99rip93

So my 1999 Miata was running fine until I overheated it extremely badly one day. The engine still ran but long story short I replaced the bp4w with a bp5a and now it doesn't fire up even a little bit.

Only the driver's side ignition coil works. If I swap the plugs on the back of the coilpack from side to side then the driver's side coil stops working and the passenger side coil starts working.

I've tried a few things to fix this and nothing has changed.

Any suggestions or insight would be very appreciated.

borka

iTrader: (1)

Did you do a compression test on the new engine?

99rip93

No I didn't. But I'm going to be honest, I'm not sure how that could have any effect on the ignition system.

rleete

iTrader: (21)

Perfect excuse to ditch the stock coils and make a COP setup.

boileralum

iTrader: (8)

The fact that switching the wiring between the coils has the coils cycle on off is an indication that you have a harness issue for the passenger coil. Check the passenger plug for cut wires & corrosion. Verify you have 12V on the blk/wht wire and ground on the black wire. If those are both good, then the brn or brn/ylw wire going back to the ECU (3G/3H) has the break.

gooflophaze

ECU is only picking up one trigger - either cam or crank, probably cam, and firing on that. Check the crank trigger's airspace.

99rip93

I've verified that I have 12v on both plugs and I've verified continuity from the plugs all the way to positions (3G/3H) on the ECU plug. I've double checked that but I'm going to triple check it tonight.

99rip93

I've swapped the cam sensors and set the crank triggers airspace to about a business card's thickness. I'm absolutely willing to replace both of these if I don't get any progress on this within the next few days.

Is there any possibility that the valve cover is somehow not seated correctly and the cam sensor isn't picking up the cam position correctly?

And perhaps should I check continuity from the cam and crank sensor to the plug on the ECU?

gooflophaze

One other thing to check is if you've got the crank timing wheel on backwards - it'll throw the timing off by something like 20 degrees and won't sync. https://forum.miata.net/vb/showthread.php?t=664969

99rip93

I'll double check the timing wheel on the crank. Thank you for the suggestion.

99rip93

Okay turns out the timing wheel was bent away from the crank pulley. Barely bent but of course it was bent enough to cause this problem. I replaced the crank pulley with one that I knew was working fine. All 4 spark plugs spark now. Thank you all so much for the help with that but the car still doesn't friggin start!

It wants to start now that all 4 plugs spark. It's almost there you can hear it nearly start but it simply wont.

All 4 plugs definitely spark. All 4 plugs get wet when I turn it over so I'm 99% sure the injectors are injecting, I'm going to try some starting fluid anyways though.

I'm also 99% sure all the timing is correct. The timing belt/sprockets and such are all as they should be with cylinder 1 at TDC. I haven't compression checked it but I can feel a bunch of compression when turning the engine over by hand soo..... that should be plenty to be able to idle for like a few seconds, right?

It really won't idle for a second but it's trying to start unlike before. I really don't know what to do at this point since I feel like I've covered all the bases. It has spark, fuel, compression, timing. Not sure what I'm missing but I've completely ran out of ideas. Whatever the problem is I'm sure it's very obvious and embarrassing. If y'all can think of anything PLEASE let me know. Anything.

der_vierte

Try to leave the idle valve disconnected, just as an idea.

Do you get starter kick back or backfires or is it just cranking forever and doesn't catch? The latter seems like not enough fuel to me, if timing and compression are fine.
Have you checked timing with a light? Try adjusting your idle ve cells and maybe adjust your cranking timing to 0, BUT DO ONE AFTER ANOTHER!

Hope this helps!

99rip93

It's on a stock ECU and the engine is entirely stock including the stock airbox and 99 exhaust manifold. I'll try with the idle valve disconnected.

It doesn't backfire it'll just fire a time or two here and there. The tach never moves and the check engine light is always on when cranking also. I've used an obd2 scanner on it and it has no codes and it shows like 230rpm when cranking when the tachometer shows 0rpm always.

I'll try starter fluid definitely.

And the TPS only goes to 83%. It's 0% when off the throttle and wide open is 83%. Is there a chance that this could be affecting the problem?

