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Discussion Starter #1
Alright i have a really weird stuttering/hesitation issue. I just got done cleaning my engine, replacing the valve cover gasket, cap, rotor, plugs about 2 weeks ago. The car drove just fine with no problems what so ever. I installed a MBC and upped the boost to 15psi on the stock CT26 with the TVSV disabled. Now when i boost below 10psi no problems, once i start boosting above 10 it starts to stutter and hesitate, sometimes really badly or at times just slightly. Now what could it be? The EGR has 3 pinhole size cracks, i have not replaced the fuel filter yet. I also have a exhuast mani. leak. On top of that when i did the valve cover gasket i didn't put any RVT sealent on the lobes (i re did it and put some on). Oil in the dizzy? Blah im confused as to why it only does it after 10psi. The weirdest thing is that when it isnt completely at normal op temps, like two ticks below it will boost without a problem all the way to 15 psi. And once it reaches normal temps it will boost fine for like 5 to 10 mins and then the hesitation/stutter will begin....? I don't understand as to why.... Anyone experienced this?

Any help or info would be greatly appreciated...

Greg.
 

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How's the timing?
 

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Discussion Starter #3
Aw crap i haven't checked that :( I have to jump the terminals and the timing should be at 10* right? or is it soposed to be at 0*?

Greg.
 

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Discussion Starter #5
Ok after testing some stuff i came to a weird situation. When i have the boost set to 15 (im guessing) it stutters/hesitates like crazy. Basically when i start to push above 10/12psi it starts to hesitate like no tomorrow. However once i cranked the boost down to 7/8 psi it runs without a hitch. No problem what so ever. Why would this happen does anyone have any idea why increasing my boost past 10 psi would cause stutter/hesitation? PLEASE SOMONE inform me as to why and how to fix this issue!

Greg.
 

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MortICi said:
I installed a MBC and upped the boost to 15psi on the stock CT26 with the TVSV disabled. Now when i boost below 10psi no problems, once i start boosting above 10 it starts to stutter and hesitate, sometimes really badly or at times just slightly. Now what could it be?
Any help or info would be greatly appreciated...

Greg.

http://www.mr2oc.com/showthread.php?s=&threadid=53

bill
 

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MortICi said:
Ok after testing some stuff i came to a weird situation. When i have the boost set to 15 (im guessing) it stutters/hesitates like crazy. Basically when i start to push above 10/12psi it starts to hesitate like no tomorrow. However once i cranked the boost down to 7/8 psi it runs without a hitch. No problem what so ever. Why would this happen does anyone have any idea why increasing my boost past 10 psi would cause stutter/hesitation? PLEASE SOMONE inform me as to why and how to fix this issue!

Greg.
What do you mean "your guessing". Do you have a accurate boost gauge?
 

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Discussion Starter #9
Im guessing cause it hesitates before it even reaches 12psi after that it just goes nuts and i can't even accelerate further cause it's so bad i just let off the throttle..... As bill states it's possible that it's knock/detonation. The engine has 200k miles on it.... Blah im going to be taking off the turbo and mani next week. So im going to drain the coolant and clean the IC as well. At which point im going to check for any loose hoses and what not. The EGR has 3 pin hole size holes in it which could cause it. Ill probably replace the Platinum NGK's with Copper ones and get new wires and a new coil. Ill also get the knock sensor from Two's R Us as well as a new fuel filter then just Seafoam the engine as well. Last time i did a compression check on the engine 3 weeks ago it was at 1st. 160 2nd. 152 3rd. 150 4th. 155. Blah the odditty of this as i stated before. When the temp is 2 or 1 tick from normal op temps it would boost fine without hesitation once it got absolutely normal temps it would start hesitating. Blah either way we will see. I just wish i knew what could (if it is) cause detonation/knock as i never heard any pinging or the like..... Any more info would be greatly appreciated....

Thanks,
Greg
 

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im having the same symptoms as you are.. but im using an avc-r.. im wondering if maybe im tuning it wrong, or my ecu is sensing knock.. i was also thinking about buying a twosrus knock sensor.. but before that i want to replace all my hoses because it COULD just be a boost leak somewhere... have you checked for a boost leak?
 

