98xj 5.3 swap (the poverty method).

[yossarian19]

I think most guys just use an aftermarket trans temp gauge.
Here's the thing, though: the sending unit is just a thermistor or thermocouple of some variety, using a voltage or current signal to drive the gauge unit.
So, figure out what the specs for the sending unit are (it doesn't seem like you need to be told "how") and set up your LCD gauge unit to display things correctly.

 

[blistovmhz]

I may end up doing that. I did see oil pressure show up via OBD for a bit, but not sure it was accurate. Gotta do more searching for GM PIDs.

So took Jeep for a drive up and down the driveway, but I can't say I'm impressed with the power thus far. Feels like something isn't quite right. Occassionally throwing a code for bank 2 knock sensor (I can't find either knock sensor, so I'm surprised it's only throwing a code for one), and getting lean reading on both bank1/2 sensor 1, but it's intermittent and whenever I look at the fuel trim, it's flapping between -3 and +3 for the most part.
Anything obvious I might be missing? Motor sounds really good, winds up instantly, seems to be in good health, but just doesn't move real good.

 

[blistovmhz]

Oh also, I'm still having problems getting OBD to connect reliably. I found that if I plug the serial wire in within' a few inches of the ECM, it connects reliably and quickly, but the farther I get from the ECM, the flakier it gets. I know the stock Jeep serial line wasn't shielded, nor is the one in my roomies k1500, but all I can think is it's gotta be an interference issue. Idea's?

 

[yossarian19]

Knock sensors are screwed into the valley cover underneath the intake manifold. From the factory, there is some foam wedged under the intake on either side.
Lean on both banks sensor 1 says the engine is just running lean. I'd be looking at poor fuel delivery or MAF sensor first. Possible vacuum leak as well.

 

[blistovmhz]

I guess I should button up the intake and throttle body before throwing time/money at it . intake and exhaust stuff is in the mail. Should have by wed. Gives me time to work out a better way to shift than just pulling in the cable .

What I find weird though, is that the o2s both throw lean occasionally, but it smells rich. Exhaust color is normal. Maybe just used to having a cat.

Still can't figure out why I'm having such a bitch of a time getting the obd to connect reliably. Same issue with both my readers, and they both work in the other truck

 

[yossarian19]

You are plugging them into the OBD2 port and depending where you move the connection, it comes & goes? Is that what's going on? 'Cause that's fairly classic "broken / damaged wire" symptoms. I've never heard of an interference issue with OBD.

 

[Hoooper]

sucks that you didn't replace the knock sensors when you had the motor out, but I would still recommend you replace the sensors and harness now before you're completely done. Also make sure to seal up the knock sensor openings with rtv so they don't fill with water and get all rusty like they probably are now.

when you look at the fuel trim, it sounds like the short term trim is hovering, what is the long term trim sitting at?

 

[blistovmhz]

You are plugging them into the OBD2 port and depending where you move the connection, it comes & goes? Is that what's going on? 'Cause that's fairly classic "broken / damaged wire" symptoms. I've never heard of an interference issue with OBD.

May very well be, though the break would have to be right near the ECM. I'll just pull the pin right out and do a new one.

sucks that you didn't replace the knock sensors when you had the motor out, but I would still recommend you replace the sensors and harness now before you're completely done. Also make sure to seal up the knock sensor openings with rtv so they don't fill with water and get all rusty like they probably are now.

when you look at the fuel trim, it sounds like the short term trim is hovering, what is the long term trim sitting at?

I still have no idea where the knock sensors are. As I couldn't find them on the side of the block (where every image on the internet seems to think they should be, I'm inclined to believe Yossarian in that they're under the intake. That'd also explain the mystery plug(s) that are plugged in under there.

Long term fuel trim was 25%, but that was before I buttoned up the exhaust. I'm goona try to give it a full hour of run time today to see if that LTFT comes down. I'm guessing it will. (of course, I can't actually test this until I get the OBD to connect reliably)

What I really need is something to compare to. I plan on taking it in for a tune/dyno when I'm done, but without ever having ridden in a sub 4000lbs vehicle with an lm7, I have no way to know what's normal. I feel like a stock 5.3 should be able to burnout my 35's shouldn't it?

