Around 6 months ago I pulled the rocker cover off my evo 7 to replace the HLAs. Due to work and another project getting in the way that's as far as it got and sat for 6 months. About 2 weeks ago I threw some new HLAs in it, put it back together, and put a new battery in it as that had died at some stage while it was stored. As soon as I went for a test drive I knew something was wrong. Immediately as it started to come on boost it would lose all power and backfire. I couldn't even drive up a small incline as it would start missing and backfiring under the load of going up a hill.

At first I thought maybe the ECU had reset because it had had no battery on it for so long. It's running 20psi and the ECU had been retuned to suit so I thought maybe it's had defaulted back to the factory tune. But I did some google searching and found a few sites saying the tune is stored regardless of how long it's not powered.

Something told me it was ignition-related. I'm no mechanic so I'm just guessing. but it felt like the spark was cutting out and back in. So I pulled the coils off and visually inspected them and they seemed fine so I put it all back together again. Then the car ran 1000 times better. it idled fine, drove fine off boost, drove fine at low boost, but as soon as I'd pass around 10-11psi it would start missing and backfiring again. It drove fine as long as I didn't fully boost it, so I've been driving it like that for about a week now. Last night I could hear a clicking noise and noticed a spark jumping from the lead that goes from the coil on the 4th cylinder to the plug on the first to the rocker cover. I thought I'd finally discovered the problem. So this morning I bought brand new coil leads and haven't touched anything else. I fitted the new leads, fired it up and now there's a check engine light plus it idles like a v8 with 5 spark plugs removed, sounds like a tractor. it now won't boost at all and as soon as it hits about 3-5psi it immediately loses all power and starts backfiring again

Does anyone have any ideas what could be going wrong? The difference between the first time it ran like **** and making it run slightly better was removing and refitting the coils. The difference between it running perfectly fine at anything under 10psi yesterday and barely being able to make it down my driveway today was just replacing the coil leads with brand new ones and nothing else was touched.

 

My suggestion would be to inspect/replace the spark plugs, and do a boost leak test.

 

Finally found my openport cable

 

Solved it finally. wires had been ripped out of the AFM plug. I assum something else being worked on it managed to catch on the wires and pull them out. Repinned the plug and it seems to be running better than ever.