cmolitor

Hi All,

After a rebuild of my '05 I find I have no spark. After all the troubleshooting advice on these forums I am left with thinking the PCM has failed. Using a scope I have checked the ESS input @ the PCM (after numerous NVRAM resets) and am consistently getting a good signal. Also, with IGN 'on', waving a feeler gauge over the sensor produces several responses, so I believe the PCM is processing the input. However, when monitoring the feeds to the coils I get nothing. Well almost nothing, I do get a voltage offset of ~1V but no pulses on either leading coil. I have checked @ the coil and @ the PCM connector. I've also done all the continuity and ground checks (#1 on pass rail for PCM) several times and all is good. I have done the spark check @ the plugs with test lights and pulling the plug and grounding the old fashioned way as well. I've replaced the coils to cover the bases also.

I am out of ideas .... seems unlikely the PCM would fail while the the engine was out, but ESD can be a nasty little bugger!

Anyone think of anything I have missed?

cmolitor

Not the PCM, but still no spark. Can someone tell where their trigger plate falls, relative to the ESS? Mine is not dead center, but offset about a 1/3 of the way towards rear of vehicle. Wondering if I am not getting a strong enough signal to PCM to register as a valid input.

Loki

iTrader: (1)

Is it possible something has triggered the antitheft system? Is the starter turning the engine?
The ESS sensors can be finicky, is this an original Mazda unit or aftermarket?

cmolitor

Turns over normally. I have tried both the original (I think) Denso ESS and an aftermarket, no difference. I wish I knew more about Mazda control systems, but I would hope if the PCM is receiving a valid ESS input no associated codes would be set (P0335 or 6). I show none either active or pending, but I'm not sure how reliable that logic is w/o a running engine!

Loki

iTrader: (1)

Silly question. Are all the fuses OK?

Red line envy

Sorry if I missed it but are they stock coils or the gm coils? If you have a BHR kit or any other check the ground for the kit and all other grounds. Especially the one from Lim to body.

cmolitor

There are no silly questions, just silly walks ;-) I've checked every fuse with a meter, both locations, all good, but can't hurt to triple check. Stock coils. Swapped the trailing with the leading just in case I had a double fault, no effect, same with the wires and plugs. Can't imagine all that failed between the last time it ran and now. Also checked all the grounds, but was planning to check all those again, along with continuity checks on all ignition circuits. Thx for the dialogue gents.

Red line envy

I found that the two grounds on the body passenger side up near fender had paint under them. And I think one or both of them are ground for ecu.

cmolitor

Wednesday update: Rechecked all fuses, none blown. Cleaned and verified (resistance less than an ohm) the 2 grounds on pass side and the 2 on top the block. These seem to be the ones for PCM and the coils. One thing I noticed was that occasionally when doing a test start I would get a single pulse on the timing light, couldn't get it to repeat consistently. Seems maybe the PCM is not receiving a necessary signal (MAF?). I had done a battery disconnect/reconnect + ESS relearn prior to one of these occurrences, 2 others were after teh car sat for a bit, never on subsequent start attempts. Which brings me back to how strong an ESS signal is required for the PCM to detect? Mazda shows 3.5 to 4.5V when running, I'm getting slightly less than 2 while cranking .....
I'll check the rest of grounds next.
Any thoughts on what other sensor inputs are required to start?

Red line envy

Just recently after my rebuild 2000km ago I had a no start issue (a couple times lol) that presented with an ess code. I replaced the sensor and still the same result. After some reading I learned if the starter is not spinning fast enough the ess won't tell the ecu to fire. I was getting a kick or two at the first of cranking then would do nothing but spin. Replace starter and fires right up.

cmolitor

You are definitely on to something there. I jumped mine and the RPMs went from ~200 up to ~300 when attempting to start and on 2 occasions I got a steady steam of pulses (fuel pump fuse is pulled) but still sporadic, but it's more than I had. From what I've read 300RPM should be sufficient. Anyone have any idea of what constitutes a 'good' number from marginal? I don't have any history on this car, but the starter looks pretty shiny and new.

cmolitor

also, I am now throwing a P0336 code, ESS range performance issue

NotAPreppie

The car should start and run (poorly) even with the MAF disconnected so I doubt that's a factor.
I've seen compression test results with RPMs as low as 170. If your start can do 200+, that shouldn't be the issue.

It shouldn't be possible to do it wrong but can you verify that the ESS tone wheel is installed properly (not flipped)?

