Cylinder 1 Misfire Under Throttle
 

Stock engine, 68k miles, new OEM sparkplug and Ignition Projects Quad Spark coil pack about 5k miles or so, E85 tune with Zack, was on 91 gas at the time.

I was driving on the freeway in 6th gear at about 75ish MPH keeping speed with throttle. I gave the pedal enough to start accelerating probably like 30% or so, basically normal driving, and noticed the car felt off. Felt like there was lack of power and hiccups while accelerating. Thought it was weird since it should accelerate since I was at 3k rpm so I gave it more gas probably around 50% or so throttle and held, that's when the CEL started to flash, but did not stay solid. Ran code and it was cylinder 1 misfire.

Car felt great when I started driving out of the garage, but feels like it got rougher when warmed up completely. This usually happens, but I always assume it's me being paranoid over the smoothness of the engine since I have Cusco engine and stiffer transmission mounts, and no codes are ever thrown so I ignore it. It was hotter day today, about 90 degrees, but this was the first time I got noticeable symptoms. What should I check in addition to swapping coils?

Thanks!

no check engine light? very odd. Misfires under load are a major catalyst damaging action and thus, newer obd2 cars are mandated to turn on the CEL in that situation.

I'd look to see if there are any stored codes and/or pending codes. Specifically misfire related.

This will let you know what cylinder to focus on.

Then you can find out if its spark, fuel or compression causing it.

For spark you can swap the plug to another hole and see if the misfire follows it. Same for the coil. Do them one at a time, as you want to isolate each part.

Compression is easy, it needs to be roughly the same as the other cylinders and above about 120 as a bare minimum. I know it will probably run ok down to about 90, and yes, it should be well higher, probably 220 or so, but check it.

Fuel is trickier with these platforms as they are both DI and PI. You can use a stethoscope to hear the injectors and see if one isn't sounding the same as the others, but its tricky. You can put a 'noid light on the PI injector harness and see if its flashing.

If you have a good scan tool, you can read various PIDS on it that will help you isolate whats going on.

Swapped the coils and logged using ECUTek. Don't know what I'm looking at so can't tell if any of the parameters are out of spec. Did not get any readable misfires, but the car does feel hiccupy when accelerating under load sometimes. Repeated yesterday's scenario on the freeway and it accelerated fine at 6th.

Are you logging this and sending logs to Zach for review?

I have not, but let me contact him. Can't seem to replicate the misfire issue today, but car does feel a bit off.

He can't magically wave a wand and produce a diagnosis.

Get a log, and send that to him with notes. :thumbsup:

What? Is Zach’s crystal ball still on back order?

Zach thinks its the injectors that needs cleaning and that the misfire was localized in cylinder 1. I could see that, but I just got misfire in cylinder 4 so it's not the plugs or coilpacks. I could see one cylinder's injectors that may need cleaning but two? I guess, I'm no mechanic, but there are many owners that have higher mileage than me that have never cleaned their injectors that aren't getting misfires so trying to cross out what is likely and unlikely.

I'm dropping my car off at the mechanic's tomorrow and want to give him a list of things that may be wrong. I can't nail the misfire to one specific cylinder. So far, I pulled codes for cylinders 1, 3, and 4 misfires so 3/4 injectors may be bad. I can't say it's injector seals since I don't seem to have the common popping noise symptom but could be a possibility. The car smells abnormally of gas when I start it up, and I got a really bad misfire when I left work today, cylinder 3, but both smell and misfire CEL flashing went away once the rpm dropped. The car prefers to misfire at lower rpm to where the torque dip is, accelerates fine from 4k to redline. High negative STFT around -14%, LTFT hovers around 0 to -4%, o2 voltage at 1.3v, but I know the flex fuel kit unplugs one of the o2 sensors so not sure if bad or good. Wished checking common things wasn't such a chore with this car. Meh just ordered a Tesla, need this car to run till December.

Vacuum leak?

Maybe, but I think it's the DI seals. The car just took a dump today, got a hard misfire code on cylinder 2 when I started it up this morning. It stopped misfiring after the rpm dropped and was driveable, but doesn't feel as smooth so it's still misfiring intermittently. Got the common DI seal symptom of popping noise when I stab the throttle so I'm leaning towards that.

https://i.imgur.com/QuiFTZN.jpg
https://i.imgur.com/EeJPUMZ.jpg
https://i.imgur.com/NTUWm8z.jpg
https://i.imgur.com/Oeb5Q67.jpg

An update for those that are interested. Mechanic did a leak down test and it showed good leak down on all cylinders. Tried swapping coils/new spark plugs and no improvement so those are out of the equation. Looked at the valve area with the manifold off and no crazy carbon build up as well. Currently, cylinder 2 has been consistently misfiring. He pulled the injectors which is pictured. They don't look too bad I think. The 3rd photo is injector 2. They're off to being cleaned and new seals installed. Possibly switching to e85 dislodged some gunk and clogged the injectors. Hopefully, that will fix the misfires.

