Ok... sorry it took so long to get back to you guys, a lot of questions to answer.

-Cruiser54 It can crank as long as 30 sec. - 45 sec. Without pressing on the gas pedal. With pressing on the gas pedal, it lasts around 5 sec (after priming) & no there is a lot of difference between cold and hot. Now I run Shell Rotella-T 15w40 in the summer... It loves that w/ no problem, but this winter, I'm running Pennzoil 10w40. So I know the oil viscosity has some play in it(to an extent) but anything thinner (on the Renix jeeps non-HO) things start to seep a bit. The C101 is a good Idea, when I built this thing a while back, I had electrically cleaned the connector(both sides) and placed di-electric grease in the fitting...then electrical taped the whole connector. They have problems...there is no hiding that.

-Jesse
* Low cranking speed due to temp-related voltage drop in battery
* El-cheapo starter not up to spec
* Thick, petroleum-based engine oil gelling at low temps
* Low flow/pressure at the fuel rail or leaking regulator
* My favorite: cheap, low-quality fractions in the fuel you're using
* Dirty/rusted ground connections making a marginal problem worse[/I][/I]

Even in cold, battery still puts out 700 cca I got a 1000ca battery Megatron+ Interstate battery...
Starter - still an option,
oil... not happening (can't change 10w40...won't do it.
I am priming the rail w/ excellent pressure of 39 psi +/-
I use 89 Octane, and i'm not even going to pretend that I use one specific gas station.
Ground Connections... I clean them RELIGIOUSLY. Read my first post... I coat them with hairspray, then dielectric grease afterwards. The jeep sees some mud every once in a while so I have to have this stuff protected.

UPDATE: I just tested my ballast Resistor, and I was getting 10.3V +/- .5V output to the pump... Eliminated it and running at 14.3V output... still a nice power band, but until the morning, when it is SERIOUSLY cold outside, I won't be sure. I connected a spark plug this morning before turning it over... Immediate spark, so that is not an issue... Prime the rail... plenty of fuel. It has to be a sensor or that ballast resistor not keeping up with the demand of Open Loop in the morning. If that doesn't solve it, I'm going to open up the Renix ECM and look for the burnt out diodes and pick up a throttle body from another jeep out back... Then starter. There is nothing left and it's practically a brand new Jeep after this.

 

Alright, Cruiser54... I feel dumb. so dumb, that I SO over thought this situation, that I don't know what to think. I was reading your renix mod's page, and came across one with the throttle butterfly. Not Idle set screw, but the Butterfly adjustment screw. My friend, of which I got the motor from... 1990 MJ pickup, had mentioned that he was tweaking with the butterfly screw in the throttle body. So I just went outside, and the set screw is all the way in! I backed it out just a smidgen. I'll see if that has any effect as well.

 

Your CPS signal runs through the C101. That is unless your Jeep had the factory CPS bypass done.

I have done a hokey C101 bypass with the CPS wires with good success.

 

Glad you looked through the write-ups!! Hopefully, you found a gold nugget!!

 

Your CPS signal runs through the C101. That is unless your Jeep had the factory CPS bypass done.

I have done a hokey C101 bypass with the CPS wires with good success.

I don't believe it has. Like I had mentioned previously, the C101 that is there, I cleaned, dielectric greased, and electrical taped the entire harness. I'll just have to wait and see if this butterfly set screw fixes anything/or ballast resistor... anyhow, if it doesn't then I might just uncover it and take a gander.

Thanks!

 

Did you "tweak" the receptacles in the C101?

 

Hmmm... Thanks guys this is a helpful thread! Never thought about the black wires from firewall and engine block being so yuckie keepin Yammer from wanting to start in the mornings,

 

Update: Well this morning it fired right up. No problems what so ever. So the latest things that I have changed was bypass the Ballast resistor for the fuel pump and adjust the Butterfly for the throttle body w/ a readjustment of the throttle positioning sensor output voltage, that my friend had previously adjusted (AGAINST ALL recommendations). So to go back and see what really made the difference, I reconnected the Ballast resistor and it still fired right up.

So, long story short, the butterfly in the throttle body was the cause. The under/over-looked but yet so practical items, can be a healing factor for you jeep. I would like to thank everyone for their input and help in this situation. It's been a LONG on-going problem.

I can't say I recommend this as a solution to everyone's problems with the cold, long crank -no start condition, but it certainly can't be over-looked. If you didn't buy your jeep, or any other vehicle for that matter new, you never know what the previous owner did to it without absolute full disclosure.

Now i'm sure you are saying, the IAC/throttle position sensor should compensate for it. When the screw is all the way in, the butterfly is completely closed in the throttle body. The channel for the IAC isn't large enough to run the 4.0L on very cold days on open loop... I guess.

 

Exactly which screw did you turn? The allen on the passenger side of the tB or the torx on the driver's side?

 

Exactly which screw did you turn? The allen on the passenger side of the tB or the torx on the driver's side?

I turned the allen screw on the Passenger side, controlling the gap between the accelerator-attached lever and the throttle backing.

I would love to know which screw you are referring to as the torx screw? I am very interested as I am not in front of the Jeep right now, and I thought I knew it inside and out...

 

What was likely happening was there was too much air passing by the throttle butterfly and teh IAC couldn't control the idle as a result. The other screw is top secret.