LT1-LT4 Modifications 1993-97 Gen II Small Block V8

Limp Mode on 24x 383

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Old 08-29-2011, 07:28 PM
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Default Limp Mode on 24x 383

ok... im at my wits end on how to diagnose much less fix what my problem is here and it dosent help i have a wiring nightmare in this car. Hopefully someone here can give me some insight. Mods are in signature. Running 24x setup in a 97 LT1. Car was just tuned by Jeremy Formato at faster proms and he went back and checked his work, everything is right on that end of the puzzle. Problem im having is after it got tuned it ran great for a day, went to take it out this weekend and it started having transmission issues. No overdrive, harsh shifting when pulling it into and out of gear, no TCC lockup... from what i can see that diagnosis out to be a limp mode condition.

Heres where my question comes in... how the heck do i diagnose it, then how to i fix it? ive checked all my pcm grounds and everythings good on that end. Cant seem to locate a fuse for it even though ive been told there is one. Only thing i havent checked for yet is voltage at the trans (ran out of time tonight). Any insight or help would be greatly apprieciated
Old 08-30-2011, 04:11 AM
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I would first find in writing, in a GM service manual, what the symptoms are of "limp mode" for an LS1 PCM. I've never experienced or know what the details are of a limp mode with the LS1 PCM. After that, you should be able to data log other parameters related to limp mode to see if, in fact, that is what is happening.

Because your description points readers toward a possible transmission problem, I would take manual (bidirectional) control of the transmission shift and lockup solenoids through EFILive (or HP Tuners?) to see if the solenoids are responding to your commands. That will assist in a transmission diagnosis.

That would be my starting point anyway.
Old 08-30-2011, 11:46 AM
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Any codes? The transmission gets all its power from one wire so if all you have is third and reverse then you likely have no power at the trans.
Old 08-30-2011, 12:49 PM
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In your Sig you don't say what year computer you are running or what version is in it. If it is 2001 and newer I believe, the trans would have had an input vss sensor on the input shaft. Could be wrong on the year though. I think your issues might be in the trans tables and compatibility mode in programming. Look to see specs on vss sensors between your year and the ls ones specifically what your computer is programmed for and the year. Also look up the lock up control for our tc and how it is programmed in the computer. Also if you changed to a larger tb the shift point have to be adjusted because moving more air through a larger tb the tps is at a lower setting to command shift. I don't know all the tables in HP tuner but it should look for rpm and speed to command a shift vs a tps position. If the tps voltage is wrong and the computer thinks it is at a position it really isn't, the trans will act up bad. Could be a good starting point to look into those things. Good luck..
Old 08-30-2011, 05:24 PM
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Originally Posted by Jpack
If it is 2001 and newer I believe, the trans would have had an input vss sensor on the input shaft. Could be wrong on the year though.
To the best of my knowledge, without exception, the input shaft speed sensor (ISS) was never used with the 4L60E and 4L65E transmissions. I think it was introduced with the 4L70E transmissions. However, I think all 4L80E transmissions do have the ISS.

For the car to leave the tuner running well and then running well for one day...something has changed or failed.
Old 08-30-2011, 07:51 PM
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yea my guess is its the power wire. Couldnt be more impressed with the 24x setup so far and im sure thats not why im having an issue. Again i ran out of time tonight and didnt get to mess with the car but its first thing on my agenda tomorrow. I do have one other question for you though S10 since i have ya in the thread. What do you guys recomend for plug wires? Im currently running a set of custom built accel 8mms with the correct coil ends and taylor heat boots on them but I still seem to be having some header contact/burning issues.

Ill give you guys an update tomorrow. Can anyone tell me which terminal I need to check voltage at going into the trans?
Old 08-30-2011, 08:38 PM
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First thing I would suspect would be the monster has died, they offer little info on what they actually do to improve a transmission but back when they used to actually have info it was like a what not to do list.

