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Renix woes for 1988 XJ 4.0/auto

Gunter

NAXJA Forum User
Location
Aurora, Colorado
still running bad.
let me explain
had some sensors that needed replacing-done.
had grounds to refresh- done
had damaged wires-repaired
had low fuel pressure-replaced pump and filter
come back to wiring harness repair and had it working perfect 60 percent of the time. runs bad? wiggle engine harness and it comes back to normal.
replaced entire engine harness from a 90 XJ. I had 2 wires to repair from rodent damage, no other issues. opened carefully up and examined for any damage in teh harness along the valve cover area and the one splice there was in perfect shape, re taped and re wrapped. harness is in really good condition.
engine runs fine when it is right, runs weak like now when not. engine is not worn out and have not touched any plugs,wires,cap or rotor. have not messed with any other wiring or components. Just engine harness and sensors. it shifts up and down all gears.
it acts like it wont advance and deliver fuel . it also shakes like it has a miss at idle.
pulled plug wires one at a time and no issues. puled injector plugs one at a time and had the two middle cylinders swapped.
at wits end here.
 
I'm away from my notes but there is a connector C101 on some Renix models. It was later removed due to flakey performance. I don't remember when it was deleted.

Another thing can be a bad shield on the ping sensor cable.

Also try wiggling the bulkhead connector and the vacuum line to the MAP.
 
So to clarify, sometimes it runs fine, sometimes not? Harness made a notable change or no? You said you haven't done any of the tune up stuff. When was it done last? It's also possible the substrate in the cat is moving around and intermittently clogging the exhaust.
 
update.
plugs are all good.
cap and rotor are ok. not bad...not great....but good.
not sure if i have my injector plugs on the right injectors. moved some around and seems to have helped the misfire some.
will the tps adjustment cause my low power situation? it is not adjusted right now.
 
update.
plugs are all good.
cap and rotor are ok. not bad...not great....but good.
not sure if i have my injector plugs on the right injectors. moved some around and seems to have helped the misfire some.
will the tps adjustment cause my low power situation? it is not adjusted right now.

Go to www.cruiser54.com and do Tip 5 just for giggles. we need that verified before adjusting the TPS.

Each injector has a black wire and a colored wire.

Here are the colors:

1- light blue
2-light green
3-tan
4-yellow
5-white
6-brown
 
Sounds like what mine did when the CPS wire was cooking in the exhaust manifold. Tie that CPS wire up well out of the way with cable ties. I tied mine to the speedo cable.

Double check your number one on the distributor cap and firing order again. The diagrams (pictures) of the number one on the distributor cap can fool you, most are a bit off.

Check and see if your exhaust is really rich. Double check your MAP vacuum line and make sure it is plugged into the right hole on the TB.
 
Go to www.cruiser54.com and do Tip 5 just for giggles. we need that verified before adjusting the TPS.

Each injector has a black wire and a colored wire.

Here are the colors:

1- light blue
2-light green
3-tan
4-yellow
5-white
6-brown
i will check grounds again and the injector to cylinder assignments. i have long ago done the ground refresh and tons of other things. pos and neg cables, the thing the coil rests on has been replaced. my new to me engine harness does not have the c101. also-- is number one closest to the radiator?
 
Sounds like what mine did when the CPS wire was cooking in the exhaust manifold. Tie that CPS wire up well out of the way with cable ties. I tied mine to the speedo cable.

Double check your number one on the distributor cap and firing order again. The diagrams (pictures) of the number one on the distributor cap can fool you, most are a bit off.

Check and see if your exhaust is really rich. Double check your MAP vacuum line and make sure it is plugged into the right hole on the TB.
already had that happen and fixed it :) and tied it off away from the danger zone :) map vac line is good.
 
so tps voltage set
the injectors are all wired correctly now.
my Ohms were 4.9 from tps b to battery neg.
wiggled and moved harness but got no change in reading.
so as the engine has ran perfectly before, i am of the mind i am dealing with a ground issue here.
i did not mess with tdc and all that yet. it was never touched since i got it.it was in the high gear only mode when i first installed the harness. but now is all gears work.
 
Ohms or volts???

"my Ohms were 4.9 from tps b to battery neg." ????

Which side of the TPS did you test?

Which pins?

Ground wire at the TPS should to the (-) battery pots for both TPS ground wires must be under 1.0 ohms.

The supply voltage should be 4.8-5.0 Volts to both sides of the TPS. The TPS is actually two independent sensors in the Renix TPS. One is for the engine, the flat three pin connector.

We need specifics as to when and under what conditions it runs good and bad.

Hot, cold, wet weather, dry, at idle in or out of gear, while driving, during acceleration. DETAILS MATTER!!!

I assume it is nice and quite when the ignition off, LOL.:cheers:
 
Ohms or volts???

"my Ohms were 4.9 from tps b to battery neg." ????
it was Ohms on the B terminal of the plug on the harness side.

Which side of the TPS did you test?


Which pins?

Ground wire at the TPS should to the (-) battery pots for both TPS ground wires must be under 1.0 ohms.

The supply voltage should be 4.8-5.0 Volts to both sides of the TPS. The TPS is actually two independent sensors in the Renix TPS. One is for the engine, the flat three pin connector . voltage was 4.8

We need specifics as to when and under what conditions it runs good and bad.

Hot, cold, wet weather, dry, at idle in or out of gear, while driving, during acceleration. DETAILS MATTER!!!

I assume it is nice and quite when the ignition off, LOL.:cheers:

my voltages are with in spec. i think i have high resistance in my grounds?
i will clean the head ground., and the block ground and then pray. after all praying worked in the search for teh Holy Grail :p
 
and really, this is a LOT less problems than the other harness.you guys are a huge help.
i will clean grounds and see if i cant bring it back into spec.
 
ground strap on head cleaned, and on ground on block above the starter cleaned and re installed. not right yet, but closer. Ohms are now under 1.0 from tps to battery neg.
and less than one from body to engine block. volts are the same. still no advance and fuel delivery to run higher rpms.
 
Test your fuel pressure.

With the engine running, see how much voltage you have on either side of the fuel pump ballast resistor.
so when it ran better, the fuel pump was replaced. it has less than 150 miles on the new pump and filter, and i already had the rubber hose come off the pump in the tank. it was holding steady on 35 psi. i can hear the pump when i turn on the key but not start it.
i made a jumper for teh wires on the ballast and that made no difference i could detect. i ll get the voltage -be right back
 
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