Engine flatlines/jumps
- Thread starter Aeroking
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Quickstop [UK]
Combating adversyty.
Re: Engine flatlines/jumps
Regarding the lockup, locking a converter too early is worse than locking it later, certainly with regard to RPM. As the RPM builds, the slip will reduce because the TC is at the stall speed. A good stall should have a 5% difference between the stator and the rotor. You mentioned 5%, Brandon - seems about right. No TCC lockup. Wasn't that your original problem?
If you lock it up earlier at a lower RPM, you have a greater difference in speeds between the rotor and the stator in the TC, more stress and wear.
It's like slipping a clutch on a manual. You don't want the engine to be revving faster than the gear or you'll burn it out. You want the RPM to be high enough that the TC is matched (stalled) to the engine.
:2cents:
Regarding the lockup, locking a converter too early is worse than locking it later, certainly with regard to RPM. As the RPM builds, the slip will reduce because the TC is at the stall speed. A good stall should have a 5% difference between the stator and the rotor. You mentioned 5%, Brandon - seems about right. No TCC lockup. Wasn't that your original problem?
If you lock it up earlier at a lower RPM, you have a greater difference in speeds between the rotor and the stator in the TC, more stress and wear.
It's like slipping a clutch on a manual. You don't want the engine to be revving faster than the gear or you'll burn it out. You want the RPM to be high enough that the TC is matched (stalled) to the engine.
:2cents:
Aeroking
e.i.
Re: Engine flatlines/jumps
I had been running 875 "R" lifters and they always bled out. so i switched to Delco stock lifters. I can rev the truck past 6000 without a load on it. I can try switching valvesprings. My springs are beehives, Manley i believe.
i tried locking it at the line, but on each shift it would give me knock ret. from hitting so hard.
i have a stack of timeslips with 112mph on them with ETs from 13.7 to 11.4. The truck literally hits terminal velocity, i'm waiting for a ripple in the space-time continuum.
I had been running 875 "R" lifters and they always bled out. so i switched to Delco stock lifters. I can rev the truck past 6000 without a load on it. I can try switching valvesprings. My springs are beehives, Manley i believe.
i tried locking it at the line, but on each shift it would give me knock ret. from hitting so hard.
i have a stack of timeslips with 112mph on them with ETs from 13.7 to 11.4. The truck literally hits terminal velocity, i'm waiting for a ripple in the space-time continuum.
Last edited:
Quickstop [UK]
Combating adversyty.
Re: Engine flatlines/jumps
Locking at the line - I'm not surprised - that's like dumping the clutch in a manual.
Locking at the line - I'm not surprised - that's like dumping the clutch in a manual.
Aeroking
e.i.
Re: Engine flatlines/jumps
valve lift with the rockers is 545 intake 530 exahust. I verifyed theres no coil bind in the springs. I had the trans slip once (my fault low on fluid) at WOT and i hit the rev limiter at 6200. But that was a quick hit, that wasnt a steady pull, like a pass in 3rd gear. 1st and 2nd gear are pretty much over at 75mph, so its a quick hit like Dave said.
valve lift with the rockers is 545 intake 530 exahust. I verifyed theres no coil bind in the springs. I had the trans slip once (my fault low on fluid) at WOT and i hit the rev limiter at 6200. But that was a quick hit, that wasnt a steady pull, like a pass in 3rd gear. 1st and 2nd gear are pretty much over at 75mph, so its a quick hit like Dave said.
dgoodhue
BuSTeD 4.3
Re: Engine flatlines/jumps
4L60's won't lock up in first gear. I try to lock mine at about 45mph. 112 is a low mph for a 11.4.
Have you tried shifting into OD just before 5300rpm (Obviously this doesn't fix your problem).
4L60's won't lock up in first gear. I try to lock mine at about 45mph. 112 is a low mph for a 11.4.
Have you tried shifting into OD just before 5300rpm (Obviously this doesn't fix your problem).
BMFB
Not to scale
Re: Engine flatlines/jumps
You are right about rpm, bit that doesn't relate to speed. You have a much greater mechanical advantage between the converter and wheels in second gear even at the same rpm. Roughly 30% less stress is put on the converter clutch in second gear as opposed to locking it in third.
