Engine stalls on hard braking e38/t42
Thread Starter
Teching In
Joined: Aug 2019
Posts: 35
Likes: 4
Engine stalls on hard braking e38/t42 Hi all,
It is an intermittent problem, fuel level doesn't matter, ruled that out. Under hard braking (panic stop) or slowing from high speed (freeway offramp) my car will stall, no codes either. I have disabled the brake torque management thinking that was causing it and no change. Any ideas? Thanks.
It is an intermittent problem, fuel level doesn't matter, ruled that out. Under hard braking (panic stop) or slowing from high speed (freeway offramp) my car will stall, no codes either. I have disabled the brake torque management thinking that was causing it and no change. Any ideas? Thanks.
TECH Senior Member
Joined: Jun 2016
Posts: 22,291
Likes: 3,616
From: Central Cal.
Look for a loose connection at the battery, and/or loose battery hold-down. Any sudden movement change like rapid deceleration might cause a bad connection to momentarily disconnect.
I know this sounds weird, but I saw cases of it on this forum. The guy with the issue and the guy who helped solve it.
I know this sounds weird, but I saw cases of it on this forum. The guy with the issue and the guy who helped solve it.
You haven't listed any mods, so I might say take it to the dealer and get it fixed 
Really though, depends on whats done to it. Could be a loose connection from above. Could also be a handful of calibration reasons.
Really though, depends on whats done to it. Could be a loose connection from above. Could also be a handful of calibration reasons.
Thread Starter
Teching In
Joined: Aug 2019
Posts: 35
Likes: 4
I should know better...
I did make sure my connections are tight and solid. It is a 4l80e behind a gen4 6.0 (C/I/H), 3000 stall converter, all tuned with HP tuners. It acts like a torque converter problem, similar to the 90's gm cars when the torque converter solenoid would go bad. It will do it 100% of the time on super hard braking, only sometimes on the high speed slow down.
I did make sure my connections are tight and solid. It is a 4l80e behind a gen4 6.0 (C/I/H), 3000 stall converter, all tuned with HP tuners. It acts like a torque converter problem, similar to the 90's gm cars when the torque converter solenoid would go bad. It will do it 100% of the time on super hard braking, only sometimes on the high speed slow down.
TECH Addict
Joined: Dec 2004
Posts: 2,177
Likes: 627
From: Florida
what cam? how 'modified' is the tune from stock?
log tcc state, engine rpm, input shaft rpm and you should be able to see if its the tcc pulling the engine speed down. it sounds like its idle/air tables to me though. watch your throttle blade % (not APP%) and MAP and see what its doing when you slam on the brakes. those should start you in the right direction.
log tcc state, engine rpm, input shaft rpm and you should be able to see if its the tcc pulling the engine speed down. it sounds like its idle/air tables to me though. watch your throttle blade % (not APP%) and MAP and see what its doing when you slam on the brakes. those should start you in the right direction.
