Losing boost at 6400rpm. Help!

[Turbo Drifter]

I've still got it in the dungeon. I may have to go back to the 1jz..........I was making more power.

You would do all that work for nothing, I can almost certanly say its not the 2jz bottom. You did a compresion check and it was fine, you have somthing else going on.

Jeremy

 

[tissimo]

Did this start happening with the new intercooler pipes?

 

[suprahero]

You would do all that work for nothing, I can almost certanly say its not the 2jz bottom. You did a compresion check and it was fine, you have somthing else going on.

Jeremy

Jeremy, that was just rambling. I'm not going to pull the motor as I know it's not in the block itself. I'm going to fix the shims and do another compression test and try to find another turbo to try. I don't know what else to do.

Did this start happening with the new intercooler pipes?

Nope, I replaced the intercooler pipes because I thought their were some leaks in them I couldn't find. I replaced them just to eliminate that as a possible culprit.

 

[pnutcar]

Sorry Jay, read the whole thing and not much is coming to me, but its almost 1:20 and my head is all sorts of everywhere. Call me when you get a min tomorrow and we can see if something dawns on me.

 

[juhanis]

i have this problem too... completely different engine/management/turbo setup.

stock 7mgte bottom/top end
- jz intake manifold
- full hks sportkit t04e turbo/long runner cast manifold/50mm wg
- hks vpc
- avcr
- safc2
- aem progressive meth injection
- supporting fuel mods



pressure checked ic piping and manifold to 17psi... no leaks. i've tried 2 ecu's, went over all the wiring. i lose boost at 5500rpm, and it drops violently. i found on my car the problem doesnt happen during open loop operation, as soon as the thermostat opens... 5,500 rpm the boost drops violently from 17psi to 10psi or less. lame. i've spent about a good month looking hardcore for this problem to no avail. i'm going to make a wot switch to trick the ecu into open loop with a 1k ohm resistor. but only during wot. i hope to god that works. but my last thing to try will be a new map sensor. it cant be anything else.

 

[suprahero]

Thanks Todd. I'll give you a call later on today for sure.

Juhanis, my map sensor is about the only thing I haven't changed. Maybe I can find another one and try it out.
The car in your signature is one of the nicest MKIII's I've ever seen.............:love:

Please keep me posted if you fix your problem.

 

[ForcedTorque]

Are you possibly running out of fuel from the one Walbro? Many 2J's run 2 of them or a different pump.

 

[juhanis]

Thanks Todd. I'll give you a call later on today for sure.

Juhanis, my map sensor is about the only thing I haven't changed. Maybe I can find another one and try it out.
The car in your signature is one of the nicest MKIII's I've ever seen.............:love:

Please keep me posted if you fix your problem.

hehe thanks for the compliment sir. i think i found a wiring gremlin today, but i'm not sure if its the source of my issues. my tps was unplugged today, and i had no check engine light... that sounds fishy. in any case i went to radio shack and made that circuit that i was talking about in that other post. so, if fixing this gremlin doesnt fix my problem, then in goes my little project box! i still didnt try changing my map sensor. so, i dont know yet. oh well, keep the hope alive. i know how annoying having this problem is.

 

[suprahero]

Are you possibly running out of fuel from the one Walbro? Many 2J's run 2 of them or a different pump.

It would run lean up top if I was running out of fuel Scott, and it's staying right where we need it too as far as the AFR's are concerned. Thanks.

hehe thanks for the compliment sir. i think i found a wiring gremlin today, but i'm not sure if its the source of my issues. my tps was unplugged today, and i had no check engine light... that sounds fishy. in any case i went to radio shack and made that circuit that i was talking about in that other post. so, if fixing this gremlin doesnt fix my problem, then in goes my little project box! i still didnt try changing my map sensor. so, i dont know yet. oh well, keep the hope alive. i know how annoying having this problem is.

Please keep me posted as to your results. I can't see the map sensor causing this, but who knows. I'll try anything to get it fixed. Thanks for your help.

