Hello all,

Back in the end of April I lost a rear coolant seal in the engine (153k miles) causing the obvious coolant spraying everywhere under the hood. Through the month of May I swapped out the engine with a rebuilt one from Atkins Rotary and cleaned up around the engine bay and so on while she was up on stands. In the first week of June she went all back together, everything cleaned up. In the last couple months I had a few random issues with the different electrical components of the car related to it's operation. It started with Sensor Circuit Malfunctions in the MAF and throttle body. Then I saw communication errors with traction control. I replaced both the MAF and throttle body and the traction control issue went away as did the Sensor Circuit Malfunctions.

Or so I thought, in the past month (I've been out of town since the end of June) or so I started getting a Sensor Circuit Malfunction for the crank-angle sensor. So following suit with the other sensors I went out and got a new one. Once installed I did the pedal reset and immediately got the Sensor Circuit Malfunction code back. At this point I figured maybe it was a ground since the engine is painted and I did some touch-up painting under the hood. Upon testing all the grounds and seeing they all showed less then 10ohms of resistance I began testing the wiring harnesses for breaks or shorts. After not being able to locate any issues in the harnesses I decided to look in the service manual for what grounding points do what and I added additional grounds from the battery to certain grounding points around the engine bay. This brought all my sensor and wiring harness grounds to .5ohms or less on my meter. This did smooth my MAF and O2 readings but no dice on the crank-angle sensor. I then hunted to make sure I didn't miss any grounds or have any other loose connections and was unable to find any.

At this point the service manual calls for a PCM replacement so I bite my lip and drop it off at my local Mazda dealership to get both a second opinion and a new PCM. Their tech calls Mazda and goes through testing all the grounds and harness a second time and lets me know that everything showed Mazda spec or better for continuity. Mazda then has him do a full reflash of the car's systems and "tap" on the top of the PCM. When all this fails to get rid of the Sensor Circuit Malfunction we agree that it must be a circuit in the PCM. I was also told that when they had the car hooked into their system they could see the PCM constantly searching to calibrate the CAS and soon as it could grab a sync it would loose it moments later.

The new PCM arrived last Friday around noon and was installed and configured by 1pm. Now the immobilizer won't take the keys. Friday ends with the car in lock out mode and the dealerships account frozen due to excessive failed key coding attempts. Finally after another complete re-flash the keys code to the car Saturday morning and the car is able to be started on the new PCM for the first time. Immediately the PCM throws the code for a Sensor Circuit Malfunction on the crank-angle sensor. In speaking with the dealership, the tech and service manager are pretty baffled at this and the Mazda hotline doesn't have an answer or even a troubleshooting process to try at this time. So I am turning to the forum for ideas. I will finally be back home either tomorrow or Thursday from my long stay in Manhattan and will be just picking the car back up since I'm not looking to run up a massive bill.

Here is a list of all sensors and components replaced:
-Wideband O2 Sensor
-MAF
-Throttle Body
-Fuel Injectors
-Crank-angle Sensor
-New LS1 coils and wires and plugs (BHR kit) (the Mazda dealership complimented on the quality of the kit)
-New PCM

Now the car does run, just has an intermittent rough idle and a long start. Often have to wait for a fresh Sensor Circuit Malfunction code before it will start. Any help or ideas will be appreciated and looked into. If any more information is needed just ask and I will provide the most indepth responses I can. Thanks in advance!

Mike

 

About the only thing left is the wire harness from the Eccentric Shaft Position Sensor (CAS) to the PCM. Have you checked continuity in the harness from the ESPS to the PCM. Also check the connectors for loose terminal pins and bad connections/corrosion.

 

I know while we were troubleshooting through Vyndictive's engine issue one of the things we had him do was clean the eShaft sensor connection and the magnet used by the sensor. Both were pretty nasty before he cleaned them up. I also wonder based on the work you had done and the sync resetting the way it is if you don't have a short on that connection.

 

that's what I kept thinking, that it had to be in the harness. I did open up a few sections to check the wires inside but haven't been able to fine anything yet and we do show a connection to the PCM. Tho at this point I will be double checking that once I'm back. I didn't go over the connector really since it felt like it made a good connection but I'll check it out too. I'm also thinking maybe if I can get my hands on a scope I'll connect it to the sensor and see what I see when the engine cranks.

I'll update tomorrow as to what I find once I'm home.

 

Check both sides of the connection, inside and outside so 4 contacts in total.

 

I checked the connectors and the harness again including for "cross-talk" between the 2 wires and everything came out good, all 0's on the wires and no cross talk. I then looked at the connectors and it appeared that the sensor end may have been opened up a little much so I pinched that close better. Haven't been able to start it cuz the battery was dead when I went to pick it up so I just used road side to bring it home. Charging now so I'll update again once it's had some time on the charger (only a 10A).

That said, I'm hoping it turns out to be a loose connector. Tho I did have a way out there though. Could there be anything up with the plate on the crank? It only goes on one way, I've tried all ways just to make sure lol cuz I've just run out of ideas. This is really boggling. It does seem to be very rich at start but don't think that would cause an issue.