 

[MoparManiac]

What I find weird though, is that the o2s both throw lean occasionally, but it smells rich. Exhaust color is normal. Maybe just used to having a cat.

Haven't read through all of this, but assuming nothing else is wrong this is classic of an exhaust leak upstream from where the O2 is.

You're pulling in air so the O2 reads lean and in turn the ECU fattens up the mixture to try and correct.

 

[blistovmhz]

Haven't read through all of this, but assuming nothing else is wrong this is classic of an exhaust leak upstream from where the O2 is.

You're pulling in air so the O2 reads lean and in turn the ECU fattens up the mixture to try and correct.

That was my first thought. Haven't managed to catch the leak in the act yet. Stethoscoped the header flanges and didn't hear anything. My try just pressure testing the entire exhaust.

Something I've always wondered though, is how can you determine the NORMAL amount of fuel consumption on a given engine, assuming no exhaust leaks? Like, yea, the ECU will richen the mixture to compensate and you'd see a brief spike in F/T, but eventually that F/T drops down to 0% as the ECU's caught up on dealing with the lean mixture. But how do you know if your motor is running way rich/lean long term?
On the 4.0L, I just know the motor so well that I can feel/hear/smell/BE an exhaust leak or a rich/lean condition for some other reason, but it's one of those long term intuitive things that I have no real explanation for how I KNOW. I just know because years of experience. Whenever I run into a fellow Jeeper on the trail, I often point out everything that's wrong with their Jeep that they didn't know about or have been trying to solve for years. I'm like a 4.0L whisperer. Not so much with the 5.3 though .

When roomie get's home, I'll have him block the exhaust output a bit so I can see if we can't make the leak more apparent. If it's anywhere, it's going to be on the passenger side collector flange cause it takes 30 minutes to get the three bolts outta that one.

Edit: Wait, is LTFT essentially telling me how the ECU is compensating long term? I always thought LTFT was just an historical average, but I'm starting to suspect that it's actually the static "this is how much extra fuel we're adding beyond what we expect should be necessary for this motor". Is this more or less accurate? Then that 25% LTFT would make a lot of sense. Massive exhaust leak, but after a few minutes of running the STFT stabilizes at 0% because that number is relative to the last time we checked STFT. Yea?

 

[Hoooper]

yes ltft is a baseline adjustment the computer uses at that condition, short term adjusts in the moment and also adjusts the ltft if the stft is not wavering on 0. 25% is the max, meaning the computer is correcting fuel by the max it can at that point.

yes the knock sensors are below the intake on Gen 3 motors

 

[NorIdaWheeler]

Im pumped you got it fored up! good job man!!! I was also very surprised at how quick they rev.


Oh man i have a lot to learn. Im getting a rich condition as well. like burns your eyes when sitting in the rig after idling for more than a couple minutes. You guys have given me a lot of things to look in to.

I have a pretty bad exhaust leak on the very back of my drivers side manifold i need to fix foremost.

Which side is bank1/bank2 on the o2 sensors?
Also, what voltage should they be reading at idle?

 

[blistovmhz]

Im pumped you got it fored up! good job man!!! I was also very surprised at how quick they rev.


Oh man i have a lot to learn. Im getting a rich condition as well. like burns your eyes when sitting in the rig after idling for more than a couple minutes. You guys have given me a lot of things to look in to.

I have a pretty bad exhaust leak on the very back of my drivers side manifold i need to fix foremost.

Which side is bank1/bank2 on the o2 sensors?
Also, what voltage should they be reading at idle?

O2's should swing between 0.1 and 0.8V pretty rapidly. I don't recall which end is rich/lean. Either way, if you watch your O2 and it's not bouncing back and forth all the way through the range, you're consistently rich/lean.

Bank1 is the same side as cylinder 1, which is drivers side front.
Bank 2 is passenger.


