benjo8

Hey guys, my name is Ben, I've had my rx8 for a little over a year now. It's an 04 6 speed manual model, and I live in western Kentucky. In my year of owning it I've had to replace the engine with a rebuilt one, but once that was done everything was good. However, it just so recently happened that the car went into limp mode. So since I knew about this forum, I went and did some research (a lot of research actually haha) after deciding it was the OMP acting up I tried to fix it and ended up breaking my radiator. So here I am after buying and installing a new radiator yesterday and attempting to adjust the position sensor on the OMP. However my car is still in limp mode after the adjustments, the CEL has disappeared, and I'm at a loss as for what to do next. I was hoping someone here could help me out, I'd really appreciate it. Nice to meet everyone!

zendrums

iTrader: (2)

Check the catalytic converter. My car was in limp mode caused by a clogged cat. I ended up destroying the honeycomb form inside the cat.

Good luck and let us know what you find

9krpmrx8

iTrader: (46)

If your car is in limp mode you should have a code. If that code is OMP related then adjusting the switch doesn't always fix it, you may need a new OMP. The issue needs to be properly diagnosed.

logalinipoo

I've seen limp mode from the sensor position many times with no code on several vehicles.

The bad thing is if you've already adjusted the sensor it is definitely off from the original settings and you will not know. I've picked up 2 good working OMP's with sensors from people for 50 bucks each.
I tired telling them to take their time adjusting and they gave up and bought another because they couldn't' get theirs adjusted. I swapped one whole pump into my car adjusted it and drove it about 2k miles then. I did the same with the second one and it's still in there working great.

Please confirm in your own words how you know it's in limp mode and what it's doing. in good detail. if it sounds like the case I'll try to describe to you the process for adjusting that takes a matter of 15 miniutes to save you hundreds of dollars and a lot of headache.

On another note I'd tell you to call me and I could walk you through it, but I'm in Saudi arabia at the moment. I should be back in the next week though.

did you ever have it running out of limp mode since the rebuild? did you **** with the OMP during the rebuild? IE take off the sensor or adjust it?

benjo8

The car was running great after the rebuild, no limp issues, easy redline everytime. The day that the car first went into limp mode I remember the car being limited to 4000 rpm or less. Whenever I tried to go over this, no matter the gear, it would try to pass it, but fail and be stuck there. Theres no power on the low end and I really have to almost force the car to take off by revving it as hard as possible ( usually around 3000 rpm). When driving, it takes at least 40 seconds to get to 35 mph. It makes it really dangerous to pull out in front of traffic as the acceleration is so bad. Now the car is still stuck at not being able to pass the 4k limit, but the CEL that was previously displayed has disappeared. This only happened after I adjusted the position sensor on the OMP and reset the ECU. I'm at a loss for what to do. I've heard that premixing may fix the issue, but I don't completely understand how the premix would circumvent an OMP issue.

I diagnosed it was the OMP after I had a tire blowout on the highway. I had to get the tire replaced so I took it to have it done, and the guy told me it's injecting a lot of oil into the engine that may not be getting burned off properly. He continued to tell me that it was probably due to an OMP issue. So to verify I came to this forum and read through as many articles as I could and compared the similarities between my issues and the issues in the posts.

I'd appreciate any help you could give me in the subject.

logalinipoo

OK, that sounds like it is definitely limp mode. I ask because other people have thought it was and it turn out to not be.

One more test to confirm. Start the car and instantly rev the **** out of it. Limp mode caused by the omp sensor will allow the car to rev when you first start it. it doesn't matter if it's hot or not. Just start it and rev it. give it 10 seconds and try to rev it again. you'll know for sure if it's limp mode.

Premix might help if it's a power issue from a fualty omp. but if it's really limp mode than it's an computer based restriction and premix won't matter. IMHO. I would premix while you are having issues just in case it's not working at all. Mystick 2 stroke JASO oil is my preference. I have no clue how much as I don't premix.

did you mess with the pumps sensor during the rebuild? just curious you might have gotten it back right. I've had mine go screwy after driving quite a while and required a readjustment.

Ok to do the adjustment. I think you need a 6mm box/open end wrench( don't use a socket or anything just an box/open ended wrench. not even a screwdriver. you'll get the movements much finer with it.

