'Lack' of power issue
Thread Starter
Launching!
Joined: Jan 2009
Posts: 241
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From: Mead, WA
'Lack' of power issue I just finished putting the 5.3/4l60e out of an 08 Sierra 4x4 into my 04 Jeep Wrangler and am having what I'll describe as power issues.
Speartech did the harness, but not the PCM. I've done all kinds of things with the tune and still have the same issues. But now it's a lot more lively around town.
There is a VSS in the trans output shaft and I believe it's the same VSS that was there factory?
Anyway, the problem is that it acts like it's in an economy mode or something. There have been a few times that the thing just flat got with it and I'm not sure what caused that, but I liked it and want it back.
It also will not downshift when you stab it, and is already in 4th gear at ~35 mph. At that point, WOT will not cause it to downshift, but if you move the selecter to D3, it will change. If you pull up to a stop, it will downshift. When in this 'power' mode, it will downshift and it will stay in the gears longer/more RPM's. Today I noticed that it's pretty much 2800 RPM's is the max when WOT and it changes gears. Until it's up to 3rd, then it won't change to 4th, however there isn't any more left to keep speed increasing.
Anyway, the speedo works and is accurate at the PCM - using HP Tuners, I can see what the computer is seeing. The tach also works. Different gas doesn't help - ie 87 or 91 octane.
Any thoughts????
Speartech did the harness, but not the PCM. I've done all kinds of things with the tune and still have the same issues. But now it's a lot more lively around town.
There is a VSS in the trans output shaft and I believe it's the same VSS that was there factory?
Anyway, the problem is that it acts like it's in an economy mode or something. There have been a few times that the thing just flat got with it and I'm not sure what caused that, but I liked it and want it back.
It also will not downshift when you stab it, and is already in 4th gear at ~35 mph. At that point, WOT will not cause it to downshift, but if you move the selecter to D3, it will change. If you pull up to a stop, it will downshift. When in this 'power' mode, it will downshift and it will stay in the gears longer/more RPM's. Today I noticed that it's pretty much 2800 RPM's is the max when WOT and it changes gears. Until it's up to 3rd, then it won't change to 4th, however there isn't any more left to keep speed increasing.
Anyway, the speedo works and is accurate at the PCM - using HP Tuners, I can see what the computer is seeing. The tach also works. Different gas doesn't help - ie 87 or 91 octane.
Any thoughts????
What axles, tire size and gearing? Since this is almost certainly NOT the tires/gears the computer expects, you may be confusing the poor thing. I put a 383 in my Wrangler, and with the 3.73 gearing in the axles and 37" IROKS, it was a dog. I knew it would be, and those gears only stayed in long enough for the 5.13's to arrive.
Thread Starter
Launching!
Joined: Jan 2009
Posts: 241
Likes: 0
From: Mead, WA
Yes, I've edited the tune for correct gear/tire... Here's what I have.
5.3/4l60E out of an 08 Sierra
~38" tires
5.13 gears
The problem is this thing has ran like a bat out of hell 3? times now, so I know it's capable of more than what I'm getting now. Also, I know it's capable of more than 2800 RPM's, which is all it gets before switching gears, even at WOT. It also won't downshift once in a higher gear.. Even in 4th at 10 mph, it might shift into 3rd, but it's not going into 1 or 2 and hawling ***. I even pulled a Superchips programmer (for 08 GM Gas) and put the performance tune in it - you know, thinking it was the tune and no dice. Does better around town, but still the same issues.
yes, I have the tune and log file available and will post them. No dice... Says the files are too big
Now what? PM your email addy and I'll email you them.