OP, did you see any LTFT / STFT being very negative during idle?

High negative STFT when starting from cold. Averaging -14% or so but once it finishes the warm up idle, it goes to around -4%. Not sure if it's the flex fuel tune, I think I read flex fuel tune has high negative fuel trims at start up idle.

cool, keep us posted on your cleaned injectors results!

Bad news on the update. Cleaning the direct and port injectors did not fix the issue. Misfire on cylinder 2 on cold start but when start up sequence finishes, does not misfire. I haven't driven the car yet since it's at the shop but they said it drives fine once the start up sequence ends. Redline pulls in 3rd gear no misfire so they think it's the tune or maybe a sensor is bad.

Swapped coil packs around, new spark plug in cylinder 2, fuel pressure good, compression and leak down good, no carbon buildup on valves.

Kinda wished I didn't fill with e85 to see if it cleared things before sending to shop. Need to drain or use up the fuel before switching to stock tune to see if its the tune.

When you say you swapped them, are you moving the IP Quad Sparks around or do you mean you are putting the stock ones back in?

Swapped the cylinder 4 and cylinder 2 coilpacks. Misfire still localized to cylinder 2.

If anyone wants to look at my logs it would be greatly appreciated. Had a few look at it on Facebook, but nothing on the logs pointed out to the problem. Just a very strange misfire. Kind of coming down to a electrical issue/ignition issue. Maybe bad sensor or a break in wire somewhere.

https://datazap.me/u/butterballz/mis...?log=0&data=31
https://datazap.me/u/butterballz/mis...?log=1&data=31

One log is during cold startup, this is where I get lots of misfires and hard misfire code in cylinder 2.

Second log is driving it around after warming up, different load/rpm range, cruising to redline. No misfire except under certain repeatable scenarios. Basically giving it about 50% load around 3k rpm can make cylinder 4 misfire enough to soft code.

Something is wrong with #2 direct injector. As soon as it switches to 100% port injection, #2 misfire count goes to zero.


That is, as long as the correct cylinder is reported to be misfiring. ...but it's one of your direct injectors.


edit: ...or the signal/power to that injector.

I think it was the coilpacks. I swapped back to OEM and did not get cold start misfires, but I didn't get a chance to log. Also drove around and tried to get it to misfire by giving it 50% load at 3k rpm, which usually starts to misfire, but did not get anything. It usually misfires cylinder #4 this way.

Didn't get a chance to log during cold start after swap, but so far signs are good.

We'll be here when it craps out again. :popcorn: ;)

https://i.imgur.com/5Y4BmBL.jpg

https://datazap.me/u/butterballz/log...31-48-49-50-51

So far so good. No misfires on cold start.

Looking good! I'm baffled but who cares? Send it.

I dunno, maybe it's too many years dealing with 60s and 70's vintage motorcycles with weak ignition systems but misfires under load just scream SPARK in my ears. I had a couple of Honda single cam cb750s and once the plugs got a few miles on them they would develop a case of the blind staggers at anything over half throttle. I eventually reworked the ignition system from points to electronic triggers and upgraded the coils and never had another problem.

Edit: and I won't even mention Brit bikes. My Nortons were testimonials to Joe Lucas' title of "Prince of Darkness."

I had a picture that was supposedly of him on my garage wall. The caption said "Be Home Before Dark." Oops I guess did mention them. The most damaging lies we tell are those we tell ourselves. :)

Looks like this one is resolved and long fixed, but I found a lot of interesting info in this thread on the same topic.

https://www.ft86club.com/forums/show...cts+quad+spark

After reading through it all, especially with 13-14 models, it looks like the pins don't make robust contact and are party to the misfires.

I have a mild misfire issue comparatively and plan on the pin tweak this weekend. I've only had two misfires recently, and I get them only when pulling to 7k, and intermittently as I haven't been able to repeat at will. So I'm not swapping parts yet to see if signal follows, just seeing if I can make it go away as one user in the other thread had good luck with.

Pin tweak didn't help me, but it is simple enough if you have the proper pliers. I left mine turned about to the point it's just noticeable. Regular needle nose are too large to fit in the connector housing. Oddly, got a CEL at the same 7k conditions, but it didn't record the code as I showed none when I checked with my reader. I even checked twice.