I expect you've already found this, but just in case you haven't...
Here's a link to an older copy for the factory service manual:
M A Z D A

Here's the FSM page for P0336
DTC P0336

And the FSM procedure for crank but no start
NO.6 CRANKS NORMALLY BUT WILL NOT START

thew

see this Thread here and then give it a try.
https://www.rx8club.com/rx-8-discuss...ff-yes-222923/

Red line envy

cmolitor

I was thinking about the trigger wheel being reversed, so yesterday I tried to flip it and luckily the Mazda engineers got that one right in that it cannot be reversed, the alignment pin holes and mounting holes don't align. Thx for links but I've been pouring over those for weeks now ;-( thx for the info on RPM's, was thinking that should be the case, but verification helps. I think I'll hold off on a new starter for a bit as it was able to start prior to the rebuild and RPMs should be high enough @ 300. I've reset the ESS profile more times than I can count and I guess the one good thing is that the P0336 code always (eventually) comes back, so the root of my evil must lurk there! Back to troubleshooting

Red line envy

Have you had the rebuilt engine running yet? Mine would not start at first and I had to push it to bump start it. After that there were other bugs but it still started after the push. Sometimes it takes a lil more of a spin to get it going the first time.

NotAPreppie

He's not getting spark. That's an electrical problem, not a fresh motor problem.

Red line envy

Yes but if the motor is not spinning fast enough the ess will throw a code and cut fire out. (No spark) If he pushes the car and pops the clutch and it starts then we know that's the problem. I just did the exact same thing about a month ago. Dealer said the same thing that it's a spark problem and all that and I had to argue my point. Once I got the starter on and it fired up I drove to the dealer and showed them. They couldn't believe it. Just saying it's worth a shot.

NotAPreppie

He reports the motor is spinning at 300 rpm.
That's faster than any S1 with the original starter and battery. That's faster than most S1's with updated starter and battery.
Hell, that's faster than my good engine spun with brand new 14-tooth starter, new battery, and one trailing spark plug removed (which was 270+ RPM).

It's not his starter. He's got ESS issues.

cmolitor

I went back and double checked my RPMs and today I am getting around 213 with jumper cables ..... not sure why the same scanner was showing over 300 just a few days prior. Regardless, the 213 is more believable from what I've read here. With the jumper cables attached I am getting intermittent spark. Timing light shows sporadic pulses and the engine pops when that happens. Hooked up my scope to the ESS inputs to the PCM and got confirmation of erratic signals. After checking all remaining grounds and PCM feeds and doing another circuit resistance check I believe the integrity of the components is pretty sound. I even sistered wires from the ESS to PCM just in case I had an intermittent open in one of those wires.

So, I am going to get a 2.0kW starter and see what happens, stay tuned!

Red line envy

I'm gonna say it will fire right up. Can't wait to hear back from you.

ASH8

Coming in late with a few Dumb questions from me, maybe worth a try? (not in any particular order)..

I guess you are not seeing any 'settled' Warning lights in IC (Instrument Cluster)?.
Not suggesting you have But have you changed the PCM at all?...if that is a no, have you renewed or changed the IMMO (Immobiliser) Unit, as I think (memory) your year RX-8 has the 'Transponder Type Ignition Key', or is it Switch-blade, either way a defective IMMO module will not permit car to start.
IF you have renewed the PCM/ECU then it must be Configured with Mazda IDS, however IF you can read some DTCodes then I doubt it is either of these two.

Agree about the Starter and Battery, the S2 Manual Starter is THE Replacement UNIT to use, more teeth faster turnover.

Also Ground Connections in the First 3-4 Years 2003-2007 Mazda had issues with poor Ground Contacts, some owners even piggy backed new heavy gauge Negative Battery/Starter Leads, from memory someone in the US was selling new specific RX-8 Ground Cable Kits.
Also the smaller Ground Terminals (6-8 wires) needed re-seating/cleaning which you have done.

Good Luck.

cmolitor

I did swap PCMs last week. Had them pull the security info from the old and transfer and flash w/ all the other updates, no change noticed. And yes, still getting codes to set with the P0336 being the only consistent code. I never got a good understanding exactly what the immobilizer does, but seems it cuts out the starter, spark and fuel???

Spent a ton of time on all grounds, cleaning and measuring resistance to verify the integrity of them. Someone had added a huge wire from the chassis to the RH side of the block, so whomever had issues in the past

Unsure of your comment about 'settled' cluster lights. With key on I have trac, brake, batt, engine(flashes a few times and stops), TPMS, flashing DSC OFF and power steering light. Key off the security light flashes about ~2 secs.

Thx for the comments!

ASH8

Who is 'them' that pulled the 'security info'?

I guess you know this but None of the modules (Immo, ECU, IC, etc) are Plug and Play.
Whether Brand New or Used.
If used must be identical Model Year and same for VIN range.
Must then be re-configured by Mazda IDS, including brand new parts.

Who exactly did this data re-configuration of the used ECU?
Wrong IMMO config will prevent car starting and YES it cuts spark.