Could a TD05H cause fuel cut on an otherwise stock engine?

[Token11b]

Basically I have been getting fuel cut when hitting boost. The only mods I am aware this car has is a MBC, arp head studs, dual valve gasket springs, exhaust valves, 2g injectors. i guess exhaust valves, and a td05h 16g. Could this be the reason I am hitting fuel cut? Is the turbo too big without having the additional supporting mods required to handle it?

 

[bryanwheat]

You probably have a boost leak.

 

[shadow001dsm]

whats the boost set at? did you do a leak down test?

 

[Token11b]

No boost leak test yet, gettin to it soon. i havent upped the boost at all it should still be sitting at stock settings (12psi i believe).

 

[2gGst98]

Do you have a boost guage? You shuld get one so you know exactly what you are boosting at. But also do the boost leak test. Are you shure you are hitting fuel cut? I have read else where that hitting fuel cut is loss of all power and like hitting a wall (dont quote me I never hit it befor).

 

[Token11b]

Pretty sure its fuel cut.. while im under acceleration the car just stops and bucks....throws me forward a little bit. its not pleasant. Most of the time I stay out of boost anyways. I do have a boost gauge.. the prior owner installed a "glowshift" boost gauge on there. i know i need to get a new gauge and invest in a wideband o2

 

[goodbuds]

did you get new spark plugs?

 

[2gGst98]

ok so you are shure you are about 12 psi try turning the boost down to 10 psi. because 12 psi on a stock t to small is diffrent then 12 on a 16g. The T25 has something like 375 CFM (how much air passes a certian point I do believe), and the 16g has 550 CFM or around their. So try turning the boost down to 10 see what happens.

If you dont know what CFM is this is easy to understand
What is CFM? Cubic Foot per Minute Airflow Measurement Flow
Hope this helps

I found the turbo chart forum also
http://www.dsmtuners.com/forums/bolt-tech/2566-turbo-chart-i-need-info-complete-corrections.html

 

[brownfinger]

There's some crazy extraneous info going on here. Fix your boost leak and come back with what else may be going on. You have a boost leak. Do a boost leak test.

Look at the "registered" dates of the people giving their 2 cents.

Then do a boost leak test. My car sure did hit fuel cut with a 14b, and a big enough boost leak.

PS: You can run up to 15 psi max. with 450s and a TD 05. You may want to rewire or upgrade the pump, though.

 

[2gGst98]

That might be alot of info but my step bro had a 16g on hit talon that was stock, and he had a MBC and boost guage. 12psi is what he set it at and he hit fuel cut everytime right befor he hit 12psi. So sorry for the info, but he set it to 10 psi and no more cut for him. This info is what he made learn when I got my gst.

I never said he didnt have a leak either, I did say to do a leak check. earlier in the thread. Info is good my friend.

also I just thought about it a boost leak that big I would think he would hear right? but I have had only a small leak and I couldnt realy miss it.

 

[92gsxbafaro]

i would make sure the plugs are good along with the coil maybe turn down the boost and see if its still happening.. if it is it most likely isnt fuel cut

 

[Token11b]

Tomorrow i will hopefully get started on the blt.

 

[sbeck]

Before doing anything you should check your plugs. Set the gap around .025" and make sure there not black or white. Black means rich and white means lean. I just installed a t28 from t25 and would have the same thing happen because I actually have boost now at around 14 psi. I tightened the gap on the plugs and now can hit 21 psi no problems. Until you get fuel mods you want to not exceed 16 psi though.

 

[born2tune]

i must agree on fuel cut. not at12 psi though, i guess elevation and psi would make a difference when fuel cut will happens "meaning not necessarily on a certian psi" but definetly happens at 16psi on 450cc injectors "stock injectors" but this may happen earlier if your fuel pump and fuel pressure regulator is not working as it should, it might be working weaker therefore bringing the fuel cut at a lower psi due to lower fuel pressure/delivery. aka starvation

 

[Boostinsideways]

Its not fuel cut, its almost never fuel. Its nearly always a boost leak.

Most common culprits are Old as shit injector seals, and worn out throttle shaft seals.