 

[suprahero]

I received the shims from Bigzavz today so I reshimm'd all of my valves, or at least the ones that needed it. I got them all perfect. All the intake's are .008 and all of the exhaust are .010........I was pretty proud of myself for getting them so perfect.......until I cranked it up. Now I have an awful sounding tick on the intake side. It never made that noise before even with the tolerances way out of wack. I was too tired to take it back apart so I'll do it tomorrow. I was just wondering what it could be. I know the shims are correct because math is my strong suit.

Anu suggestions are greatly appreciated. Thanks.











<This infraction thing is a bit embarassing.

 

[IJ.]

It will expire and dissapear on it's own.
(on Monday)

 

[Bigzavs]

jay, ive got my 268s at .010 on both sides (thats how the guy that did the shimming set them) and they are noisy as hell too, he said its fine tho, and im not gonna argue with him considering his cars

 

[suprahero]

It will expire and dissapear on it's own.
(on Monday)

the infraction or the noise...............hopefully the noise.

 

[IJ.]

Infraction :biglaugh:

 

[tissimo]

did you recheck them after putting the new shims in? Then your math wouldn't be in question.

 

[juhanis]

i did some toying with the tps wire today on my car... and i re grounded my piggybacks to a chassis ground and not an ecu ground. i made sure that my safc2 was getting a good ground and a nice solid connection. before my safc2 was registering an odd tps voltage without my foot on the pedal. so, i took care of that, and then i went over some of my wiring on that tps wire and checked the connections with a dvom. i drove the car a little tonight, my back tires were bbq'ing at 17psi in 2nd, and then i hit the dreaded 5,500rpm, and it held! so, i waited for the car to go into closed loop, i turned the car off on the freeway, and allowed the ecu to power down. i turned the key back on, (just to make sure that the problem wouldnt return in closed loop) and nothing. it held again. odd part was my afr's were all over the place, the car under boost was about 10.8-11.2:1 at 17psi with my meth on. (safe enough for me) now that i finally have some results, i'm going to install all my piggybacks on a boomslang harness and repair the little pieces that were cut into on my factory harness, and then i'll have a nice little extension and i'll be able to remove my piggybacks. basically, i'd check the wiring from the engine bay to the ecu (if you already havent done so) with a dvom, they do wonders for finding gremlins. but i can tell you its most likely electrical. i know mine is. good luck, i'll try to take some good pics of my "voodoo harness", and maybe my project box. and i'll post up some more tomorrow. ps: i know my valves are in spec also. (one less possibility)

 

[suprahero]

did you recheck them after putting the new shims in? Then your math wouldn't be in question.

It's not the math that is wrong, it's the grinding that I did to one of them to make it work. I"m going to have to order one that is .007 thick. I made one that thick, but it must not be perfect.

i did some toying with the tps wire today on my car... and i re grounded my piggybacks to a chassis ground and not an ecu ground. i made sure that my safc2 was getting a good ground and a nice solid connection. before my safc2 was registering an odd tps voltage without my foot on the pedal. so, i took care of that, and then i went over some of my wiring on that tps wire and checked the connections with a dvom. i drove the car a little tonight, my back tires were bbq'ing at 17psi in 2nd, and then i hit the dreaded 5,500rpm, and it held! so, i waited for the car to go into closed loop, i turned the car off on the freeway, and allowed the ecu to power down. i turned the key back on, (just to make sure that the problem wouldnt return in closed loop) and nothing. it held again. odd part was my afr's were all over the place, the car under boost was about 10.8-11.2:1 at 17psi with my meth on. (safe enough for me) now that i finally have some results, i'm going to install all my piggybacks on a boomslang harness and repair the little pieces that were cut into on my factory harness, and then i'll have a nice little extension and i'll be able to remove my piggybacks. basically, i'd check the wiring from the engine bay to the ecu (if you already havent done so) with a dvom, they do wonders for finding gremlins. but i can tell you its most likely electrical. i know mine is. good luck, i'll try to take some good pics of my "voodoo harness", and maybe my project box. and i'll post up some more tomorrow. ps: i know my valves are in spec also. (one less possibility)

Thanks for the info. I'll go check my wiring from my TPS just to make sure it's done correctly. Keep me posted on your findings.

