Detroiron

Hey guys,

I have gone thru just about every LS1 swap on here and gained a bunch of info. Most on here have sent in their ECM and harness or modded the harness themselves. I have a 98 LS1 I want to put in my Cutlass and I would go the modified harness/reprogrammed ECM route that so many here have done except....I don't have the ECM or harness.

Sure I could buy them, but all the ECMs for a 98 ls1 I can find are $300 and I have to buy the harness and mod it too...not to mention to fuse blocks, O2 sensors, pedal ect....add up all the parts and I am better off getting a GMPP kit. The only thing is I don't see a kit for a LS1 from them, just LS2 and up. Some of the others sell a kit, but want you to send in the ECM, which brings me back to my question.

What is my best route? Do any of the GMPP kits work on a 98 ls1?
Does anybody else sell one?
Will a different year ecm and harness work?
I would rather just buy a complete kit, ecm to pedal, as I don't think I will be saving any money tracking parts down, sending out for reprogram and modding together from where I am starting from.

Also I don't know if I will go with a th400, 700r4 or 4l60e, will these kits work with the e-trans? What do I have to get in that area? Any draw backs with LS mounted to th400 besides mpg and overdrive? Just asking because I got a bunch of them already.

What do you think is the best route for the best price? Any insight would be greatly appreciated.

Detroiron

Also I have access to a 130k mi. 5.3 that includes the pcm and harness. It may be cheaper and easier to just buy that and put it in and save the 5.7 for something else when I have more cash. What do you say about that?

Detroiron

Hey guys,

Ok, I did more research and I see that the 98 ecms are a bear...and some people ask about using a 99-04 Ecm on a 98. Most advice they get is to re-pin their 98 harness to the 99-04 ecm. will this work. I never find out because the treads all go cold.

As I have neither a ecm or the harness can I get the 99-04 ecm and harness and hook it up to my 98? Seems like the only difference is some gauge cluster wires, but what about on the engine, what needs to be changed.

Most of the treads about this die out without a conclusion and are years old. ANY help or point in the right direction would help out alot.
Thanks.

Detroiron

.....and I am back again.

Now I found a few posts here and on other sites where it seems you can use a 99-04 ecm and harness on a 98 as long as you change a few things like the water temp sensor. I am not forsure that this will work as again, the posts don't have any results. Anybody know about this?

owen v8litew8

I had a 98 computer, motor and harness, I sent the computer and harness to john at speartech for rework and he swapped me up to a 99+ computer and modified my harness to work with that newer computer. he was great to deal with, pricey but very relaible and open to all of my questions which was a plus. dependable shipping, accurate timeframe, etc. made him easy to work with.

yeah the oil temp sensor, etc. have a few different wire configurations on the 98 stuff so they are the oddball setup, you are better off with all 99+ stuff.

the newer computers have better capacity (higher resolution computing, etc.) so they are a better product to use.
you can buy a truck computer on the cheap and have it reflashed to the camaro program too, thats always an option.

Detroiron

Owen, thanks man! That seemed to be what I was finding, but was not sure about it. I can find 99+ all day long and because I have to buy a harness anyway I will now just buy all 99+ stuff and mod the harness to my engine myself for the experience of it and to save money. If not I will send it out, just got to save more cash to do that.

I esp. like the truck computer reflash, I did not know that and I found a bunch of them for real cheap near where I live. I see alot of ecm's that are listed as 5.3 auto and some 5.7 manual at the junk yard, you are saying none of that matters as it can be redone correct. I assume that goes for the trans also. I would like to use a 4l60e but I may use a non electric auto. So does it matter what trans the ecm had, or can that be reflashed too? I also assume that if I use a non electronic trans it would not matter.

Do you remember or have a short list of just what might have to be swapped sensor wise to work with the newer harness? Oil temp, water temp that kind of thing? I hear it is not alot so I can probably figure it out, but if you already did....This is really the only issue with the 98's right, got any other tips I should know?

Again, thanks alot! I feel alot better about getting the 99+ stuff now.

BTW, that rx7 you sold sounds like an awesome project. One of my friends and I always wanted to put a v8 in his old Daytona, maybe we will now. If you don't mind me asking what do 80's rides like that with ls engines sell for? The more different the better to me.

bczee

iTrader: (12)

You should be able to use 99+ harness and ECM.. just need to make sure the sensors are correct for 99+. should be no issue coverting to the 99+ setup.

Pick up a 99-02 F-Body ECM (or any other car/truck that used the correct ECM, 411??).. and then have someone (john / Speartec) flash and change it to the Correct trans and other settings you need (tire, gears, delete codes for VAT, Emissions, etc).

Detroiron

bczee, thanks man!

I can't wait to get into this project now. Awesome advice from you guys. I didn't realize all this aftermarket stuff is for sale now. I visited this site about 5 years ago and am just now getting around to doing something so I found it again. Very helpful.

bmf5150

I think u can sell that 98 computer for triple what the newer computer will cost!

Detroiron

That would be awesome, except I never had the computer or the harness. I was looking to buy a 98 but then I saw the price and heard the troubles so I was hoping to buy 99+ stuff....they say I can so I will go that route. To bad tho, I could have used the extra cash!

Thanks.