Rebuilt & tuned up RENIX running very rich - help me save it from the SMOG demons

[Royal Nonesuch]

Re: Rebuilt & tuned up RENIX running very rich

Got busy with work over the weekend, come back and look at all the replies! Thanks guys.

The Midas that I go to already had a 2.5" Magnaflow high flow catalytic converter sitting on the shelf I've heard there could be some issues if you choose to install it yourself, but I confirmed from my Midas that claim is not true, at least not in my location - doesn't seem to be a concern with my smog shop either. So, if you'd like I can take a photo of the new converter, which has the part number, etc.

Thanks, I found the list of CA-compliant magnaflows for the XJ on their website. They also have a dealer/shop listed a few minutes from me, so I am going to swing by there this week and chat with them about it.

A new converter installed at a shop will probably run about 150-220$ including the cat. The place you took for smog, was it only smog or a repair shop. A lot of times shops will re-test for free if you use them to repair your vehicle.

He has a lift/does repairs too and is a cool dude. I'll ask him about it, good idea. Maybe I can order the new cat and have him slap it in.

I think the 703 injectors you had in there fouled up the o2 sensor.

When I put the 703s in my 89 and scoped results on my snap on brick, the motor would go into closed loop but quickly reduce the STFT (short term fuel trim)
values to the point of Open Loop

The 703s dump too much fuel for the Renix to handle.

If you had them in for a while they probably messed up your cat converter too.

Look on Ebay for a Snap on MT 2500 .

Its they only way to check your Loop Status and other data

Very interesting. According to my records, I installed the 703s in mid-december last year/1800miles ago. The 02 sensor was installed in late May this year, so I imagine that is still good. During the time I ran the 703s I did do a few good 4x4 trips stressing it offroad. I have been watching ebay for SnapOn 2500s, they're pretty affordable but I'm not quite at the point of buying one yet. I might ask in the local chapter section if anyone wants to loan one out for a case of beer :yap: I'd love to be able to read that live data.

A direct fit, CA approved CAT is in stock at RockAuto for $157. I put one on my 88 last year when it failed.

I noticed that as well. Yours passed after install?

Perhaps the "new" injectors are bad?

Volvo 746s work great in the Renix Jeeps.

NEVER a bad idea to eliminate the c101.

It's the man himself! :worship: Thanks for all your contributions to the renix folks, they have been so helpful to me rebuilding this thing.

I tested the 703s with a harness pigtail and a 9v and each one functioned. They also click rhythmically at the same pace when I listened to them with a digital stethescope. I'm currently running the original injectors that were in the Jeep when I bought it. I will keep an eye out for 746s on future junkyard trips.

The only thing stopping me so far from c101 elimination is that I have no soldering experience nor iron. Quick question for you - while trying to locate my two sensor grounds for your Tip #6, I was able to locate the factory splice by the MAP Sensor, but not the splice near the engine near the manifold air sensor as the instructions say. There aren't even any brown/white wires there. Here's a photo of the splice I was able to locate

Thanks again for all the replies - you guys rule.

 

[Royal Nonesuch]

Re: Rebuilt & tuned up RENIX running very rich - help me save it from the SMOG demons

Before I forget, and in case it's related - in my year of tinkering with this Jeep, I have not been able to figure out what these two plugs are supposed to connect to. They're both located directly underneath the MAP sensor and have purple/white & white/black wires. They look just like the harness side plug for the CPS (which shares same wire colors). I actually accidentally connected the CPS to one of them once and panicked because of the sudden no-start, until I figured it out.

Ideas?

 

[cruiser54]

Re: Rebuilt & tuned up RENIX running very rich - help me save it from the SMOG demons

If your Jeep has had the factory CPS bypass done, you could have an extra connector which shoulda been clipped off.

No better way to learn soldering and using shrink tubing than to do a C101 elimination!!!!

 

[Royal Nonesuch]

Re: Rebuilt & tuned up RENIX running very rich - help me save it from the SMOG demons

If your Jeep has had the factory CPS bypass done, you could have an extra connector which shoulda been clipped off.

