Throttle Hiccups >:( This shouldn't happen!!
 

I really hope one of you guys is more helpful than the dealership on this one. Ok Ill start off with a list of mods and recent work just to get you in the loop.
-WMW 15% pulley
-CAI
-brand new JCW plugs
-all fluids checked and topped

Ok now down to the problem, it only happens under heavy acceleration where alot of torque is needed. Example being, I'm going say around 60 in 6th gear at 3k rpm and i floor it, it sounds like the throttle is blipping and I can feel a loss of power for just a split second. :sly: Sometimes it happens a few times in a row. I've had it happen in every gear except 1st.

I brought it into the dealership for the same problem about a month ago and they quickly found that 3 of my plugs were cracked... easy fix, in go the jcw plugs (after seeing my pulley haha) and the problem is gone for a little while. Now its back, not nearly as bad as before (before the *service engine light was on) but still noticeable.

Could it be my distributor? Ive never checked it/cleaned it and im pretty sure its the same wires and box that came off the line 78000 miles ago haha. I'm just wondering what this could be, would a dyno tune help? Is my ECU trying to compensate for the new boost and messing with fuel delivery? Help please!:confused:

Thanks guys, any reply is appreciated!

The number 3 coil gets rusty for some reason very often. Taking off the wires and making sure they are clean may help. At a point plugs are worth changing and checking the plug gap is .30 - .32.

Slipping serpentine belt?

I dunno.

1. how's the mileage?
2. what was the code - you mentioned you had a SES light at some point earlier...
3. how long between the new plugs (which cured the problem for a while, right?) and the problem re-occurring?
4. have you looked at the plugs again since the issue re-appeared?

Slipping belt....hear a squeel??
Or possibly the dreaded yo-yo....

PS
a mini had a coil and wires...no rotor/cap....
the coil tips can corrode...
The mini's plug wires a very short, but you could check them with an ohm meter...

I'm not sure what the code was, but the techs at the dealership seemed to think that it was the plugs, and I gotta admit those plugs looked pretty bad when they showed me. It's been about a month since the first problem started, but I haven't looked at the plugs since they put the new ones in maybe I should do that. First I think I'll clean the distributor though, I'm pretty sure ive noticed some rust before.

https://www.northamericanmotoring.co...k-plugs-3.html

Seemed a good thread, and might come in handy.

The conditions you describe correspond to maximum cylinder pressure, at which point a really healthy spark can be right handy.

That's only one line of inquiry though - could be fuel too although that seems less likely to me.

Cheers,

Charlie

I was able to do a bit of snooping earlier and the 3rd terminal on my ignition coil is really corroded, I got rid of alot of the rust but there is still some black buildup that I'm going to have to take a wire brush to, hopefully that will take care of the problem but we'll see!

The other side of that connection is the wires. Wires last a lot longer these days it seems, but if you have never changed them, it could be time. If the issues doesn't go away, it is almost necessary to change them and rule that out if they are original. The factory ones are good, but after a period of time they may become the weak link.

Ok here are some pictures of the ignition coil after I took it off, sorry about the graininess I couldnt find my slr so I used my phone haha. The first is the number 2 coil point, and the second is the number 3, which as you can see looks alot dirtier than the first. The problem was though that it wasnt all carbon/rust, the little point looks actually deformed, almost like it was hit with a tiny welder. The little sharp lines that were on the other ones are not there. The last pic is a shot of the underside, aren't you supposed to change it once the bottom turns white?

Anyways, once I put it back on the check engine light came on even though the car was running as normal, hopefully it finally picked up on it. I dropped it off at the dealership because it is still under warranty. Maybe this time they will actually replace something :nod:. It seems like if you aren't throwing a code the dealership doesn't care. I'll keep you guys posted!

***Heres a link to a video of the problem in action!**** (turn your speakers up and listen closely)

http://www.youtube.com/watch?v=V4JbYtbIiDU

http://i285.photobucket.com/albums/l...726_134930.jpg

http://i285.photobucket.com/albums/l...726_134940.jpg

http://i285.photobucket.com/albums/l...726_135456.jpg

Scottish Doc, how did you make out with your problem? I listened to your video and I think my MCSa is doing the same thing. Did cleaning/replacing the coil pack solve it?

sorry it took me so long to reply, but yeah it was pretty much just the old coil pack. Get an OEM one! they are more reliable than the performance ones

Thanks for the tip. I had the same problem with my Mini sputtering on heavy acceleration. Since there was no code the shop didn't diagnose it. After watching the video I decided it was the coil or wires. I cleaned the electrodes on the coil and performance seemed to improve, but then it started getting worse. I had the shop replace the coil and wires and now it is running strong with no problems.

Thats great to hear! I hate it that some shops have the mindset that if there isn't a code being thrown then there isnt a problem... glad to hear you worked out and happy that my video helped someone out!:thumbsup:

Glad to see someone else had this problem and a fix. Last roadtrip I took this happened to me and it rattled the bolts off the exhaust. I had to drive the remaining 2 hours with a practically open header. If you have an OBX, those supplied bolts/springs SUCK!

My MCS is an 04 w/ 180k btw.

That video was great...pretty much exactly what I'm getting with my '05 MCS right now. I checked the coil last night and the #3 was slightly corroded, it almost completly wiped of with a cloth though and when I drove to work this morning I tested it out and the sputtering was significantly less.

I have a new belt at home to put on and a tensioner tool that should arrive today so I'll be replacing that as well (I have 66K mainly highway miles on my car and have never changed the belt unless the dealer did when they put the pulley on about 4-5 years ago or so).

I was contemplating swapping out my iridium plugs for some new ones and changing the wires and coil at the same time, sounds like that's the route I need to take.

Thanks again for the video!

It looks like I resolved this issue on my '05 MCS...

I changed the serpentine belt - that helped overall considering the one I took off was in bad need of replacement, but it did NOT fix the hiccup.

1 week later I had a big maintenance weekend and put on new rotors, new brake pads, flushed the brake fluid, changed the oil, changed the spark plugs and the ignition wires.

Obviously brakes and oil wouldn't affect the hiccup, but the plugs and wires seem to have fixed the issue!

I think the problem on mine was the #3 spark plug itself was not torqued down to 20 ft lbs! When I removed the #1 and #2 it took a good turn of the ratchet, but #3 took significantly less and the washer on it didn't look as compressed as the other 3 plugs.

So anyone with this issue might first check the terminals on the coil and make sure they're cleaned up, then check the torque on the plugs and make sure they're all seated to the level they're supposed to be. If they are, try changing the plugs out and then the wires...I think this is what fixed it for me!