Mysterious Shudder/hesitation Please Help!

[QRI05E]

Hey guys, lately i have been noticing when accelerating in 2nd and 3rd to get a very slight shudder/hesitation at around 2500 - 3500RPM then perfect to redline... i have recently fixed my coils, gapped the sparks, ran injector cleaner and cleaned the AFM.. 100% its not a misfire... more of a jerky shudder but its very minor... nothing to be too worried about im sure but it just feels like the car is bit sluggish...

Mods are:

Full 3" exhaust with split dump

Turbotech set to 9psi (not spiking)

K&N Panel filter

My Suspicions:

1. Fuel Filter?

2. Stock SMIC not coping?

3. Clutch on its way?

Any advice is greatly appreciated!

Regards,

Sarkis

[Taso84]

Hey sarkis, how are u re,

From the sounds of it could be a exhaust manifold gasket, but unlikely, more info needed, ie does it make a weird noise?

[QRI05E]

Hey Taso, im good thanks buddy! urself?

Nope theres no exhaust leak or any induction noise... the exhaust is about 6 months old and i perfect condition.. what other info do you need for dignosis? its a very slight jerk/shudder feel...

[mad082]

i've got the same problem. only started doing a day or 2 ago. i've been fiddling with the boost a bit as in the morning when the car is cold i've been getting boost cut till it warms up. i've put an air/fuel ratio guage on and it is leaning right out when it hesitates, then goes rich for the rest of the rev range and feels like its being held back.

i know its not plugs cause i only put new plugs in a week ago, (not even a full tank has been used since they went in), and i taped up the coil packs when i did it. i ran sweet until i put a dump pipe and cat on and boost cut was killing it. so i wound the boost down and it was still fine. then this hesitation started yesterday so i put the air/fuel gauge on.

going to recheck all exhaust bolts for loose ones when the car cools down. was planning on putting it on the dyno next week, then this happens. what a pain.

[QRI05E]

I dont think my problem is exhaust related, any other suggestions that might cause this?? could boost increase be a problem? fuel filter might need changing?

cheers

[mad082]

ok, well i haven't checked my exhaust bolts yet, but i did change the way i had my boost controller, boost gauge and bov hooked up. i had the boost controller working from the manifold side of the cooler, and i've changed it to the turbo side of the cooler. seems to have made it go away.....for now.

[QRI05E]

I dun get it sorry... could you be bit more specific? i have my turbotech hooked one end fron the hose off the intercooler pipe near the air filter box and the other to the acutator hose. I have followed the instructions from the turbotech thread... could it be the spring inside jamming some how therefore not boosting smoothly?

[mad082]

i had it hooked up the right way, but when i put the front mount on the boost contoller was getting its boost reading from the bov hose. what i did today was to take in the little penis shaped tip that the waste gate pipe hooked onto on the factory cooler pipe (that wasn't used with the front mount) and weld it onto the pipe that goes from the turbo to the intercooler. this way i don't get so much boost spiking at night.

i had to do a bit of adjusting of the idle afterwards.

[QRI05E]

Hmm now you got me worried as i was going to install a Gktech FMIC and run the boost control off the BOV hose... i have never welded in my life LOL is there any other hose i can connect to the boost controller which wil minimise boost spiking????

[mad082]

sadly no. but if you take it the pipe and the nipple to any engineering shop, or possibly exhaust shop and get them to silver solder it in for you. using a normal welder could be too hot for it and make more of a mess. but silver soldering is done with an oxy torch and is just as strong. i'll post up a pic of where i have attached it to when i get a chance.

[QRI05E]

Thanks for that i appretiate it... what if i removed the turbotech and ran a single hose from the BOV hose to the acutator? therefore using the acutator as the boost control? would it still spike then??

[mad082]

not very likely, but it would still be possible. but usually the more boost, the more the spiking varies. but not having a boost controller would mean that you would only be running 5psi boost.

also, how old are your spark plugs?

[QRI05E]

My plugs are about 12,000kms old... there NGK Platnums gapped to 0.8mm... im changing them to NGK coppers next oil change... before i installed the turbotech, my boost gauge showed 8psi on high boost mode on the stock solenoid... i would love to run the turbotech cause it has really made a difference at constant 9psi... im just concerned about the shudder/hesitation... what can it be?

[race_snooze]

i have the same stutter.

after putting in shell extr 100 ron its fine.

mods are fmic, remapped ecu and all the rest of the normal shit.

[Quinny]

I have a similar problem to what you have described, my car is stock apart from exhaust and filter, no aftermarket boost control, stock cooler etc.

I have a hesitation around 2500-4000 under acceleration, always comes on when boost starts, cruising off-boost, it is ok. Mine feels like the clutch slipping though, then it gets over 4000, revs ok, but feels a bit restrained (like there it is still slipping a bit).

[QRI05E]

Well i have heard some bad things about Shell fuel as i had used it for many years.. i have switched to BP Ultimate and only recently i have noticed the shudder/hesitation.. could this be due to the fuel??? there both 98RON...

[Quinny]

Well i have heard some bad things about Shell fuel as i had used it for many years.. i have switched to BP Ultimate and only recently i have noticed the shudder/hesitation.. could this be due to the fuel??? there both 98RON...

If your problem is the same as mine (sounds pretty similar), but I doubt it would be fuel. My car was doing it when I first picked it up, then I put Ampol 95 RON (oops....) fuel in it, still happened, then Caltex Vortex 98, same thing....

[QRI05E]

Yea Quinny, however my clutch is not slipping.. it breaks traction in 2nd and it pulls VERY well to redline without hesitation.. the only thing it feel like a minor "hiccup" on low revs...

[Quinny]

Yea Quinny, however my clutch is not slipping.. it breaks traction in 2nd and it pulls VERY well to redline without hesitation.. the only thing it feel like a minor "hiccup" on low revs...

Ok, different problem, just ignore me.

[mad082]

if your clutch is slipping then it will rev out without you actually travelling any faster (like wheelspin, but its the clutch that slips not the wheels), and you would be able to smell it. how far up did you tape the coil packs? when i first did mine i only went up the rubber stalk, but then when i changed the plugs i did the last bit at the top around the body of it. it ran smooth for a while after that, but then a few days after i put dump pipe, new o2 sensor and cat on it started playing up.

when it stopped doing it i had moved the wastegate line and i had to adjust the idle and tps.

might be worth putting a new fuel filter on. they aren't that expensive, and it is possible that you have had a tank of dirty fuel. or if you want to do it on the cheap you could just take it of and flush some fuel through it backwards and that would take any big crap out of it.