No better way to learn soldering and using shrink tubing than to do a C101 elimination!!!!

Well, that would explain one of them for sure. The other one will remain a mystery I guess :confused1

I put in an Amazon order for a soldering iron, wire, and heatshrink. Time to learn!

 

[cruiser54]

Re: Rebuilt & tuned up RENIX running very rich - help me save it from the SMOG demons

Well, that would explain one of them for sure. The other one will remain a mystery I guess :confused1

I put in an Amazon order for a soldering iron, wire, and heatshrink. Time to learn!

Way to go. Take your time. One wire set at a time. You'll be fine.

 

[Saudade]

Re: Rebuilt & tuned up RENIX running very rich - help me save it from the SMOG demons

Hard to tell the colors of the wires. The purple/white is the CPS. Mine is still connected using the connector. The other could be the Intake Air temp. My IAT connector is different but it is only 2 wires.

For your other question, yes I passed smog once I put the new cat on.

 

[Royal Nonesuch]

Re: Rebuilt & tuned up RENIX running very rich - help me save it from the SMOG demons

Hard to tell the colors of the wires. The purple/white is the CPS. Mine is still connected using the connector. The other could be the Intake Air temp. My IAT connector is different but it is only 2 wires.

For your other question, yes I passed smog once I put the new cat on.

The spare connectors are both purple w/white line and white w/black line. The CPS will plug into either of them but result in no-start condition. One comes out of the firewall directly underneath the MAP sensor, the other comes out of the harness. Maybe a once-botched twice-fixed CPS bypass? It's not the IAT, mine's a two-wire/two-pin as well.

Also, I think I might be onto something - after doing a couple of hours of fruitless reading I came across an old post regarding another renix guy failing smog w/similar numbers to mine. He eventually discovered his ignition coil was arcing causing incomplete combustion; once he replaced it he was good to go. It's a nice dark moonless night outside, so I immediately went out and started the Jeep. Once my eyes adjusted to the dark I stuck my face down as near as I dared:

It's like a goddamned lightning storm in there holy shit how have I never noticed this. There are arcs to the head irregularly near the plug boots, and there are other random arcs from the wires where they are near metal (i.e. A/C compressor). It's like a disco in there when I manually open the throttle a bit :woohoo:

I hate premature excitement but am I correct in thinking that goes a long way to explaining a rich via incomplete combustion, possibly also causing my low erratic idle situation?

 

[88trailcrawler]

Re: Rebuilt & tuned up RENIX running very rich - help me save it from the SMOG demons

I had a hell of a time getting my XJ to pass smog 3 years ago. I didn't read your entire thread and I am no expert. The forum walked me through a laundry list of issues I'll do my best to share.

Catalytic converter. will definitely help, throwing one on my even get you to pass, but if there is something else wrong, you'll just burn up the new before your 2 years is up.

Oxygen sensor. Read up on how to test it. I found my old spare tested better than my recently installed on.

Cooling system. Make sure it's ALL in good operation.

EGR valve. Read up on how to test.

Manifold gasket. Test for leaks. I had a very slight leak. You can use starter fluid to find them.

Vacuum leaks. Same.

Tune up. Obviously

MAP Vacuum line to the throttle body.

Exhaust/manifold leak. I had a leak at the doughnut seal, was blowing hot air on the block and I think messing with the O2 sensor.

Tire size and gearing. I am on 33's and 4:56, didn't have a problem, but have read bad gearing/tire combos can mess up the testing results.

Testing location. I went from a smog Nazi to a guy who wanted it to pass. World of difference.

That's all I can remember off the top of my head, it was a difficult process. But in the end the XJ passed with flying colors and has since ran better than ever.

Also - is one of your mysterious connectors for the underwood light?

 

[Ecomike]

Re: Rebuilt & tuned up RENIX running very rich - help me save it from the SMOG demons

Try my Renix O2 sensor tests in the old thread here

http://www.naxja.org/forum/showthread.php?t=1012701&highlight=oxygen+test

 

[Royal Nonesuch]

Re: Rebuilt & tuned up RENIX running very rich - help me save it from the SMOG demons

great list of tips

Thanks! I've gone over just about everything you listed, and my smog guy is very cool and didn't ask me about a few underhood things he could have noted. He was purely running off the numbers, and actively tried to help me troubleshoot them at the shop.

