Sure dead injector would cause the others to run rich - the computer decides how much fuel to dump in based on the reading from the O2 sensors, which get exhaust from all 6 cylinders combined. So the ECU not knowing better assumes that all 6 are firing. Actually I'd expect the other 5 to run 20% richer just to make the exhaust stream look similar to the ECU.

Is the Renix design the one with the vacuum fuel pressure regulator? I'm on my phone but don't see that mentioned yet. It'd be this disc-looking thing at the front of the fuel rail where the supply and return lines connect. On the rear is a vacuum line that runs to the manifold. Pop that off and see if it's wet... If yes, then that can cause hard starts, rich running, and MAYBE a failed fuel pump, but that would be pretty convenient lol

 

I would check that new Cps. Just a minute with a $5 meter from Harbor Freight ANYWAY!(Lol)....(they seem to be capable of almost anything. The modern day equal of the infamous condenser). A problem with that map tube will make it supper rich, I hope you made sure it's flawless. The same meter will let you check the two temp sensors that, unless I'm mistaken can also make it over rich. Salad's logic is sound, as usual, I'm just not so sure the 02 has the "authority" to call in so much fuel. I thought it was more to put the final touch on the mix after the MAP, IAT, and ECT sensors took a whack at it. (intake air, & engine coolant temperature). Maybe though? Anyway you need to get'r hitten on all 6.

Cruiser or somebody can correct me here if I'm wrong. I think you can just swap the wire connectors between 5 & 6 injectors and see if the miss moves. The fuel will still be there, just a fraction of a second timing won't stop it from burning. Also you might RAP that injector with a screwdriver handle.

Myself, I might pull that plug, ground the body of it and see that it's actually sparking. I guess if you first pull the rear wire off the ballast resistor to kill it with no fuel, it shouldn't start when you test spark.
Did you gap the new plugs? They do get dropped. (.035)

This link here has a post by Programo, #171 IIRC. You might pm him about injectors. Also Precision Injectors ..maybe on Ebay. Also, I got my 703's cheap at the JY. Ended up being 3 trips....but I like the JY!

https://www.cherokeeforum.com/f2/10-...08854/index12/

Injector color codes? I came up with this: Golf anyone?


LITTLE BALL, LONG GREEN, TEE YOUR WHITE BALL...................................


Light Blue, Light Green, , Tan, Yellow, White, then Black.

If you know the pair in the middle is right, you only need to check one on each end.

 

It would be good to know if you're getting a pulse to that injector.

Look at the injection wiring haresss near the back of the head. Is it chafed or worn through?

 

I piddled a little bit this evening.I pulled 5 and 6 injector wiring and swapped them. So i now have #5 wiring on #6 injector and #6 wiring on #5 injector. I pulled wiring off of #6 injector and no change{which was really #5 wiring} i then put it back on and pulled wiring from #5 injector[#5 wiring} a major change. So im 99% sure it is #6 injector.

I then checked the relay that got it back running all the connections looked good but looks are deceiving. I checked the resistance on the MAT sensor it was 1325 ohms i think i read it should be less than 1000 so it may be bad, but the engine was cold so i' m not sure. I checked the resistance on the new CPS and it was 286 not sure what its supposed to be. Tried setting the TPS i got 4.06 volts from AD and 0 volts from AB so something is not right there. I haven't found the CTS yet. The fuel pressure regulator is vacuum operated and seems to work no gassy smell when i pulled the vacuum hose and pressure is running at spec but it does bother me that it looses pressure so fast on a new pump.

I did gap the plugs to specs they are cheap champions i haven't really used champions much i have been running split fire plugs which work, nothing special i have never really fixed anything by changing plugs. I just though i would give it some new stuff. The old jeep has been bulletproof for many years all i did was drive and change oil and grease and it would always crank and go. I was thinking of changing the coil and then i forgot to put plug wire #6 BACK ON THE LAST TIME I CRANKED IT AND I KEEP HEARING THIS POPPING NOISE AND I LOOKED AND LISTENED and then saw the plug wire with a 3 inch insulator arcing to a radiator hose bracket so i decided the coil was fine.

