Supra Performance question (need a hint to what you think may be the problem)

Grandavi

Active Member
Sep 25, 2008
2,663
5
38
Calgary, Alberta, Canada
Okay, as most who have read my posts will know.. my car sits as follows:

Rebuilt short block (Wiseco Pistons 0.5 overbore, polished rods and crank), rebuilt head, 550 RC injectors, Denso MKIV Fuel pump, Aeromotive AFPR (set to 25 psi currently), DM 7MGTE Intercooler kit (CX racing actually), 60-1 Turbo (bought used with approx. 3000 km on it), 3" exhaust from turbo back (Raptor racing DDP with integrated turbo elbow with divider), AEM Uego Wideband, Lexus AFM. All installed and built by RCTS here in Calgary. The only questionable item is the 60-1 as its the only part I bought used.

The intercooler has been smoke tested and all the vacuum lines, intercooler pipes, etc.. are tight and there are no leaks that I can find. The turbo has acted funny since the upgraded intercooler was put on with its normal 10 psi (I believe that's stock wastegate on a 60-1 CT26) dropping to 7.1 psi (according to the HKS EVC-S boost controller reading).

So, I take it out for a wash and drive yesterday out of boredom and because I haven't had a chance to drive it thanks to snow. While I'm out, I peg it in 2nd gear and when the turbo kicks in, It quickly ramps up to 12 psi and the wheels break free a bit for a nice feel. Then I pop into 3rd find an open spot and go WOT. At about 4200 rpm, my boost is falling from 12 down to about 10 psi and then the engine cuts (just like fuel cut) and then kicks back in and holds at 10 psi (roughly).

The car did that 3 more times during an hour test run to see if anything was not working. It stalled on me once while coming to a red light after boosting.

Now, due to the boost dropping after it peaks (and I may have the boost controller setup incorrectly, haven't gone over it yet) the car doesn't feel all that spiffy.. and the odd cut I am getting has me worried, so I park the car. My standalone unit has arrived so I am scraping up funds to install it (HKS Fcon Vpro specifically made for a 7MGTE), but until then I want to figure out if this turbo is the issue or if I should be looking elsewhere.

I have suspected that the actuator on the turbo may be malfunctioning as I cant find any issues with the intercooler. The wastegate itself may be an issue as well.

Therefore, I ask for input so I can see if I can track this issue down. I either want to straighten this out prior to the stand alone install/tune or just get the T4 setup and be done with it. Would rather avoid the T4 if I can simply because I am dumping money in this car faster than I am making it at this point. (the perils of not being a wizzy mechanic and having a limited understanding of the turbo system)

Thoughts?
 

Enraged

A HG job took HOW long??
Mar 30, 2005
1,844
22
38
Victoria, BC, Canada
I'm curious what you mean by "smoke test". The piping needs to be pressurized to your boost pressure (or higher preferably). Something might not leak at 5 psi, but will at 12 for example.

Have you had the car tuned yet? If you are on the stock ECU and have a vented (not recirculated) blow off valve that could be the cause of the stall. The stock ECU doesn't like losing metered air.

If the actuator is original (not replaced when the turbo was upgraded) it might be on it's way out. You could try shimming to see if that helps, or just get a replacement since they are pretty cheap.
 

Grandavi

Active Member
Sep 25, 2008
2,663
5
38
Calgary, Alberta, Canada
I have to double check but I believe it was tested at 14 psi.

The actuator didn't look new like my 57 trim did, so it may be the culprit. I'm just not sure how many problems can be linked to it. The hks bov (authentic) is recirculated and it was somewhat tuned on the dyno (my tach wouldn't give a signal to the dyno so wasn't used). That's how we turned the fuel pressure down. One we dipped it to 25 from 35 the smoking at the end of the dyno runs went away. Reg figures I was over feeding the 550's at 35 and it was washing the oil off the cylinder walls. The AFRs stayed at around 11.3 on the dyno at WOT. Now, if I can trust my AEM UEGO readings I am getting under 10.0 (lowest reading) at WOT like I did originally and it's sitting at 15.0 - 15.5 at idle, which is not normal for the car.
Something odd going on. My stand alone arrived today but I'm about 4k shy for that, the innovative wideband and the tune.