5.3/4l60E out of an 08 Sierra
~38" tires
5.13 gears
The problem is this thing has ran like a bat out of hell 3? times now, so I know it's capable of more than what I'm getting now. Also, I know it's capable of more than 2800 RPM's, which is all it gets before switching gears, even at WOT. It also won't downshift once in a higher gear.. Even in 4th at 10 mph, it might shift into 3rd, but it's not going into 1 or 2 and hawling ***. I even pulled a Superchips programmer (for 08 GM Gas) and put the performance tune in it - you know, thinking it was the tune and no dice. Does better around town, but still the same issues.
yes, I have the tune and log file available and will post them. No dice... Says the files are too big
Now what? PM your email addy and I'll email you them. Trending Topics
i put 1 00 ls1/4l60e in my 95 firebird. im having the same problem. its called "limp mode" or "safe mode". take a look at your MAF, TPS and any other senser that help the PCM tell the tranny to shift. im still working on mine. i had spear tech do the wire harness and the PCM. im waiting to get it back from him now.
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Verdad Gallardo Thread Starter
Launching!
Joined: Jan 2009
Posts: 241
Likes: 0
From: Mead, WA
Pretty sure... VCM suite shows TPS at 20-80% and from what i've been told that is a different measurement and to look at some other PID and I'd see that 0-100%. It made sense and they knew exactly what I meant, so I never looked.
I'm not sure if it's limp mode or safe mode - I think I have more power than what would be available in those. The trans does shift. I can drive down the freeway pulling my camper at 80 mph. It just won't down shift unless I'm coming to a stop. I can move the selecter to D3 and it will shift from 4th to 3rd.
No, I haven't. But I could drag a passenger with me and make them try it 
i put 1 00 ls1/4l60e in my 95 firebird. im having the same problem. its called "limp mode" or "safe mode". take a look at your MAF, TPS and any other senser that help the PCM tell the tranny to shift. im still working on mine. i had spear tech do the wire harness and the PCM. im waiting to get it back from him now.
i looked at your log and im wondering if your problem isnt with the tps or electric pedal... when i scan my girlfriends trailblazer the tps shows accurate in the same scanner config as my trans am. the trailblazer has the electric throttle body as well...
the electronic pedal systems have a saftey feature built in ... if there were to be a problem or a discrepancy between the throttle input and the tps in a regular car with the electric pedal it would display reduced power on the dash.. im wondering if there is something wrong with your pedal sensor or tps sensor? thats all i can think of.. maf and map sensor seem to be functioning ok as they change with engine speed and throttle input. the only other thing to affect the transmission is the TPS. With closed being 19% and the max being 83% it may not be falling into the correct tables for the transmission to shift properly or the computer is putting it in the reduced power mode...
maybe get a f-body computer and a cable throttle body and then you know you have full throttle... lol
also your getting some serious knock retard. have you tuned this at all?
the electronic pedal systems have a saftey feature built in ... if there were to be a problem or a discrepancy between the throttle input and the tps in a regular car with the electric pedal it would display reduced power on the dash.. im wondering if there is something wrong with your pedal sensor or tps sensor? thats all i can think of.. maf and map sensor seem to be functioning ok as they change with engine speed and throttle input. the only other thing to affect the transmission is the TPS. With closed being 19% and the max being 83% it may not be falling into the correct tables for the transmission to shift properly or the computer is putting it in the reduced power mode...
maybe get a f-body computer and a cable throttle body and then you know you have full throttle... lol
also your getting some serious knock retard. have you tuned this at all?
Last edited by got-a-ls1; Apr 8, 2009 at 11:31 PM.
Thread Starter
Launching!
Joined: Jan 2009
Posts: 241
Likes: 0
From: Mead, WA
i looked at your log and im wondering if your problem isnt with the tps or electric pedal... when i scan my girlfriends trailblazer the tps shows accurate in the same scanner config as my trans am. the trailblazer has the electric throttle body as well...
the electronic pedal systems have a saftey feature built in ... if there were to be a problem or a discrepancy between the throttle input and the tps in a regular car with the electric pedal it would display reduced power on the dash.. im wondering if there is something wrong with your pedal sensor or tps sensor? thats all i can think of.. maf and map sensor seem to be functioning ok as they change with engine speed and throttle input. the only other thing to affect the transmission is the TPS. With closed being 19% and the max being 83% it may not be falling into the correct tables for the transmission to shift properly or the computer is putting it in the reduced power mode...
