Cranks No Start after Turbo Replacement

D

DatsunZ

Greenie N00B Member
Greenie Member
SOLVED… see whole thread for more info…

So my pretty much stock Speed6 needed to undergo exhaust surgery after a number of holes were starting to get annoying and some boost issues that I had a feeling might be catalyst or exhaust leak at a turbo gasket. Got deep in there to replace the the factoy downpipe with a 3” aftermarket from Circuit Werks I got cheap locally (after $10k in dog surgeries these past 12 months I unfortunately needed to do this cheap). Anyway I discovered a broken turbo stud and a cheapo eBay rebuild turbo lurking in there that was clearly not holding up, so it turned into a turbo replacement. I replaced with a rebuilt K04 that I found locally, looks like a Chris Ward rebuild and everything feels tight and smooth.

All that to say that I’m pretty sure the turbo is not at fault as to why the car won’t start now.

2006 Mazdaspeed6 w/ 142k miles. No serious mods beyond a few reliability parts described below.

Symptoms:
- cranks but will not start. Once or twice I could smell some faint fuel, and there is the occasional thumping like it is trying to fire over.
- CAN Codes U1900, U2516, U0100, and I had a code pop up that had to do with the Instrument cluster but after clear it hasn’t returned. (See photo)
- multiple batteries, chargers, jump packs tested in combination. Makes no difference though when using battery only it seems to get large voltage drop.
- tested grounds and fuses and none were blown or had crazy high resistance. Except for a few fuses that will go from 0.2ohm resistance with key off to 4-8ohm with key on which seems weird.
- original credit card fob worked fine before and had battery recently replaced. Now it won’t unlock the doors and the keyless entry button won’t function (immobilizer issue???)
- ECU is on Versatuner completely base tune since the only mods are CS BPV, EBCS in bleed mode, and CS HPFP internals.
- tested coils (1 is brand new) and they all ohmed out the same. Wires to the coils also had 12v on power, 5v on reference, and ~50mV on the gnd (is that normal to have some small voltage on that ground?)
- EGR valve was cleaned of carbon while it was out, and I followed the instructions on this site so the solenoid was removed and never submerged. Now the solenoid is getting nearly too hot to touch with key on engine off (possible internal short, or short at ECU???)
- we did try to weld a nut onto the broken turbo stud for removal, but the battery was fully out of the car and the welder ground was on the turbine housing next to the broken bolt. And I’ve welded on this car before without any issue.

Any help would be appreciated, but I did go ahead and make an appointment to tow it to a dealership in a few days since I’m thinking a module got fried somehow. If you want anymore info for troubleshooting I’ll try and get you any data or answer questions.

Thanks in advance for any help you offer!IMG_6048.png IMG_6040.jpeg
 
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JohnnyTightlips said:
Check the purple circle ground. Make sure it is attached.
Click to expand...

I’ll give it a check when I get off work, though I didn’t remove any ground wires only connectors for the main engine harness on the driver side. I did go through a number of ground wires and cleaned some up, including one near the HPFP, but the one I cleaned up was in a slightly different location with a 2-pin connector to a small module. I wouldn’t find it hard to believe that ground you mentioned may have gotten damaged by welding, though if it is messed up it’s probably only the first step in diagnosis.

thanks for the helpful picture. I’ll update later when I check it.
 
Checked the ground wire connected near the HPFP. For Speed6 it appears to be in a slightly different location. It was in very good condition and had continuity to the negative terminal. I gave it a little clean anyway.

Update on my own sleuthing because I hate when troubleshooting threads end with no explanation or never post updates.

- Yesterday the key fob started functioning again. Possibly it was functioning the whole time, as in my last year of ownership it is sometimes very picky and only works when Mars is in retrograde on the 3rd Tuesday of the month or some weird shit like that.
- Fuel Rail pressure reading at >400psi during cranking
- The U0100, U1900, and U2516 are gone, but…
- Now it has code B1318 which seems like a BCM malfunction code.

