New starter, cranks for a few seconds then there's a loud pop

[Dakota Biddinger]

So I just put a new engine in my 95 eagle talon tsi, then put the starter in it. When I went to start it up it cranked for a few, then there was a loud pop and a slight smell under the hood. It only pops once and then cranks for a few seconds longer then pops again. Anybody know what it could be?

 

[Murdertalon]

Are you talking like a backfire pop or.. did you go from 7bolt to 6bolt? check firing order. Also your timing could be off 180* so check that too.

 

[Dakota Biddinger]

The flexpipe is blown on my exhaust so that would make it louder. It could just be a backfire. Mines a 7 bolt and always has been, my firing order should be right, and I did the timing when the engine was on the engine stand

 

[Murdertalon]

Have you checked sensors to make sure your CAM and Crank are both picking up? if your getting spark and injectors firing they both should be. I plugged a set of noid lights into my injectors before just to make sure.

 

[Dakota Biddinger]

They both should be picking up and everything is connected right

 

[Boomdeeze]

Like stated prior, check your spark plug wire order and your cam angle sensor is installed 180* out (6 bolt/1G CAS only). How is your mechanical timing?

 

[Dakota Biddinger]

Spark plug wire order is right and all timing is good. I'm not sure what you mean when you say 180 out

 

[boostdawd]

He is referring to the adjustable cam sensor on some engines, mostly 6 bolts. Its mounted on the passenger side of the valve cover. If u have stock sensors for the 7 bolt then this may not apply to u.

 

[Dakota Biddinger]

All my sensors are stock

 

[Dakota Biddinger]

Everything should be connected right, and we went through the engine on a stand before actually putting it into the car. A few friends thought it could be a backfire? The flexpipe is blown so all the noise would basically come out of the bottom of the down pipe.

 

[Dakota Biddinger]

So we found out that it was because I have a 2g ecu and 1g sensors and coil pack, so I rearranged the plug wires on the coil from 4123 to 1342 and it doesn't backfire anymore

 

[Murdertalon]

So we found out that it was because I have a 2g ecu and 1g sensors and coil pack, so I rearranged the plug wires on the coil from 4123 to 1342 and it doesn't backfire anymore

Glad you figured that part out, so is it running now or still working on it? Yeah that sounded like a loud pop would be back fire, and that is usually timing related/ in this case timing of wrong plugs firing.

 

[Dakota Biddinger]

I'm still working on it. I get my no cruise control throttle cable on Friday so I'll probably actually try to start it up then