low idle renix

Ok.

If the o2 heater circuit isn't working, that could cause problems.

Also, if there is an exhaust leak above/upstream of the o2 sensor, the PCM (ECU) will interpret the o2 sensor data as the engine is running lean and it will richen up the mixture.

The EGR and EVAP purge (combo on the Renix) can lead to a rich condition.

What injectors are you running? I don't know if you already posted that, too lazy to go back through all of the posts again.

the CTS--coolant temp sensor, driver's side of the block down low--could definitely lead to a rich condition.

Too early opening of the thermostat or too cold of a thermostat--rich.

How is the spark? Blue and snappy or yellow and weak?
 
well if i can get away from kid duty for a few i will try and recheck the O2 circuit again. reading through a thread by Ecomike he states that when testing the O2 sensor it should swing voltage back and forth from 1v to 4v at idle, then 2v to 3v at 2000rpm. mine seems to do both at idle. sometimes 1v to 4v and sometimes 2v to 3v. and never go above idle. maybe i have a faulty sensor, or wiring.

i have tightened all the intake and exhaust bolts. can not see if there are any cracks in the ex manifold but i can not hear anything even with a stethoscope. i suppose there could be a slight leak at the down pipe connection but that is allready down stream of the sensor, not much but some.

all new EGR, but i admit i have not given the EVAP as much attention as i probably should. you may have come on to something with that one for sure. it IS almost 25 years old.

injectors are new. well new to me. got them from the online guy that so many on here was using. can not remember the name at the moment. he cleans, flow tests, and sorts them. seems to have a pretty good business.

CTS is new, but i found 2 more used ones in the shop. one of them has a broken connector but still useable.

new stant thermostat. stock temp. (195 i believe)

have not checked spark color since i am doing this solo. no helper. but i can make a remote starter and check some evening when wife is watching the kids.

next step: check O2 sensor and wiring. AND check the EVAP system. (good point, thanks for posting that)
 
update: it seems i may have figured out my main low idle stumble issue. after a multitude of swapings, changing things, checking, i thought i would get back to basics and try to research all i can (again). after reading up on the function of the pulse generator in the distributor i thought i would give mine a double check. tests were good, but something did not jive. the leading edge of the rotor plate (whatever it is called) was not lining up with the magnetic generator when what i thought was #1 piston. all i have seen and read showed number one to be roughly at 5 o-clock on the dizzy. even the cap has a number one embossed onto it. but this new aftermarket (oriellys auto) dizzy may be different from the old one. turns out the the #1 plug wire should be at roughly 3 o-clock. this leaves the leading edge of the steel rotor plate window right at the magnetic pick up exactly when the #1 cylinder is starting it's exhaust stroke. just where it is supposed to be. if looking at the dizzy cap, my new #1 plug wire is located at the first terminal clockwise after the mounting screw. the one on the right with the square mounting spot. after re-seting the dizzy at the new location the jeep runs MUCH better. no long extremely high idle at start up, now it is just the normal high idle then quickly comes down to a decent idle. it still seems a little low untill it really warms up to operating temps, but this may be from all the "Uncle bob" maneuvers i did. after cleaning the throttle body i set the plate as close to the body as i could without it touching. it may need to be opened just a hair more. but even as it sits i think i can now weld on the new cat and get the thing smogged so i can drive it again and do my build. pretty stocked today.
 
if you look at the picture on your link you will notice that the window was cut at the second terminal clockwise from the mounting screw. which is where most everyone seems to say is number one. BUT if i do it this way the METAL rotor thing will not align up correctly with the magnetic pickup of the pulse gen. and there is NO way to change the location of the metal piece on the dizzy. i understand the clocking procedure, but that would not work here as the base would need to be turned one complete terminal width.
 
i suppose you could cut the locating tab completely off, but that would leave nothing to hold the dizzy in place. plus doing so would not remedy the issue. the magnetic pulse gen pick up only has two settings for adjustment and is very limited. so by twisting (Clocking) the base housing, you would also be twisting the pulse gen pick up that is mounted inside. so again the wire would still need to be placed on the prior terminal. i will look to see if i have an extra dizzy in the shop and take some pics of what i am trying to describe. basically what it seems is that the metal rotor seems to have been mounted in a different location and can not be changed because the plastic rotor sits in a smal slot in the metal part. i suppose one could try and make another hole and mount the plastic rotor one terminal width over.
 
i dont think you understand. i am not talking about clocking the dizzy to get the ignition rotor to align up better. i am trying to get the pulse generator to align up at the correct spot (at the point of the #1 piston starts it's exhaust stroke). if i wanted to modify it i would need to have the magnetic pick up re-located inside the dizzy housing. just clocking does nothing for the pulse generator location as it moves with the housing. or i would need to reposition the ignition rotor on the metal housing.
put it this way. if i clocked the dizzy enough so that the pulse gen pickup lines up with the leading edge of the metal cover so the ecm gets a signal when the piston is at top dead center, i would need to put the #1 plug wire at the next terminal counter clockwise since i now have moved the dizzy houseing (clocked) that much. which is basically what i did now without needing to cut the mounting tab (locating bracket).
the main difference here is that this dizzy has the pulse gen window in different relation to the ignition rotor.
 
