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Cranks perfect after sitting two days, renix 4.0


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Are you getting power and ground to the O2 sensor?

 

 

 

Red is Power from 87A on the relay. Black is ground. Grey is input to the ECU. 

 

I tested it with the car cranked, crawled under there and unplugged the connector, and I saw 12V on the red wire using the ground inside the same connector.  I saw nothing with the car not cranked or running.

 

I also replaced all the relays on that side as well, I forgot that from my list.

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I'm going to go ahead and try to get the new CTS installed anyway, then hook up a new gauge and take a video and will post it, but I think the idle is acting correctly, steady, and strong.

 

Should I try to seafoam it or marvels mystery oil?  When I replaced injectors there was build up, I cleaned the injector holes, but could something be blocked up inside intake manifold?  It only has 127k, but who knows.

 

I know some people love those things and some people say they ruin engines.

 

I already did a can of BG44k in the gas tank.

 

I could add a new fuel pump as well?

 

Try another renix ECU from eBay?

 

I'm running out of ideas, any of these sound good?

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No Seafoam. 44K is way better. 

 

If you wanna try an ECU, I'll donate a known good one to the cause if you pay shipping. Then, we'll go from there. 

 

I appreciate it.  I will do the CTS this weekend and check vacuum and then if that still leaves me with no new information, I will pay to have the ECU shipped to try it out.

 

I am also thinking about getting an MT2500 from eBay, that should give me lots of hints.

 

Thanks for the offer!

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So I did some work this weekend.  I replaced the CTS with a BWD one I picked up from OReilly's.  It was reading spot on like my MAT sensor based on ohm chart in FSM.  This seemed to help a little.

 

I also learned the O2 sensor I had originally in there from my friend was not a Bosch or an NTK, but an OEM sensor, he had an OEM one laying around he knew was good.  It wasn't brand knew, but he believes never used and just been sitting on a shelf in the shop.

 

Things run the best with the OEM sensor.

 

I have now put in 2 brand new NTK sensors and today I decided to purchase a brand new Bosch O2 sensor and it acts like the NTK but even worse, so I returned it.  Side note, the Bosch and NTK appeared to be the exact same sensor, side by side they looked identical and had the same stamp markings on them and everything.  My first NTK was from Amazon and my second from RockAuto, the Bosch was from OReilly's.

 

I will say the flucation and idle wasn't as bad with after the CTS was changed with the NTK sensor, but still better with the OEM one, and still not perfect.

 

So I went to my friends shop to hopefully borrow a scan tool, he didn't have the jeep1 adapter, so no good there.  But...  He did have another 89 Comanche in the shop that was running great, same everything as mine.  So I knocked out the tamper proof plug on that one to look at the air bleed and it was just like mine was originally, pretty much all the way tight, or clockwise, that's two 89 Comanches, with the tamper proof thing still in place, having their default settings all the way tight.

 

So I also did the vacuum tests.  I made some videos.

 

The first video has the air bleed screw turned out 2.5 turns counterclockwise.  This increases the idle, but not by a ton.  You will notice the difference between park and drive is not that substantial anymore, less than 100 RPM, I can only assume it was the new CTS sending some different signals..

 

I'm getting about 17-18 Hg warmed up (brand new calibrated vaccum gauge).  I think it's pretty steady, but maybe not after others watch it, it is moving.

 

https://photos.google.com/photo/AF1QipN1C9llQqRkisnucH0VlwW0Qi3VJRSLEGQUzakh

 

 

I then made a second video.  This video I tightened the air bleed screw all the way in like it was originally and like it was on the other 89 Comanche.  The idle was a little smoother, but still rough.  There is also hardly no change between park and drive with RPM's and it's a more steady 18 Hg on vacuum gauge.

 

https://photos.google.com/photo/AF1QipNnH2EKAg6pvGRp-VssZxWf_AZWPfXlYZJX25ft

 

 

So I think I'm going to go ahead and order an MT2500 I'm been watching on eBay to get additional data.  This should give me even more information.

 

So this is some new data, any new thoughts or ideas?

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Today I added some Marvels Mystery oil, I'm a couple weeks from an oil change, figured it would not hurt and maybe somethings not seating all the way. It's a long shot.