Yea, I was super surprised how quickly it all came together. Read hundreds of threads on these swaps and seeing most guys spending a minimum of 3 months to get the motor in and running (nevermind the truck drivable), and that's really the only reason I held off on doing the swap myself for so long. Took me 2 weeks of evenings, and two solid weekends (including shipping time for parts) to get it fired up and driving up/down the driveway.

Going to pick up an XJ shifter and some 3/8 rod ends for the t-case linkage today. Hoping to have it in tonight, as well as take a look for exhaust leaks.

Oh right, on the back of the drivers valve cover there is a vacuum/air port which I assumed was supposed to tie to the top of the intake. Makes a pretty loud hiss, but I can't find any evidence of a leak. Sounds like the hose itself is making the noise. I just wanted to know if anyone knows for sure where all the vacuum stuff is supposed to go? It's entirely possible I've got something wrong there.
I've only found two ports on the valve covers (driver rear and passenger front) and they're both tied into the intake. Is that correct?

@NorldaWheeler, how's your power? We still haven't seen any burnouts from you yet!
All the 5.3/XJ video's I've seen are either in the dunes or running stock size tires and video shot from 500m away, which really doesn't give me any good indication of what to expect.

 

[NorIdaWheeler]

O2's should swing between 0.1 and 0.8V pretty rapidly. I don't recall which end is rich/lean. Either way, if you watch your O2 and it's not bouncing back and forth all the way through the range, you're consistently rich/lean.

Bank1 is the same side as cylinder 1, which is drivers side front.
Bank 2 is passenger.


Yea, I was super surprised how quickly it all came together. Read hundreds of threads on these swaps and seeing most guys spending a minimum of 3 months to get the motor in and running (nevermind the truck drivable), and that's really the only reason I held off on doing the swap myself for so long. Took me 2 weeks of evenings, and two solid weekends (including shipping time for parts) to get it fired up and driving up/down the driveway.

Going to pick up an XJ shifter and some 3/8 rod ends for the t-case linkage today. Hoping to have it in tonight, as well as take a look for exhaust leaks.

Oh right, on the back of the drivers valve cover there is a vacuum/air port which I assumed was supposed to tie to the top of the intake. Makes a pretty loud hiss, but I can't find any evidence of a leak. Sounds like the hose itself is making the noise. I just wanted to know if anyone knows for sure where all the vacuum stuff is supposed to go? It's entirely possible I've got something wrong there.
I've only found two ports on the valve covers (driver rear and passenger front) and they're both tied into the intake. Is that correct?

Thats how mine is

@NorldaWheeler, how's your power? We still haven't seen any burnouts from you yet!
All the 5.3/XJ video's I've seen are either in the dunes or running stock size tires and video shot from 500m away, which really doesn't give me any good indication of what to expect.

I will tell you that in low range the thing is an absolute monster and will roast sticky 42s all the way into third gear on asphalt. I was honestly surprised by he power.

In hi range. not so much. its a dog. still way more power than the 4.0 but with 42" tires and the relatively high gearing in the th350 it certainly isnt a race car. Lucky for me it never gets taken out of low range. lol


saturday i got the motor up to temp and watched it switch into closed loop and checked the o2 voltages. they both were bouncing between 0.4 and 0.7 volts.

 

[Hoooper]

Oh right, on the back of the drivers valve cover there is a vacuum/air port which I assumed was supposed to tie to the top of the intake. Makes a pretty loud hiss, but I can't find any evidence of a leak. Sounds like the hose itself is making the noise. I just wanted to know if anyone knows for sure where all the vacuum stuff is supposed to go? It's entirely possible I've got something wrong there.
I've only found two ports on the valve covers (driver rear and passenger front) and they're both tied into the intake. Is that correct?

The passenger front is supposed to go to the intake right at the throttle body, it actually has a path through to the front of the throttle body so its not under vacuum, at least for the cable TBs. If you have it at that port its the right spot. My drivers side vent makes an awful hissing as well, but it is in the right spot, its just the amount of air I guess is passing through there makes a lot of noise.

