Fuel Cut due to what?

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Emeraldage

New Member
Oct 13, 2011
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So got my turbo motor and everything running it's awesome. I have no boost gauge or sensor figured I'd just save for a boost controller for the two in one. My only mods are a 3" dpp with a 3" exhaust. We didn't mess with the block but the toyota mechanic said something has been worked on before in the block. We completely redid the head.

Okay so I'm getting some fuel cut usually around 3500 when I feel full boost power, but then will keep pulling. Ocassionally it won't fuel cut. I got a code 34 of course, most told me probably a boost leak. I got new clamps for all the piping and torqued them pretty strong. Everything got new gaskets and torqued to spec. I ran it once on a colder day and I would only get like a .2s fuel cut around like 3200 felt like a little miss and it will pull strong. I tried plugging the hose and using my compressor to put air through the system, didn't hear anything obvious.

I do not know what was done to the turbo before but it had no shaft play and still spun perfectly. The wastegate is really friggin hard to open by hand but I don't know if it's supposed to be like that or not it's my first turbo.

Could it be linked to TPS? My TPS isn't perfect it has a 1300rpm idle, sometimes drops down to a normal 900rpm idle but then goes back up again.

Could I actually be hitting a fuel cut for too much pressure? Maybe there was work done before that I don't know off on the turbo? Turbo starts spinning at 2400rpm and really feels like I got full boost about 3000-3500rpm and pulls crazy hard till the troque starts to drop around 5500rpm..

Thoughts? Sorry for the essay :D This car is like 2-3x as fast as it was with the NA turbo even with the lower 3.73 gearing.. There's no way it's just an extra 40 hp and 60ftlbs or so lol
 
DeMoN2318

DeMoN2318

New Member
May 24, 2012
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Arizona
Sounds like fuel cut...

DDP and Exhaust, and rebuild head will flow alot more air and cause fuel cut...


Its not the TPS, fuel cut is triggered by the AFM voltage signal...

Get a boost gauge
 
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Emeraldage

New Member
Oct 13, 2011
322
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Ohio
Got my boost gauge installed. Went WOT in 3rd at 2k rpm. Boost went up to ~12psi, at like ~3300rpm hit fuel cut, dropped to like 6-8psi and kept pulling for the rest of the rpm without a cut.

Does this sound like a stock turbo? I thought stock ct26 were quicker on boost than that, and I have a fresh head and a dpp as well I figured it would be lit earlier, I've read most are full boost stock at 3k.
 
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Emeraldage

New Member
Oct 13, 2011
322
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Ohio
Explain what you mean by bogging? It still pulls pretty hard, def faster than my rich running 7mge but not nearly as hard as it does before fuel cut.

Well I'm sure it's a ct26 but I thought ct26's are supposed to be on boost faster than 3300rpm? Especially when I have a redone head dpp and exhaust. I wasn't wondering if it was a different turbo I'm wondering if it's had work done or a 57 trim or some kind of rebuild like that? I'm still new to turbos but I would never think a turbo would still be running so well after 25 years.

Now I have to decide between a paint job and lex/550s :(
 
Backlash2032

Backlash2032

New Member
Sep 20, 2010
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Shit, I can make boost below 2000 rpm... Granted it's in 4th gear and only a pound or two but I can get full boost by 2500

Sent from my HTC6435LVW using Tapatalk
 
akito

akito

Keep Laughing.You're Next
Jul 31, 2006
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Springfield/Va
Check to see if your turbo is shimmed. But it does sounds like fuel cut, i was on the same set up, 3" turbo back, intake, FMIC, non shim stoc ct26 and i hit fuel cut at 11lbs and it hits real strong. Next step for you would be bigger injectors/ Lexus AFM and SAFCII + tune.
 
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Emeraldage

New Member
Oct 13, 2011
322
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Ohio
I've been doing like 2nd and 3rd gear pulls. On the highway when i'm crusiing at 2500rpm I can push the gas down and get a spool.

I'm just saying I wasn't hitting that peak 12psi till like 3200rpm or so. I feel like it's a 57 trim rebuild or something, I wouldn't expect to high FC at such an early rpm on stock turbo lol. The previous people rebuilt the block so maybe they did work on the turbo too not sure how I could tell.
 
DeMoN2318

DeMoN2318

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May 24, 2012
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Arizona
I have a totally stock CT26 and i hit fuel cut at 3200 in 3rd...

What is your question here? are you wondering if what you are experiencing is fuel cut? or are you wondering if your turbo is what you think it is?
 
1

1James

Lurker
Mar 19, 2009
60
1
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Bay Area, CA
It is easy to tell if your CT26 is upgraded, pull off the accordion hose and see if your inducer is larger than the stock one.

Image is stolen from Bishop's site and rehosted to not tax his bandwidth:
10253994_10100251112600264_5318346168872939258_n.jpg
 
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Emeraldage

New Member
Oct 13, 2011
322
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Ohio
Oh that's cool I'll take a look at that sometime, too bad the friggin according hose feels like it melted on the turbo it's so hard to get off lol.

And to the other guy, both really. I was just trying to figure out if I was having a boost leak or having boost cut due to too much air/boost whatever. Cause I couldn't find any other places that I could possibly have a boost leak.
 
DeMoN2318

DeMoN2318

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May 24, 2012
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Arizona
Fuel cut is going to be around 11-13 psi...you said you get to 12 and then get what you think is fuel cut. Its fuel cut...

Lex/550 in your future I see
 
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Emeraldage

New Member
Oct 13, 2011
322
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0
Ohio
Yeah I agree that it's obviously fuel cut now that I can see my boost pressure :p

Lol. Is it normal for it to 'bog' after fuel cut like he said? As in after it hits fuel cut it'll keep pulling but at like 7psi or something? I noticed too after I hit fuel cut and let go of throttle, my idle drops far until the engine light turns off and then it goes back up.

Wish there was an easy to way to drop a bit of power lol.. Muffler shop expanded the pipe around my dpp instead of welding a flange so I can't just swap back to stock dp. Have to decide between a paint job or like 100 horse power.. lol..
 
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Emeraldage

New Member
Oct 13, 2011
322
0
0
Ohio
Damn :( Cold night so I tried going out boosting again... Although I didn't get FC but something else was happening.. Once I wou ld hit my 10-11psi somewhere around there, it would slowly drop all the down way to about 5-6psi or so at higher rpm until I left off.
 
D.J.T.

D.J.T.

Member
Aug 25, 2010
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Arkansas, United States
Backlash2032;2003731 said:
Fuel cut at 15 psi? Unless your on lex afm and 550s I woukdnt be complaining.

Sent from my HTC6435LVW using Tapatalk
Click to expand...

It creeps. Have DM 11 psi actuator and stock actuator. Same story.

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