PCM Diagnostics & Tuning HP Tuners | Holley | Diablo

Po751

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Old Apr 20, 2008 | 12:11 PM
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From: _Nor caL_ (Bay areA)
Default Po751

got this code few days ago. i cleared it with alil code checker my friend has. car is still doin samething. i have a 3500 stall and have been having problems with the car shifting under WOT since i put it in. my speedo is off by as few mph on the car. but it has always been off, and i never had problems with the car shifting. will deleting this code with hptuners fix my problem? ive read abit bout this PO751 and it seems alot of people get it after installing a 3200 stall or larger, but i cant seem to find a thread where they got the problem resolved. just info on how to fix it. my tunner says its the VSS causing the issue. but i changed the speed sensor and still have the same problem.the connector and cables that plug into the speed sensor all seem fine. but for some reason the mph needle wont start moving until i pick up some speed. so ill be going bout 10mph already and the needle will bairly start to pick up. i could careless bout the speedo being correct. my main issue is the car shifting. does anybody know a solution to the problem? the main gear it seems to lock me out of is 2nd. ill start off in 1st from a stop, and it will take off fine. but rpms go high and wont shift into second till the mph reads about 7-10mph. and when rolling the car wont let me manually downshift into 2nd. but it will let me manually downshift into 1st. and when punching it from a roll slow enough it will downshift to 2nd but then hits the rev limter. and if i punch it and its suppose to drop into 2nd due to how fast im going the car will just bounce off the rev limiter, and act like 2nd gear is a neutral.


thank you for all the help in advance!
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Old Apr 21, 2008 | 02:20 PM
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From: _Nor caL_ (Bay areA)
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well went to my tuner had the codes turned off so they cant be detected no more. and im still have the same fuking issue! its really starting to irritate me! the only gear it seems to be locking me out of is 2nd. every other gear works fine, and pulls hard.

only other symptoms i have is the car stayin in 1st until the speedo passes 7-10 mph. after that it will shift. also when im driving and say i wanted to do a 2nd gear punch and manually downshift to 2nd it wont do anything. it just acts like i droped it in neutral. but if im going slow enough it will skip 2nd and go to 1st. could it be the shift sylinoid thats fried? if it is ima bout to go buy that bitch and swap it out. do you think my vss is really screwed up? cuz its also still giving me the problem where the mph wont move till after im already rolling. i think its bout 10-15 real mph before it starts to climb. my tuner told me to get a new pig tail and splice the cables. he thinks its a bad connector. i sure hope so! if it aint that then im changing the sylinoid.
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Old Apr 21, 2008 | 03:35 PM
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sumbody has got to beable to help.

please!
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Old Apr 30, 2008 | 09:46 PM
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Originally Posted by stangkiller2005
sumbody has got to beable to help.

please!
Lets make that two of us that needs the help for a code 0751.
My vette will slip in fourth when hptuners is showing the its in fourth with the convereter locked. The RPMs should be around 2000(3.15gears) at 65mph but with even a very small throtal opening it acts like its unlocking and stalling up 600rpms or more. It is not unlocking.. even using hptuners to comand lock in fourth it does the samething. Locked in third on the dyno the converter held 614rwhp and 533rwtq so the converter doesnt slip. Comanding lock in third on the street everything works as it should. My tuner thinks that the solinoid should be changed but we will leave that up to a local performance trans shop to deside.
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Old Apr 30, 2008 | 10:42 PM
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From: _Nor caL_ (Bay areA)
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Originally Posted by petercln
Lets make that two of us that needs the help for a code 0751.
My vette will slip in fourth when hptuners is showing the its in fourth with the convereter locked. The RPMs should be around 2000(3.15gears) at 65mph but with even a very small throtal opening it acts like its unlocking and stalling up 600rpms or more. It is not unlocking.. even using hptuners to comand lock in fourth it does the samething. Locked in third on the dyno the converter held 614rwhp and 533rwtq so the converter doesnt slip. Comanding lock in third on the street everything works as it should. My tuner thinks that the solinoid should be changed but we will leave that up to a local performance trans shop to deside.
the solenoid is really easy to change. but like you said it would be good to have a performance tranny check it out. i have given up. styll same problem. i think i just compleatly fried 2nd gear.
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