 

[WiscoXJ]

Knock sensors are under the intake between the heads on the valley cover. There's a tsb out for them. GM had some issue with them. 2 black circles

 

[blistovmhz]

I will tell you that in low range the thing is an absolute monster and will roast sticky 42s all the way into third gear on asphalt. I was honestly surprised by he power.

In hi range. not so much. its a dog. still way more power than the 4.0 but with 42" tires and the relatively high gearing in the th350 it certainly isnt a race car. Lucky for me it never gets taken out of low range. lol


saturday i got the motor up to temp and watched it switch into closed loop and checked the o2 voltages. they both were bouncing between 0.4 and 0.7 volts.

High 02 = rich exhaust. Same as mine, though I'm pretty sure mine is only on bank 2. Mine I'm pretty sure is going to be the passenger collector flange.
Post some videos man!

The passenger front is supposed to go to the intake right at the throttle body, it actually has a path through to the front of the throttle body so its not under vacuum, at least for the cable TBs. If you have it at that port its the right spot. My drivers side vent makes an awful hissing as well, but it is in the right spot, its just the amount of air I guess is passing through there makes a lot of noise.

Welp, I guess that rules out at least one possible problem .

Knock sensors are under the intake between the heads on the valley cover. There's a tsb out for them. GM had some issue with them. 2 black circles

Yea, found. Do they both run to the same connector (that blue/black on one top of the intake)? If not, it's entirely possible I wired one to ground, which would explain several other little issues.


Got the shifter pretty much working. Not a chance of getting it to work with the stock center console at this point, which doesn't upset me as those consoles are terrible anyhow. Just need to weld up and arm rest and coffee holder and I'm happy. Bonus, easier access to the drift lever.

Using the stock GM column shifter cable which turns out to be exactly the right length for my routing. Cable goes from trans, rearward, wraps back toward the front and comes up into the engine bay under the booster, then wraps back into the cab through the oval hole that was used for that cable on the auto's. Mine just had a plug in it.
Cable then routes under the heater vent (the one that goes through the console) and to the shifter. I'll get pictures tomorrow.

Ground out the detents and added a few weld beads to get all the shift points proper. Took a while and now I hate my life, but it's done. Of course, once installed in the Jeep, the cable is too long and has to be adjusted again about 1mm (and the adjuster is under my booster).

 

[blistovmhz]

Well, the OBD thing I suspect was me frying both readers. Neither is able to connect to the other truck now either. Suspect that I had a bad signal for a while, and while I was sloppily splicing wires together, I probably shorted power to signal on both devices. Ordered two more. Should be here Friday.
Meanwhile, I'll get the shifter working properly today, and maybe start working on the hood.

I still can't decide what I want to do about the intake/alternator/hood. I can find an ls6 intake pretty cheap, but then I have to swap out the water pump and alternator/ps bracketry as well correct?

 

[yossarian19]

The car intakes can be used with truck spacing accessories. IIRC it uses the car water pump & tensioner with spacers behind it.
If you want, you can swap to F-body or Corvette accessory setups (saving 3/4 or 1 1/2" off the front of the motor) but I think spacers behind the pump are cheaper & easier if all you want is a shorter intake.

I think you wind up having to change / adapt your injectors when you go to a car intake, too, so either get a complete intake with rails & injectors (then buy a wiring adapter harness) or look into physically adapting the truck injectors to the car rails. You could also buy aftermarket rails and fab up some brackets to attach them to the intake after shoving your truck injectors in there.

 

[John D]

I think you wind up having to change / adapt your injectors when you go to a car intake, too, so either get a complete intake with rails & injectors (then buy a wiring adapter harness) or look into physically adapting the truck injectors to the car rails. You could also buy aftermarket rails and fab up some brackets to attach them to the intake after shoving your truck injectors in there.

I used an LS1 intake and 28# injectors, then I bought 8 connectors with wires that were correctly colored and spliced them into the truck harness. It worked very well.