Easy way to tell if your throttle shaft seals are worn, remove the Intercooler pipeing, remove the throttle cable. Let it sit over night, if your throttle plate is hard to move by hand, your have nearly a 100% chance of having bad throttle shaft seals. They will cause stick/jamming of the throttle plate in addition to massive boost leaks.

Other common boost leaks include :

Pipe Couplers or Stock "Soft" Intercooler pipes (spray the the insides with hair spray to get a better seal or switch to t-bolt clamps if your still using worm gear clamps. If your "soft" intercooler pipes are cracked it might be time to upgrade.

BISS Screw or the Base Idle Speed Set Screw. This screw has a small o-ring that may be worn, or missing. It can also dry out over time and crack if the cap is missing. Very very cheap and pretty easy to replace.

Throttle Body and Throttle Body elbow gaskets. Chances are these may have never been changed on your 20 year old car, they get brittle, and crack. Pretty cheap and easy to change.

Intake manifold to head gasket. This gasket is a coated metal gasket from the factory, chances that this has failed are slim, but if a cheap inferior gasket was installed, or the stock gasket was reused the previous owner may have been incompetent and not gotten a proper seal. Pain in the ass to change.

You can make a boost leak tester for about 7$. Skip lunch tomorrow, gather the proper supplies from lowes and a local tire shop... If you don't have a spare coupler laying around it might be a bit more expensive.

If you don't have an air compressor, most gas stations have air pumps.

 

[bryanwheat]

Boost leaks cause fuel cut yo.

 

[Boostinsideways]

Boost leaks cause fuel cut yo.

Yeah technically true, But he isn't actually running out of injector or fuel pump @ 12psi on a 16g I am running 16g on my 7-bolt and I am running pretty damn close to stoic past 4k, and pretty rich before that.

 

[bryanwheat]

It isn't about running out of fuel, it is about running more air thru the maf than what is meant to be seen by the ecu. There is a certain amount of airflow that the ecu looks for to cut the fuel off so that there is no damage done to the engine. lets say for instance the ecu cuts fuel after reading 400cfm of air. The turbo is pulling 400+ thru the maf, but only 200 of that is going into the motor and 200 is leaking out. You will hit fuel cut but only show wastegate pressure at the gauge(higher if turbo can keep up).

 

[RadDsm]

I am running pretty damn close to stoic past 4k

I hope not when you are in boost.

 

[mndizzum]

This is definatly from the MAF. My friends mod list included a 16g and a 255 pump on a brand new motor with no boost leaks. It did the same thing until we swapped to a 2G MAF.

 

[bryanwheat]

This is definatly from the MAF. My friends mod list included a 16g and a 255 pump on a brand new motor with no boost leaks. It did the same thing until we swapped to a 2G MAF.

Oh yeah, it happened to your brother once so ever car with similar symptoms i something way less common.

 

[knochgoon24]

I can't believe the bad info being said in this thread.

No boost leak test yet, gettin to it soon. i havent upped the boost at all it should still be sitting at stock settings (12psi i believe).

You have a MBC. It runs whatever pressure you set. The stock boost control system has been bypassed.

Pretty sure its fuel cut.. while im under acceleration the car just stops and bucks....throws me forward a little bit. its not pleasant. Most of the time I stay out of boost anyways. I do have a boost gauge.. the prior owner installed a "glowshift" boost gauge on there. i know i need to get a new gauge and invest in a wideband o2

Sound like fuel cut. "Not pleasant" is the dead give away here. I'm running a Glowshift gauge in my car, for now, and it's decently accurate.

ok so you are shure you are about 12 psi try turning the boost down to 10 psi. because 12 psi on a stock t to small is diffrent then 12 on a 16g. The T25 has something like 375 CFM (how much air passes a certian point I do believe), and the 16g has 550 CFM or around their. So try turning the boost down to 10 see what happens.

375 and 550 CFM are peak air flow numbers. CFM stands for Cubic Feet per Minute. It's the amount of air at standard atmospheric conditions being consumed by the engine. Even though a 16g will flow a lot more than a T25, he's only at 12psi. He shouldn't be hitting fuel cut, even with a 16g, at 12psi.

That might be alot of info but my step bro had a 16g on hit talon that was stock, and he had a MBC and boost guage. 12psi is what he set it at and he hit fuel cut everytime right befor he hit 12psi. So sorry for the info, but he set it to 10 psi and no more cut for him. This info is what he made learn when I got my gst.

I never said he didnt have a leak either, I did say to do a leak check. earlier in the thread. Info is good my friend.

also I just thought about it a boost leak that big I would think he would hear right? but I have had only a small leak and I couldnt realy miss it.

Your step brother must have also had a boost leak. Not to be rude, but I'd stop taking advice from him. His car obviously wasn't running right, and it seems that he didn't know any better.

You can sometimes hear the big boost leaks, but even the small ones will cause problems. If you do a search for how to do a boost leak test, you'll find enough info to lead you step-by-step on where to check.

i would make sure the plugs are good along with the coil maybe turn down the boost and see if its still happening.. if it is it most likely isnt fuel cut

It most likely is fuel cut. And even if he turns the boost down, large boost leaks will still cause it to hit fuel cut.

Still, are part of the regular maintenance when buying a used car, you should check the plugs. If you have misfire issues even after getting ALL of the boost leaks fixed, then we'll start helping you diagnose things like a bad coil pack.

i must agree on fuel cut. not at12 psi though, i guess elevation and psi would make a difference when fuel cut will happens "meaning not necessarily on a certian psi" but definetly happens at 16psi on 450cc injectors "stock injectors" but this may happen earlier if your fuel pump and fuel pressure regulator is not working as it should, it might be working weaker therefore bringing the fuel cut at a lower psi due to lower fuel pressure/delivery. aka starvation

Fuel cut is ECU related. It doesn't know what the fuel pressure is or if the fuel pump is up to snuff. Fuel cut and running lean feel totally different. "Not pleasant" is the key words here. If the car was going lean, he probably would have described it as a misfire or a loss of power.

Its not fuel cut, its almost never fuel. Its nearly always a boost leak.

And boost leaks are the leading cause of fuel cut.

Most common culprits are Old as shit injector seals, and worn out throttle shaft seals.

Easy way to tell if your throttle shaft seals are worn, remove the Intercooler pipeing, remove the throttle cable. Let it sit over night, if your throttle plate is hard to move by hand, your have nearly a 100% chance of having bad throttle shaft seals. They will cause stick/jamming of the throttle plate in addition to massive boost leaks.

Other common boost leaks include :

Pipe Couplers or Stock "Soft" Intercooler pipes (spray the the insides with hair spray to get a better seal or switch to t-bolt clamps if your still using worm gear clamps. If your "soft" intercooler pipes are cracked it might be time to upgrade.

BISS Screw or the Base Idle Speed Set Screw. This screw has a small o-ring that may be worn, or missing. It can also dry out over time and crack if the cap is missing. Very very cheap and pretty easy to replace.

Throttle Body and Throttle Body elbow gaskets. Chances are these may have never been changed on your 20 year old car, they get brittle, and crack. Pretty cheap and easy to change.

Intake manifold to head gasket. This gasket is a coated metal gasket from the factory, chances that this has failed are slim, but if a cheap inferior gasket was installed, or the stock gasket was reused the previous owner may have been incompetent and not gotten a proper seal. Pain in the ass to change.

You can make a boost leak tester for about 7$. Skip lunch tomorrow, gather the proper supplies from lowes and a local tire shop... If you don't have a spare coupler laying around it might be a bit more expensive.

If you don't have an air compressor, most gas stations have air pumps.

Finally, some good solid info.

Yeah technically true, But he isn't actually running out of injector or fuel pump @ 12psi on a 16g I am running 16g on my 7-bolt and I am running pretty damn close to stoic past 4k, and pretty rich before that.

For the sake of your engine, I hope you aren't running near stoic under boost. With my small 16g, I'm already hitting 22psi @ 4k and running 11.3:1 AFR.

 

[Killa_dsm]

I say its a boost leak. Do a boost leak test.

I think the problem is that not everyone posting understand the concept of fuel cut and why it happens. My explanation is basically the same as bryanwheat's.

When the ecu sees a certain airflow it cuts fuel. So the amount of airflow the ecu sees is what causes it to cut fuel. A boost leak will make you hit fuel cut sooner. For example, if your running 17psi on your gauge but have 3psi worth of leaks, then your MAF will be telling the ecu that your flowing 20psi worth of airflow. In turn bringing on fuel cut sooner.