Back to the CPS sensor it fits in a platic grommett that covers about a 3 inch hole i'm still not sure thats back in place right when your under there you cant really see it you just have to feel, anyone have any thoughts on checking that for alignment. I think i will pull the fuel rail tomorrow and replace that injector we will see how that goes

Thanks again everyone. This is a great forum!!!!!

 

Look for something that's common to ONLY that cylinder #6.
When it misfires it puts extra O2 in the exhaust, richening everything. ALL cylinders will go rich - a normal reaction.

Sensors, CPS, TPS, Fuel pump, pump relay, grounds, temp sensors etc are common to ALL cylinders. Cannot be their fault. They would affect ALL cylinders.

If pump pressure is low, ALL cylinders will be low.

Ignition - Put a plug in the end of the #6 plug wire, ground the shell, look at the spark. It should be a crisp blue spark, if yellow, red etc - replace wire. Also Check inside the cap.

Noid light flashes like the others? If it does, it's not the wiring or PCM. no flash - check wiring from there to the PCM.


Don't bother chasing codes - there won't be any.

Check compression.
If compression is good, then the only thing left is the injector itself. Swap it with a another cylinder's to see if the problem moves.

Based on your symptoms, I suspect compression is very low on 6, cracked head/gasket?

But we can find out more without tearing it apart - don't panic - yet.

First remove the valve cover - make sure the pushrods are still in place - haven't fallen off, and they move up and down just like the other ones - same amount of movement. Use your finger - put it on the rocker to feel it - then compare with others.

Let us know what you find so far.

Next step - a leak down test.

 

POST #1
I would do the AC voltage test Cruiser posted in post 10 before I worried about the CPS. Sort of like when you go to the doctor, they listen to your hart even though you just went in for that rash..again! Lol. It does sound like you need an injector, (at least), but I'd want to see that plug firing myself before I went there. But great...get'r firing than you can figure out the rest from there.

Mine was bleeding off fuel, (&Pressure), through my leaking injectors. It would start faster if I did the "poor mans prime" turning the key to off and on a few times before starting it.

Sounds like you're gonna get it!

Sensor stuff>> http://www.lunghd.com/Tech_Articles/...iagnostics.htm

 

I pulled the fuel rail this afternoon before i even tried to start it so i was sure the pressure had leaked down over night.When i pulled the suspect injector off the rail gas shot out like a canon. I didn't check it this afternoon but every time before when i had the gauge on it the pressure leaked down to 0 at the scrader valve within 15 minutes so why did i still have pressure on the #6 injector the supply line was still hooked up. I had the bright idea to replace the #6 injector without pulling the rail all the way out, well that didnt work out so i pulled the rail and put all new o rings on the bottom of each injector and replaced #6 with an old one i had that was leaking but was firing at the time i took it off. It was a little sluggish cranking but once running i think the miss was gone, I say i think because i couldnt run it very long because i had a leak at the regulator and the old # 6 was leaking i guess being in a box for 5 years didnt fix it. About that time my wife comes out and says i think we need to mow we all know what that means( quit doodling around and mow the grass) so i didnt get to finish.

So tomorrow i will get some new seals and finish up hopefully. Any input on which injectors to get from the chain auto stores thats about all we have left around here NAPA closed and dealers are expensive. When i get the leaks all sealed up then i can evaluate the engine a little better.

I appreciate all the help i was determined to get it this time and i think i may have with you guys excellent advise.

 

Idk? Maybe they have Bosch..# ends in 703. I got these here, $8 after tax & fees at the JY. I hear there are Ford ones as well. Maybe someone can chime in. For A Renix Jeep!.

 

I got all of my gas leaks stopped with new o rings. The old injector i installed in #6 is now firing with no leaks, i can pull #6 wire off now and definitely tell the difference. I SET THE TPS WHERE I AM NOW GETTING .8 VOLTS. I checked my CPS and it is putting out .4 volts AC not .5 like recommended. It is still difficult to crank . It runs better but still not top notch . I havent really has it on the road yet to get it fully warmed up to see how it runs. The tank is almost empty and i dont want to put more gas in it untill im sure im not going to have to pull the fuel pump.

