So which ECU are you running now?

How differently does it run?

 

The stock Renix. Not much seat of the pants difference but it seems smother and mileage went up. I swapped them out a few years back but plan on playing with it more when I make some engine changes.

 

The 87 ECU then is what's in it?

 

Yes, the 87 one is in it. The people I bought it from installed the HP when it was new. I bought the Jeep from them a little over 5 years ago and changed to stock about 4 years ago.

 

I use the 89/90 ECUs. Number ends in 428 or 429. Auto and manual in that order. I've used them interchangeably with no issues.

There is a 9 HP difference between an 87 and a 89 to 90 ECU.

 

Thanks, I will pick one up and try it out.

 

Show us your mistakes. LOL

 

I installed a 90ECU in my 87 and was not impressed. It ran much richer and I lost a lot of vacuum. I messaged Cruizer and he was nice enough to offer some ideas. An old brain cell came alive and I remembered that I retarded my synch sensor to run richer with the 87 ECU. Advanced the sensor and it leaned out and my vacuum is higher while cruising than before. Good part of my mistake is that this 90 ECU should give me the fuel I need for my engine build. Worth the upgrade and thanks for your help Cruizer.

 

Here's an update.