As far as your issues go I cant say much without seeing a real log. Free revving is no where near learning g how your valve train is working going down the track because you don't have 20psi of boost trying to push it open. What are your seat pressures and what are you running for boost behind them
You are right about rpm, bit that doesn't relate to speed. You have a much greater mechanical advantage between the converter and wheels in second gear even at the same rpm. Roughly 30% less stress is put on the converter clutch in second gear as opposed to locking it in third.
As far as your issues go I cant say much without seeing a real log. Free revving is no where near learning g how your valve train is working going down the track because you don't have 20psi of boost trying to push it open. What are your seat pressures and what are you running for boost behind them
Aeroking
e.i.
Re: Engine flatlines/jumps
still diagnosing, went back to the track tonight and trapped 111mph again.
The datalog knocks and goes rich no matter how much boost or timing is used, right at 5300. It tries to do it in 2nd gear, but the engine is accelerating so fast, it just shows as a blip on the way to 5600 shift point. But in the long 3rd gear pull the truck noses over. The truck doesn't run rough, or buck. After a run, the plugs are soaked. In the tune I keep the VE the same from 5000 to 5500, yet the wideband dives from 11.9 to 10.5 right at 5300. The problem goes away if I stay WOT for over 5 seconds, the wideband comes back up, the knock goes away and the engine screams from 5500 up to 6000+.
- verified cam timing
- verified cam specs
- verified valve spring seat pressures, install height & coil bind
- swapped distributors (stock, reman, ProComp)
- changed ignition module (Delco, BWD)
- changed coil (delco MSD)
- removed MSD 6AL
- swapped plug wires (Taylor, Delco, MSD)
- swapped plugs (5s, 6s, plug gap everywhere between 20 and 35)
- swapped cap & rotor (MSD, BWD)
- verified timing up to 3000rpms with timing light
- verified rotor phasing
- verified crank reference angle (standalone ecm)
- zeroed out all the modifiers in the tune
- turned knock sensor off
- changed fuels (93, methanol, VP110, C16)
- boost levels from 10 to 25, rock solid control in the datalog
- checked every ground
:tdown:
still diagnosing, went back to the track tonight and trapped 111mph again.
The datalog knocks and goes rich no matter how much boost or timing is used, right at 5300. It tries to do it in 2nd gear, but the engine is accelerating so fast, it just shows as a blip on the way to 5600 shift point. But in the long 3rd gear pull the truck noses over. The truck doesn't run rough, or buck. After a run, the plugs are soaked. In the tune I keep the VE the same from 5000 to 5500, yet the wideband dives from 11.9 to 10.5 right at 5300. The problem goes away if I stay WOT for over 5 seconds, the wideband comes back up, the knock goes away and the engine screams from 5500 up to 6000+.
- verified cam timing
- verified cam specs
- verified valve spring seat pressures, install height & coil bind
- swapped distributors (stock, reman, ProComp)
- changed ignition module (Delco, BWD)
- changed coil (delco MSD)
- removed MSD 6AL
- swapped plug wires (Taylor, Delco, MSD)
- swapped plugs (5s, 6s, plug gap everywhere between 20 and 35)
- swapped cap & rotor (MSD, BWD)
- verified timing up to 3000rpms with timing light
- verified rotor phasing
- verified crank reference angle (standalone ecm)
- zeroed out all the modifiers in the tune
- turned knock sensor off
- changed fuels (93, methanol, VP110, C16)
- boost levels from 10 to 25, rock solid control in the datalog
- checked every ground
:tdown:
It's just a six
Super Member
Re: Engine flatlines/jumps
I might have missed it, but have you swapped out the MAP sensor?
Cant remember where I read it ,but there are cheap/ bad MAP sensors that have had leaks in them.:2cents:
It might not be linear @ certain boost levels.
I might have missed it, but have you swapped out the MAP sensor?
Cant remember where I read it ,but there are cheap/ bad MAP sensors that have had leaks in them.:2cents:
It might not be linear @ certain boost levels.
Throws
Active member
Re: Engine flatlines/jumps
Especially the MSD ones. There was a shit run of them. I went with a Turbo TA 3 bar that looked and ran perfectly.