maybe get a f-body computer and a cable throttle body and then you know you have full throttle... lol
also your getting some serious knock retard. have you tuned this at all?
the electronic pedal systems have a saftey feature built in ... if there were to be a problem or a discrepancy between the throttle input and the tps in a regular car with the electric pedal it would display reduced power on the dash.. im wondering if there is something wrong with your pedal sensor or tps sensor? thats all i can think of.. maf and map sensor seem to be functioning ok as they change with engine speed and throttle input. the only other thing to affect the transmission is the TPS. With closed being 19% and the max being 83% it may not be falling into the correct tables for the transmission to shift properly or the computer is putting it in the reduced power mode...
maybe get a f-body computer and a cable throttle body and then you know you have full throttle... lol
also your getting some serious knock retard. have you tuned this at all?
I asked about the peddle on HPTuner forum, and they said it was something to do with the SAE or something and if i PID'ed some other it would show correct. i wonder.....?
hmm i dont know then... very weird.. the only electric throttle ive scanned is a trailblazer and the tps did show correct.. i have no idea about the new ones and id assume they know better then me on the hptuner forum.
its not throwing any codes at all?
go test drive an 08 like yours came out of and see if your scanner sees the same... i dont know other then that. Atleast if you did that you could see if the tps thing was normal... make sure to use the same configuration in the scanner as you use on your jeep, dont change anything. then download the tune and then put it in yours... lol
but definately try using the vcm controls to select your gear.. if that doesnt work id suspect a wiring problem or electrical problem in the tranny.
its not throwing any codes at all?
go test drive an 08 like yours came out of and see if your scanner sees the same... i dont know other then that. Atleast if you did that you could see if the tps thing was normal... make sure to use the same configuration in the scanner as you use on your jeep, dont change anything. then download the tune and then put it in yours... lol
but definately try using the vcm controls to select your gear.. if that doesnt work id suspect a wiring problem or electrical problem in the tranny.
Thread Starter
Launching!
Joined: Jan 2009
Posts: 241
Likes: 0
From: Mead, WA
That's why I put the Superchips tune in this thing - to see if it was a tuning issue. I've even put the OEM stock tune back (had to, or the Superchips wouldn't work) and had the same issues.
I'm down here in Moab right now, running trails for the Easter Jeep Safari and I've found that in 4 low, this thing constantly get's it. Very fast launch and sounds mean. Gratned, my transfer case has 4:1 gears in it, but why would it be so much different? If I need to change my shift points to get it to react this way, then I will. But I just can't understand why it behaves this way and can't believe that a stock truck would as well.
I'm down here in Moab right now, running trails for the Easter Jeep Safari and I've found that in 4 low, this thing constantly get's it. Very fast launch and sounds mean. Gratned, my transfer case has 4:1 gears in it, but why would it be so much different? If I need to change my shift points to get it to react this way, then I will. But I just can't understand why it behaves this way and can't believe that a stock truck would as well.
TECH Fanatic
Joined: Sep 2008
Posts: 1,639
Likes: 525
No power Seems odd it runs great when you in 4 wheel low?
Where are you pulling your Vss signal from? Has to be from the output shaft of the tranny. Is it off the tail shaft of the transfer case?
Just thought.
Where are you pulling your Vss signal from? Has to be from the output shaft of the tranny. Is it off the tail shaft of the transfer case?
Just thought.
Thread Starter
Launching!
Joined: Jan 2009
Posts: 241
Likes: 0
From: Mead, WA
I also tried to shift the trans using VCM controls, and I am able to.
The only times I have been able to see the higher output is in 4lo, or with VCM suite opened up and the controls open. That's not always happening though, because sometimes with it opened up it runs 'normal'.
i think the 4lo thing might be because the torque has been multiplied 4 times I can easily turn over 3k RPM's. Where as in 2hi, i can't.
Did I already mention that I have tried the Superchips power programmer in all of it's modes and I dont' see a difference? The only difference I see is a little more power below ~3k rpm's. No change in shift points, etc.
