jbVHO

iTrader: (2)

I have tried to do a little research on this topic, but can't really find a good answer. But, what I am trying to find out is what kind of issues could I run into if I got a motor, harness, and computer out of a truck that was equipped with a 6L90E, and then I try to put a 4L65E, 4L80E, etc behind it in order to make it run in my Nova?

I know it will physically bolt up to the engine, but I am wondering more about wiring and programming problems that would exist. Also, this is more of a hypothetical type of question because I have not bought anything yet and I am just trying to address any potential problems beforehand. I have pretty much narrowed down my engine selection to the LY6, which is much easier to find in the 6-speed version.

Any help is appreciated.

Thanks

rsz288

May be no exact answer on this but GM does use both 4L65E and 6L80E in some cars. Slightly different calibration for each.

You will need a new transmission harness and an external transmission control module.

poorhousenext

I'm no expert on this, but I'm in process of doing a build with LS3 and 4L65E. Speartech is building harness(S) for my build. John Spears is one who alerted me to problem.

The one problem I ran into with the LS3 computer was it's need for ISS signal from transmission. My 4L65 did not come equipped with ISS sensor, so I had to go back and have one retrofitted into transmission.

Late model 4L65E/4L70E come with ISS sensor.

Below is picture of connector with ISS pins. If your 4L65 connector doesn't have those pins, it will need to have ISS sensor installed. They are indicated by red circles.
Not cheap to do upgrade, cheapest I heard of is around $450.00 dollars.



I've since heard that there may be a software patch work around that may solve problem without having to upgrade trans.

I believe all the 4L80Es have ISS sensor and Plug.

The attachment information came from Chevy High Performance Magazine article on transmissions swaps 61-72 Chevelle and from PACTC website.

Link to article.

http://www.chevyhiperformance.com/te...ech/index.html

Link to PACTC "Performance and Transmissions & Parts" Center

http://www.transmissioncenter.net/

Jimbo1367

I too have a LY6 with its matching ECM. I spoke to John Spears a few months ago about moding my ECM and fabing a harness for me. I mentioned to him the donor truck came with a 2wd 6L90E but I wanted to run the 4L65E that I had. He mentioned he has a computer for the 4As that will run it. He said he can add the wiring when he builds my harness.

I need to find out if he can add dual electric fans to the ECM. Anyone have any experience on this option?

Jimbo1367

What is a ISS sensor?

poorhousenext

MAybe this will help. You may know it by another name.

Turbine speed sensor (TSS)
This may also be known as an input speed sensor (ISS). This sensor sends a varying frequency signal to the TCU to determine the current rotational speed of the input shaft or torque converter. The TCU uses the input shaft speed to determine slippage across the torque converter and potentially to determine the rate of slippage across the bands and clutches. This information is vital to regulate the application of the torque converter lock-up clutch smoothly and effectively.

Bo185

You will need a TCM for the transmission and the harness from it to the ECM.

The 4l70's in the trucks and 4l85's in the Vans with the ECM have a TCM for the trans. The 6l80/90 have the TCM internal to the trans. The Gen IV ECM no longer controls thee transmissions.

But why not just run a 6l90???

Jimbo1367

But why not just run a 6l90???[/QUOTE

for me, it was a packaging issue. And not having a welder where my car is. I would like a TCI 6X though. But honestly........ 6K is ALOT of money for a trans.

jbVHO

iTrader: (2)

Thanks for the good information everyone. Keep it coming...



In order to fit it in my car, it would require a good bit of trans tunnel cutting and I wanted to try and avoid that and focus on getting the engine and trans swap correct because it will be the first time I have ever done that.

Also, if I have to cut the tunnel I would go ahead and go with a T56 and then that presents some more issues with the hydraulics and that goes back to my point of first wanting to get the LS engine in the car and get the electrical and fuel systems working pretty good.