2G Stalls When Decelerating/Revving Down

[Chriztopher]

Engine Throttle/Idle Cut Out/Stall When Decelerating/Revving Down

When I let off the throttle completely the engine stalls out. The RPMs fall to zero. I have to keep revving it or down shift to stop it from cutting off when it falls out of boost. The larger and faster the RPM drop the more likely it is to stall. The higher I adjust the BISS the less it happens. I have to idle over 1500 to get anywhere.

What I have done so far…
1. Replaced the BISS with a junker part. The o-ring was in good shape and I wiped it with silicon sealer.
2. Replaced the IAC with a junker part. I tested it before install and I worked great.
3. Checked voltages, all seems good.
4. Cleaned out the throttle body and replace the throttle body gasket.
5. I have boost/vaccum tested the piss out of it. I found a few small leaks and a leaky stock BOV (surprise) and replaced it with a Synapse Synchronic and plumed it to be most responsive. It holds pressure better than a U-boat now but has not helped the stall issue at all.

I am at a loss. Please help me keep my car running.

 

[92AWDHX40]

Terry's Talon Troubleshooting Tips #3 - Fast Idle (aka. Idle Surge)

Could be a boost leak, have you adjusted the biss screw properly do you have a logger, dsmlink?

 

[mitsukid124]

could be the stop screw, my friends subaru had the same issue and once he adjusted that it wouldn't stall. it also helped to use his safc to tune a little on the lower end.

 

[Chriztopher]

Like I have said, it holds pressure like a Uboat. I have boost tested it to 30psi. I have stopped the minor leaks. Not one single bubble now. That had no effect on the problem.
No I don't have a logger yet.

 

[Djsniperwolf]

Loggers are awesomely cheap now! The kicker is they can scan your CEL. If the system is holding pressure for atleast 30 seconds then that is ok.. Have you checked the FIAV for leaks or clogs? Also..

Have you bypassed the FIAV? If so, don't... The FIAV has a wax style signal.. If you bypassed the coolant lines then you are ultimately setting your engine to limp mode as the FIAV will never fully close without the coolant lines..

 

[Chriztopher]

"Loggers are awesomely cheap now! The kicker is they can scan your CEL."
-I am not throwing any CELs. I was planning on getting a DSM Link Lite if my car will run someday and I can tune it. Would you suggest moving that up in the mod list to trouble shot this issue?

"Have you checked the FIAV for leaks or clogs?"
-No, I will blow them out tonight. (a new tip!! Thanks) To be clear the FIAV is the metal sensor underneath the throttle body with a coolant in and a coolant out line? I have installed a second TB with all the sensors attached so that is not likely the problem unless they were both clogged.

"Have you bypassed the FIAV? If so, don't... The FIAV has a wax style signal.. If you bypassed the coolant lines then you are ultimately setting your engine to limp mode as the FIAV will never fully close without the coolant lines.."
-I have not bypassed the coolant line.

Please keep the ideas coming

 

[crash89]

Is your blow off valve recirculated!?!?!?!

 

[EvilTSi_97]

Is your blow off valve recirculated!?!?!?!

I am willing to bet with this guy this is your issue. Sounds dead on with what's going on.

 

[bryanwheat]

“Loggers are awesomely cheap now! The kicker is they can scan your CEL.”
-I am not throwing any CELs. I was planning on getting a DSM Link Lite if my car will run someday and I can tune it. Would you suggest moving that up in the mod list to trouble shot this issue?

“Have you checked the FIAV for leaks or clogs?”
-No, I will blow them out tonight. (a new tip!! Thanks) To be clear the FIAV is the metal sensor underneath the throttle body with a coolant in and a coolant out line? I have installed a second TB with all the sensors attached so that is not likely the problem unless they were both clogged.

“Have you bypassed the FIAV? If so, don't... The FIAV has a wax style signal.. If you bypassed the coolant lines then you are ultimately setting your engine to limp mode as the FIAV will never fully close without the coolant lines..”
-I have not bypassed the coolant line.

Please keep the ideas coming

It will not set the engine to limp mode, it will just idle a little high, which is correctable with the biss screw.

 

[Infamous33]

Perhaps try something simple first? Disconnect the battery to reset the ECU. The idle strategy may be messed up if the old ISC had issues. Just one of those quick things that could fix the problem. Next, are you grounding the plugs before setting the idle? If you aren't totally certain on it, follow this VFAQ
1G BISS Adjustment

Not saying you don't know what you are doing, just trying to help

Doh !!!!!
That was the 1g, here is the 2g
http://www.vfaq.com/mods/BISS-2G.html

 

[91darkdsm]

100% on the bov, are u venting to the atmosphere? if so recirculate it and your good to go. id guess you proly stumble a lil on acceleration as well am i correct?

 

[Chriztopher]

Is your blow off valve recirculated!?!?!?!

Guys have faith in me my BOV is recirculating. As you may know, the Sychronic can be plumbed for different responsiveness. I have it plumbed to be most responsive.

Perhaps try something simple first? Disconnect the battery to reset the ECU. The idle strategy may be messed up if the old ISC had issues. Just one of those quick things that could fix the problem. Next, are you grounding the plugs before setting the idle? If you aren't totally certain on it, follow this VFAQ
1G BISS Adjustment

Not saying you don't know what you are doing, just trying to help

Doh !!!!!
That was the 1g, here is the 2g
2G BISS Adjustment

Thanks for a new tip. I will give this a try. I am desperate.

100% on the bov, are u venting to the atmosphere? if so recirculate it and your good to go. id guess you proly stumble a lil on acceleration as well am i correct?

The BOV is recirculating and the acceleration is excellent. I am flowing more pressure with the new compression ratio so I spool up at 2,000 rpms and am under boost by 3,000. If the car could stay running it would be a LOT of fun.

Terry's Talon Troubleshooting Tips #3 - Fast Idle (aka. Idle Surge)

Could be a boost leak, have you adjusted the biss screw properly do you have a logger, dsmlink?

Thanks for the doc. This was educational even though it did not lead to a resolution with my issue. I feel like a Jedi Master now in DSM throttle issues.

EXPERT HELP NEEDED!
I have not been able to resolve this issue in the last 11 months. I have had the car to three different shops and they are dumbfounded. I have spent over seven grand on this car. I have spent almost every Saturday working on it and trying all the ideas you have suggested. I am still a GD probationary member so I cant post this issue in the big boy forum. Would one of the proven members be willing to post this issue in the big boy forum? Please! I still can't keep this car running. If I cant solve the problem within a year I am going to sell the POS DSM and go back to tuning cars that don't suck.

 

[ryancampbell98]

Has this problem ever been solved? Every thread I see it doesn’t seem like anyone came back from this and it’s happening to me.

 

[FIBA M - EC17PSE]

Has this problem ever been solved? Every thread I see it doesn’t seem like anyone came back from this and it’s happening to me.

its a post from 2011! they have not even been on since 2015! not the correct post to grave dig here