Limp Mode Issue Resolved
 

Wanted to share with anyone facing similar limp mode issues what my resolution was
(as many problem threads end in no answer once op gets it fixed).

A friend with me had a obd2 imagine that. Only codes were rear o2 and misfire cyl 2.

04 manual - zero idle/starting issues.
New ignition about 2k miles ago
d585 coils / new plugs / msd wires
no cat (midpipe)
119,500 chassis (49,5k 2nd motor under warrantee from p/o)

Problem started 2 nights ago coming home from a really intense storm, 4+" of rain, standing water on the highway, no one going over maybe 45 in a 65. I go to leave around 4:30am and my series 1 is in limp mode, won't get above 3000 rpm if that. Hills are worse at around 25mph tops, felt a lot like a rev cut (not fuel cut). Otherwise it started and ran fine, no odd sounds/vibrations, power 1-3k felt normal.

I swapped my old coils as my only codes were misfire cyl 2 and the rear o2 (from no cat). Checked the SSV which moved fine. Did the NVRAM brake pedal rest and battery resets. It is extremely annoying there was not a code for this connector misreading/shorting! >:|

Long story short I pulled the pass front wheel off to pull the OMP connectors (as everything I read said limp mode is "always" OMP). Sure enough, the OMP switch connector pointing straight down, was completely full of water. Dried them out, put die-electric grease in the plugs, battery back in and CEL turned off. Let it warm up, and limp mode had gone away.

I know water in plugs is a common issue (like power steering which also happened on mine) but if you have limp mode CHECK YOUR OMP. Don't waste time looking at anything else until you know the OMP wires, plugs, etc are dry, not shorted/stripped. From most of the other stories I've read, the codes don't tell you it is a OMP issue.

You must have drove thru a shit ton of water to get your OMP that wet. Do you have an under tray and all the factory splash guards? Oh, and the OMP is the most common cause of limp mode.

it was a lot of water, pretty surprised it got that soaked. last time these connectors were off was at the block replacement.

I read a lot of your troubleshooting in threads I was reading btw 9k so thanks
(also lost a lot of brain cells from the op's)

I have replaced the oem tray with a aluminum tray I made with a cnc plasma table at a friends machine shop + aluminum side supports to replace the floppy ass mazda ones. fender liners are gone.

Thanks for the info, you never know when it may come in handy. I like your undertray too.

Ah I see your problem. The factory tray has holes in it for that reason, to drain off water quickly. Very nice tray, I like the the uprights. The tray is a lot thicker than mine but I am using factory plastic uprights.

if you look at his pictures the issue is that the car is lowered way out of it's effective geometry range as evidenced by the excessively angled control arms. This thing must scrape on bubble gum wrappers it's so excessively low. The control arm pickup point appears to only be an inch above the pavement, if that. The aluminum under-shroud is a huge water scoop in any puddle over 1" deep.

fubar


.

That control arm looks like a potholes next victim.

Limp Mode
 

Hey guys, I'm new here but have been referring to your forums for issues pertaining my rx8 for years now with great success thanks to all you brilliant 8 owners that help out on these forums, I've fixed everything from Power Steering issues, all the way to a simply DIY for plugs and wires, So i'm quite familiar with my 8 by now thanks to you guys, I've just had this one issue since i purchased the car and i can't seem to find the fix, Limp Mode but it's a little different. here goes;

The car starts up, runs and drives decent but when I take the car for long drives, and shut my car off after atleast 45min of driving i'm in limp mode, Now if i wait for long enough the car will be fine again, Or if i reset the ECU with the 20 brake stomp thing, But it seems like everytime i drive somewhere 45 min or further and shut my 8 down it always starts back up in limp mode, I've owned the car for a few years now and i've realised probably about 2-3 times since i've owned the car when i go to really give it to pass someone like pushing the car, Nothing to crazy, It'll cut out and put me in limp mode (very dangerous when your trying to pass someone and your car just cuts to limp mode) i've changed the coils plugs and wires (with cheap ebay replacements they were new though) Any help would be amazing, Thanks!

Coils plugs and wires fixed my limp mode. Was surprised myself.

