I have a 2004 Mazda RX-8, Base Model.

I bought this car in hopes of getting it to run. Main issue is that the car will not rev past 3k rpm, even with the gas pedal all the way to the floor. I had multiple engine codes when i plugged it in. I replaced the spark plugs, spark wires, and ignition coils. That cleared all but one code. I still have a P2109 code on it. I checked the forums and the big thread with this code ended up having a PCM replacement as the solution.

The 3k RPMs take about 10 seconds to even reach that high up, it revs the engine up really slowly, doesnt matter what gear its in(P,N,D,R). I havent checked the cat, or oil pump yet.

I took the car on a drive, it still shifts, I got it to 3rd gear, at 28mph...lol, which i dont know if its a significant detail, but thought i would share.

Any suggestions?

 

As mentioned in the other thread that you appropriately deleted, here are some additional questions to help us see if we can determine what the issue is:

1) You said in the other thread that the car was a salvage. What was the issue that caused it to get that title? Details about the extent of any damage?

2) do you have the same issue with the struggling RPM and strained limit in neutral as you do when driving? It matters because most issues are either load based or not load based, and this can help rule out one set or the other.

3) Does it start easily? Do you have any trouble getting it started?

4) How does it idle? Can you pull MAF g/s data from your scan tool? (I assume you have one) What g/s are you pulling at idle?

 

LOL thanks.

1) I got it after it was fixed, from the repairs, looks like it was hit in the front drivers side....

2) It happens the same while driving or in neutral.

3) It starts pretty easily, like maybe 2 seconds to get it going.

4) It idles just fine. Sounds normal. I will try to get the g/s data, this weekend, cuz its bout to snow soon.

Thanks for the help!

 

Ok, so the same with neutral vs driving indicates that this is not load related. We can tentatively rule out physical flow problems (airflow in or exhaust out) and fuel problems, as they would cause the engine to react differently between no-load and load.

The fact that it starts and idles fine tentatively rules out compression loss (and compression improves as you increase RPM, which is in the opposite direction of your problem).

I would then leave the list open at a sensor problem or ignition problem. So, one of these (until we can eliminate or add anything else):
- Plugs (replaced)
- Coils (replaced)
- Wires (replaced)
- MAF sensor (dirty, unplugged, wires damaged)
- E-shaft sensor (dirty, unplugged, wires damaged)
- Throttle position sensor
- OMP failure (tripping limp mode, though I'd think this would be a hard-cap, not a "Struggling to get there" cap)


I'm sure I'm missing an option or three or more.

 

Have you tried resetting your NVRAM? (20 brake pedal press)

 

Yeah I have tried that. I had no effect.

 

I have to check the MAF, E-shaft sensors...

I forgot to mention that i replaced the throttle body i bought from raceroots on here.

OMP is oil metering pump right?

 

yes, omp = oil pump.

Check for clogged hoses or damage to pump

 

oil metering pump, correct. Not the main oil pressure pump though. That is internal to the engine, and is mechanical and shouldn't be related to your issues here. The OMP is electrical, and if it fails or is disconnected, the ECU is supposed to go into limp mode, which does limit the RPM. I've never seen it, but it should be a limit like the 9k fuel cut limit, not a "struggling" limit.

See if you can pull data for the throttle position sensor (there are actually several), and see if there is anything there that might be "Capping" the sensor data. Like it sees actual position as 100%, but it's only sending ~10%.

 

every time I open these threads I get instant facepalm reading the stuff people automatically suggest every freaking time like polly want a cracker parrots

search "limp mode", which it is likely in, usually the OMP or DBW system, did this occur before or after you changed the TB? You can double check this by having the ignition key turned to the on position and then holding the throttle fully down and looking to see if the throttle butterfly plate is WOT or not, it likely is not which will mean limp mode

 

yeah its clearly limp mode.

team is right on suggesting the throttle. P2109 is a throttle position sensor code. you've changed the throttle body and you have a code for throttle position.

there have been times this ended in PCM replacement but in your case so far id bet not

 

In the original thread by the OP (which may have been deleted), limp mode was the first thing that was suggested, and the oil pump being the fist place to check.
OP made this new thread, and a few more points were passed for OP's consideration.
Just so you know

 

I found out what was wrong. There was a loose connector in the PCM. Got it reseated in there, and it runs again! amazing what a little unseated prong can do....

 

Gratz!

And you were about to part it out for junk

 

LOL. Never! I dont know what you are talking about.

But thanks for your guys' help. It was appreciated.

 

the vacuum seals, check on the right side of the engine and look down, there should be two rubber **** on the holes are there? I had the same problem, fixed it right away

 

Ummmm
It's nice that you want to help ... but look at the post date.

 

Can you send a picture of that cable that was loose, please and thank you

 

This post is from 6 years ago. I kinda doubt it. But also, none of them should be loose, so not sure what the picture would accomplish. If you have the same issue, investigate the wiring to the OMP and the OMP itself. The problem is there.