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1649 Views 8 Replies 2 Participants Last post by  Maine-Rider
Got a 2003 Silverado 1500 Z71 with 93300 miles. Going from 1st gear to 2nd gear there seems to be a hesitation/rough shift. It doesnt always happen. Really depends on how I accelerate etc. Ive done alot of reading and it seems to be a common problem. I plan of getting my transmission fluid changed (not flushed) as well as filter. I would like to add an additive to try to smooth things out. Does anyone know what I should do or try? I was looking at the SeaFoam tranny additive. I also heard spark plugs can smoothen things out. Is that true? I picked up a set of ACDelco iridium spark plugs as it wont hurt to change them anyways. Should I change wires too? If so what kind? Also what kind of tranny fluid and filter should I use?

Sorry for all the questions and thanks in advance!
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Got a 2003 Silverado 1500 Z71 with 93300 miles. Going from 1st gear to 2nd gear there seems to be a hesitation/rough shift. It doesnt always happen. Really depends on how I accelerate etc. Ive done alot of reading and it seems to be a common problem. I plan of getting my transmission fluid changed (not flushed) as well as filter. I would like to add an additive to try to smooth things out. Does anyone know what I should do or try? I was looking at the SeaFoam tranny additive. I also heard spark plugs can smoothen things out. Is that true? I picked up a set of ACDelco iridium spark plugs as it wont hurt to change them anyways. Should I change wires too? If so what kind? Also what kind of tranny fluid and filter should I use?

Sorry for all the questions and thanks in advance!
Is the Hard 1-2 Shift only happen when the truck is warmed up??
I wanna say yes, when its warmed up. But to tell you the truth im not 100% sure, haha.
The reason I asked is, the Below link is regarding the.....Harsh 1-2 Shift on the 4L60e's.

Link,
http://www.gmtruckclub.com/forum/showthread.php?54475-LOOK-HERE!!!-Trouble-code...p1870.....for-harsh-1-2-shifts.....
Thanks for the info. Ill look into getting it scanned. The engine light was on when I bought the truck. Come on a few days before I went down to get it when he was driving it to the gas station. It had been sitting for a couple months before that. He went and got it scanned and came up as a fuel pressure thing above fuel tank. It went off after a few hundered miles of me driving it. Popped back on a few weeks ago for a day then went back off. Will the codes still come up if the engine lights not currently on? Im now woundering if the light came on because of tranny issue. All this has accured within 2 months btw.
As far as the Check Engine light coming on and then going off and the Trouble Codes still being present.....They would still be Stored until Cleared, If you have the Trouble Code...P1870, in most cases you would need a Transmission Shop to Scan for it.....and you will not know what Trouble Codes you have until you have the Truck Scan.
If thats the problem do you know roughly how much it is to get fixed? Also if it comes back clean with no codes what do you suggest I should do? Additives, plugs, wires, new fluid and filter etc.

Thanks
If the Problem turns out to be Trouble Code P01870......in the link it expresses that the Valve Body may need to be replaced, and the Cost to do this, it all depends on what a shop would charge, I would check with local Transmission Shop's for pricing, if no codes are stored.....you could look at some of the Following,
.....Replace Air/Fuel Filter's
.....A Cleaning of the MAF Sensor and Throttle Body/Injector's
.....A Set of Plugs/Wires.....and then see how the truck runs' after Replacing these items.
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