mdrizzyo

Hey guys!
I posted awhile back about accidentally ordering a 4 port when I needed a 6 port. Little update, I did end up getting the 6 port from the company. Had to pay return shipping and then the new shipping fee on top of the difference for the 6 port (~500 dollars extra) but it's all squared away. The new engine is great! Good compression, everything is looking just fine. My new problem is that the ECU seems to be fried. We're getting an oil pump code. We replaced the oil pump, and then we checked to make sure EVERYTHING was wired correctly. At first the old ECU left the car immobilized. My boss (I work at a repair center) looked at it and got it cranked. It started right up, and it continues to start right up like a top every time. But now when we test drove it, it ended up in limp mode. We keep resetting the codes just to be able to move it back and forth, as needed to fix other cars. It doesn't go into limp mode until we get it on the road. You can rev it all day. Won't die, nothing like that. My boss noticed a little burnt spot on the ECU and said he's thinking that's what it is. You guys have any experience with this stuff? We're getting a locksmith out here to program the key to the ECU now, just really praying that's our issue.

9krpmrx8

iTrader: (46)

You mean oil metering pump. The oil metering pump code will cause limp mode and that means the OMP position sensor is out of whack or it was damaged during the pull or installation. Unless you did something really stupid like hook the battery cables up backwards, the ECU is fine. And the key should not need reprogramming either if you just replaced the engine.

Your shop is exactly why people should learn to troubleshoot their own issues. Your boss doesn't have a clue.

mdrizzyo

You're totally right, we don't have a clue. That's why I'm here asking you guys. This is my first car project, try to understand that we don't all have years of rotary experience under our belts. We don't see a lot of Japanese vehicles, we do a lot of Euro and Diesel. This is a totally new ball park for us. Thank you for your help!

9krpmrx8

iTrader: (46)

Cars are cars. You run the code and follow the troubleshooting procedures. Searching helps too since limp mode related to the OMP has been discussed about a million times.

dannobre

iTrader: (3)

Very often the positioning switch fault doesn't set a CEL....it's easy to tell if you are on limp mode... reset the ECU...start the car. If the throtitle works for about 8 sec and then stops opening properly you have a limp mode. Most likely from the pump

if the car revs normally then it's likely something else 😎

dannobre

iTrader: (3)

Very often the positioning switch fault doesn't set a CEL....it's easy to tell if you are on limp mode... reset the ECU...start the car. If the throtitle works for about 8 sec and then stops opening properly you have a limp mode. Most likely from the pump

if the car revs normally then it's likely something else 😎

mdrizzyo

This is his boss, lol So we ohmed the metering pump and everything checked out. I ve even swapped it just to make sure. I checked live data and no matter with the metering position sensor stays at 7. I tried moving the location seeing if it would change then tried multiple locations and clearing the memory. The reason i was thinking its pcm related is due to running a continuity test and checking wires and connections and everything. connected to the pump and position sensor. The position sensor that was suppose to come with the used jdm motor was damaged along with just about every sensor on the motor, (EBAY) , but the pcm casing was actually dented on oneside causing the pcm to get so hot it would literally burn your hand, so EXPERT RX8 guy, if live data won t change when i change the position sensor adjustment and it immediately goes to limp mode after a few seconds on start up then whats the next step? Sadly we dont get alot of rx8s i really think the engineering is cool and enjoy driving them, but support is limited due to smartasses drawing conclusions up and posting their guesses on diagnosis. Just kidding but i swapped the position sensor and put it back in the location it came in. Also it drove down the road great to we threw and new battery in it and reset the memory. Any info on your area of expertise will be greatly appreciated. But we did indeed follow the trouble shooting diagnostics off shopkey with our own issues. Thanks,

mdrizzyo

Thanks dannobre we have already done those steps and swapped the jdm pump to the pump with the old motor.

9krpmrx8

iTrader: (46)

How was the ECU damaged? Was this the original ECU from the car or did it come with the JDM engine? If not why wasn't the original ECU used?

If the OMP on the Ebay engine was damaged, does this mean you swapped on the undamaged OMP from the original engine?

mdrizzyo

It's the original ECU that came with the car. It was damaged with a dent in the housing. could visibly see where it was heating up in the inner housing. The pump wasn't damaged but the position sensor was damaged. Swapped it from the old motor. and then I swapped the pump from the old motor to the new one just to make sure.

9krpmrx8

iTrader: (46)

Well using a known damaged ECU isn't very smart. Did it work fine while damaged on the original engine? and you should have swapped the whole pump assembly with the sensor from the old engine to remove any user error. Lot's of variables in play now.

mdrizzyo

This won't make it seem any better, but I actually bought the car with the bad engine. Got a screaming deal on it (or so I thought). With everything being tested to make sure it's in good working condition, do you think it's worth towing from our shop to a mazda dealer? (40 miles away, so it's a big tow fee). They informed me they would program everything for 233 bucks, to include programming a new key so I have a spare. What would be your first step from this point?

mdrizzyo

with the ECU knowingly being bad, it seems like the only logical thing that could be going on.

9krpmrx8

iTrader: (46)

So your car with a bad engine and damaged ECU was tested to make sure it is was in good working condition? Just set it on fire and be done with it.

mdrizzyo

well i didnt know it was damaged till it was heated!!! its not like i was expecting it to have a dent in the housing and seeing it heated up, besides. After i knocked the dent out it did not heat up anymore. sometimes not everything is so cut and dry. I was hoping it would work fine so he wouldnt have to spend two hundred dollars at a dealer to get a new one programmed. I DID ALSO SWAP THE PUMP AS WELL after the p 1668 problem persisted after intital diagnostics. The original engines main eccentric bearings were totally done. it was bought not running. hoping a simple engine install would put this rx8 back on the road. Sometimes with repairing cars for a living especially these European Reverse Flow Turbo bmws and New Diesel Vehicles isnt so cut and Dry. I imagine the original owner must have dropped the pcm or something try to figure out why the car wouldnt start, sadly it simply had no compression.

In order ;
1. Installed JDM engine and used the pcm that came with car since PATS wasnt enabled.
2. Noticed pcm was getting very hot and had a communication error with our Snap on Verus scan tool disassemble the pcm noticed the inner cover was shorting on the pcm board. fixed housing.
3 Then went ahead and through a new battery in it.
4. After battery was installed the p 1688 code was set and car went into limp mode.
5. Did initial diagnostics, tried clearing the code. tried adjusting the position sensor multiple times.
6. Noticed code would immediately return after a few seconds on start up.
7. Then ohmed out both pumps when engine cooled down and both were within spec.
8. Went ahead and swapped the pump out for clarity and peace of mind.
9. Our Shop key says the problems for the code.
Are a possible Short to Ground on metering pump Circuits.
Metering pump external leaks or pump switch failure.
or pcm. So knowing know after the pcm was shorting on the housing and doing the process of elimination.

Lol telling us the variables in play now. Sometimes thats part of working on cars for a living but i did step by step diagnostics so far from our ShopKey Program. Im not a mind reader i didnt know the ecu would be shorted to the housing and in any case i would still try to use the pcm if knocked the dent out of the housing. So he wouldnt after to spend money at the Mazda dealer.
I even went as far as going to forums and finding out about the position sensor which imformation is scarce on . On shopkey. So i have been troubleshooting this issue.

Squeegee

wow that is "too much"