na8: Engine Won't Start, Weak spark?

sailaholic · Postby **sailaholic** » Sun Oct 02, 2011 9:49 am

having some trouble getting the engine to start while trying to put the adapatronic in.
Car is a 93 build / 94 compliance NA8

Problem:
Car just cranks and cranks, very rarely does it even catch or stumble. The area smells strongly of fuel when cranking.
Pull the leads and leave them sitting in rocker cover.......no spark (they would spark a few weeks ago when i was chasing a misfire at idle)
Put a spare plug into the leads, leave it on the rocker cover, spark looks small and weak to me, generally yellow.

Done so far:
When i first plugged the adaptronic in, the car would start and run straight away, though the hot idle was a bit screwy.
Fiddled around and got the TPS working properly (required changing the pins for the Toyota TPS).

Got all the plenum re assembled, car would start and run, but a bit rough. Swapped MAPS to an ITB map Andy had given me.
Car started and ran but was very lean, played around with the map long enough that the car got to full operating temp.
Decided to go back to the basic NA8 map and start from there rather then playing with the ITB map for now.

car started and ran but very rich (9 - 10 : 1 on my AFR gauge). Played a little bit then Switched the car off for some reason (i forget now). Couldn't get it to restart. Some times the previous starts had required a little bit of throttle pumping so tired that. No start, didn't even sound like it caught.

Tried re flashing the ecu to no effect, checked TPS calibration and re did it (reads opposite to Mazda, but the closed switch still operates normally), have swapped out the adaptronic for the standard NA8 ecu, same deal, tried the Mazdaspeed ecu i have for the ITB kit, it sounded like it would catch on 1 cylinder only and run for a bit if you kept the starter winding. would die within 5 second of stopping the starter.

Checked the coil packs, secondary windings are within specs (9.9 and 9.5 k ohms) for 94-97. The manual doesn't mention anything about a separate ignitor like the NA6.

Checked with 1red5 (previous owner), coil packs were replaced with new genuine units 30k km (4 years) ago.

suspecting it might have been flooded by this point, Left the car overnight with the plugs out and paper towel in the holes. Battery on charge.

Tried it again this morning, still with the Mazda speed ECU in it, kicked / stumbled twice and went straight back to jut turning over and not doing anything. Car was low on fuel, but not empty, put another 8 liters in anyway and it now reading just under a 1/3 of a tank. no change, still smells of fuel.

Going to see another car this morning and try swapping my coil packs on to it and see if it runs. Will also get a clean set of plugs, but i think this is grasping at straws.

Anyone have any thoughts?

Cheers

manga_blue · Postby **manga_blue** » Sun Oct 02, 2011 10:52 am

1. Could the ignition timing be way out? Has the cam angle sensor been moved? Is it back on the old mark?

2. In OEM form, the injectors and coilpacks relied on 2 good solid earth leads bolted onto the front of the inlet manifold. Without those both spark and injector operation would go weak. Where are those 2 earth leads now? They need to be bolted onto the engine somewhere.

3. Cam sensor plug OK?

4. MAIN relay OK? Mine went dodgy after playing with the TPS once. Took ages to find it. Same symptoms as weak earth leads until it fails totally.

sailaholic · Postby **sailaholic** » Sun Oct 02, 2011 2:46 pm

Haven't played with any of that, but will check, especially the earths, when I get home.

How do you check the main relay?

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tbro · Postby **tbro** » Sun Oct 02, 2011 5:39 pm

Are the plugs wet, as in lots of fuel in the cylinder??

Check the green plug on the rear of the head, it may not be reading properly and going into closed loop and flooding the motor.Don't ask :roll:

Also check earths for the ecu as Phil has stated these little shits need a good earth or you'll be up sh*t creek.

manga_blue · Postby **manga_blue** » Sun Oct 02, 2011 7:53 pm

sailaholic wrote:Haven't played with any of that, but will check, especially the earths, when I get home.

How do you check the main relay?

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All care, no responsibility. :frown:

MAIN Relay pinouts.jpg

Remove relay.
C is the relay trigger wire, D is the trigger earth.
A is the main 12V feed to the relay (test that's it's always on)
B is the 12V supply to the ECU, injectors and coils
Run a heavy wire from A to B (this mimics normal operation where 12V switched on to C will close the relay and full power will flow from A to B.)

