Thadeous

I used to freak out everytime I worked on my car because it ran like hell afterwards. After two or three times that I had to disconnect the leads and researched. There I find out that the ECU can take several dozen warm up cycles to truly lock down the performance of the engine.

I get that, and after installing a new radiator, the car seems to be back to "standard" running shape after the first couple of days.

But, man it runs like hell for the first few warm ups. Like Hell. Misfires, bad idling etc. Should I check something else, besides just blaming it all on the ECU? It seems to be running fine now, but I think I must not be running close to stock if it takes that long for the computer to figure out my game.

Any comments?

Parsnip

Are you 'refreshing' the ecu after every upgrade? You shouldn't have to unless your upgrading/replacing an ignition related part. Also how have you been refreshing it?

cruiser54

Renix doesn't need any disconnecting or rebooting. OP, have you ever clicked on the "pink link" in my signature and done any of the stuff recommended there? Great place to start. Pay particular attention to Posts # 1, 2, 3, and 5.

Thadeous

In regards to how am I re-setting the ECU. . .

I am doing so (i believe) by leaving the battery disconnected for quite some time. I have read this can reset the ECU. Not to mention that I most likely have been jamming my postive terminal against the body which will cause a reset as well.

Cruiser: Thanks a bunch for the tips. When time permits I will have to checklist those items and tear through them one at a time.

cruiser54

Doesn't reset the ECu. Does about much good as running around the house shouting Koom-by-ya three times.

highmileage

I normally go into the living room stop and can't remember why I'm there? just like a RENIX... LOL

DFlintstone

It is true Thadeous. the Renix has no memory. The later PCM's are said to, but up to (and including), 90, when you turn the key off, well that's it. It has no light, stores no codes. You start fresh every time.

Plugs, wires cap/rotor, vac leaks, MAP tube, fuel pressure/filter, sensor ground test. CPS, AC Volt test.

Your symptoms make me want to suggest looking inside the dizy cap for condensation when it's goodn' cold.

cruiser54

You're describing my life to a tee........

Thadeous

I appreciate the tips, but I am totally shocked by them.

Literally, both times I have disconnected the battery to work on the Jeep, and then reconnected everything the car ran awful. Super rough idle, misfires, loss of power etc. However, after 24 hours or so, Molly begins to run normally without any issues. Full power, no misfires, good idle etc.

Keep in mind, I am not storing the Jeep during these sessions. They tend to be about 2 to 5 hour ordeals, and not multiple day events.

Confused. The jeep is still fun though.

cruiser54

Weird. I have never had a Renix do that.

Thadeous

And it is like clockwork good sir. Within about four or five start up cycles it is running like gold again. I have no idea if it's ECU is not causing the problem.

cruiser54

I doubt it's the eCU.

Can you imagine how many REnix Jeeps I've seen/worked on as Service Manager and Shop Foreman at a dealership from 1980 through 1992 and never seen this? Battery replacements, disconnscts for long repairs etc?

Thadeous

Not calling you naive or unaware. . .just can't imagine what would cause a 24 hour problem and then vanish. . . Unless there is a gremlin under the hood.

cruiser54

Perhaps you should click on the "pink link" in my signature and review my write-ups on eliminating/preventing gremlins in a Renix?

DFlintstone

I wondered before, then more now , the Cat! I resisted at first. Theo, the ECU just doesn't have a memory. Just doesn't. (on a separate note my TCU seems to be behaving?)...after some stuff.

There is a vacuum test for restricted exhaust. Google, Or Crusers "pink" , or the same in my my Sig. Once I just loosened the manifold > header pipe bolts to find a clogged CAT. That "K" car was a dog! Cat restriction fixed, .... Well she was happy..happy enough anyway!