RENIX stumbling from idle to 3ooo rpm

[cs641]

I have an AMC Eagle running a 1990 RENIX 4.0 that is stumbling from idle to 3ooorpm. At 3ooo it literally takes off like a rocket until you drop below that RPM.

At idle it’s pulling 26* of timing and the light is not jumping around. At 3ooo it’s a steady 35*

When it acts up it will misfire and backfire thru the intake and pop thru the exhaust.

TPS is brand new and properly aligned.
IAC is newer and cleaned.
CPS is brand new from Hesco
MAT sensor is new
MAP is new and properly installed
Fuel pump and filter are new. Pressure is between 32-40 depending on RPM.
FPR is new

Have tried with 02 hooked up and disconnected.

I’m beyond stumped. Car was sitting for about a decade before I purchased it.

 

[phydeaux33]

I have an AMC Eagle running a 1990 RENIX 4.0 that is stumbling from idle to 3ooorpm. At 3ooo it literally takes off like a rocket until you drop below that RPM.

At idle it’s pulling 26* of timing and the light is not jumping around. At 3ooo it’s a steady 35*

When it acts up it will misfire and backfire thru the intake and pop thru the exhaust.

TPS is brand new and properly aligned.
IAC is newer and cleaned.
CPS is brand new from Hesco
MAT sensor is new
MAP is new and properly installed
Fuel pump and filter are new. Pressure is between 32-40 depending on RPM.
FPR is new

Have tried with 02 hooked up and disconnected.

I’m beyond stumped. Car was sitting for about a decade before I purchased it.

Try coolant temp sensor on the side of the block drivers side, its what the PCM is reading to put it in closed loop. Your description sounds like it's stuck in open loop and when you hit WOT it runs right as it should.

 

[cs641]

Will do. When I go WOT it does take a while for it to get to that sweet spot

 

[Unclewolverine]

Double check your cap and rotor. I recently had the metal strip come out of my rotor and it ran like crap down low, but basically fine up higher.

 

[cs641]

Replaced the distributor today along with the plugs, cap and rotor. Also did the distributor index mod from Cruiser54. Problem persists.

 

[Ecomike]

Replaced the distributor today along with the plugs, cap and rotor. Also did the distributor index mod from Cruiser54. Problem persists.

Check it again. It is super easy to get it wrong, several times.

 

[cs641]

Checked, checked and rechecked. For kicks and giggles I tried it at every possible angle throughout the entire motion range of the distributor. Problem persists.

 

[Ecomike]

It is crazy super easy to crisscross 2 plug wires

 

[cs641]

Plug wires are not crisscrossed.

I installed a brand new crank position sensor, and now the problem only comes back after the car is warmed up