Use tire chocks, a jack and jack stand. and definitely use all of them. chocks on the drivers rear tire front and back. put your jack just under the passenger mirror. Raise it just enough to get comfortably underneath. and drop the jack stand behind the jack under the passenger door. that way it's out of your way.

From underneath take off the sensor. then put it back on. The shaft will not line up if you have the holes lined up. turn it counter clockwise until it drops onto the shaft.
Then turn it clockwise to get the screws in. it will be about 1/8th turn.
screw the screws down just enough you can turn the sensor without much force but it stays in place.
Turn it all the way counterclockwise and snug down the screws about 1/8th turn. Just enough it is difficult to move.
Start the car(DO THIS BY YOURSELF) don't be a dumb *** and have someone start your car with you laying under it.
Rev it hard. Limp mode?? probably yes. Kill it

Now to adjust.
loosen the screw on the front of the car only. just the 1/8th turn or so. it will still be snug but you can move it. Now try to turn just the front side of the sensor as little as you can. if you can nut move it very little by hand. then put the wrench on the front bolt and tighten it while applying pressure with your hand and you can get very small movements.

Total movements if you take your time you can get 10+ per a side of the sensor.

Now snug down the front bolt 1/8th turn and go start it again, rev it and wait. Then check for limp mode.

Repeat this process for the entire length of movement from the front slot of the sensor. If it bottoms out then leave it and move to the same process for the back of the sensor.

If it is the sensor you'll find it. If you're young and move quick you can do each adjustment and test in under a miniute. If you're old like me you don't get up and down so easy then it will take longer.

Once it's working take a scribe and make a line front back and side of the sensor. that will allow you to put it back in the exact same place it you have to remove it again. or give you a starting point for a readjustment later.

benjo8

During the rebuild process the OMP was not touched. Today I went out and started the car to do the rev test that you suggested. However when I tried this the car would still not rev past 4500 rpm even when I had just started the car. Also it may be important to note that the car was shaking fairly roughly when it did get to 4500 rpm. I continued to try to stop/start the car and rev it fresh each time to the same result. Does this mean that it isn't the OMP, and if this is the case do you have any idea what it could be? Thanks for your help this far!

logalinipoo

Have you checked the Cat? Do you have a way of pulling OBDII data to look at a few things. If you don't have this than the easiest and cheapest is a bluetooth OBDII dongle and the torque app on a smart phone. I highly recommend you get something to monitor the engine data for problem solving.

The bad thing is you now have 2 problems it sounds like. Problem 1 and now the Sensor. The rev test should be able to identify when you get the first problem fixed then you can use that process to adjust the omp.

As for additional ideas. I'd first check the OMP and throttle body wiring There are 2 plugs on the OMP. I would probably remove the intake and have someone push the throttle and watch the throttle plate move to see if it might be the throttle body. Have you checked spark plugs wires and coils?

It gets to be a pretty big guessing game now without pulling data like maf, fuel trims, and afr.

Clad8

I sent the car into limp mode when I installed my Sohn adapter by messing with the sensor.

Anyways I had to adjust it multiple times and clear the ECU with the 20 pedal stomp before it worked. logalinipoo had a great post on how to go about it. I would add that I finally got it working after turning the sensor clockwise from the 0 position. It's about 2 degrees. It's very minute and just slightly. Once it's withing range, the ECU will adjust it back to where it needs to be, but if it's off, the car will stay in limp mode. GL getting it fixed! Do post if you figure it out

benjo8

Hey guys sorry it took me so long to reply, I have had a lot of school work this past week and I was waiting on a Bluetooth obdii sensor to come in. I just went out side to pull codes off the car, and the only one that came up was a P0410 code for the secondary air injection system. I'm still at a loss as to what to do to fix the car. It's become quite an inconvenience as I can't even drive it to work. The oil hasn't been changed in a couple thousand miles, I was thinking about trying that next. But I'm also reaching the point of not wanting to put more money into the thing just to have it still not work. Once again, any possible solutions are welcome to hear. You all have been a great help.

Clad8

The code for the secondary air injection could put you in limp mode.

Here you go

https://www.rx8club.com/series-i-tro...t-fail-173980/

Have a read, solution is in there, tons of people with your issue.