 

Well great...I guess. Put enough enough gas it it to give it a good run? Blow it out and see where you are. Cruiser has the real experience with Renix, but I don't think .4 is gonna give you any trouble. I'm learning here myself. I'm very curious if replacing the #6 injector alone will stop the other five from sooting up. It's my thinking that you still have something making it run that rich, I suppose I'm about to find out! I suppose I would pull all the plugs and give them a good cleaning, or a good hwy trip might clean them up.

Cleaning the IAC and TB, and adjusting the TPS are all good maintenance to have done. Guess you can skip cleaning the IAC. Below is Cruiser's TPS writeup to add to what you have.

When you say "difficult to crank", I read "slow to start.....Renix always takes a second. It will never "pop right off", but more than count of three or four and you still have something up.

The first, most common cause for a delay is issues with the fuel pressure. If turning to key to on, then off, a few times first, then starting it cuts down the crank time you can suspect something there.

I just wanted to add...one reason I changed my injectors. The engine was hot, and I did that "poor mans prime" above a few times. I was watching to see how the pressure would drop while it was sitting. (more than 20 lbs in 1/2 hr is one spec, IIRC, Btw) Then I think I primed it yet again. Longer story shorter...when I finally started it I had a real miss from one or two cylinders that had gotten flooded while I was doing that. Injectors were leaking into the cylinders. Dropping my pressure sitting, and no doubt not helping my mileage.

So, like you are doing I guess. Clean it up, give it a good run. I suppose checking the two temp sensors might be next. if it's still rich.

I've seen some clearly smart guys saying to change that 02 sensor every 60K. I know for sure mine was toast. Ran fine but I go extra bad "knocking around" mileage. Was getten 18 on the highway though..go figure. I might guess the ECU default is set close for that?

If all else seemed OK and I was still scratching my head with a lack of power I might loosen the nuts holding the header pipe flange to make an exhaust leak. I had that work great once with a Dodge with a clogged cat. Night and day. Or I suppose pulling the 02 sensor would do it as well.

Anyway, please do let us know if the new injector left the other plugs running clean.
RENIX TPS ADJUSTMENT
Before attempting to adjust your TPS be sure the throttle body has been recently cleaned.
It's especially important that the edges of the throttle butterfly are free of any carbon build-up.
IMPORTANT NOTE: Using the positive (red) lead of your ohmmeter, probe the B terminal of the flat 3 wire connector
of the TPS . The letters are embossed on the connector itself.
Touch the black lead of your meter to the negative battery post.
If you see more than 1 ohm of resistance some modifications to the sensor ground harness will be
necessary. The harness repair must be performed before proceeding.
I can provide an instruction sheet for that if needed.
MANUAL TRANSMISSION:
RENIX manual transmission equipped XJs have a three-wire TPS mounted on the throttle body.
This manual transmission vehicle TPS provides data input to the ECU. The manual transmission
TPS has three wires in the connector and they're clearly embossed with the letters A,B, and C.
Wire "A" is positive.
Wire "B" is ground.
Key ON, measure voltage from "A" positive to "B" ground by back-probing the connectors..
Note the voltage reading--this is your REFERENCE voltage.
Key ON, back-probe the connector at wires "B" and "C". Measure the voltage. This is your
OUTPUT voltage.
Your OUTPUT voltage needs to be seventeen percent of your REFERENCE voltage. For
example: 4.82 volts X .17=.82 volts. Adjust the TPS until you have achieved this percentage. If
you can't achieve the correct output voltage replace the TPS and start over.
AUTOMATIC TRANSMISSION:
RENIX automatic transmission equipped XJs have a TPS with two connectors. There is a flat three-
wire connector, same as the manual transmission vehicles have, and it is tested the same as the
manual transmission equipped vehicles--FOR ENGINE MANAGEMENT RELATED ISSUES.
However, the automatic TPS also has a square four-wire connector clearly embossed with the letters
A,B,C, and D. It only uses three wires and provides information to the Transmission Control Module.
Key ON, measure voltage between "A" positive and "D" ground. Note the voltage. This is your
REFERENCE voltage.
Back-probe the connector at wires "B" and "D". Measure the voltage. This is your OUTPUT
voltage. Your OUTPUT voltage needs to be eighty-three percent of your REFERENCE voltage.
For example 4.8 volts X .83=3.98 volts. Adjust the TPS until you have achieved this percentage.
If you can't, replace the TPS and start over.
So, if you have an automatic equipped XJ your TPS has two sides--one side feeds the ECU, and
the other side feeds the TCU. If you have TRANSMISSION issues check the four-wire
connector side of the TPS. If you have ENGINE issues check the three-wire connector side of
the TPS.
For those with a MANUAL TRANSMISSION--the TPS for the manual transmission XJs is
stupid expensive. You can substitute the automatic transmission TPS which is reasonably priced.

