Renix Computer Question

[Firyls]

Did a little testing at lunch, if I kill the power from the Ignition Switch (pin 11) to the computer ignition in (Pin B8), the engine will still remain running. Does this sound like normal operation, or is the computer supposed to be getting continuous voltage from B8 to keep the engine on?

After I severed the ignition power to the computer (engine still on) I measure voltage across B8 and its not giving off any power, so the engine remains on with no power at all on the B8 ignition wire to the computer.

 

[Firyls]

Took the time to sit with a multimeter and properly repaired the original computer, and it now works as far as engine performance, but has joined the other 2 computers in not shutting down the engine when the ignitions is off.

So is looking like the original faulty computer was masking another electrical problem with the ignition.

 

[Ecomike]

At this rate you are about to become our resident Renix ECU expert, and with only than a dozen posts on !!!!

 

[Firyls]

For anyone that might be following this thread, I figured it out this morning, a previous owner had spliced together the Yellow wire (ignition), and one of the orange wires.

I am guessing a previous owner thought the broken computer issue was a fuel delivery issue (as did I when I first got it), and spliced those together to force the fuel pump to run non stop.

Anyhow, removed the splice and now everything is running great, and the ignition switch turns the engine on an off. Consider this case closed.

 

[cruiser54]

Don't forget that 5-90 would like to have any spare ECUs

 

[5-90]

Please?

Also, any notes you generated while working inside the cases... You can send the notes to me, or put them up at my RENIXPower group (groups.yahoo.com/group/RENIXPower) - since that's where they'd likely end up anyhow. I'm working on a RENIX "brain trust" there...

 

[xjtrailrider]

While at a friends shop today i mentioned that i was chasing an idle issue on my 90 RENIX. He reached into his tool box and handed me a "known good" 1990 RENIX ECU!

He has used it many times over the years to help diagnose/eliminate RENIX issues. The case has never been opened, it is #EF8953005428

He gave it to me to keep as he no longer see's many of the RENIX era XJ's at his shop anymore. He also gave me a new ignition module and coil. He has a whole box of good sensors that he will give as soon as he finds them!

An interesting comment from him was that he doubts mine is an ECU issue. He thinks its a communication issue from a sensor to the ECU.

He found a few bad ECU's over the years but it is rare.

 

[cruiser54]

I always recommend unplugging every engine/ignition connector in the engine bay, spraying out both sides with an electronics cleaner, putting some dielectric grease on the connectors and pluggin them back together.

FWIW, have you ever refreshed ALL your grounds? The ones at the dipstick tube stud are for very important sensors and since the sensors work by varying the ground, that connection can cause all sorts of issues.

 

[5-90]

While at a friends shop today i mentioned that i was chasing an idle issue on my 90 RENIX. He reached into his tool box and handed me a "known good" 1990 RENIX ECU!

He has used it many times over the years to help diagnose/eliminate RENIX issues. The case has never been opened, it is #EF8953005428

He gave it to me to keep as he no longer see's many of the RENIX era XJ's at his shop anymore. He also gave me a new ignition module and coil. He has a whole box of good sensors that he will give as soon as he finds them!

An interesting comment from him was that he doubts mine is an ECU issue. He thinks its a communication issue from a sensor to the ECU.

He found a few bad ECU's over the years but it is rare.

I think I've heard of four RENIX ECU failures, I have three of them. All were blown injector drivers (which Mr_W - in Czechoslovakia - sorted out a repair for. It's around here.)

This would be a new one - which is why I'd like to collect it for analysis.

As far as test sensors, most of the RENIX sensor (except the HEGO and TPS) are standard GM parts of the vintage - so replacements are easy to find.

For cleaning - you can use electrical contact cleaner (preferred) or brake parts cleaner (acceptable - watch for silicone & rubber seals.) Next time someone tells me to my face that they've "cleaned" their electrical connexions with WD-40, I'm going to bash them in the head with a hammer. It's not that I mind making money, but I'd rather make money by not fixing user-caused problems...