Aem Ems And Firing Order

[sen2two]

I have an 80's (i think 80's) 302 non roller motor in my Fox. I cant get the car to start at all. Just cranks with no indication of starting.

Is it possible that my firing order is off? I thought that would be controlled by the cam and distributor, and not matter in the software...?

Anyone here familiar with this? I'm sure the same goes for MS and other full standalone computers.

 

[sen2two]

Also, the car runs good (not great) on the stock computer. Something just dosnt seem right. It almost sounds like a small backfire upon start up. But always starts right up. I daily driver it as is and cruises fine. But not the cleanest idle.

The motor was "built" before it came to me. I have no idea what cam it has.

Is their a way to tell what firing order I have? I know people do change the firing order with cam swaps on these older motors occasionally...

 

[General karthief]

It's just a matter of swapping to the non ho firing order and see if it runs better. You should tell right off if it is wrong. Get the engine right before you switch computer systems.

 

[Mustang5L5]

What ECU are you running?

If you run the non-HO firing order with a HO computer, the injector firing sequence won't be correct in relation to the cam timing events.

 

[sen2two]

I had the a9L before I put the AEM EMS.

So I'm guessing I should swap the plug wires from 1-5-4... to the 1-3-7... firing order on the stock computer and see if that works out.

 

[General karthief]

What firing order are you running with that a9l

 

[Mustang5L5]

With a9l, the injectors fire in the 351 firing order.

Non HO use the standard 302 firing order and batch fire.

 

[jrichker]

Remove the #1 & #3 spark plugs. Put your finger in #1 spark plug hole. Crank the engine over until you feel compression on #1 cylinder. Slowly turn the engine until the TDC mark and the timing pointer line up. Mark TDC on the balancer with chalk or paint. Put your finger in #3 spark plug hole and crank the engine 90 degrees. You should feel pressure trying to blow past your finger. If you do not feel pressure, repeat the process again. If you feel pressure, it is a HO engine.

No pressure the second time, remove spark plug #5. Put your finger in #1 spark plug hole. Crank the engine over until you feel compression on #1 cylinder. Put your finger in #5 spark plug hole and crank the engine 90 degrees. If you feel pressure now, the engine is not a HO model, no matter what it says on the engine.

Using a small carpenter or machinist square to mark the harmonic balancer off into 90 degree sections may be helpful here.

A 15/16 deep socket & breaker bar or ratchet may be used to turn the engine.

The HO firing order is 1-3-7-2-6-5-4-8.
Non HO firing order is 1-5-4-2-6-3-7-8

 

[sen2two]

I am running the A9L computer currently on the stock MAF.

I have the plug wires configured in the Non-HO firing order (1-5-4...)

When I swap the plug wires to the HO (1-3-7...) firing order, the car will not start. And back fires loudly. But when swapping back to the Non-HO, it starts up quickly as usual.

So... What would be my best option here? Cam and distributor swap to correct HO firing order? That's a lot of work that I really don't want to go through at this point. Or is there a better option? Ideally, I would like to find a way in the AEM.

 

[Noobz347]

What am I missing here?


If it runs great with the stock ECU, why are you installing ans AEM EMS?

Have you compared the pin-outs between the two? What tune is loaded in the EMS? Who configured the AEM and who tuned it?

 

[sen2two]

I am installing and AEM EMS because I have a Novi 1000 set up and 60lb injectors to go with it. As well as the other things to support it.

I chose the AEM for two reasons. One, plug and play is a huge thing for me since this is my daily driver currently. So downtime can be a real hassle. Two, I have tuned 3 other cars using AEM so I am familiar with the tuning software.

I will be doing the tuning. I managed to get the car to start and sound like it wants to idle for about 2 seconds, but then just dies. I haven't been able to get it to stay running. I think one issue is the firing order. Which is why I am trying to figure out if its possible to correct that in the AEM.

Before I put the AEM back in, I want to try and resolve the issue. Other than that, the car has no issues mechanically.