Here’s my list of do’s and don’ts to help keep your 87-90 Renix Jeep running it’s best!
4.0L Oxygen Sensor (o2)
Renix can be a little picky with o2 selection and needs a good 0v to 5v swing to hold Closed Loop properly.
GOOD:
– NTK / NOS Mopar / ACdelco 23553: Highly recommend for it’s nice swing and more forgiving range.
BAD:
– Bosch 12009 NOT RECOMMENDED for lack luster swing, occasionally not moving at all, and having a harder time holding closed loop.
4.0L Flexplate
Video: https://www.youtube.com/watch?v=CgUsJi0Jq2U
The Renix Flexplate is different then newer 91+ High Output engines and are not interchangeable!
Some aftermarket replacements were incorrectly made and their timing marks are off by a very large margin. If you have an ok Idle but it wants to die under any throttle, you may have a bad replacement flexplate!
GOOD:
– Omix-Ada 16913.11 or 33002675: Confirmed correct part from VintageJeepParts.com. I’ve heard JEGS works too.
BAD:
– Pioneer FRA-333 Flexplate from Orielly caused a No-Start. (Instagram Tipoff)
– ATP Flexplate mentioned that it looked identical to the Pioneer. (Instagram Tipoff)
– 91+ HO Flexplates WILL NOT WORK so make sure to use the older flexplate during a swap!
4.0L Spark Plugs
These old Renix engines seem to prefer the old copper spark plugs over the fancy iridium plugs. If you are having poor acceleration or backfiring, check you’ve got the right plugs!
Don’t forget to check the Gap too: 0.035″ !
GOOD:
– CHAMPION 344 {#RC9YC} Copper Plus: I’ve had good luck with the OEM recommended plugs.
Bad:
– Any kind of fancy Iridium Plug is not recommend for its poor performance in Renix.
4.0L Fuel Injectors
Video: https://www.youtube.com/watch?v=dstyjD5Hy9Y
Renix uses a lower flow rate injector then newer 91+ HO does, and the ECU is not very tolerant to more fuel so keep a close eye on the actual numbers or you’ll for sure have an over-rich condition!
The number of Holes an injector has only affects its spray pattern. The Injector Flow Rate is what will tell you if it’s compatible, as stock renix injectors are rated at 19.6lbs/hr at 43.5 PSI.
GOOD:
– Genuine Bosch Injectors seem to work well:
– 0-280-155-702 _ 19.0 lbs/hr 4 Hole Volvo
– 0-280-155-746 _ 19.0 lbs/hr 4 Hole Volvo
– 0-280-155-712 _ 19.4 lbs/hr 4 Hole Saab
– 0-280-156-161 _ 22.8 lbs/hr 12 Hole Ford (Ok on my 4.6L Stroker, NOT so well stock!)
BAD:
– Any HO Injector will likely be too rich for a stock Renix setup.
– Cheap Knock off Injectors that may not be their labeled flow rate!
4.0L Fuel Pumps
Tip from Charles William: Bosch or Nothing!
GOOD:
– Bosch 69302
BAD:
– Airtex / Delphi / Carter / ACDelco
Intake Manifold Air Temp Sensor (IAT)
The stock IAT sensor has been long discontinued so we will need to adapt a similar sensor instead.
Tip from David Groeneveld:
– GM part 213-190 will replace it but requires the intake manifold port to be retapped to 3/8″NPT (stock is 1/4″NPT) and replacing the pigtail connector as well. This will update the sensor to a currently used part with the correct resistance range.