[Mahzy]

2012 Mazdaspeed3
So, I park my car in my garage to do some maintenance.
1. Change valve cover gasket
2. Change Plugs
3. Change oil and filter

so, first thing first, I disconnected the battery just out of habit. Pulled the plugs, then valve cover. Replaced plugs, and taped off and put a coat of paint on the valve cover. (I sanded down everywhere a screw goes in to be safe for random grounds)Replaced the gaskets and re-seated the cover. Tightened the cover down, reconnected the boots and connectors that had to be unplugged (cam sensor) so all is back to how it needs to be. Next, simple oil change, then reconnect battery. Now car is fully back to exactly how it was when parked except, new plugs, oil, and better looking valve cover.
now, the car will not start but will turn over and some tries catch for a split second but leads to nothing. There is spark, all sensors are working. LPFP hums, the only thing I do not know how to check or address is the HPFP.
Any and all help welcome because I’ve been at this for 2 days and a lot of money in replacing any and everything. Thanks!

 

[Mahzy]

For note, engine is throwing no codes either.

 

[arathol]

Unless something totally unrelated to your work has happened, its something you did or didn't do.
If everything is connected properly, the only thing different would be the plugs. Check the plug wires and put the old plugs back in just to see if that makes a difference. You say there is spark, how do you know?

 

[Mahzy]

I have tried the old plugs as well. And checked spark how anyone would? Pulled the plug out, left it in the boot and checked for spark? I reversed my work all the way down besides putting the old gasket and oil back in. Thank you for the input, I’m beyond stuck on what it is.

 

[Mike C]

Any chance you've changed the firing order?

 

[JoeMini]

Yes ... firing order
Also ... reconnecting connections ...
Here is my stupid question of the day ... is the battery dead...did it lose its charge?

 

[Mahzy]

Yes ... firing order
Also ... reconnecting connections ...
Here is my stupid question of the day ... is the battery dead...did it lose its charge?

How would the firing order be changed? I’m new to Mazda’s. I put everything back exactly how it was to a T, but I will check on that later. And no, battery is fully charged and new, also tried starting with a jump box to be sure. As I said, nothing is different besides new plugs, vc gasket, and oil.

 

[JoeMini]

Sometimes this can happen with no codes
Like the throttle position solenoid at the gas pedal might be faulty, or have an internittent short; where it is not telling the ECU the position of the plate in the TB.

Another thought is a faulty ignition coil

This may help :

 

[Mahzy]

Update: tried everything mentioned and tripled checked all my work again. Still nothing. Only thing I’ve not tried to watched the video linked above. I’m losing hope honestly.

 

[arathol]

Can you check to see if there is actually fuel in the cylinders? If the injectors are delivering fuel you should be able to at least smell it when you remove a plug, and there should be gas on the plugs.
Any chance you disturbed something else, such as the crank position sensor or HP fuel pump connector?

 

[JoeMini]

Can you check to see if there is actually fuel in the cylinders? If the injectors are delivering fuel you should be able to at least smell it when you remove a plug, and there should be gas on the plugs.
Any chance you disturbed something else, such as the crank position sensor or HP fuel pump connector?

The video above goes thru exactly that fuel pressure , fuel pump, fuel fuse and relays and other possible they has seen as a cause to check

 

[Mahzy]

Can you check to see if there is actually fuel in the cylinders? If the injectors are delivering fuel you should be able to at least smell it when you remove a plug, and there should be gas on the plugs.
Any chance you disturbed something else, such as the crank position sensor or HP fuel pump connector?

I’m going to go to the garage after I get off work tonight and run through everything in video I was linked to in regards of the fueling system. I feel my fuel pressure sensor or injector relay are faulty. But I will update tonight around 11:50-12am est.

 

[Davids3]

Try starting fluid. If it starts you have a fuel problem. If not you have an electrical issue. Less than a minute to test this.

 

[RocketmanKarl]

Forget for the moment what you changed, you have an engine that cranks without starting, so work the problem. You need 4 things to have your engine start: Air, Fuel, Spark, and a Happy Computer.

Usually if the computer isn't happy, it either won't crank at all, or it will throw a code (such as a crank or cam sensor). Since it cranks and doesn't throw a code, this might not be your problem. However, one thing that often won't throw a code, but will stop your engine from firing is a bad MAF sensor. Try unplugging it and start the car. If it starts, you have a bad MAF.

Next is AIR. Does the engine crank evenly, or is there a loping rhythm to it? If it lops, one or more cylinders isn't getting compression. If it ran fine before your work, but doesn't get compression now, you either don't have a plug in properly, or something got left under the valve cover and is keeping valves from shutting completely. Other things to check: follow the path of air from the air filter box all the way to the intake manifold. Is there a blockage in the air intake path (a rag left in there, or a mouse moved in while parts were sitting on the bench, etc)?

Fuel. After cranking, does the exhaust smell like fuel? If not, you can confirm this with a short spray of starting fluid (if it fires on starting fluid, you have air and spark, but no fuel). If you aren't getting fuel, then check the things mentioned in the Car Guys video. If it won't start with starting fluid, then one of the other things is also a problem.

Spark. There is only a spark at the end of the coil and the plug itself, the wiring leading up to the coils are low enough voltage that they won't arc. If you can verify that the plugs are sparking that's great. If they aren't, you need to work backwards to test each of the coils, then the harness. Another key point is that the spark has to happen at the right moment. I wonder if you haven't mixed up the wires (swapped the wires for the cylinders), so that the cylinders are sparking at the wrong time (someone else called this "changing the firing order"). I've done that on an older chevy and it confused me when it ran worse after a tune-up, but I found I'd gotten two plug wires reversed.

Sometimes these four things happen in concert. For instance, if the MAF sensor is bad and is telling the Computer that there is no air going into the engine, it will then cut the fuel to get the "right" air/fuel mixture, so you had an unhappy computer thinking it had no air and therefore not delivering any fuel.

Hope this helps.

 

[Jcorona26]

If you can take pictures of the work you did and upload here. Last summer I took out my fuel injectors to clean and thought I put everything back together just like it was, then my car wouldn't stay running. Kept stalling out. I was going crazy because I thought I did everything right, well it so happens I forgot to put back one hose in the back of the intake manifold. What I'm trying to say it's possible you think you did everything right but it can just be 1 little thing out of place. If you can take good pictures I will compare them to my Mazdaspeed 3.

 

[jibkid]

Wow. Ur having the exact same issue as I am! Let me know if you figure out how to get it running.

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[jibkid]

My problem appeared very similar to yours. Turns out the harmonic balancer pulley had slipped a couple teeth. After exhausting all other possibilities I stuck TDC pin in and spun til #1 cylinder was in position removed and reset the pulley changed washer and bolt. Retorqued to spec and it started right away. Had me stumped for 2 weeks....

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