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Discussion Starter · #1 ·
Help, I went from 3:15 gears to 3:73 gears, car is running great but on interstate when i stomp it while in 4th gear it downshifts to what i think is 1st gear. cause the rev limiter comes on real quick , then the check engine light comes on with this slipping code, I went back to my tuner and he reset the wot shift points, but its still kicking down and throwing this code.So could my tranny or converter be bad within 100 miles already? or is this something that you just keep playing with untill you finally get the wot shift points right?I did all sorts of gear reading and serching on here for a year before i did the swap and never heard of gears killing a perfectly good tranny before, thanks for the long read im just puzzled and worried....
:WTF
 

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p1870 is a transmission slip code. the 4L60E trans are notorious for this code. before you have the trans rebuilt make sure the speed sensors are ok.
 

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Discussion Starter · #4 ·
Thanks for the replies, Im hoping when i take it back to my tuner he can tweek the wot shift points and correct it, Ive been driving the car all day and when i manually shift it ( and i mean hard) it doesnt set off the code only when im in 4th and running about 65 and stomp it , so we will se how it all works out, is there a way to tell if the speed sensor is bad?
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Thanks for the replies, Im hoping when i take it back to my tuner he can tweek the wot shift points and correct it, Ive been driving the car all day and when i manually shift it ( and i mean hard) it doesnt set off the code only when im in 4th and running about 65 and stomp it , so we will se how it all works out, is there a way to tell if the speed sensor is bad?
thanks
did they reprogram your pcm to the new gear ratio? if not they need to do so because with the new gear ratio and not setting the pcm to the speed sensors it is confusing the transmission. also have you checked the trans fluid to see what color it is and if there are any metal shavings or a burnt smell. i can tell you its not in the convertor that is rarely ever the problem. a word of STRONG advice..if the fluid id brown, smells burnt, or has metal shavings in it DO NOT change the fluid, fresh and clean detergent fluid will finsih the trans out and you will be rebuilding in less than a month. 4L60e's have a serious problem with the drum cracking and breaking in the transmission, if this is the case if you have it redone the part you should use is called THE BEAST its made of metal not aluminum and will not break as easy. lst of things to check
1. check fluid for discoloration, smell, metal shaving
2. reprgram pcm to new rear end specs (this will change shift points)
3. check all readings from speed sensor and make sure they are accurate, if they are not dead on REPLACE THEM IMMEDIATLY
4. do not use aftermarket speed sensor AC DELCO ONLY!!!!!!!!!!!!!!!!!!
check these things then let me know what the results are and i can give you some further direction.

hope this helps
 

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i almost forgot if you have to gave the trans rebuilt dont let them upsell you on so called performance parts. you dont need that with the computer driven trans. also make sure they replace ALL the clutches and make sure to ask for the old ones back. also do not put any kind of a stall convertor iin there go back with factory specs. your engine is not set up for any more than factory and if you want more performance get a hypertech scanner and change your shift points. that is where you will get the most form your trans and keep it daily driveable and reliable. if you need anything let me know
 
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