Car Breaking up with more than 10 psi of boost

[1jzMoe]

as the title says, all i did was change my oil and spark plugs. I checked the coils out, plugs, for vacuum lines that came off and cant find anything, the only other thing is i see one of the coil clips are boken, would that cause the problem, I ordered new ones from toyota. Just trying to see if it can be anything else, and the plugs are gapped to .030. The car is a 1jz.

 

[suprahero]

Do you have a wideband? I was wondering if it is running rich. Was it doing this before you changed the plugs? I changed mine and noticed a large hole in one of my vacuum lines where it had rubbed up against a pulley. It still ran good, but it couldn't have helped anything. Have you tried resetting the ecu and seeing if it helps or if you have any codes? Just grasping at straws.

 

[1jzMoe]

i checked the codes and didnt have any, and i also reset the ecu. Looked for any lines that were disconnected or had holes and didnt see any, i don't have a wideband, the tune i did on it was pretty good, mattonedime down at RRev tuned it a couple of months back. It is more like a stutter, like the timing was way off, but it runs perfect up to 10 psi.

 

[suprahero]

I don't know much about the 1jz yet, but I'm trying to learn. It sounds like a boost leak, but you said you looked for one already. Are the twins still running good? I hear nothing but horrible stories about them.

 

[1jzMoe]

thats the funny thing they are running fine, I just checked again and dont see anything i check the top and bottom. I am learning the 1jz's too anything i dont know i learn as i go. I know mechanical work to a certin point and i have someone helping me out that used to be a toyota tech, and they are stumped too, but she never worked on the JZ engines before.

 

[IJ.]

Check the coils for cracks.

 

[1jzMoe]

Ok well i finally got to change the plugs and coil, but that wasnt the problem, my boost controller is acting funny i think, i didnt even change the setting and it was hitting boost/fuel cut which every one it is, and turned it off and it was running fine, turned it back on without changing anything and had it at low boost and still the same problem, then i turned the setting(everything) all the way down and it ran fine. and it doesnt matter where it was on the origional settings high or lo boost it always did it. all i did was change the oil and plugs. the boost controller is a greddy type s. What do you guys think? why would it all of a sudden do it after i change the oil and plugs it is i hitting boost/fuel?

 

[1jzMoe]

ok well i was wrong, today it is still doing the same thing, yesterday i had the boost controller on and stepped on it and it seemed like it hit boost/fuel cut twice real quick at ~13 psi the it boosted up to 16psi fine and stayed there with no problems twice. if I'm in first gear and step on the gas it doesn't seem to do it, but if I'm in second gear at say 10-20 MPH and step on it it has the problems, what do you guys think. I'm stumped and don't know where to look now. i checked plug gaps, changed coils, o2 sensor.

 

[JonnyRedline]

its ur boost controller bro...what kind are u using? im having a similar problem with mine and i have a hks electronic...i know for a fact its the bc cause i fucked with it one day and it only boosted to 10psi then started breaking up badly...i turned down the boost and it boosted to 17psi! it must be hooked up wrong.

 

[1jzMoe]

i am using a Greddy type s, how do i check it? i did a simple check and i know it is activating the solenoid, but i don't know if it is opening the wastegate or not. I didn't change with the way it was hooked up, or even touch it, mabye i can see if someone is using a the same boost controller as me and swap them out and see

 

[Tim]

why don't you just bypass your boost controller and see if the car breaks up above 10psi. The car will run a tad bit more than 10psi without the boost contoller so if it runs fine without it then you found your problem.

 

[1jzMoe]

ok i will try that and see what happens.