Hey guys here a issue we been working on for bout a week now i got a 99 gmc sierra z71 full bolt ons etc its got fully built tranny new clutches servo shell band build valve body with shift kit 3200 circle d converter heres the issue truck ran great went in shop pulled top end apart just headers manifold heads p&p valve job put bak together fired right up hadent touched pcm or tranny and all it goes in first fine but basically no 2nd shifts really slow its like main line pressure is low replaced tps it was good we have every gear cept 2 and no converter lock up anyone got a clue?

 

Im sure somone has some idea this one is kicking my *** performabuilt said may map sensor miss calibrated?

 

Who built the trans?

 

Will the car shift manually?

 

im at a tech school currently we built the trannys it will shift manually but if u put in 2nd it will almost b like there is no gear so upshift to 3rd then its good the tranny was stout before we brong it in and it wasnt touched im leaning towards electrical mayb?

 

im going to check the map sensor tomorrow if that aint it ill trully be stumped

 

Check your servo travel and be sure the band clearance is within factory spec. also make sure you did not roll one of the seals on the servo when you put it in.

 

As stated above id check the servo.Does it have 4th gear?

 

Hi Guys I spoke with this gentleman today while he did not get a trans from us, Here is what he told me, Prior to the heads and intake work the trans worked fine no issues, Now upon reassemly of the heads and intake etc this issue can up imediatley.

 

Exactly what I was thinking too - there is a problem with the 2nd gear servo seal. If there is clearance to the body/frame that should be easy to check.
I realize that something related to the engine mods should be the most likely culprit, but a messed up sensor might lead to a softer or harder than normal shift, but not a no-shift condition.

Keep us posted. I am certainly curious to learn from this too.

 

ok heres the update had a mil light was c0281 brake switch circuit that was do to a bad ground fixed that yes i have forth didnt have lockup bout to go on dyno soon as see if i can get everything right map senser may has got bumped around during install so i made sure thats tight next is the servo i think ill pull that out before going on dyno

 

latest update pulled servo its crystal clean nice tight seal clearence is good next droped pan and pulled accumulater that sealed up good and tight too lil clutch material but noting otta the ordinary got a older guy coming in at about 12ish been doing trannys all his life this may b last resort as of right now

 

were pulling the tranny somtime next week ill update on what we find out