UK RX-8 FD Engined Race car
 

Hi All,

Building a race car here that's near completion in the UK and have encountered a couple of problems that I'm hoping someone would be able to help with.

We have the car running using an Adaptronic, with an RX-8 OMP fitted with the stock throttle body to keep all the DSC system intact.

Here is a clip of the car running, and my build thread below.


mazdarotaryclub.com

Problem is, the car will start up OK rev up fine to over 5K but after 3 or 4 stabs on the throttle the engine goes to tick over from the cars I've seen in limp mode this seems different as the car will not come off tick over.

All wiring continuity from the pedal through the ECU and to the throttle body is fine.

I also have no OBD connector operational thats the same if I only connect the stock ECU without the Adapronic

All of the door wiring, air con, heater, air bags etc are unplugged and gone, could this be a related problem, any ideas please .

The wiring could be a problem if you messed up any of the can bus wiring. Wait, you are running an adaptronic ECU for an RX-8 on a 13BRE? Or is that and REW?

Reset the ECU...with the key on...throttle plate should open normally

If you start the car...and about 5-6 sec later the throttle plate stops reacting normally and will only open about 5%.....you are in limp mode...likely caused by OMP problems. You either have a faulty pump..or a wiring fault.

You can fault check the harness...but the easiest way is to use a known good OMP and if it doesn't work...check the wiring after...cause usually it is the pump position switch or a problem with the connectors

And when you get tired of all the BS from the DBW throttle closing when it shouldn't etc.....then you will go to a cable throttle like I did :)

Thankyou for the reply's,

Don't really want to fit a cable as it looses all the great things that happens to the RX-8 chassis

We have the RX-8 OMP that literally bolted straight to the FD block.

With the OMP we have two ports blocked off with just two to feed the REW injectors but I don't think this would be a problem as I dont think the OMP will know its not pumping oil out of two of the ports.

Thing that's puzzled me about this if its in limp mode, normally if its in limp mode you normally need to do something to get it out of it, with this you just turn the key off and start it up again

One thing we are struggling with is that we have no live OBD port so we cant read any codes off.

Anyone got an OBD wiring diagram at all please.

BTW, I have deliberately not cut any wiring.

You need to see the OMP thread on how to adjust the position sensor on it. Taking an OMP and bolting onto another engine can impact the position sensor adjustment point. There is nothing about the adjustment in the FSM.

Otherwise the Adaptronic has zero control over the DBW or OMP systems so they need to be fully intact and operational or the factory ECU default into limp mode. As discussed in the OMP thread, when it goes limp mode for the position sensor there often is no CEL code.

Can't go to a mechanical TB with the RX-8 Adaptronic unit. For all intents and purposes it is a piggyback setup. It needs the DBW system for idle control and to keep the OE PCM happy. Doing so would require a different aftermarket ECU.

None of the other stuff you mention should affect anything. I'm leaning toward the OMP position sensor. You will see that the holes for the two sensor screws are slotted. This allows the sensor position to rotate on the OMP body. Mark the current position with a paint marker or something. Loosen the screws and rotate the sensor a bit in the CCW direction, lock it down, and retry. Keep at it until you run out of adjustment, but usually it doesn't require anywhere near that much. So give that several tries and see if it makes any difference. If for some reason you already took the sensor loose then start in the full CW direction and start adjusting CCW from there. That will likely take longer to reach the happy spot. Assuming this is the issue.


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Many thanks Team RX8,

We have now sorted the OBD wiring and have read the codes, sure enough PO 1688 is amongst the 16 codes we have brought up.

Removed the two OMP pipe bungs started the engine and nothing came out,. would this happen with an out of adjustment position sensor?

Also I now need to find out from Adaptronic or somebody who maybe knows on here if we need a front O2 sensor as my guy now thinks this closed loop facility may only be available on the stand alone Adaptronic only.

Do you know if any of the other codes below other than the OMP with throw the ECU into limp mode so we don't cure one bit and still have another going on ??



PO113
P2008
PO443
0037
0031
0000
0102 map sensor
1688
2259 air solenoid
0661 solenoid
0037 cat sensor
0031 front O2 sensor
0113
0300
2201
1300

Really appreciate this help.

Do you have the MAF plugged in. Seems to me it acts weied without the IAT sensor in rhe mix

No MAF as we though we would be able to use the integrated MAP sensor in the Adaptronic to take over this function

If you have the BBC wiring still plug it u n and see...mine faulted without it

Sorry but what is the BBC wiring ?

Lol....autocorrect on my phone...must think your you're a Brit ;)

Just the stock wiring :)

Sorry and thank you

Pretty sure because the rx8's omp(I believe-about 95% sure)rotates in the opposite direction from the earlier models.

Again people, you can still have dsc and a mechanical throttlebody...There's no real need to have the smaller dbw. Cive if you want more contact through pm's.

Many thanks for the info dznutzuk as it gave me something else to check and elimiate.

Checked the direction of shaft on an FD and FE engine and they both turn clockwise.

Tomorrow I will try a different OMP on the car and see what we get.

I know it may come to that yet but I really dont want to fit a cable unless I have to

Check the actual gears on the omp shaft inside the cover and you'll see this, unfortunately...

Not sure why you need the pump hooked up to the engine on a REW anyway...they are fine with Premix only. ( just zip tie it someplace accessable until you get everything working :)

Race car especially...easy to add mix to the fuel

Λ Yup Λ

I would happily just premix but we are using the piggyback Adaptronic so we need to make the RX-8 OMP pump work somehow to stop the stock ECU going into limp mode.

Arrrrrggggggggg, this means I'm really missing something as both engines turn the OMP shaft the same way so I don't understand why the RX-8 would then turn backwards

Only solution I can think of if this is correct is to get the ECU broken into to remove the limp mode map---------then I can premix

The pump doesn't need to be hooked up to the engine to work correctly for your application. It has no way to know if it is pumping or not...you just need to have it plugged in to the harness and have the switch set correctly if it is wrong. It is actually easier that way to adjust the switch till it works...much easier access ;)


I had mine zip tied to the ABS pump area until I got tired of the throttle issues...and just deleted it altogether...but I'm not running an Adaptronic so I have no issues with needing the stock ECU to run anything except the dash. For that I just retained the stock trigger setup and the oil pressure and temp sensors

Subbed, this is going to be interesting as I am looking to do something similar.

I have my omp in a plastic bag behind my front bumper, I didn't need to adjust anything-just as it came off the stock motor. Like this, it won't go into limp mode Clive.

Huge thanks guys, I will hook another OMP to the car today and see what we get.

We bolted the OMP onto the engine ( it fitted) and plumbed it on to OMP pipe ports because I presumed the OMP spindle needed to turn to let the ECU know it was working