I have another question. Could my Crower upgraded springs and retainers be causing this. I think these were made for the Large core cams, and I have the small core cams. Does anyone know what the stock spring pressure or heigth is suppose to be? Here is what Crower writes about their s/r.

New Supra Valve Springs and Titanium Retainers Crower's new Toyota Supra 2JZ valve springs and titanium retainers are available for the high lift, high rpm applications. The new single valve spring delivers 15% more pressure across the board than the factory part. Also, with a coil bind of 0.820", the Crower spring allows for more cam lift than factory springs will allow. Crower titanium retainers weigh in at 7 grams vs. stock steel at 14.5 grams. Pickup additional rpm's by reducing valve train weight. Part #: Description: O.D./I.D.: Open Pressure: Seat Pressure: Coil Bind Wire Diameter

Stock Single Spring: 1.024/0.710: 1.325 = 50#: 1.050 = 100# 1.000 = 110#: .915: .128 68195-24

Single Spring: 1.042/0.750: 1.325 = 82#: 1.050 = 148# 1.000 = 159#: .820: .14

I'm just wondering, since this is the only thing different than the first build, if these springs and retainers could be a little too strong and making my valves open up and not seat properly while under high rpms. What do you guys think?

I found a place that sells 1jz 1mm oversized valves, but they're 600.00 and I don't really know if they're worth it or not. I don't know how much horsepower larger valves will give you. I know it lets more air in, but how much horsepower could thie equate too? I think I"m going to remove the head and have it rebuilt and make sure the spring rate or heigth is correct. I've got to get some answers on that from some searching I guess. What I need from you guys is your opinion on wheter the oversized valves are worth it. Thanks.

 

[suprahero]

I shot 69 today................bump.

 

[RacerXJ220]

It's not the math that is wrong, it's the grinding that I did to one of them to make it work. I"m going to have to order one that is .007 thick. I made one that thick, but it must not be perfect.


Thanks for the info. I'll go check my wiring from my TPS just to make sure it's done correctly. Keep me posted on your findings.

I have another question. Could my Crower upgraded springs and retainers be causing this. I think these were made for the Large core cams, and I have the small core cams. The springs should have nothing to do with your loss of boost, I seriously doubt stronger aftermarket springs would cause valve float.

I'm just wondering, since this is the only thing different than the first build, if these springs and retainers could be a little too strong and making my valves open up and not seat properly while under high rpms. What do you guys think? The spring pushes to close the springs, not push them open. They are stronger and help prevent valve float at high RPMS, and reduced mass for even higher rpms.

I found a place that sells 1jz 1mm oversized valves, but they're 600.00 and I don't really know if they're worth it or not. I don't know how much horsepower larger valves will give you. I know it lets more air in, but how much horsepower could thie equate too? I think I"m going to remove the head and have it rebuilt and make sure the spring rate or heigth is correct. I've got to get some answers on that from some searching I guess. What I need from you guys is your opinion on wheter the oversized valves are worth it. Thanks. If you're staying with a GT35R, I'm not sure if the HP per $ cost is really going to be worth it, however that all depends on how much you're willing to spend. I say spend the money on other mods, like a new turbo. I still think this is turbo related, despite everyone else's opinions, I'm sticking with it until the problem is fixed, then I will happily rejoice that I was wrong. If your T3 housing will fit on my GT40R........

 

[suprahero]

If I remove my bolts, then I have a T4 housing. You're not even at home are you? If you are then I will gladly drive up there and try out your turbo. Give me a call sometime Jeff, 205-243-0622