Your tiresize/gearing note is interesting though, and something I have wondered about - I'm running 31" Cooper S/T Maxxs (load E IIRC) on stock 3.55, which is a pretty heavy tire for that but should be okay. The main concern with that in the back of my head is that my speedo-gear is off a few teeth for my tire size - I'm not sure how that comes into play with the CA dyno test at 15 and 25mph. The test is run based off the dyno screen rather than the gauge cluster, but who knows. I have a few shitty stock takeoff sets I'm eyeing on craigslist for my next smog run if I can get them cheap enough.

Try my Renix O2 sensor tests in the old thread here

http://www.naxja.org/forum/showthread.php?t=1012701&highlight=oxygen+test

I have this thread bookmarked but it gets a little over my head :looney: I have a few different spare o2 sensors including my original that I might end up bench-testing if I get desperate enough.

I changed out my plug wires for a higher quality Accel set the other night - underhood lightning show/arcing is significantly down (still see it lightly at the plugs/boots) but it did not affect my chronic low 500rpm @ idle issue, which I still think is one of my main and only symptoms.

Bigger Update
I made two adjustments which have resulted in major gains:

I was researching replacement MAT/air charge temp sensors, and after staring at enough photos of new ones online I noted something - all of them have factory thread sealant on them. Some time ago when I cleaned mine I remembered wirewheeling the old gunk off. This seemed relevant, because the MAT sensor is tapered and doesn't seat flush with the manifold as far as I can tell. Perhaps the intake vacuum is pulling in a little air from outside and causing a false reading?

I decided to pull mine out and remedy that while running another ohm test on it. I ran the engine to get it somewhat warm, and pulled out my MAT. I took an IR temp reading (~125deg F) of the inside of the intake manifold through the mounting hole, lightly screwed back in the MAT and hooked up the voltmeter. The ohms gradually decreased to 800 as the sensor adjusted, which should be right in range according to the LungHD chart. I'm pretty confident the sensor is good, so I reinstalled it with some high-temp thread sealant and let it cure overnight.

While I waited I did some more obsessive Google searching, and ran across injector harness pigtail wiring color codes that Cruiser had posted some time ago. I went out to double-check mine and found that 3-4 and 5-6 were switched!!! I swapped them to match what Cruiser posted:

1-light blue
2-light green
3-tan
4-yellow
5-white
6-brown

I started it up and it ran like ass; stumbling and shaking badly. I gave it some throttle and let it idle but it almost died so I shut it down and called it a night. Today I got more time to play with it and tried again - it still ran badly. I know the RENIX doesn't store codes or data as far as most knowledge goes, but I tried disconnecting and touching the positive/negative battery leads and then starting it again. It turned over immediately and ran quite well! I let it idle awhile and it sat steadily at ~650 RPM - I adjusted the butterfly stop a quarter-turn until it read 750 and took it for a drive.

It runs very smoothly! Once I got home and parked it in idle awhile, it kept a solid 750rpm which is a nice improvement over my usual seeking @ ~500. When I quickly flip the throttle with my finger it doesn't hesistate/bog anymore. I also noted that my exhaust fumes smell a hell of a lot better - still sulphury so I imagine my cat is killed and does need replacing. I have no idea how the injector plugs got switched around, as I'm super anal about labeling things during teardowns. Somewhere along the line I must have gotten cocky and skipped that, who knows.

Next up is to seafoam the heck out of it, then get the cat conv replaced, possibly throw on some smaller tires and get it checked again. Will post back results.

 

[cruiser54]

Re: Rebuilt & tuned up RENIX running very rich - help me save it from the SMOG demons

Thanks! I've gone over just about everything you listed, and my smog guy is very cool and didn't ask me about a few underhood things he could have noted. He was purely running off the numbers, and actively tried to help me troubleshoot them at the shop.