Typically limp mode is caused by an issue with either the oil metering pump or drive-by-wire throttle system.

MAF but I guess you can consider it part of DBW.

i have a troubel code P0300 on my 06 and i was wondering what could cause that i replaced plugs wire and coils is there something that i missed??? please help!!!!

Lots of potential reasons for the misfire but the far most common on our RX's our coils, plugs and wires... Dirty MAF is probably the most likely culprit after the above with a failing fuel pump and clogged cat not far behind.

Thanks for the help

Rx8 Limp Mode
 

Thanks for the advice guys, I just got back from a long weekend camping trip, and will Post back as soon as i can with some Engine codes, I've read about the OMP causing limp mode, and my car was actually throwing a code for the OMP circuit low or something like that according to the dealer, I'll have the engine codes up on here as soon as possible thanks

I’m having a slightly different limp mode issue with my 04 rx8

on start up, wouldn’t rev passed 5k. And was very slow getting there (probably around 20 seconds pedal to the floor)
its happened 4 times now, on both hot and cold starts. Shut the car off and restart it, and it’ll run perfect. No limp mode. And hasn’t acted up at all driving, just on start up.
Check engine light came on, but there’s no codes. Including the code I had prior to the limp mode issue. The seal on my gas cap leaks, hasn’t been repaired but I can’t even pull that code now.
Spark and maf readings were in normal range
not really sure where to look!

limp mode is under 4000 rpm, you likely have a different problem

check the cat converter condition first, which a bad cat will block flow out of the engine.

then SSV control operation and whether it might be stuck, which controls the secondary ports and flow into the engine past 3800 rpm. It it doesn’t open then the engine is only flowing through the primary ports and starving for air.

https://www.rx8club.com/series-i-tro...6/#post4492789

Ended up giving error code p0441

Code P2106: Throttle Actuator Control System Forced Limited Power

Saw something about purge Solenoid. Can anyone confirm proper resistance. I tested it based on values in another forum, which were way out from mine but It hasn’t acted up again since my original post.

the issue is the P2106 code which is malfunction of the drive-by-wire throttle body system, the evap purge solenoid is an emission issue that won't affect how the car runs

bad throttle body
throttle body wiring connector not fully seated or bad
bad wiring
bad pcm


https://cimg2.ibsrv.net/gimg/www.rx8...b0779e9441.jpg

Checked all harnesses, rang out with meter to pcm. All wires associated with throttle harness checked out.
Cleaned throttle body and checked voltage and resistance on harness and throttle body. Nothing seemed out of sorts other than 4.9 v showing on tp1 and tp2 sensors on wiring harness. No codes thrown for the sensors though so I assume that’s normal?
Anyways... after resetting the ecu no code came up again. Just the CEL light and still limited power.
Is there any way of diagnosing the pcm. I’d expect more computer related issues if that was the case.

if a CEL is indicating there has to be a code associated with it.

There’s not. Obd reader says mil on. No stored or pending codes Wondering if it might have anything to do with the aftermarket automatic car starter?
Took the fuses out and it reved up for a cycle before going back into limited power. First time it’s gone out of limited power in a week now.

maybe the obd2 device isn’t sophisticated enough to determine the problem.

did you try to adjust the OMP switch? Long shot, but it’s the #1 reason for limp mode and no code, the CEL usually doesn’t show for it

maybe your switch is right on the edge of misadjustment

Screws aren’t going to come out without breaking. Do you know what the resistance on the sensor and motor harness should be by chance.
That would tell you if adjustment is necessary too wouldn’t it?

[QUOTE=Mac91;4922447]Screws aren’t going to come out without breaking. Do you know what the resistance on the sensor and motor harness should be by chance.
That would tell you if adjustment is necessary too wouldn’t it?[/QUOTE

It's not a resistance... it expects a response based on stepper motor position... so it will open and close the switch. The trick is knowing where the stepper position is and when its switching. So far I haven't found a way to reliably set it with a scanner
I found that if you turn it all the way clockwise and then place the switch back on and take up the slack on the switch it seems to work more often than not... you still have to play with it sometimes