-P
Especially the MSD ones. There was a shit run of them. I went with a Turbo TA 3 bar that looked and ran perfectly.
-P
Don W.
Stab it and steer it
Re: Engine flatlines/jumps
I looked at the slips. He's just getting to the 1/8 to quick to be at 112. Also look at the intervals between 1000' and the 1/4. All under 2 secs. That's haulin'.
Look at this slip of my sub 12 run. Similar. Not quite as quick at the bottom but pullin' hard at the top. I remember this run. I could tell something was happening 'cuz it just put me back in the seat at the top end.
https://dl.dropboxusercontent.com/u/86797850/11 second slip.jpg
I looked at the slips. He's just getting to the 1/8 to quick to be at 112. Also look at the intervals between 1000' and the 1/4. All under 2 secs. That's haulin'.
Look at this slip of my sub 12 run. Similar. Not quite as quick at the bottom but pullin' hard at the top. I remember this run. I could tell something was happening 'cuz it just put me back in the seat at the top end.
https://dl.dropboxusercontent.com/u/86797850/11 second slip.jpg
Aeroking
e.i.
Re: Engine flatlines/jumps
i have two 3bar map sensors, both not MSD ones. I've swapped them back and forth with no change.
The datalog has a flat MAP value that matches what I see on the boost gauge, so I ruled that out long ago.
I can try turning the closed loop off and see if it still goes rich.
i have two 3bar map sensors, both not MSD ones. I've swapped them back and forth with no change.
The datalog has a flat MAP value that matches what I see on the boost gauge, so I ruled that out long ago.
I can try turning the closed loop off and see if it still goes rich.
It's just a six
Super Member
Aeroking
e.i.
Re: Engine flatlines/jumps
little update. I did test and tune Friday night with the knock sensor off.
First run was 13psi, low timing
60ft- 1.68
330- 4.96
1/8et- 7.78
1/8mph- 86.5
1000et- 10.24
1000mph- 99.3
1/4et- 12.33
1/4mph- 106.8
Second run I upped the boost to about 22, and timing in the high teens
60ft- 1.69
330- 4.87
1/8et- 7.58
1/8mph- 91.3
1000et-9.91
1000mph- 104.5
1/4et- 11.90
1/4mph- 111
still no improvement. But made the drive back home without a broken parts, which is always good.
but today I went for some pre-dawn freeway runs and tried Dave's tip of leaving it in 4th. I have always left it in 3rd gear and tried to wind it out. I changed my governor weights and springs years ago to shift 2-3 at 5700, which it does perfectly.
However, when I put it in 4th and wound it all the way out, it shifted 3-4 crisp at 5200 WOT, and not 5700 lift the 2-3 shift.
I haven't changed the governor weights in a few years. I wonder if the transmission doesn't like being pushed past its shift point. After I get back from Carlisle I will play around with the weights and springs again.
little update. I did test and tune Friday night with the knock sensor off.
First run was 13psi, low timing
60ft- 1.68
330- 4.96
1/8et- 7.78
1/8mph- 86.5
1000et- 10.24
1000mph- 99.3
1/4et- 12.33
1/4mph- 106.8
Second run I upped the boost to about 22, and timing in the high teens
60ft- 1.69
330- 4.87
1/8et- 7.58
1/8mph- 91.3
1000et-9.91
1000mph- 104.5
1/4et- 11.90
1/4mph- 111
still no improvement. But made the drive back home without a broken parts, which is always good.
but today I went for some pre-dawn freeway runs and tried Dave's tip of leaving it in 4th. I have always left it in 3rd gear and tried to wind it out. I changed my governor weights and springs years ago to shift 2-3 at 5700, which it does perfectly.
However, when I put it in 4th and wound it all the way out, it shifted 3-4 crisp at 5200 WOT, and not 5700 lift the 2-3 shift.
I haven't changed the governor weights in a few years. I wonder if the transmission doesn't like being pushed past its shift point. After I get back from Carlisle I will play around with the weights and springs again.
It's just a six
Super Member
Re: Engine flatlines/jumps
Did you try it in open loop?
Did you try it in open loop?