 

Thanks for the instructions on setting the TPS. I sert it only using the 3 way plug not the 4.

I am coming to the end of my knowledge base it is still cranking poorly. It takes about 30 seconds to crank. I turn the key on let it on until the buzzer stops crank it over for 5 seconds nothing crank it for 5 more seconds get a pop and this goes on for a couple of more tries and then it starts. I have good fuel pressure 31 running 39 without vacuum line hooked to regulator. I can pull the fuel rail again but im not really sure what i would be looking for. I can pull the pump but again what am i looking for i have good pressure. Other than the slow cranking everything seems normal.

 

I checked my fuel pressure after letting it set over night and it was still 25 pounds. Still difficult to crank , wonder if its jumped time.

 

I have checked a few thing but am at a loss of what to do next. I got underneath and put a wrench on the harmonic balancer bolt so i could turn the crsnk and check for tiing chain lag everything sems tight and good .The engine starts shaking at higher RPM. I was going to try to check the timing with a timing light and could not find a mark on the harmonic balancer, does anyone know how to do this on a 90 cherokee.

 

Ok. Let's get clear on the symptoms/problems you have right now. It's nutty hard to start, then runs pretty well, except it shakes at higher rpm? Not that you havn't been clear, it's just a long thread.

I guess from the snapping you heard with that wire off the spark sounds good. Is it a strong blue spark? Checking it right when its messing up would be nice. (around that time). In my signature, that link has Cruisers coil/ICU contact cleaning.

An idea, Cold starting, will she fire right off if you use starting fluid? Or does it seem more flooded?

Mine will fire right off even with the TPS un-plugged, but with the MAP plug off, I get one good kick, (starts for barely a second), it then just cranks. I didn't keep at it to see if it would eventually start. The MAP sensor ground is the left, (drivers side on the plug). A pretty easy check to see that you have less than one ohm from there to batt neg.

I might double check that CPS output. Also there could be trouble with it's signal getting through to the ECU. There is even a factory by-pass for that, running a new wire right through the firewall to the ECU. It's plug looks good?

There just IS NO timing adjustment on these. It will even run fine with the wires to the cam sensor on the dizy unplugged. ECU does it.

Just the other day a guy had mid range power issues. It seems it was his IAT, (or MAT) (Intake or manifold temp). Cleaning mine I found a funky, intermittent wire. Working (I think?), mine gets down into the 700 ohm range hot. Much cooler, but not cold I saw it at at over 2000. The ECT sensor has the same chart, I havn't gotten to mine yet, but I expect to see lower numbers since it is actually IN the coolant....Idk, if yours was "open" maybe it could flood it when you are trying to start.

HEY! Just remembered something. If you floorboard it cranking, the ECU will shut off fuel to the injectors, (while it's getting max air). If she starts better like that you can suspect flooding.

Anyway I'm glad Cruiser put that guy onto the IAT. Cleaning mine and repairing the wire should help my mileage.

 

Very doubtful it jumped time. Super uncommon on these engines. Need to know your CPS output. You've got classic symptoms.........Takes less time than tying your shoes.