Your tiresize/gearing note is interesting though, and something I have wondered about - I'm running 31" Cooper S/T Maxxs (load E IIRC) on stock 3.55, which is a pretty heavy tire for that but should be okay. The main concern with that in the back of my head is that my speedo-gear is off a few teeth for my tire size - I'm not sure how that comes into play with the CA dyno test at 15 and 25mph. The test is run based off the dyno screen rather than the gauge cluster, but who knows. I have a few shitty stock takeoff sets I'm eyeing on craigslist for my next smog run if I can get them cheap enough.



I have this thread bookmarked but it gets a little over my head :looney: I have a few different spare o2 sensors including my original that I might end up bench-testing if I get desperate enough.

I changed out my plug wires for a higher quality Accel set the other night - underhood lightning show/arcing is significantly down (still see it lightly at the plugs/boots) but it did not affect my chronic low 500rpm @ idle issue, which I still think is one of my main and only symptoms.

Bigger Update
I made two adjustments which have resulted in major gains:

I was researching replacement MAT/air charge temp sensors, and after staring at enough photos of new ones online I noted something - all of them have factory thread sealant on them. Some time ago when I cleaned mine I remembered wirewheeling the old gunk off. This seemed relevant, because the MAT sensor is tapered and doesn't seat flush with the manifold as far as I can tell. Perhaps the intake vacuum is pulling in a little air from outside and causing a false reading?

I decided to pull mine out and remedy that while running another ohm test on it. I ran the engine to get it somewhat warm, and pulled out my MAT. I took an IR temp reading (~125deg F) of the inside of the intake manifold through the mounting hole, lightly screwed back in the MAT and hooked up the voltmeter. The ohms gradually decreased to 800 as the sensor adjusted, which should be right in range according to the LungHD chart. I'm pretty confident the sensor is good, so I reinstalled it with some high-temp thread sealant and let it cure overnight.

While I waited I did some more obsessive Google searching, and ran across injector harness pigtail wiring color codes that Cruiser had posted some time ago. I went out to double-check mine and found that 3-4 and 5-6 were switched!!! I swapped them to match what Cruiser posted:


I started it up and it ran like ass; stumbling and shaking badly. I gave it some throttle and let it idle but it almost died so I shut it down and called it a night. Today I got more time to play with it and tried again - it still ran badly. I know the RENIX doesn't store codes or data as far as most knowledge goes, but I tried disconnecting and touching the positive/negative battery leads and then starting it again. It turned over immediately and ran quite well! I let it idle awhile and it sat steadily at ~650 RPM - I adjusted the butterfly stop a quarter-turn until it read 750 and took it for a drive.

It runs very smoothly! Once I got home and parked it in idle awhile, it kept a solid 750rpm which is a nice improvement over my usual seeking @ ~500. When I quickly flip the throttle with my finger it doesn't hesistate/bog anymore. I also noted that my exhaust fumes smell a hell of a lot better - still sulphury so I imagine my cat is killed and does need replacing. I have no idea how the injector plugs got switched around, as I'm super anal about labeling things during teardowns. Somewhere along the line I must have gotten cocky and skipped that, who knows.

Next up is to seafoam the heck out of it, then get the cat conv replaced, possibly throw on some smaller tires and get it checked again. Will post back results.

Getting the injector wires switched is a new one on me...

NO plug wires should be arcing at night, ever.

What plugs are you using?

 

[Royal Nonesuch]

Re: Rebuilt & tuned up RENIX running very rich - help me save it from the SMOG demons

Getting the injector wires switched is a new one on me...

NO plug wires should be arcing at night, ever.

What plugs are you using?

Welp, I do try to be different :dunce:

With the new plug wires, the "arc" is very faint - a soft blue electrical flash even my excellent eyesight has a hard time catching. It's located in the plug well. I've been running Champion Copper RC9YC which are gapped to .35. After I switched the plug wires I threw in a set of Autolite 3924 to try something different - I have not looked at those running in the dark yet.

 

[mtbxj87]

Re: Rebuilt & tuned up RENIX running very rich - help me save it from the SMOG demons

Did the champions have carbon deposits on the porcelain?