NA8 MAIN relays can be prised apart and have their contacts cleaned just like old fashioned dizzy points.

sailaholic · Postby **sailaholic** » Sun Oct 02, 2011 8:12 pm

Cheers mate, will give that a try

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timk · Postby **timk** » Mon Oct 03, 2011 11:00 am

If you sort out the ignition issue you should consider turning on the flood clear mode that is activated when you are cranking at WOT. It has saved me a few times when my cranking pulsewidths were excessive.

sailaholic · Postby **sailaholic** » Mon Oct 03, 2011 11:20 am

Yah, that was turned on, even turned the full cut rather than just the reduce. Tried sustained cranking at wot, no change.

Haven't had a chance to get back to, it yet, probably won't till thursday. :-( .

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sailaholic · Postby **sailaholic** » Thu Oct 06, 2011 11:26 pm

these are the earths I assume? They look a bit small, but I work with big cable at work.

uploadfromtaptalk1317903489863.jpg

Unplugged / re plugged the cam angle sensor.

Checked the earths above. All clean under them and tightly secured.

Bridged the fuel injection relay. No effect.

Will send andy an email in, the morning too see if he has wisdom.

temp sensor at the back of the head seemed ok.

Both coils are definitely creating sparks but not at the strength I would expect.

Cam angle sensor hasn't be moved.

Any more suggestions?

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93_Clubman · Postby **93_Clubman** » Fri Oct 07, 2011 1:09 pm

sailaholic wrote:Checked the coil packs, secondary windings are within specs (9.9 and 9.5 k ohms) for 94-97. The manual doesn't mention anything about a separate ignitor like the NA6.

Checked with 1red5 (previous owner), coil packs were replaced with new genuine units 30k km (4 years) ago.

Going to see another car this morning and try swapping my coil packs on to it and see if it runs. Will also get a clean set of plugs, but i think this is grasping at straws.

Did you end up trying another set of coilpacks, or have you had a chance to compare the sparking of another NA8 to yours?

Was similarly unimpressed by sparking when fault finding some time ago & ended up immediately going to coil on plug. Fault turned out to be totally unrelated (i.e. fuel), so as far as I know my coilpacks were ok.

sailaholic · Postby **sailaholic** » Fri Oct 07, 2011 1:17 pm

No unfortunately didn't get a chance to check against another NA8, or swap coil packs.

.
The car i was planning to do it with was only just starting on a jump pack when i got there, so wasn't able to fiddle.

Hoping to compare against a NA6 tonight, to give me an idea.
Plan to nip down to repco today get some aero start and see if that makes a difference.

manga_blue · Postby **manga_blue** » Fri Oct 07, 2011 1:30 pm

Sorry, mate, no further suggestions but at least you know you've got decent power and earth for the whole EM system now. It's a start. Can't help thinking the problem lies somewhere in timing control though. Would be nice if you could get a timing light to work well enough to see where it's firing, even when just cranking.

sailaholic · Postby **sailaholic** » Fri Oct 07, 2011 1:39 pm

Yah i agree, a bit stumping. Plan to grab a timing light off a mate tonight and do just that.

The car is currently Cat-less. So the fuel is easy to smell. But though i would try some aerostart as it should be easier for a weak spark to ignite.
If the spark is in the right place, and the aerostart doesn't help, might have to put it on a trailer and send it to MX-5 Plus or similar.

Cheers for the help everyone. I'll be sure to let you know when i (or someone else) get it figured out.

Steampunk · Postby **Steampunk** » Fri Oct 07, 2011 2:24 pm

I'm sure Richard/MX-5Plus would lend you a coil pack, but it's seldom he has NA8 specific parts. Worth a phone call.
Has the engine "sneezed" at all? ie. after a period of cranking, and then letting it sit for a while, and then try to start again, did the engine ever make a really abrupt (and loud) puffing sound?
This indicates there's enough spark energy to combust the fuel vapours in the cylinders. If it hasn't sneezed then that pretty much confirms the weak spark theory.

Not knowing anything about the Adaptronic, would there be anything in the software that is causing this? ie. somewhere in "cranking" or "cold start enrichment" whatever it's called in their software that might be influencing the timing or reducing fuel flow significantly?
You mentioned that you turned the "flood clear" mode on, have you turned that off since you tried other things?

Where is the fuel smell coming from? tail-pipe? engine bay? I hope its the former.
What time are you home this evening?