Will have a slightly used AEM uego for sale when I do.., lol
 

Grandavi

Active Member
Sep 25, 2008
2,663
5
38
Calgary, Alberta, Canada
If it is a boost leak it must be coming on after a bit of sustained boost. If I trusted this turbo I would agree, but there are no boost leak sounds and nothing that has been found yet. I may just take the turbo into Alamo turbo and have them checkit over. If its having issues they can fix. If its not minor I will get a new turbo or just go T4 and be done with the wondering...
Just would like to solve it prior to changing anything again so I know I'm fixing the right area. Looks like either way I gotta shell out a few more shekels...

And I cracked the lower lip on my bumper... It finally tagged a parking block... Lol. Ah well have to respray it anyway.
 

Supra mn

New Member
Oct 10, 2012
84
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Jacksonville/Nebraska
If you don't trust the turbo and think the actuator may be bad, why not just test that? A new actuator is alot cheaper than a new T4 turbo.
Hook a bike pump up to it and pressurize until the wastegate opens. You can put a piece of tape on the actuator and watch it move. if it's opening too much at a low psi, there's your problem.. Or atleast part of it.
Its really simple and there are plenty of write-ups around here and on google on how to do it.
 

Grandavi

Active Member
Sep 25, 2008
2,663
5
38
Calgary, Alberta, Canada
I should be able to use my air compressor. I have control for the psi setting.
That is, if I could get some free time. This has been a 14 - 16 hour per day 7-day-week for the past two weeks. I may just drop it off with my mechanic and say "solve it". Doesn't look like I will have any free time until Sunday.

Now... Off to google the test procedure. It's funny how google works better than the forums internal search features.
 

#04

New Member
Sep 7, 2009
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Cambridge
if you think its a boost leak... I use one of these, they are quite nice as they are used with the engine off, and slip into where-ever (air-filter location)

p1933809_1.jpg


link; http://www.son240sx.org/showthread.php?125466-SGM-Boost-Leak-Tester
 

IndigoMKII

New Member
May 9, 2011
2,181
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0
Madison, Virginia
Supra mn;1933751 said:
If you don't trust the turbo and think the actuator may be bad, why not just test that? A new actuator is alot cheaper than a new T4 turbo.
Hook a bike pump up to it and pressurize until the wastegate opens. You can put a piece of tape on the actuator and watch it move. if it's opening too much at a low psi, there's your problem.. Or atleast part of it.
Its really simple and there are plenty of write-ups around here and on google on how to do it.

A bad waste gate actuator won't cause symptoms like fuel cut unless it's stuck closed.

The PSI not holding is simply because the waste gate hole can't flow enough and spikes up to 12 PSI and settles around 10, it also doesn't help that the CT26 runs out of breath around 5k RPM.
 
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Grandavi

Active Member
Sep 25, 2008
2,663
5
38
Calgary, Alberta, Canada
The CT26 running out of breath is why I am leaning towards a T4. The sad part is, my DP and current turbo would not be useful at that point. (nor would the manifold, but its still the stock original, so not too many tears over that).

Went out and reset up the boost controller and with the new settings I don't get the fuel cut anymore, I think it was the controller being set up incorrectly (still learning its setup - electronic HKS EVC-S). Also went to see my 7MGTE HKS Fcon Vpro as it is in now and took pics of it. The plug is for a 89+ so will have to make a new plug, but we are thinking of just running the standalone and pulling out the stock ECU.

Different issue happened though after I saw the standalone unit. Had my car idling by itself outside the shop while going over the next stage and after about 20 minutes it started smoking out of the tail (whitish with no smell). Odd...
Then went and did a couple pulls (had it cut out only once in third gear during a boost spike, its set for 14 psi max) and during a 2nd gear pull, I got a nice puff of smoke out of the tail followed by a check engine light. Fun!