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Sounds like it could be a weak ignition component failing or some type of mechanical issue. If all your mechanical stuff is known to be in good condition I would check to make sure ALL your ignition components. It sounds like you could have a bad coil, or igniter. Check those, even if new, to make sure they are working properly. Get a known good part and test it.
My car has been having the exact symptoms as you. At low boost, 12-15 PSI it would rev to problem, but at higher PSI, 18++, it would misfire really bad. So far we have traced it to what we believe is a bad MSD box, so I am replacing that with a OEM igniter. Good luck.
 

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*sigh* just replaced cap+rotor today and nothing.. is it possible you point me to a pic or some sort of description of the "coil" and ignitor? i have no clue where these things are.. and how do you test them to see if they're bad?
lol for me its anything after maybe 10psi that it wont climb the RPM band so smoothly.. put it this way, a 2001+ celica GTS kept up right next to me =/
 

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Discussion Starter #13
The ignition coil is right under neath the fuse box in the engine bay there are three bolts holding down the fuse box. Unscrew them move aside and youll see the coil. Im still waiting for my Brother in law to bring my car back so i can get to work on it. Im prolly going to buy a hose replacement kit and replace all the vacuum lines. Simply im gonna work my ass off to figure out the cause of this. As i stated i get no CEL's nothing no sign as to what it could be, i guess trial and error will tell. Clogged cats have a chance at causing this but who knows....

Greg.
 

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Discussion Starter #14
Alright i found out something else. Now when the car is at normal op temps and it just got there. It will still boost fine with not hesitation. However after 10-20 minutes at normal op temps. and in between that time period the hesitation will develop? Could my IC be heatsoaking that fast? Or do i have a vac/boost leak somewhere?

Greg.
 

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1st off buying an ATS racing knock sensor isn't gonna fix your problem. If you get code 52, then the ATS ks is a cheaper replacement.

Your intercooler isn't heat soaking that fast and I wouldn't think its a vac leak.
 

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Discussion Starter #17
Well then if it isn't those two then what could it be? Bad coil/igniter? Too much carbon build up in the intake mani.? Im lost as to what would be the cause..... Blah...

Greg.
 

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MortICi said:
Ill also get the knock sensor from Two's R Us as well as a new fuel filter then just Seafoam the engine as well.

did you get the new fuel filter yet? im gonna replace mine also, as i think it might still be the original one... if it is, it HAS to be clogged.. no way a 14 year old turbo car's fuel filter cant be clogged by now. =/
 

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MortICi said:
I installed a MBC and upped the boost to 15psi on the stock CT26 with the TVSV disabled. Now when i boost below 10psi no problems, once i start boosting above 10 it starts to stutter and hesitate, sometimes really badly or at times just slightly.
Greg.


Is the car just hesitating, or is it misfiring? If its a hesitation I would first check make sure everything is connected and your spark plugs are ok. If its misfiring then it could be a weak ignition component. Even if they are new I would check them again. Look at the plugs make sure they are ok, check the wires for cracks, and use an ohmeter and check resistance. A scope would be a nice tool to use, but if you don't have access to one its ok. You can either get a known good ignition coil and igniter, or you can use an ohmeter and see if its resistance is within spec. Primary sides will always have really low resistance,maybe just a few ohms and secondary sides will have a much higher resistance, a few K-ohms. I don't remember the exact numbers off hand though, sorry.

MortICi said:
The EGR has 3 pinhole size cracks, i have not replaced the fuel filter yet. I also have a exhuast mani. leak. On top of that when i did the valve cover gasket i didn't put any RVT sealent on the lobes (i re did it and put some on). Oil in the dizzy? Blah im confused as to why it only does it after 10psi. ...

Greg.

Your EGR shouldn't be causing this. If it gets stuck open then you will get a rough idle, and at higher RPMs would just make your car slower. I don't remember if they default close or open when they malfunciton though. They aren't supposed to function at cold engine, idle, or WOT conditions. I think if you have a pinhole size cracks thats just less EGR getting into the cylinders so all it should affect is your MPG, and very very slightly your combustion temps. I would fix that exhaust manifold leak as well. Oil in the distributor should give a constant hesitation, but should get worse with RPM, not necessarily boost. Well these are my .02. :)
 

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Discussion Starter #20
Ill replace all the Ignition components one more time this time with NGK coppers and get a new dist cap o ring. Ill replace the coil and the igniter. Ill also replace the fuel filter and do a coolant flush and change cause right now the color is a brown/dry wall white. Ill also check the timing just to be sure we will see. So basically a boost/vac leak wouldn't cause this as my idle is perfect and there is no misfire occuring at idle.

Greg.
 
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