Hey folks, I was hoping someone might be able to help me with a problem. It just started happening today, but if I go full throttle (or 80% and up) my car starts misfiring really bad. If I do a full throttle pull and let it misfire for a bit, I get a misfire code generated.

I've had problems with the recirculating/bypass valve before when the rubber diaphragm developed a hole in it (so it wouldn't open up and allow air to bypass). Kraftwerks sent me a new one and all has been well. I suspect that I might be having another bypass problem but it seems to me like it is jumping from being open to closed, whereas before it would just stay closed. I took it off while the car was idling and the vacuum was holding it open.

As a troubleshooting step, I have a 90 degree copper pipe that I used to remove the bypass valve from the system and to just have the air bypassed constantly. When that copper pipe is installed the car drives great. Full throttle up to redline with no problem, so I think that has eliminated coil/ignition problems.

So here's what my thoughts are:
1. Bypass valve has failed. It is binding internally.
2. Vacuum source to the bypass valve is leaking (but it does hold vacuum, just not boost apparently)
3. Fueling issue. Car isn't getting the fuel it needs. I think this is the less likely scenario as I don't hear any detonation, and when it's happening it's like a "off/on" bucking sensation, like the boost is going on and off.

If I gingerly press on the throttle the car will accelerate fine (with the by pass installed).

Suggestions?

 

Problem progressed to happening with my supercharger bypassed, so I went out and picked up some cheap platinum spark plugs. Put the gap at .040, used plenty of dielectric grease in each ignition coil, and now the problem is gone. I'm guessing my ignition coils are failing and this will just be a temporary fix.

 

Pretty sure its the coils.

 

sparkplugs/coils

 

Had this issue in the upper RPM's on the freeway in 4th and 5th. I would get a stutter and let off some on the throttle and the car would pull fine. Fast forward to Sunday and I did a hard pull onto an freeway on ramp with bad stutter, all the way home I would get it any time I went past 0psi. Checked my map on the FIC and I'm still clamped below the voltage the ecu sees for anything past 0psi. I didn't notice any stutter in vacuum tho, but my wife drove it the other day on the street and said she felt it stutter in vacuum. I ordered 4 coils from rockauto and picked up 4 NGK BRK7e spark plugs. Hope it takes care of the stutter I plan to gap them @ .28

I popped one of them (NGK BRK7e) out to check the gap and they are @ .40 but I cut the tip and side gapped them when I put them in. I'll try these "as is" but gapped down.

If anyone is supercharged or turbo and is running an FIC please PM me your map as I'd like to cross reference your setting with mine. I've had a lot of back and forth on what is the proper setting on AEM FIC forums

OP best of luck and please update this thread when you get it all fixed!

 

Oops, forgot to update. My problem came back after greasing up the coils, etc. I replaced the coils and now the problem is gone. It has been running great since I replaced them in early January.

 

Awesome! good to hear

 

How much & where did you get your replacement coils? Cheapest I've found is $99 for a set of 4 on ebay, but who knows if those are even worth trying out?

 

I bought the Beck Arnley ones from Rock Auto. The picture shows the pink rubber bottom on the coil but all the ones I received have the blue rubber (which I believe indicates it's a newer model of coil).

 

Thanks for the info

 

What plugs you running? And at what gap? Was one or more of the coilpacks burnt out looking where it meets the plug? I came across this thread https://www.fitfreak.net/forums/fit-...tutter-21.html and I guess I've gotten lucky I got 90K out of my stock packs. 40 of those have been supercharged.

 

Update: while waiting for the new coil packs to come in I went ahead and re-greased the problem ones and also disassembled them to clean out the terminals, I also did the new plugs @.30. The car runs like a champ again! I still plan to just put the new set of coil packs in and hold on to these encase I have issues down the road. Just FYI for those who come across this and have not already bought the packs to take a look at the ones to see if you cant get up and running again.

 

Update: So the re-greased coil packs only worked for a little while until I had the stutter come back. Lucky for me I already bought the replacements and have been issue free ever since. Plugs are @ .35 now and mileage has gone up some from both the re-greased and new coils over the tired untouched coils. I have been driving with the bad coil for quite some time come to find out. I thought the issue was in my tune on the FIC and what I had the MAP clamped to. I used to only get the stutter when going up a high elevation pass on the 15 freeway. Turns out the bad coil would only show up on this high stress pass and not the MAP clamp issue I thought it was. I've made the drive now with the new coils on the same tune with absolutly no issues in drive-ability!

 

The only thing re-greasing the boots does is you clean the contacts while removing and replacing the boots to re-grease. The grease does not increase contact by itself. You would get the same result just taking the boots off and cleaning the contacts.

 

Actually it would insulate the boot again... the issue was never a lack of spark or contact. There was an arc at high load/RPM letting the spark jump through the boot to the engine. The inner springs and resistors in the old coils were in perfect working order.

http://ftp.pwp.att.net/w/a/wayneorwi...ric_grease.htm

 

And you have confirmed this how?