block off via replacing the banjo bolts with solid bolts. Leaving the OMP plugged in causes the ECU to know its still there. You of course would have to premix at this point.

BUT, if the S5 OMP is Dying/Dead, blocking it off in this fashion won't do **** for keeping out of limp mode. The OMP will still trigger limp mode, even if its blocked off-- why, because its dead/dying.

S5 ECUs need a working (or at least not malfunctioning) OMP to keep from limp mode. If the OMP is not hooked up, or if its bad, the ECU will throw the car into limp mode.

ddub

S5's are stupid.

And it's MOP.

Kenteth

Bah. OMP

EDIT: and S4s ******* rule 2nd gens. S5 have so many design flaw "upgrades". Like stupid ball joints, dash harnesses, and stearing column knuckles that don't have set spines

andrew lohaus

man sucks to hear that. i geuss th only thing you can do is reset the ecu and hope it doesnt come back. through a little pre-mix in just to be safe i have seen s5 omp's go for about $100 on ebay so it might not be too bad of a fix.

tie pilot

that's what I gathered.

like I said, I haven't reset the brain at all yet, but every time I crank the car it runs normally for 5, 10, or even 20-30 mins. then the "check engine" light comes on and I'm back to limp mode (oh, I have been premixing ever since I drew the code).

kenteth... when you said "buy a cheap OMP, mount to firewall, blockoff and premix" are you suggesting that I just get a new unit to keep the computer happy, and not actually use it, but premix instead? this sounds like the best idea i've heard = ) I really don't like baptism by fire, but this episode has grown my interest in premixing for it's own sake.

ddub

FSM says MOP so I say it's an MOP

RotaryResurrection

iTrader: (8)

I keep OMp's and ecu's in stock if anyone needs them. $150 shipped each or $250 shipped for the set (and yes, they do go out together a large percentage of the time, no way to know).

Kenteth

Well, basicaly any OMP thats not telling the ECU to jump into limp mode will work. Its an absolute crap-shoot when buying omps unless they are tested good. Mounting the thing on the firewall is inside the engine bay, close enough to the stock harness that you won't have to mess with it much, and easy to get to if you want to remove it later. I'd only do it that way if I was removing my orignal one though.

To be honest, if I was going standalone anytime soon, I'd sell you my omp cheap. Its been blocked off (bolts replacing banjos) for about 12k miles now.

tie pilot

I guess I have some luck: I was able to score an s5 MOP on ebay for the relatively low price of $40 shipped. only problem is, according to what you've all been saying about MOP / ECU going down in pairs, if I plug this unit in and get the same symptoms, I can't really complain to the seller, huh?

But if the only error codes the brain was putting out were 13 (manifold pressure) and 27 (MOP), would it be a safe bet that the ECU is still ok? I mean, if it were fried, wouldn't it be throwing all kinds of codes left and right?

p.s. I suspect code 13 is due to my aux ports being seized (and the actuators removed).

igottafc

iTrader: (6)

another thing MIGHT be that if the cars charg system is low, it will send it into limp mode. This happened to me several times before i got my new alt and Bat. I did throw MOP codes. After i replaced everything, it never happened again.