You bought a cheap junk transmission and I sincerely hope you find a simple fix but..........................................
Old 08-30-2011, 09:11 PM
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Ive heard that from some people but i can say so far monster has been a stand up act and they seem to really stand behind there product. I hope im wrong but unfortunately its all my budget would allow at the time so its what i went with. I can say for a fact though I have friends who have had great luck with them and they run there cars alot harder than i do.
Old 08-31-2011, 11:36 AM
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http://shbox.com/1/harness_connector_faces.htm
Old 08-31-2011, 07:26 PM
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Ok good news and bad, trans is fixed... short a fluid change (some of the fluid in the pan was indeed burnt) it was indeed a short in that power wire. Ok that brings us up to my newest problem (thats right, fix one, make another). This actually has happend before just not as severe this time. I had been having problems with the car cutting off and not restarting for a few seconds.... all our assumptions led us to believe it was due to the fuel pump loosing power for whatever reason it may have been. Basically what would happen is every once and awhile the car would just shut off, id pull off the road, wait a few seconds, key over and it would start back up no problem. Well tonight it did it at the end of the driveway... except there was no restart. I keyed it for a good 10 mins with nothing. I decided since i was so close to home id take advantage of this situation to see what was going on and i pluged the scanner in. I had no crank or cam signal which is the same condition I had first trying to start the motor last month because i hadnt disabled VATS... so just for ***** and giggles I decided to reflash jeremys tune into the car... low and behold the car started and idled fine. Now im really confused and doubt it has anything to do with the fuel pump. So guys... thoughts? Its an obnoxious problem i see getting worse and i dont really want to have to carry my laptop with me every time i take the car out
Old 09-01-2011, 04:53 PM
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i lied apparently, trans is still slipping just as bad as before, no improvement, guess last night was a fluke. Im starting to believe the above the monster is dead comment. They put in a ticket on it and are supose to call me back with tech support tomorrow... we'll see if that happens but i somehow have my doubts. Since im pretty sure ill be putting a new and better tranny in it... who should i go with? TCI, Performabuilt? open to suggestions. My budgets not unlimited but Im not gonna skimp this time
Old 09-01-2011, 06:25 PM
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I used Pro-Built Automatics like 8 years ago when my car was a ZZ4 cam only 20K mile a year daily driver, couple years of that and I totalled it hitting a deer which allowed me to buy a second car and make bigger mods. 5.5 years ago I did the first heads/cam setup from AI and Dana at ProBuilt just had me redrill a single hole in the separator plate to account for adding about 100rwhp, been fine since and I added even more power with another heads/cam update a couple years back. Car has been running mid to high 11s for the last 5+ years a good 70K+ on the tranny in an over 2 ton car. Not a lot of fancy parts, since it was built for a milder application it has stock sunshell and servos, stock planetary gears, pretty basic but well setup and it works well. 60ft times for the last 2-3 years have been in the 1.5s with 3800stall Edge converter and 4.10 gears.
Old 09-02-2011, 10:06 PM
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Originally Posted by maxplusten
i lied apparently, trans is still slipping just as bad as before, no improvement, guess last night was a fluke. Im starting to believe the above the monster is dead comment. They put in a ticket on it and are supose to call me back with tech support tomorrow... we'll see if that happens but i somehow have my doubts. Since im pretty sure ill be putting a new and better tranny in it... who should i go with? TCI, Performabuilt? open to suggestions. My budgets not unlimited but Im not gonna skimp this time


Well I hope it's something youcan fix in the car but if not tell monster Jaycen says F^^k you very much. lol. I am on my 3rd and it is giving me problems and leaking from odd places. I have put a total of 2500 miles on 3 Yes 3 of thier monster *** loads of crap. I will say for the most part they have held up thier end untill the last time when they fubard my last warrenty request and I ened up paying 400 bucks. If it blows this time it will be going through their front window. Search my threads if you want some shiter reading. lol
Old 09-03-2011, 08:08 AM
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Trannies are a thing that even when built terribly can last long enough for people to have initially good feedback on. This leads to a lot of very poor builders surviving a lot longer than they should and often having a great reputation while doing it.

On tranny builders you really need LONG term feedback. For a performance 4L60E I would only use ProBuilt, Rossler or FLT
Rossler is the one who builds the 4L60E for the low 9 second Donovan block full weight Impala that has been to the pump gas drags a couple times. Guy has to manage the power otherwise 100ft out of the hole the engine will strip the teeth right off the pinion gear of the 8.5" axle, he hasn't updated his ET in a long time but I know the car is approaching 160mph in the quarter with soft launches.

Now granted that is not going to be a normal 4L60E build but the fact Rossler can make it work atall says the man knows what he is doing.
Old 09-05-2011, 06:44 PM
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well just an update, Monster finnaly got back with me. They wont be honoring my warranty because i didnt buy one of their convertors... funny how no one tells you that when you order. So basically im out 1500 bucks but I kinda saw that coming. Taking it to a local guy tomorrow to rip it appart and see what he can do with it while i start getting some stuff ready to do what i should have done from the get go. Six speed swap time. Got a T56 here local for a pretty good deal. Just gonna see if i can gather up the rest of the stuff for cheap then ill start wrenching over the winter while im working on all the other odds and ends. Hopefully if they can get the auto straight for now ill get to drive it and enjoy it for a few weeks till its time to put her away



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