Cranking RPM with a full battery is low and voltage still sags. Looking at the main positive cable it appears to run to the starter first then to the Alternator. The resistance on the wire isn’t absurdly high, but is it possible that a bad starter solenoid (from high amperage pulled through somehow from a spike caused by welding) could be robbing all my electronics of the power they need since it is the first inline power sink???

My next course of action before it goes off to the dealer is to try and remove Versatuner from the ECU. I’m sure I need to do that for Mazda to access the ECU and if I can’t write to the ECU than it is likely fried.
 
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Easter Bunny said:
jump it from another car if the voltage is dropping while cranking
Click to expand...

I have tried every combination that can be done with my old battery, new battery, running car and jump box possible with no luck. The only thing I haven’t tried is making new connections with new wire to try and bypass grounds/power wires that are controlled by modules.
 
Hmmm.. you sure that ground wire johnnytigh circled is on ?

Battery terminals all cleaned and making good connection?

May sound dumb ,but sometimes the ol.. push the car in netrual and put into gear and release the clutch gets the car running with a dead battery..

Spark plugs in good shape? Any fuel leaks underneath?
 
You could also check the battery fuse hot wire as it likes to melt from time to time. I know that is more common on the gen pu but it's worth checking. It is usually under some plastic so might be hard to see. I suppose it could be a dead ecu if you welded with it all plugged in but if your ground was close it should be using that and not running through the ecu. Did you smell the ECU to see if the smoke monster was released?

The pic I linked is for the ignition coil ground so if that is not working you will not get them to fire.
 
So I got the car to fire up during my lunch break today. I’m gonna mark this solved and then share what I did, and my hypothesis about what the issue was, but admittedly I am not sure what the actual problem was and which of the steps I took that fixed it.

IMG_6049.jpeg
Red - this is a ground wire that I believe @JohnnyTightlips was talking about, mine was still shiny with factory zinc and had continuity but I cleaned it any way.
Green - this is a small module with a 2 wire connector that also appears to ground to the engine given the locating bracket is metal and bolted down. Cleaned this one up as well though it spec’d out fine with multimeter.

After cleaning up those two grounds there wasn’t much difference. Still cranked w/ no start. I possibly heard a bit more thumping like a cylinder would almost fire and the cranking speed seemed higher. This was with a new battery and jump box. I had my old battery on a massager overnight for the 2nd time since it was only 18 months old didn’t want to give up on it yet.

I ran codes using my phone OBD2 app and got only codes B1318 and another B code that was impact sensor related. After this I flashed back to the factory tune with out issue so the ECU/PCM seemed to be functioning fine. I had heard FORSCAN might be a better deep diagnostic platform that was free so I hooked up to it and confirmed that the codes I was getting were resulting from low voltage at the related modules (BCM & SAS).

*I took a risk with my modules in the following section, some of the stuff in FORSCAN can cause issues if you do not know what your are doing*

It still wouldn’t start at this point so I ran some of the self-test procedures along with an SAS related reset. After this attempts to crank sounded a lot more promising and I cranked the vehicle for a few seconds until so I could pull codes again. This time no codes were present and it started up on the next attempt.

I have 2 hypotheses for why this happened:

1. Due to the strangeness of the car starting out with tons of codes and electrical gremlins after the turbo install, but those codes going away over time with the battery unplugged, it’s possible that some modules got reset by a power spike (welding) and needed time to communicate with other modules. The module tests in FORSCAN may have caused those modules to start communicating correctly by running them through self tests and taking them out of a protection mode.

2. The inertia switch fault code that I was only able to read using FORSCAN may have been telling the car it was in an accident or flipped over causing the vehicle to cut fuel. This likely occurred from the violent rocking of the engine that was necessary to get the downpipe and turbo out, then to fit the new turbo in. The SAS reset may have told the module it’s all good which turned the injectors back on. When I rebuild I’m sure as shit going to get the AC hose reroute kit.

Hopefully this is helpful to anyone who runs into similar electrical gremlins like I experienced.
 
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