Motor cutting out after catback installed. WTF?!?

[dc3_1132]

I installed a used 2.5" Magnaflow catback exhaust a week or two ago. Shortly after the install, when I crack into the throttle very hard and spool the turbo up, the motor cuts out a little bit. It only does this when excelerating hard. It runs fine with normal driving. What would be causing this? It never did this with the stock exhaust.

I STILL haven't reflashed my S1 and installed it. After I install the S1 will this stop? I know that I have changed the backpressure, therefore changing the air/fuel mixture of the car. I would have thought the stock PCM would have made up for the exhaust change.

I am planning on changing plugs and wires when I install the S1. Hopefully one of the three things will fix this.

I was hoping someone could tell me if they have had this problem or if there is anything else I should look for.

Thanks,

[Mean Green]

Stock wires suck. If using the stock Copper Plus plugs then gap at .035.

[CREWZIN]

If you do the wires (and maybe plugs at the same time), how about taking off the negative battery cable for a few minutes so when you put it back together the computer can learn about any new adjustments. Can't hurt.

[AlexJB]

What Crewzin said.

I used to do this reset on my smart car every time I made a change and it really helped.

[OCCrewzR]

#1 It may be and is most likely the PCM needs to 'relearn' for the change of 'conditions' that has occurred. Manly back pressure difference.

#2 It MAYBE the converter is partly clogged and under boost and cant flow...I guess the blow off valve would go off constantly if that where the case???

Let us know if the relearn does it or not.Go from there.

[Mean Green]

What plugs do you have and what are they gapped at? Sounds like the high rpm stutter.

[dc3_1132]

Originally Posted by Mean Green

What plugs do you have and what are they gapped at? Sounds like the high rpm stutter.

That is a good way to put it, but only under hard throttle. I could probably slowly take it all the way to redline and it not hesitate, but I am guessing from 3k rpm (with turbo spooling) and up is when it does it the most.

{Mean Green} I don't know what kind of plugs are in it or what they are gapped at. I have only had the car a month and half or so. Better plugs/wires were on my list of "to do's" anyway.

{OCCrewzR} I don't think the converter is partially clogged because the BOV acts exactly the same with the Magnaflow catback as it did with the stock exhaust. The car only has 31K miles on it. I wouldn't think the cat could clog up with only 31K miles on it. I would also think if the cat was getting clogged, it would have acted up with the stock muffler on it. (Could be wrong) The car NEVER cut out/sputtered/hesitated until I put the catback on it. I do have a little bit of an exhaust leak where the new midpipe connects to the back of the cat. It sounds like poop, but it shouldn't have any effect of the way the motor runs.

I had thought about pulling the negative wire off, but I figured the PCM would relearn itself after driving it a couple times. My Neon has never had a problem with any upgrade I have made to it. Actually, shortly after I put my CAI on it, I had a check engine light. All I had to do is drive it around for an hour or so to let the PCM figure out I had changed something and the CEL went out and hasn't came back on since. I didn't have any problems when I put the K&N filter in it and did the airbox mods on the PT. Also, no problems with the 3" charge pipe upgrade.

I will pull the battery cable off and give it a try. It can't hurt anything to try.

[Mean Green]

The reason I asked about the plug gap is because my brand new '03 GT had the high rpm stutter that the dealer could not figure out. It did not stutter when you did not get on it, only when you really pushed it. A friend told me to drop the stock .050 plug gap down to .040 and the stutter disappeared. When you go stage 1 I'd try .035 for the gap.

[dc3_1132]

Originally Posted by Mean Green

The reason I asked about the plug gap is because my brand new '03 GT had the high rpm stutter that the dealer could not figure out. It did not stutter when you did not get on it, only when you really pushed it. A friend told me to drop the stock .050 plug gap down to .040 and the stutter disappeared. When you go stage 1 I'd try .035 for the gap.

Interesting!!

I will still try the resetting of the PCM first. I still don't understand why this started after switching exhaust. It just doesn't make any sense to me how a better flowing exhaust would make the car run worse.