 

I also adjusted the throttle body stop again. I did it on the vehicle this time, but I loosened stop almost a full turn, making gap smaller, lesa air. I got my feeler gauge, my smallest one is like paper and it's .0015. I adjusted the stop looser until I could just barely push that feeler in between butterfly and body. I thought about going another 1/8 turn looser, but left it where it was.

 

I still have the air bleed all the way tight. I checked two other 89 Comanches I know in the area and knocked off their caps and they were the same. Cruiser, you mentioned they should not be all the way tight, seems like some were or people are putting the plugs back in after adjusting them? When I mess with it, it will increase the idle, but it takes a lot of turning before it cannot control it anymore. With small adjustments, the computer seems to take over.

 

Anyway, with idle stop adjusted better and air bleed all the way tight, TPS re-adjusted correctly, it's still running. No stalling or anything. In drive with the AC on, it is idling close to 700 RPM pretty steady, once you cut off the AC though it goes pretty low, I would say maybe 520 RPM, and it will settle to 550-580. So not bad haven taken so much air away.

 

Curious where others air bleed screw landed and if I should keep messing around with that?

 

My bidding ends in about 4 hours on a MT2500 with lots of accessories, fingers crossed I win it.

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I got the MT2500 in the mail today and hooked it up.  The vehicle had been driven home and was pretty warmed up.  I let it sit long enough to unpack the box, figuring it out, and get it connected.

 

It worked!

 

So I made a video of all the readouts while they were happening, it was easier than typing them all out.

 

I'm not sure how to read it all.

 

It says the exhaust was lean, and I'm running with the air bleed screwed all the way in, so that implies a vacuum leak maybe, only thing left would be exhaust/intake gasket, replaced everything else.

 

The o2 voltage isn't fluctuating like I though it would.  I currently have the used OEM sensor in there not the NTK.

 

So here is the video, let me know what you learn from it!

 

https://photos.google.com/photo/AF1QipM9hLrBNavPSpk3zMdCFsJXVWlQxgU1WwAENptC

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Reading through the manual it looks like my o2 reading is way high and should be closer to 2.5v, meaning it's lean...  The man vac seems good at 59, or 17 Hg give or take, but the map vac is lower, not sure if that's normal...

 

I always thought you got lower vacuum readings when leaking, but these seem normal.

 

I'm thinking I have a vacuum leak somewhere, all the hoses are new, new injectors and o-rings, and I've tightened the exhaust and intake manifold bolts to spec, but it must be leaking somewhere on the intake and exhaust manifold, or somewhere inside, but my compression test was good.

 

Any other insights will be helpful...

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So I did some more research.  The o2 sensor being stuck at 4.98 and not moving meant it was dead.  So we have an answer to the question about the original o2 sensor, it was not working.

 

So I put the new NTK into the car, warmed it up, and took another video.

 

The car did run better with a bad o2 sensor, stuck in open loop, not sure why.

 

My "charge temp" is only 125 when the vehicle is fully warmed up, not sure if maybe that is the problem?

 

Here is the latest video.

 

https://photos.google.com/photo/AF1QipNQyb3mc66XAFMNI5uvqivjVTXi6NZ7WpvKv139

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I took out the MAT sensor and cleaned it, put it back in. When I crank, the MAT sensor shows 118 and just stays there, the coolant temperature goes up to 210, settles back down around 206 or so, but the MAT is just staying at 118. It did in the previous video go up to 125 and then 127.

 

What is the normal temperature of the intake at operating temperature?

 

I then unplugged it, the car still runs, maybe a little better, and it shows on the MT2500 247, which I assume is the max value, but probably just runs the same.

 

Not even sure if it's the issue or not, just assumed it would be closer to the CTS temperature, but maybe not, maybe 118 is accurate.

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It looks like the RPM's drop every time the o2 voltage goes down, then the o2 voltgage goes back up and the rpm's go back up...  I assume that's why it ran better with a broken o2 sensor that was stuck at 4.98, it was at least more steady...

 

I'm leaving the good o2 sensor in there, just need help on what to try next?

 

Replace exhaust/intake manifold gasket?  Rebuild the head because a valve is not seating or something?  Compression was good, but didn't do a leak down test, only compression test.

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