View Full Version : Hitting 6 psi then sputtering occurs

07-01-2010, 03:33 PM
for those that don't know. i have a 2nd gen 3sgte with an electronic boost controller that i hooked up yesterday and tvsv is disabled. no other mods.

Last night i let the car warm up and then left the house. i drove for 4 miles then tried to boost. when the engine hit 6psi it just started sputtering. i also noticed that the temp gauge was reading as though the coolant temp was really low. the needle was only half way to its normal position. i drove back home and noticed that the upper radiator hose was a bit swollen and had a small leak. i had noticed the hose swelling before and figured it was just weak.

so this morning i replaced the hose and let the car idle for awhile before driving it. i then test drove the car and it still sputtered at 6psi. it will hit 6psi, sputter for a few seconds, boost up to 8psi, then drop back to 6psi and sputter.

the temp gauge is still giving a low temp reading as well. as soon as i got home i dropped a thermometer in the radiator and got a reading of 192 degrees.

i have gotten no engine codes before, during, or after this problem.

07-01-2010, 04:04 PM
Check the sensors/wires on the front of the water neck. Also check the sensor at the bottom of the radiator near the AC.

I know when the wires go sheared on one of the sensors on my water neck it had similar behavoir.


07-01-2010, 04:04 PM
boost leak test? a massive boost leak will only allow the turbo to hold low boost in the manifold but run so rich it will misfire.

the temp gauge could just be the temp gauge sender. it uses a separate sensor from the ECU's temp sender.

another possibility for the misfire would be a corroded ground on the igniter/coil bracket, or an igniter that's on its way out. the igniter gets ground through the bracket mount to the firewall. corrosion or a bad connection there severely limits coil current resulting in a weak spark. i ran a dedicated ground wire on mine.

trying to think of stuff to check first that doesn't cost $$...

edit: the car would hold boost fine before the boost controller install? or has this been happening before you added that?

07-05-2010, 05:47 PM
You're on new plugs? Using the 3s coil?

07-05-2010, 05:51 PM
This problem sounds almost familiar if by 'sputtering" you mean "jerky". When i first got my car everything worked great. One day at a light I took off, as soon as I hit boost the car jerked. If i pushed it it would make boost but still jerky. As long as I drove the car below boost it was fine. Purred like a kitten. I changed a ton of stuff but in the end it was the plug wires. Worked fine ever since (knock on wood)

07-05-2010, 07:07 PM
Sounds like ignition related or a boost leak.

07-06-2010, 10:55 PM
so i did a boost leak test just now. i pressurized the intake to only 10 psi and found a big ass leak. i had air blowing out the back of the ebc stepping motor. there is a little pinhole back there that i guess is part of a bleeder for a failsafe or something, idk. so i'm guessing the stepping motor is shit.

the plugs are new. the cap and rotor are new. i also installed a new fuel filter.

i rechecked the gap on my plugs earlier and they were pregapped at .035. i gapped them to .031.

i am using the 3s coil.

07-06-2010, 11:11 PM
if it is not a boost leak could be AFM related would put the car into limp mode and 6psi would be the absolute most it would allow you to boost... did you cap the tvsv on both ends?

07-06-2010, 11:26 PM
Im with the others and think its ignition related. But it started after installing the ebc? Did you remove the ebc to test again?

07-06-2010, 11:26 PM
yeah, the tvsv is capped at both ends.

i'm just going to put everything back to stock.

07-07-2010, 12:26 AM
yah put everything back to stock boost see if it goes to the 8ish PSI level and see what happens..... I could swear I had this happen to me when I installed a boost controller wrong and did not cap the TVSV right.

07-07-2010, 02:13 AM
everything is back to stock and i pull 8-9psi no problem.

the question i have is why was there air bleeding out of the EBC stepping motor? is supposed to do that being there is a hole back there? i know that it is hose #2 on the diagram that the air is bleeding through. i unhooked the hose from the turbo and blew through it. the air came out of the bleed hole on the back of the stepping motor. so that was my leak.

this is the diagram i used to install the EBC.


this is how my tvsv was capped off.

