Vortec 454 problems

[98k1500]

Hey all, I just got a 98 cclb one ton With the l29 454 and it's idling way to high and it's throwing a high idle code, any ideas why? Also the 4l80e shifts great but it isn't going into lockup in od any ideas?


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[SAATR]

Possible bad IAC motor or vacuum leak for the high idle, and maybe the CTS for the OD issue. PCM makes the trans shift later and stay out of lockup until the engine reaches a certain temperature, so a faulty CTS could cause the issue. Easy way to tell is to get a scanner and see what temp the PCM is seeing. Pull the IAC and clean it to see if it helps the idle any. While you're at it, check for vacuum leaks. The throttle blades being gummed up could also cause them to stick slightly open and produce a higher idle than commanded by the PCM. Let us know!

 

[98k1500]

Well I figured out the idle. That little screw that your not supposed to move was ran all the way down! Still haven't figured out the tranny thing though. Any other ideas?


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[outalne94z71]

if the ecm coolant temp sensor is not hooked up or is bad it will cause the ecm to not lockup the od

 

[98k1500]

Where is the cts? Is it not the same one that controls the gauge?


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[dirtridinz71]

Where is the cts? Is it not the same one that controls the gauge?


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No its not the same sensor. Not to sure on the bbc but with the sbc the cts is on the intake at the front near the tstat housing.
I've had the same problem with the cts causing lockup issues with my 700r4 in my 92.

 

[98k1500]

Alright well I don't have access to a scan gauge but if the cts is cheap I'll replace it



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[98k1500]

It wasn't the cts


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[98k1500]

Any other ideas


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[SAATR]

How are you testing whether or not it is going into lockup?