I haven't checked with a timing light. I don't have a timing light at the moment but I'm willing to get one if you think that'd help. I'm a novice here but I'm not sure how much a timing light would help with a stock crank pulley, a stock ECU, stock everything. Y'all are smarter than me but I'm not sure how the timing could really be off with stock everything as it should be so like I said if you think a timing light could point me in the right direction I'll definitely try it.

gooflophaze

Replace the plugs - or at least have some good cheap ones ready to swap in. Old ones are possibly fouled which may not be the root cause, but I don't think it's doing you any favors. Might also want to try and swap the coil packs around - move 1-4 to 2-3 and vice versa, coil packs might've gotten switched up in the swap.

99rip93

I've swapped the coil connectors back and forth and they're definitely the correct way around. It backfires when I swap them.

I'll also try new plugs but I did try the set that was 100% functioning beforehand. But I'll definitely try some new ones just to be safe.

Thank you for the suggestions

99rip93

Okay I tried with the idle valve unplugged and nothing changed. I tried starter fluid just to be safe incase the gasoline was a million years old, same thing, no progress.

I acquired a timing light, a simple one that has no readouts or anything, just hook it to 12v and hook it to a plug wire and cranked it and the timing light didn't flash at all. I pulled the plugs out and grounded them on the valve cover and they sparked.

So I figured the timing light was broken. I took it over to a running car and the timing light worked fine. Went back to my miata and the timing light doesn't flash one bit. I made sure I had proper 12v and ground on the light and I tried hooking it around cylinder 1's plug wire and cyl 2's. Nothing from the timing light.

Am I stupid? The plugs spark when I ground them on the valve cover and the timing light works fine on another car. Doesn't work at all on my miata.

Any help would be appreciated greatly!

Oh and der_vierte it doesn't get starter kickback or backfire. It just cranks forever and never catches. Almost like there's no spark.

99rip93

OKAY Turns out cylinder 1 and 4 don't spark again. That's why the timing light doesn't work on cyl 1. I tried it on cyl 2 again and it definitely works. Idk what I was doing last time I tried it on cyl 2 to think that it didn't work on cyl 2 but it definitely does.

I confirmed that every single plug sparked when grounded on the valve cover when I started working on the car today. After I confirmed that they all spark I put them all in and put a timing light on cyl 1 and got nothing. After that didn't think to bother to double check that they all still have spark when grounded on the valve cover. I tried the timing light on cyl2 and didn't see any flashes either. I tried the timing light on a running car to confirm the timing light worked properly and it did. I went back to my miata and decided to just check for spark again and now cyl1 has none.

I'm just beyond confused at this point.

I'm going to continue to take all the help and suggestions you guys are willing to give but jesus christ this is frustrating.
Thank you all for helping!

der_vierte

Confusing...

So there is no spark at all right now?
Do not flood your engine. You can use flood clear mode to prevent this.
Your TPS needs calibration when its showing 83% max full throttle. Easy task in tuner studio. But that is NOT your problem here, just make sure its fine, when its acutally running.

Typical miata faults are broken plug wires and bad coil packs. Maybe try to swap some known good working ones in?
Does it spark/start with the stock ecu right now?

​​​​​​

99rip93

I decided to just double check again but it currently has spark on all 4 cylinders. Last night I absolutely saw no spark on clyinders 1 and 4. Perhaps the battery was just pretty dead from cranking many times that night. This morning with the battery charged all 4 spark again. Hopefully that's all it was but it's back to "normal" now so I'll try the timing light again in a couple hours.

The engine is entirely stock and I've tried with 2 different stock computers. Also I've tried 2 coilpacks and 2 sets of plug wires and they all perform identically but I'll swap them again just to be sure...

All I've been testing is the stock ECU and sometimes with the bp5a ECU. I don't have any other ECUs in my possession.

Thanks again. Hopefully I'll see something on the timing light later today. Surely I'm just missing something very simple.

99rip93

Alright I got the timing light to work now. I have all 4 plugs plugged into their wires and laying on the valve cover. I'm watching them all spark with the timing light around the cyl1 plug wire. So they're all firing and they're at about 7 or 8 degrees when just turning over at like 250rpm with the starter motor.

I still see no reason why this isn't running right now. I seriously doubt it has too little compression but what on earth could be the problem if it's has fuel, I try starter fluid, it has spark, it sparks at 8 degrees advance, it seems to have plenty of compression by just turning it over by hand. What the hell else could it be?

At this point all I haven't done is a real compression test.

Like I said I'm really thankful for everyone's time and insight.