i have a 07 rcsb new body 4.8 4l60 3.73 I recently bought a comp xr275 cam and a trailblazer converter. I went ahead and installed the converter before the cam and drove it for a couple weeks and it stalls out nicely but I've noticed between 40 and 60mph it locks and unlocks constantly when you get it above 60 it locks up and does great. Any time it's in 3rd or 4th gear not under a load it locks and unlocks every 3 to 5 seconds. It didn't do it with the stock converter I'm just trying to figure out what may be causing it or what I can do to fix it. Is it something that can be tuned out can I just not use that converter in my Tranny or what?

 

Sounds like it needs to be tuned. When you change the converter, the values that are in there are no longer valid and the PCM is trying to figure it out.

 

i thought the same thing but i was told by a transmission guy that it wont change because its a smaller converter but i cant help but think that wouldn't matter.

 

With a smaller converter, it's also looser. Meaning it takes more revs to get it going.

The guy you asked is and idiot.

 

you sound like you know him personally lol
i just wanted to verify my thoughts and see if anyone else may have had this trouble

 

What brand converter is it? Did you check converter to flexplate clearance? A lot of Trailblazer/VJCX converters are shorter than the V8 converters and need to be shimmed.

 

This is a trail blazer converter. I've heard several people using them for a small stall speed so I went with that. I'm hoping it can just be tuned out.

 

I never had that issue with my TB stall behind a stock 5.3 in a 4x4 ECSB, it made about a 400 rpm difference flashing and did help it off the line some.

I did have major hunting issues (lock/unlock constantly) with a vigilante converter in a different truck before it was tuned. A loose converter will definitely confuse the stock tune lock up values but I'd have a hard time thinking a TB stall would do it.... Worth looking at if you have access to data logging but it might be a symptom of more trans issues i.e. weak pump or low pressure from wear and tear.

 

I know that. I'm asking for more details on it. Is it a used factory converter? Did you check flexplate to converter mounting pad clearance? If the clearance is excessive, you can break the transmission pump. Ask me how I know...

It should be able to be tuned out though. You could also fix it in the valvebody.

As as a precaution, clean your MAF sensor with MAF cleaner. If it's dirty it will read less airflow and reduce line pressure which could result in bigger problems.

 

Oh sorry I didn't understand your question. It's a new converter I bought from orileys. The clearances check out. I got the cam in yesterday and drove it yesterday not tuned and it didn't lock and unlock like it was doing so it kinda confuses me even more now