Hey guys,

I've got a real weird one-

Last night on the highway, about 30 mins into my trip the car starts backfiring like crazy, stalls out- so I pull to the side. I pull the plugs, check for flooding, nothing. Wouldn't start either. About 20 minutes later, crank again and it starts up fine as if nothing was wrong. Then again later that night, on the journey home- same thing happens, lots of backfiring, but this time it felt like it was running on one rotor, I pulled to the side and called a tow truck home.

Tried starting it up again today, backfired like crazy, "idled" at 550rpm on one rotor then after playing with the throttle a bit, the second rotor kicked in and it seemingly ran fine again. Then, it seemed about every 5-10 minutes or so, it goes back on one rotor, sometimes stays on one rotor backfires and stalls out, or sometimes the second rotor kicks back in and it regains idle.

My AFR reads really really lean as this happens, around 17:1.

I've pulled the plugs, rotated them around still didn't solve it. Leaving the plug on the engine and cranking over confirmed spark from both leading plugs, I didn't bother to test the trailing.

So- any ideas? I'm currently in the middle of taking off the UIM to move around the injectors, perhaps a bad injector on the primary rail. Is there anything else that would possibly cause this?

Does it make sense that a bad injector would kick in and out intermittently, or does it sound more like a spark issue? Possibly the ignitor failing? Or maybe bad wiring?

The engine is an 88 T2 in an 84 FB, no BAC, no emissions, running off a megasquirt ecu, stock 550cc injectors. Also, the engine has been recently rebuilt (1200km on the clock), so I'm not running any boost right now.

Thanks,

 

One of your coils is miss firing imo. Do you have rpm readings when that happens? Also, check your ECU ground...under the intake.

Take a compression test if you can.

 

I do have rpm reading, its not the stock ecu- I'm running on megasquirt which gets its rpm from the CAS. My ecu ground is on the strut tower and secure, I've checked that and my other grounds already.

 

Well... I swapped the injectors, seemed okay at first, but first drive out- symptoms started up again. Anyone have any ideas?