Wheelhaus

iTrader: (2)

^ that sounds like some sort of misfire or bad plug issue, maybe not enough spark or possibly timing is bad enough in certain load cells of the ECU that its not igniting the fuel at the right time, or not at all. Bad tune? I'm no engine expert but that would be my first guess.

Dus10

Yes my '05 MR does it also. Here's some of my observations.

I've data logged it and can't see the reason. It's not knock, I do know that. I also know that these cars are very spark plug picky. Put bad plugs in and it will hesitate constantly; it seems to like the stockers and NGK's.

I've also noticed that it doesn't do it, as bad, when the plugs are brand new. But it does not seem dependent on temperature like some people. It does it regardless of temperature, but, it seems worse when cold (air is more dense?).

I have the boost cut setting maxed out to 319 so I know it's not boost cut.

It doesn't seem RPM dependent either, it seems more load dependent. WOT in 1st or 2nd and it does not do it at any rpm. But cruising along in 4th gear at 3500RPM and I go WOT, it puts more load on the motor and as soon as the turbo starts to get around 14psi it does it. The "hiccup" as some people call it, and sometime there's a pop from the exhaust.

But like some people say, if you're smooth on applying the throttle it won't do it (less load). Only under high load / high boost conditions... although I don't know if it's necessarily high boost but how fast the boost comes on.

Some people are saying that it's caused from the ignition retarding massively; but the only time the car retards the ignition is when it gets knock count past 6 on the knock sum sensor and then you'll see the octane rating on the data log start to drop from 100 to 90-something and I've never seen it retard the timing during the "hiccup".

Still haven't been able to pin-point the cause...

petey pab

iTrader: (18)

well my car is untuned at the moment. just changed the plugs and wires, again, and it stopped for about a day then started right back up. only it doesnt do it as much now. but could the ecu be starting to go bad? the car only had 60K miles on it.

Thegame

iTrader: (26)

Resurrecting an old thread... I have the same issue as described all over the thread. Mine only has happened in 5th. Stock plugs with about 18,000 miles on them. Custom tune. Usual bolt on mods. No clutch slippage. Was the solution ever determined?

suekie

iTrader: (7)

my 03 had this same too common of a problem. I changed the spark plugs with the ngk 7's and gapped to .026 and helped. Came to figure out that i had a bad tank of gas. I asked my wife where she got gas at and it was some little gas station (that i believed before to water down there gas). I let the gas run all the way out and then filled it up with Chevron, and no more problem. My car seems to like the 93 Chevron (it's the techron haha j/p). So I think it was a combo of the plugs and gas. I would still check for boost leaks, and your BOV. Also check and see where your boost is set at. Maybe lower it down to around 20.

afmafia

iTrader: (12)

anyone figure out the problem

afmafia

iTrader: (12)

bump

srcevo8

iTrader: (10)

When I had this issue it was when I got my car back from the dealer. They replaced the ECU so it was a stock ECU map in combination with my mods. Once I got tuned things were flawless.

Are you guys fully stock and having this issue?

afmafia

iTrader: (12)

maxim im fp greened

afmafia

iTrader: (12)

bump anyone find out what the problem was

mojo

iTrader: (4)

My 03 started having this hesitation when boost surge peaked at WOT only. It would feel like a strong bump 1 or 2 times then back to normal all the way to redline.

I've never had this happen before so I was concerned and started trying what I could think of to fix it. I thought maybe I got a bad tank of gas so I ran the fuel down and put in about 4 gal of 100 but that didn't help.

I have a meth kit spraying windshield wiper fluid and I thought maybe the nozzle was partly clogged or the pump was going out so I cleaned and checked all of that. No difference.

I tried turning the boost down a couple lbs that helped a little but it just felt a little less abrupt when it hesitated.

Checked for boost/vacuum leaks.

I also had a set of stock used iridiums I threw in just to see and that made the problem much worse. I had changed the plugs 3 days prior about the time it started having the hesitation from NGK BR7ES to NGK BRP8ES gapped at .026. So I went and bought a new set of BR7ES gapped them to .024 and that felt much better about 60% better but not fixed.

I noticed that the Walbro I had put in about a year ago was whining very loud. I had read many post about whining Walbros but I had never noticed mine whining at all even when I was trying to hear it.

I happened to see this thread resurrected and read all 10 pages trying to figure out what it could be. In one of the post the guy solved the problem with fuel pump replacement and plugs so that got me thinking it might be the fuel pump. A friend had a used Walbro that we stuck just now and the problem was solved! No more hesitation.

The gas tank was full when we replaced it so it was completely submerged in fuel but when we took it out it was very hot. Maybe others have a failing fuel pump and don't know it.

I still don't understand how the new BR7ES plugs made it feel better before installing the pump but it did.

newMRevoNyne

iTrader: (18)

I recently had the problem too, but I had to fill up at a small gas station that may not have had the best quality gas...I usually fill up with Chevron or Shell, I will burn up the bad gas and fill up with the good stuff and report...

petrey253

iTrader: (2)

bump...

My car stated having this problem as well about a month ago. I was suprised at how many people are having the same problem as I am.
My story is about the same as the majority of people on the thread. I first noticed it when I was entering onto the freeway. Didn't really pay much mind to it until it started happening more frequently. Now pretty much everytime I put a moderate to heavy load on the engine after 2nd gear it will rev up about 500 rpms, drop back down to where it was then take off as if nothing happened. I just changed my oil and spark plugs and it didn't seem as noticeable going through gears, but when I was just in 3rd and went WOT it was the same as before. Hopefully someone can open this thing up and find the problem.

--Pete

crazybaldhead

Its the clutch. I noticed this post was made in 2007, surely by now your clutch would have been sliping in third and needed to be changed.

PWevo

iTrader: (13)

This same thing is happening to my car too. In 3rd-5th gear, at about 2800 rpms i punch it and once I hit boost at about 3k rpms it does the same lunge forward, back off for a second then hold all the way to redline. I have captured this happening on the dyno. I've heard clutch slipping, wastegate puck stuck, to what everyone's said in this thread. I don't know what to believe. My car has 16k miles, stock clutch, stock plugs, mods in sig running 21 psi. This problem only happened after I got my megan o2 housing installed, to throw another twist to the mix.