 

[Royal Nonesuch]

Re: Rebuilt & tuned up RENIX running very rich - help me save it from the SMOG demons

Did the champions have carbon deposits on the porcelain?

A little bit, yeah, due to it running so rich. The plugs were new so it wasn't too bad. I'm going to seafoam it tonight under the cover of darkness so my neighbors don't get nervous, and check to see about arcing with the new Autolites.

 

[Royal Nonesuch]

Re: Rebuilt & tuned up RENIX running very rich - help me save it from the SMOG demons

Got the C101 eliminated over the last couple of days - went pretty smoothly, if a bit tedious. Found both of the sensor ground 3-way splices and joined them up together carefully with plenty of heatshrink. Took my time, double-checked everything and apprehensively turned the key when it was all done. Jeep started right up and runs well! Might be my imagination but it seems to crank/turn over significantly faster now.

Before:

After:

The wire lengths were a little wonky due to the horizontal orientation of the C101 (something I didn't think about) so I had to tidy them up with judicious amounts of self-adhesive tape/zip ties. I love that stuff. There were two wires on the engine side of the C101 that had no corresponding ends on the firewall side - I panicked for a minute or two, and then noticed that they were the same colors as the CPS and my mystery plugs. I imagine that confirms this thing had the factory CPS bypass done at some time.

As to the weird arcing: I spent some time routing/separating my plug wires to keep them away from each other and other metal things. Didn't seem to make much difference, and I still note faint flashes at the base of the plug boots and occasionally along the wires. After letting my eyes adjust further in the dark, I can even detect a few streaks of electricity for 1" or so as they go down the plug wire? Either I'm going insane, have electrical superpowers or it's just my good eyesight ( I can always freak people out reading tiny text at distances). Whatever the case may be, the engine is purring like a kitten so I'm not too worried about it.

Tomorrow I'm hoping to get the catalytic replaced since mine is continuing to rattle a bit - I thought about trying to pass with the old cat in case it's still good, but I'm tired of wasting time at the smog shop. I hate unfinished threads so I'll report back either way :spin1:

 

[Ecomike]

Re: Rebuilt & tuned up RENIX running very rich - help me save it from the SMOG demons

I don't care what most others say, I have found evidence the the Renix ECU does store and use some limited sensor history that can be cleared by disconnecting the battery and clear up poor running. But keep in mind cleaned battery/cable contacts can solve the problem. Congrats on your success so far. Long live Renix XJs!!!!

Thanks! I've gone over just about everything you listed, and my smog guy is very cool and didn't ask me about a few underhood things he could have noted. He was purely running off the numbers, and actively tried to help me troubleshoot them at the shop.

Your tiresize/gearing note is interesting though, and something I have wondered about - I'm running 31" Cooper S/T Maxxs (load E IIRC) on stock 3.55, which is a pretty heavy tire for that but should be okay. The main concern with that in the back of my head is that my speedo-gear is off a few teeth for my tire size - I'm not sure how that comes into play with the CA dyno test at 15 and 25mph. The test is run based off the dyno screen rather than the gauge cluster, but who knows. I have a few shitty stock takeoff sets I'm eyeing on craigslist for my next smog run if I can get them cheap enough.



I have this thread bookmarked but it gets a little over my head :looney: I have a few different spare o2 sensors including my original that I might end up bench-testing if I get desperate enough.

I changed out my plug wires for a higher quality Accel set the other night - underhood lightning show/arcing is significantly down (still see it lightly at the plugs/boots) but it did not affect my chronic low 500rpm @ idle issue, which I still think is one of my main and only symptoms.

Bigger Update
I made two adjustments which have resulted in major gains:

I was researching replacement MAT/air charge temp sensors, and after staring at enough photos of new ones online I noted something - all of them have factory thread sealant on them. Some time ago when I cleaned mine I remembered wirewheeling the old gunk off. This seemed relevant, because the MAT sensor is tapered and doesn't seat flush with the manifold as far as I can tell. Perhaps the intake vacuum is pulling in a little air from outside and causing a false reading?

