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Renix CPS problem history

Ecomike

NAXJA# 2091
NAXJA Member
Location
MilkyWay Galaxy
Has anyone ever had a bad Renix CPS that started the engine perfectly, but made the engine run rich and missfire during acceleration, and miss fire, back fire out the exhaust with a rich fuel smell at rpms above idle (1500-3000 rpm, and gets better as the engine warms up, worse on the cold start up).

I know this happens with the HO 91-01 jeeps, but I have never heard of it with the Renix CPS. Renix CPS has always been a no start issue.
 
I've had the CPS do everything you describe, but it usually didn't happen until the CPS heated up. A series of incidences, was when I'd drive my son to work every morning, five miles out five miles back, the engine would start really acting up at 9 1/2 miles. Some mornings at the same intersection a half mile form home. I initially thought it was a MAP issue because of the excess fuel/rich running condition.

But most of my CPS issues was re-starting a warm/hot motor.

Really rich on a cold motor was a leak in my MAP vacuum tube and/or a bad contact on the MAP connector. I found both when I was trouble shooting, don't really know which was the main cause, I fixed both at the same time.

Heard of this happening with a faulty sync sensor, injectors batch firing instead of sequence firing. Never happened to me. The motor wouldn't run right until the intake heated up.

I have had some cross fire issues, ignored my plugs so long the gap spread, carbon dust in the distributor cap from a worn rotor contact, spark would jump from pole to pole inside the distributor cap. I eventually notched the scorch marks in the inside of the cap. Spark would occasionally jump from plug wire to plug wire or find a path around the cable boot. I always assumed it was a resistance issue (high) because of the worn electrodes and high resistance in the plugs. Once the spark scorches a path around the spark plug it will continue to occasionally follow that path. Brake cleaner and a clean rag will usually remove the scorch path carbon.

Kind of reminds me of when my O2 sensor wire cooked on the exhaust, the insulation melted inside the foil shield and I was getting a short between wires and/or the shield foil. Bucking, miss firing got worse when the motor heated up, best guess is I wouldn't notice (or it wouldn't get bad) until the motor started transitioning from open to closed loop
 
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I remember somebody did a clutch job on a renix put a new cps in while going it, then it ran like crap. I think his solution was drilling out the cps bracket because it was too thick holding the CPS slightly too far away.
I think it was one of Cruiser54's tips that helped him but I need to find that thread again, also think his jeep idled fine but under load in gear had problems. But he didn't have a heat issue as I recall it was there all the time.


Sent from my iPhone using Tapatalk
 
I remember somebody did a clutch job on a renix put a new cps in while going it, then it ran like crap. I think his solution was drilling out the cps bracket because it was too thick holding the CPS slightly too far away.
I think it was one of Cruiser54's tips that helped him but I need to find that thread again, also think his jeep idled fine but under load in gear had problems. But he didn't have a heat issue as I recall it was there all the time.


Sent from my iPhone using Tapatalk

Just click here and view Tip 7.

http://cruiser54.com
 
Not sure how I would rule out the Dizzy sync sensor being an issue with Renix. I always heard it just caused a very slow start when it went bad. Mine starts right up.

Thanks for the replies. I updated this thread if you all would please read the latest on this saga there and let me know if I missed anything.

http://www.naxja.org/forum/showthread.php?p=246499899#post246499899

Thanks!!!

I've had the CPS do everything you describe, but it usually didn't happen until the CPS heated up. A series of incidences, was when I'd drive my son to work every morning, five miles out five miles back, the engine would start really acting up at 9 1/2 miles. Some mornings at the same intersection a half mile form home. I initially thought it was a MAP issue because of the excess fuel/rich running condition.

But most of my CPS issues was re-starting a warm/hot motor.

Really rich on a cold motor was a leak in my MAP vacuum tube and/or a bad contact on the MAP connector. I found both when I was trouble shooting, don't really know which was the main cause, I fixed both at the same time.

Heard of this happening with a faulty sync sensor, injectors batch firing instead of sequence firing. Never happened to me. The motor wouldn't run right until the intake heated up.

I have had some cross fire issues, ignored my plugs so long the gap spread, carbon dust in the distributor cap from a worn rotor contact, spark would jump from pole to pole inside the distributor cap. I eventually notched the scorch marks in the inside of the cap. Spark would occasionally jump from plug wire to plug wire or find a path around the cable boot. I always assumed it was a resistance issue (high) because of the worn electrodes and high resistance in the plugs. Once the spark scorches a path around the spark plug it will continue to occasionally follow that path. Brake cleaner and a clean rag will usually remove the scorch path carbon.

Kind of reminds me of when my O2 sensor wire cooked on the exhaust, the insulation melted inside the foil shield and I was getting a short between wires and/or the shield foil. Bucking, miss firing got worse when the motor heated up, best guess is I wouldn't notice (or it wouldn't get bad) until the motor started transitioning from open to closed loop
 
the distributor sync sensor just helps locate if cylinder 1 or 6 is coming to tdc. without the sync sensor the ecu guesses what cylinder is coming to tdc. once its running its not noticeably different.

now a crank sensor can cause that exact issue. i had a 99wj and the sensor was physically loose. under acceleration engine movement or the wind from the flywheel would cause the sensor to move back just enough to not see the teeth. during this stumble the rpm's would drop to 0 almost instantly and then bounce back up.

same thing happened on my xj but the wires melted on the exhaust. and it would bounce and hit the exhaust shorting out the signal.

also a renix will only try and fire on cylinder 1 or 6 during start up. this adds to the seemingly longish startups.
 
I disconnected the sync sensor today in a test and it had no effect, good or bad.
 
Well this story has gotten worse with no fix that was tried working or confirming the cause yet. By worse, I mean it barley runs at 300-500 rpm even at WOT, and spits, pukes, bucks and backfires some. Unburned fuel is obvious. About to try a new Renix CPS, as everything else has been tried and tested.

Has anyone ever had a bad Renix CPS that started the engine perfectly, but made the engine run rich and missfire during acceleration, and miss fire, back fire out the exhaust with a rich fuel smell at rpms above idle (1500-3000 rpm, and gets better as the engine warms up, worse on the cold start up).

I know this happens with the HO 91-01 jeeps, but I have never heard of it with the Renix CPS. Renix CPS has always been a no start issue.
 
New CPS was 3 times worse signal than the old one. Even with all the recommended CPS mods. Had .60 volts on the old one cranking. New one was .20 volts AC

I fixed it with 36" crow bar and hammer, :twak:

and I now have .65 Volts AC cranking!!!

One must know where to hit and how hard to hit it.

I used the Force!!! :laugh3:

It did not fix my problem. Turned out to be the sheer pin holding the dizzy gear in place on the dizzy shaft. It finally completely dies today.
 
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