ok i am now understanding your comment about the hold down clamp STILL holding the dizzy even with the locating tab removed. apparently my jeep did not come to ME with a hold down clam. the dizzy was being held in place by the bolt holding down onto the locating tab. i figured it was one in the same. locating tab AND hold down clamp. i googled it and found pictures of the separate hold down clamp. so my question is, does the locating tab go where the hold down clamp bolt goes, or is the notch of some sort on the block? if the locating tab is counter clockwise the hold down bolt hole, then that would make sense why my pulse gen pickup does not line up.
 
bummer, was hoping the locating tab was supposed to be on another notch or something. again i CAN do the clocking procedure, but i would have to clock it one full terminal width. my ignition rotor lines up pretty good all ready. it is the pulse gen rotor that does not. unless of course i do what i did. seems to be pretty much perfect now.
 
I'm not understanding how, and have never heard of any other way to sync the sync generator except by indexing the distributor. Some of the distributors were off pretty far from the factory though and needed to be turned a fair amount. Perhaps yours is off a tooth?
 
cruiser54 said:
I'm not understanding how, and have never heard of any other way to sync the sync generator except by indexing the distributor. Some of the distributors were off pretty far from the factory though and needed to be turned a fair amount. Perhaps yours is off a tooth?
Click to expand...

How does it run with teh dizzy harness unplugged?
 
you can synce the pulse gen by indexing the dizzy. but for every degree you turn the base closer to the pulse generator, you are moving the ignition rotor away from its terminal on the cap. vise versa, when you index the dizzy so your ignition rotor lines up with the terminal on the cap, the more you will miss align the pulse gen cap (metal cover). you mentioned being a "tooth off" well in a sense when you index the dizzy by cutting the locating tab and turning it, you are basically doing the same thing as being a tooth off only by indexing you have adjustment. so it all depends how much you turn the dizzy when indexing.
 
the FSM says the pulse gen pickup should line up with the leading edge of the metal rotor when number 1 piston is at the begining of its exhaust stroke. which is when number 1 is at bottom dead center and number 6 piston is at top dead center of it's compression stroke. so when the ignition rotor lines up with number 6 terminal on the cap the pulse gen metal rotors leading edge SHOULD be right at the magnetic pick up. but with mine the leading edge was lining up with the pick up earlier when number 3 was at top dead center of its compression stroke. so the by moving all the wires one terminal counter clockwise and reseting the dizzy so the rotor now points to where number 4 used to be and now making that number 1, everything lines up perfectly. the drawing in the chiltons style manual shows number one bing 1 terminal clockwise of the right hand screw of the dizzy cap (where i have mine now). but that is just a drawing so take it for what it is worth. but most people have number one on the second terminal clockwise of that screw. the only way to make both the ignition rotor to line up on number one and the leading edge of the pulse gen rotor to line up would be to re-mount the magnetic pulse gen pick up, OR drill a different hole on the metal cover where the ignition rotor inserts moving it one terminal width counter clockwise.
i know. confusing huh. i really want to try and make a video of what i am trying to describe.
 
How's it run with the sync generator unplugged?

I see nothing in my FSM referring to adjusting the sync generator. Just a description of it and how it tells the eCU whether the crank is on #1 or #6 TDC. And, of course the replacement procedure with no reference to adjusting it. Are you looking at a 91 and later manual?
 
Last edited:
exactly. that is what i am trying to get at. there is no adjustment. all though there IS a small metal tab that holds it in place inside the dizzy housing that has (2) mounting spots. no adjustment, but two settings. it is one or the other. but it is only a few degrees differance. also if you read it carefully, it describes how the synce gen pick up tells the ecu how the piston 1 or 6 is at top dead center. not by the leading edge hitting the pick up at TDC, but when it hits the pick up when the 1 piston is begining it's exhaust stroke then calculating from there. then again i MAY have misread it. but that is the way i understood it. when i get time i will go back and re-read it AGAIN. stay tuned, there may be a big apology coming your way.lol
you also cannot change the relation between ignition rotor and sync gen rotor.
i have yet to try and run it disconnected. i will let you know.
 
No apologies needed. We're all on a quest here. I'm curious if there is a change with it disconnected. Here's why. We never replaced a Stator except when we happened upon it not working while scanning for another issue. In other words, it, by itself caused no driveability issues. The reason the dizzy indexing was important was that the ECU said "Fire" when the rotor wasn't near the dizzy cap terminal it needed to be near to.
 
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