I decided to pull mine out and remedy that while running another ohm test on it. I ran the engine to get it somewhat warm, and pulled out my MAT. I took an IR temp reading (~125deg F) of the inside of the intake manifold through the mounting hole, lightly screwed back in the MAT and hooked up the voltmeter. The ohms gradually decreased to 800 as the sensor adjusted, which should be right in range according to the LungHD chart. I'm pretty confident the sensor is good, so I reinstalled it with some high-temp thread sealant and let it cure overnight.

While I waited I did some more obsessive Google searching, and ran across injector harness pigtail wiring color codes that Cruiser had posted some time ago. I went out to double-check mine and found that 3-4 and 5-6 were switched!!! I swapped them to match what Cruiser posted:


I started it up and it ran like ass; stumbling and shaking badly. I gave it some throttle and let it idle but it almost died so I shut it down and called it a night. Today I got more time to play with it and tried again - it still ran badly. I know the RENIX doesn't store codes or data as far as most knowledge goes, but I tried disconnecting and touching the positive/negative battery leads and then starting it again. It turned over immediately and ran quite well! I let it idle awhile and it sat steadily at ~650 RPM - I adjusted the butterfly stop a quarter-turn until it read 750 and took it for a drive.

It runs very smoothly! Once I got home and parked it in idle awhile, it kept a solid 750rpm which is a nice improvement over my usual seeking @ ~500. When I quickly flip the throttle with my finger it doesn't hesistate/bog anymore. I also noted that my exhaust fumes smell a hell of a lot better - still sulphury so I imagine my cat is killed and does need replacing. I have no idea how the injector plugs got switched around, as I'm super anal about labeling things during teardowns. Somewhere along the line I must have gotten cocky and skipped that, who knows.

Next up is to seafoam the heck out of it, then get the cat conv replaced, possibly throw on some smaller tires and get it checked again. Will post back results.

 

[Ecomike]

Re: Rebuilt & tuned up RENIX running very rich - help me save it from the SMOG de...

A rich running engine from say a bad O2 sensor or bad O2 sensor wiring, etc (running rich for any reason)..... can damage a new cat very quickly!!!!

Great info, thank you. I'll find a good shop. Being that the cat was okay a year ago I figured it would still be good, but I didn't take trails into consideration - I've probably driven it harder in the last year than the old thing had seen in it's other 26 years. :yap:

Did you pick a CA-approved cat in particular or just go with whatever the shop suggested?

 

[Royal Nonesuch]

Re: Rebuilt & tuned up RENIX running very rich - help me save it from the SMOG demons

Final Update and Resolution

Got the catalytic replaced on Friday with a universal-fit CA compliant Magnaflow for $238 out the door at a small local shop. Took them an hour. Midas wanted "$400-$500" for the same job.

Driving away I noticed immediately that the jeep accelerated better and idled less lumpily. The rattle was gone as well. I wish I had asked to see the old cat but safe to say it was pretty well shot. Once the Jeep is at operating temp now the exhaust barely smells like anything other than hot metal. Cruised down to the SMOG place today after a spirited highway drive. The tech was glad to see me back but I could tell he was a little skeptical of my swapped pigtail story. He put it on the dyno in test mode first and everything looked good, so he ran it through the full test. Passed with flying colors!

After the test the tech congratulated me, and said it would have taken a mechanic shop an awfully long time to think to check out the pigtails.

The heavy 31s on 3.55 gears didn't seem to factor in at all in my case, so assuming everything else is running correctly it seems safe to say that's not a concern for future thread readers. I left the 60mm bored throttle body on as well, so that's also confirmed okay. I suppose that about wraps it up. I just got a set of 746 injectors and an o-ring/filter kit in the mail, so once I get those cleaned up I'll be putting those in and ditching my stock injectors/selling the 703s.

Thanks everyone for your suggestions and experience. I hope to not see you all again in two years :laugh2:

arty:

 

[mtbxj87]

Re: Rebuilt & tuned up RENIX running very rich - help me save it from the SMOG demons

:clap::clap::clap: