Cuts Out Under Boost..

[YouGotSpooled]

I still havent got this problem solved.

Okay, running stock boost the car runs great. Once you turn the boost up to 9psi or more, it cuts out under WOT at around 4000-4500rpm. It only cuts out for about a second, then without taking your foot off the gas it will resume and continue to boost and pull hard the rest of the way. Sometimes, it wont cut out.. other times it will, the only time it wont is when im running stock boost. I have had it up to 13psi of boost, without hitting fuel cut.. and I will get the same problem but it will sort of pick and choose when it wants to do it.

It feels like a total loss of all power for about a second.

Funny thing is, it wont do this in first gear.. only 2nd, 3rd and 4th.. havent tried 5th yet.

Any ideas? Ive replaced spark plugs.. checked pipes.. I was thinking maybe it could be a weak coil pack?? But I wanted opinions before I go buy one.

-Thanks

 

[Supraboy89]

you are probably hitting fuel cut. does it happen the moment you shift. if so u need to back the screw out of the afm. but dont do so if u dont have mods to support higher boost

 

[starscream5000]

First gear doesn't build boost very well, it doesn't sound like you are blowing out your spark, because it you did, it should do it constantly once it starts...

 

[jdub]

Pull your EFI fuse for a minute to clear codes...when it does it again, check your codes. If you have a code 34, it's fuel cut.

BTW - adjusting the AFM screw out will not increase boost or correct for fuel cut...it will be a *global* correction to allow more unmetered air past the AFM and can help to correct a rich condition. But only to a small extent.

 

[YouGotSpooled]

It doesnt happen the moment I shift.

Ive checked the codes, and I do not have a code 34 anymore (I had it when I had a shimmed waste gate) and Ive cleared them, drove it and i get 24 and 52. And how do you adjust the AFM screw anyways? Where is the screw located?

thanks

 

[bigaaron]

Air Temp and Knock Sensor codes, that would do it for sure.

You might need a new afm, do the test procedure on it with an ohm meter.
http://www.cygnusx1.net/Supra/Library/TSRM/MK3/manual.aspx?Section=FI&Page=96

Knock sensor is usually a broken wire, but the knock sensors can also crack at the base where the plastic joins to the metal.

 

[YouGotSpooled]

I changed the AFM electronics, no luck with that.

I went driving with about 13psi of boost, and if I shifted hard into second or third, it would cut out. If I went into second or third easy, it wouldnt cut out and then I would hit WOT and it doesnt cut out. So I guess it does only do it when I shift. :nono:

 

[johnathan1]

Check for boost leaks...

 

[Supraboy89]

to backout the screw u have to drill out the aluminum plate blocking it. it is on the bottom of the afm then u will see the screw

 

[YouGotSpooled]

I did that and turned it out all the way..

Still was cutting out at around 13psi, but wouldnt do it at about 9.. Then I heard a "jittery" kind of noise coming from the exhaust under acceleration... Get home, park it in the garage and I get to see steam coming out of my hood.. And its dripping a puddle on the floor.. Im hoping its just my water pump..

The car also seems to be running kind of hot..

Oh I wish it could run good for more than a week.

 

[tte]

Do you have an aftermarket downpipe or stock one?

Cheers,
Roy

 

[YouGotSpooled]

its a custom made 3" downpipe. It didnt make this noise before i did the AFM mod and turned up the boost.

 

[crisp]

I could be "all wet" here guys... but "might" he be pushing boost into the water jacket when he begins to "pressurize"? (Blown Head Gasket)

That condition WILL cause "similar" hesitation as you begin to generate pressure... and will DEFINITELY lead to such issues as COOLANT all over the FLOOR after a "high" boost run. Did the TEMP spike and was there any "hesitation" or "surging" during acceleration? (Possibly indicating coolant IN THE CYLINDER CHAMBER as well as the water jackets...)

-crisp

 

[YouGotSpooled]

It was sort of a surging feeling I guess youd call it.

The car has a MHG and ARP Studs.. So I hope to god the HG isnt blown.. And I dont think my temp gauge is working properly, and my low coolant light didnt go on (But was below the full level in the resevoir).

 

[Supraboy89]

I could be "all wet" here guys... but "might" he be pushing boost into the water jacket when he begins to "pressurize"? (Blown Head Gasket)

I agree

 

[Supraboy89]

your raidator may be stopped up to. u also may have a little boost leak

 

[YouGotSpooled]

"stopped" up?

 

[crisp]

It was sort of a surging feeling I guess youd call it.

The car has a MHG and ARP Studs.. So I hope to god the HG isnt blown.. And I dont think my temp gauge is working properly, and my low coolant light didnt go on (But was below the full level in the resevoir).

Did you re-torque the ARP chromoly sticks after a few full heat cycles? (And install them to the SPECIFIED lower torque level WITH the provided lube? OVERTORQUE will cause a JOINT to FAIL as well... but as you suggest, the MHG on a "true" head should not fail if torqued properly...)

-crisp

 

[Supraboy89]

check it for cold spots. u also need to fix the temp sensor that is a must. if u are still hitting fuel cut u have a boost leak

 

[jdub]

Just a suggestion...turn down the boost...before you kill the motor.

You really need to learn more about this car before you start adjusting things (like the AFM screw) without having a clue as to what it will do. You need to fix the codes like Aaron told you...the rest of this thread is leading you down the wrong path.