#04;1933809 said:
if you think its a boost leak... I use one of these, they are quite nice as they are used with the engine off, and slip into where-ever (air-filter location)

p1933914_1.jpg


link; http://www.son240sx.org/showthread.php?125466-SGM-Boost-Leak-Tester

Is this still buyable?
 

seoul4korea

New Member
Nov 6, 2008
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San Diego, CA
www.supraforums.com
Grandavi;1933914 said:
The CT26 running out of breath is why I am leaning towards a T4. The sad part is, my DP and current turbo would not be useful at that point. (nor would the manifold, but its still the stock original, so not too many tears over that).

Went out and reset up the boost controller and with the new settings I don't get the fuel cut anymore, I think it was the controller being set up incorrectly (still learning its setup - electronic HKS EVC-S). Also went to see my 7MGTE HKS Fcon Vpro as it is in now and took pics of it. The plug is for a 89+ so will have to make a new plug, but we are thinking of just running the standalone and pulling out the stock ECU.

Different issue happened though after I saw the standalone unit. Had my car idling by itself outside the shop while going over the next stage and after about 20 minutes it started smoking out of the tail (whitish with no smell). Odd...
Then went and did a couple pulls (had it cut out only once in third gear during a boost spike, its set for 14 psi max) and during a 2nd gear pull, I got a nice puff of smoke out of the tail followed by a check engine light. Fun!




Is this still buyable?

Oh snap! Here comes a blown HG!
 

Beals

JZA70 TT-R
Feb 3, 2009
591
0
16
Alberta, Canada
seoul4korea;1933916 said:
Oh snap! Here comes a blown HG!

But the turbo was used it could be kaput as well. he'd had no luck with his ct upgrades. I suggest going to Albert if he has time rather then DM.

I once raced a skyline in my jdm sl500, very foolish, yes I won by a ridiculous ammount of car lengths but my car was smoking and pissing anti-freeze. turns out I blew a frostplug
 

Grandavi

Active Member
Sep 25, 2008
2,663
5
38
Calgary, Alberta, Canada
Yeah, Im actually talking to Albert right now :)

No.. not a Head gasket.. lol.. but if it was I wouldn't be concerned... At least that is under warranty.. :p
The engine and head are both newly built and assembled by the shop that probably understands 7MGTE's better than most. I would be happy if it was a head gasket really... because if this was me doing all the work myself, I would have the engine out and stripped down for the hell of it and starting over. Little problems are why I pay these guys to work on my car. I did NOT want little problems.

It could be the turbo and because its pissing me off, I think I will buy another turbo, swap 'em and see if it solves it. Then have the 60-1 looked over and if its good, just sell it as is. If not.. toss it.

Because of where my build is at, I am better off staying with a CT26 upgrade, but for any "real" power gains I think I don't have much choice but go with a true turbo (T4). At least from everything I read/hear that is where I should be at.. especially if I'm sinking another 5k into a standalone and tune. (actually.. more like 3.5k.. but Im guessing with all the additions of wiring, sensors, gauges.. its going to climb to 5.)
Whats another 2-3k on top? lol. (I'm so far gone already....)
 

Beals

JZA70 TT-R
Feb 3, 2009
591
0
16
Alberta, Canada
I think a properly rebuilt ct-26 plus a tune could make 500whp, you may need cams though for a little extra low end torque (even though the higher revs wont make much of a difference with the stock turbo).
 

Grandavi

Active Member
Sep 25, 2008
2,663
5
38
Calgary, Alberta, Canada
I'm only shooting to break the 400 rwhp mark. If I can do that I "should" be happy. Reliability trumps speed for me, I just don't feel like my build is reliable yet. It vexes me
 

IndigoMKII

New Member
May 9, 2011
2,181
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0
Madison, Virginia
Beals;1933999 said:
I think a properly rebuilt ct-26 plus a tune could make 500whp, you may need cams though for a little extra low end torque (even though the higher revs wont make much of a difference with the stock turbo).

Uh? I don't think a CT26 will get over 450 with an amazing tune unless you crank the compression way up with one hell of a clipped turbine and E85.