PS: I do have the Walbro pump from BHR and installed per MM's diy.

 

Huh? You mean the sensor on the eShaft? It only does go in one way and the harness should click in. And just because I can..thanks Jon for your handy M$ Paint Arrow. :D



Was there any corrosion on the connections?
Did you clean the magnet?

 

the sensor is only 3 weeks old, and the connectors were still shiny, tho I still used some electronics cleaner I had on them and then let it dry good. And ya, that plate lol.

 

Hrmm....reset the NVRAM yet? (Again stolen from Jon)

1) Turn the key to the 'ON' position (do not start car).
2) Rapidly press brake pedal 20x within 8sec.
3) The oil pressure gauge needle will sweep to the middle and back down indicating the NVRAM was cleared.
4) Turn key to the 'OFF' position, then start car.

 

ok, seems the tightening of the pins in the plug fixed the sensor error. Now it's flooding itself lol but I can fix that with a flash and I may take a peak at the fuel rail since there is a weird noise coming from that location shortly after you shut the car off. Sooo I'm thinking I had a couple things going on and one was the little regulator may be stuck but I'll dig into that later. For now I'm going adjust the fueling.

Anyone ever had issues with the fuel rails before?

Also, the 2nd O2 doesn't do anything with fueling right? Cuz that's been my belief and so I don't have it installed right now

 

The regulator thingy you are talking about it a pulsation damper

What kind of noises is it making?

They used to fail on FD's...and cause fires...but haven't heard anything about problems on the 8

You shouldn't have to modify the tuning if you have stock injectors and FP.....??????

 

stock injectors, walbro FP. I wouldn't think so either but you can see the misty clouds of fuel.

It makes an audible woosh-ish sound with a bit of a gurgle to it. It's hard to explain but if I can I'll try to get a sound clip if people want. But I was thinking it had to do with the fuel system. There is no leaking fuel under the hood tho.

 

Maybe coolant bubble? The pulsation damper shouldn't cause problems with the fuel delivery at idle at all....

You don't need the second O2 sensor...front one is working though right?? No new CELs?

I would try and deflood it and assume the fuel is correct till proven wrong..before you change the fuel tables too much

 

It'll make the sound whether you start the car or not, just have to turn the ignition on and off.

 

Sounds like the damper then.....If it was me I would PU a used one somewhere and replace it just to be sure....not sure if it would be worth trying to take it apart. Don[t think you can buy the diaphragm or anything anyway

I have a couple lying around if you can't find one closer

 

Little extra information:

I have confirmed the new PCM is an 2005 MT CA-Emissions unit that has been flashed to run the car and work with the immobilizer. Though I do not feel this makes a difference outside of my efforts to hack and provide PCM ROM definitions. I have confirmed that the PCM is now able to (so far) accurately read the crank-angle sensor without any Sensor Circuit Malfunctions. This is all good news and may mean that I have had more then one(1) issue that has been giving me a rhythmic pulsed idle (she will idle and smooth out then suddenly flood with fuel and the idle will jump) as well as the longer hard starts (the Mazda techs said it sounds like the car is flooding itself on startup).

Several months ago I put in a new set of P1 injectors (the nice little red ones) but I did keep my old ones around even tho their nozzles are covered in crud. I have considered testing the injectors as the issue by swapping in the old injectors temporarily but first I am curious if the damper could have this kind of effect. Under load (ie. while driving) the car operates perfectly now but will often stall when it attempts to come down to idle.

If the fuel flow from the Walbro pump were to be pulsed could this cause the injectors to release more fuel then intended?

I did follow the guide on the forum for the Walbro's installation and it had been function fine in the car for about 2 months prior to the coolant seal on rotor #2 letting go so I don't feel as tho anything is wrong with it's installation.

That said, the fuel rail (ya ya stupid me) was left with the inlet uncovered on the engine for about 5 weeks while the swap and clean up was going on. Could this have caused the diaphragm to dry out or in any way become damaged so that it won't function correctly anymore?

I have my doubts about a bad injector solely based on my operating gas mileage. While running (and moving) I see a solid ~20mpg, it is only when I am idling or starting the car that fuel can be smelt out the tail pipe. During traffic and times of long idling I do see a heavier use of fuel (in my mind beyond the level it should drop to and has dropped to in the past).

Now just keep in mind most of the fuel system (minus the FP and P1 injectors) has 161k miles on it.

-Mike

PS: Thanks for everyones help so far, between this post and others I have had few issues with maintaining the car.

 

alrighty, the car is definitely running crazy rich at startup and idle. Since I did change the P1 injectors I am thinking I can try swapping back the old P1's back. But that's a project for tomorrow.

For tonight I will be looking into fuel issues and fielding any ideas from the forum. I may still change the damper on the car just in case it's a surge issue but I feel as tho this is more then likely an injector issue.

Quick questions:
Will the car start with only the P1's hooked up?
What could cause the car to inject more fuel then necessary other then bad injectors?