07-07-2010, 11:40 AM
I may have hooked the hoses up incorrectly on the EBC stepping motor. The diagram i used above is for a different model. I just assumed it the same one with an extra port.

I found the correct manual and it shows port 2 connecting to the turbo(also the tvsv port but i'll just cap that off) and port 3 connecting to the wastegate. I had it the other way around as was shown by the above diagram. As soon as i fell like getting off of the couch i'll go hook it up again and see what happens.


07-07-2010, 02:42 PM
it made no difference hooking the EBC up differently. i would get around 9psi before it starting sputtering and jerking. i put everything back to stock and it is still acting the same way. the ecu is not throwing any codes and on the way home from a test drive it wouldn't boost over 5psi.

i guess i'll try a new set of plug wires.

07-07-2010, 03:38 PM
Bruce, what plugs do you have? How many miles are on them?

07-07-2010, 05:03 PM
dude you are waaaaaayyy over simplifying things.


^^ Just follow that exact instructions... if you brought it back to stock like I said to do before and you hit that 8-9psi then clearly you have something wrong with the setup.

the tvsv simply needs to be capped at one end and the waste gate on the end that goes to the tvsv..... the side that goes from the wastegate - > turbo needs to have the boost controller on it.

If you hook things up wrong you will go into a limp mode and the most the car will boost is 6psi with slight hesitation Ive had it happen before!

07-07-2010, 05:08 PM
I have some standard NGK's BKR6ES with about 100 miles on them.

07-07-2010, 05:27 PM
i hooked up the EBC exactly as it is supposed to and the tvsv was capped off at the wastegate and the line going to the tvsv.

when i first hooked the controller up it was driving fine and hitting 13psi. i cut the car off and went for a ride a few hours later and began having problems. the thing that strikes me as being odd is the fact that i haven't even turned the boost controller on and the motor will boost to 13psi. it's supposed only boost to factory set psi when the controller is powered off.

everything is back to stock now and the problem persists.

07-07-2010, 09:30 PM
i had a coil go bad that wouldnt let me boost past 4 psi once. everywhere else was fine though. btw. the 5s and 3s coils are the same core part number with a different mounting bracket if you wanna try that.

btw- if the boost controller is broken ill refund your money, i had no way of testing it before i sold it.

07-07-2010, 09:30 PM
awesome double post

07-08-2010, 02:25 AM
the 5s coil i have is different than the 3s. the coil to distributor plug wire for the 3s has a much larger terminal.

for right now i'm going to run without the EBC and see how it acts. i drove it earlier and it seemed fine. it was boosting at 9psi. the only problem i am having is after i drive for about 20 minutes the timing starts to retard and i'm only boosting at 5psi. i'm guessing it's heatsoak from the tmic. i insulated the bottom of the tmic and am about to go for a 30 minute drive to get a good idea of what's happening. it's getting dark so i'm hoping the cooler temp outside will prove that theory right.

07-08-2010, 04:07 AM
i drove the car for 1 hour. mainly on the highways. it drove pretty good and i was boosting at 9psi. the only problem i had was when i would take it up to 4500rpm the ecu would pull timing and restrict the motor to 5psi. after i waited about 1 minute i was able to boost at 9psi again.

so i'm guessing the problem is heatsoak or ignition. i guess i'll buy some plug wires and colder plugs and try that. i need to ditch the top mount too.

sometime in the next few days i'll wire up my led's for the knock detection.

07-08-2010, 04:09 AM
if the ecu gets a knock signal will it throw a code?

07-08-2010, 05:12 AM
I do not believe so. I think it just retards timing to get the knock to go away

07-08-2010, 05:41 AM
No code if knock is detected. Knock/knock response is only evident if you install a TVSV LED.

07-08-2010, 04:43 PM
I replaced every single vacuum line and adjusted the afm idle screw back to the factory posistion. The vac lines going to the ps pump were questionable to me and a couple others had split ends.

I went for a ride and the motor did great. It held boost and i took it to redline several times without the timing retarding and boost being limited.

We will see how it does. If it drives well for a few days i'll hook the EBC back up and see what happens.