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Trouble shoot 4.3: swap into TJ, warm run problem.

TanTJJim said:
Sounds good. I'm an idiot and forgot to ask for what codes it might have stored too, that would be helpful
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Nothing was stored other than from me unplugging the sensors when checking them. I cleared those.

The prior owner setup a blue LED light in my dash to indicate them, it was on.

So it said
MAF
IAC
TPS
And air idle control
 
Trashman said:
Nothing was stored other than from me unplugging the sensors when checking them. I cleared those.

The prior owner setup a blue LED light in my dash to indicate them, it was on.

So it said
MAF
IAC
TPS
And air idle control
Click to expand...
Definitely no surprise there, nothing there that helps unless they come back after you clear them and drive it for a bit.
 
Let see if I can drop another $100 on it today:homer:

With Halloween stuff, and the kiddos, I likely won't play with it
 
Had some time to go over the Jeep in the daylight today.

Tightened a few possible vacuum leak areas, may have found 2 possible locations.

Buttoned up the hoses/wires for the fuel system. I had to unplug the pump/sending unit wire while the Jeep was running to route it better. The Jeep ran no different for those 5 or so seconds.

Drove to Napa, grabbed some MAF sensor cleaner.

It drives fine now, but coughed once when lugging it around a corner. Off of stop lights/signs though it seems fine now.

Making progress, but all is not 100% yet.
 
Cleaned the MAF. Parked in Neutral, the miss is gone with throttle stabs.

Visually, I saw no difference before/after on the sensor.
 
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Fuel pressure

49 engine key on/pump on

Approx 52psi running, stays there when adding throttle.

Bleeds off to around 28psi off in the first 5min. Kinda holds there, then slowly drops.

Still misses.

140° barely noticeable of at all

160° starts missing. Annoying but manageable

180° misses badly.

Unplugged 02 sensors, it didn't like that


I believe 02/MAF are doing their thing as both show negative results when unplugged.


I don't believe it is open/closed loop issue. I believe it is physical temp dependant.

That leaves me considering, coil, ign control modual, fuel pressure. 52psi is close to the min 55, but still not there.

Possibly need to figure out how to punch out the TJ factory fuel regulator.
 
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20241109_092123.jpg
20241109_092135.jpg
 
I am guessing that second photo is approx "clean spot" from a leaking injector
 
Key on, 49 psi. No visual leaks, but pressure slowly drops still.
 
1. 49 psi is too low, the 4.3l system wants 55-60psi meaning it's always running lean. The ECM is trying to compensate which is why disconnecting the O2 sensor made it worse.

2. You may be onto something thinking there's an issue with that spider injector setup. If it's not the line to the injector itself that's leaking, pay close attention to the fuel pressure regulator too, it's very common for those to leak and cause the issues you're seeing.

3. Whatever direction you go, make sure you put a new gasket on that intake plenum. I had a suspicion that gasket was leaking and now's the perfect chance to replace it.

At this point you know fuel pressure is low, that needs to be fixed. The only other thing I'd suspect is the fuel injector "spider".

edit. If you want to throw parts at it the TPS sensor could be suspect too.

If you do replace it, do yourself a favor and get the same style you have now where the wiring and injector go directly to each intake port. The older style with the injectors by the black plastic connector are complete garbage.
 
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Being temp related, I would suspect the temp sensor, is there a way to diagnosis or plug into to see temp recording
 
TanTJJim said:
1. 49 psi is too low, the 4.3l system wants 55-60psi meaning it's always running lean. The ECM is trying to compensate which is why disconnecting the O2 sensor made it worse.

2. You may be onto something thinking there's an issue with that spider injector setup. If it's not the line to the injector itself that's leaking, pay close attention to the fuel pressure regulator too, it's very common for those to leak and cause the issues you're seeing.

3. Whatever direction you go, make sure you put a new gasket on that intake plenum. I had a suspicion that gasket was leaking and now's the perfect chance to replace it.

At this point you know fuel pressure is low, that needs to be fixed. The only other thing I'd suspect is the fuel injector "spider".

edit. If you want to throw parts at it the TPS sensor could be suspect too.

If you do replace it, do yourself a favor and get the same style you have now where the wiring and injector go directly to each intake port. The older style with the injectors by the black plastic connector are complete garbage.
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2006 Jeep TJs have a pump that puts out 60psi. I may just buy one of them rather than try to get my current setup punched out. It seems what I have is regulating as it should sadly :laughing:.

I sprayed around the intake and found no vacuum leaks.
 
Trashman said:
2006 Jeep TJs have a pump that puts out 60psi. I may just buy one of them rather than try to get my current setup punched out. It seems what I have is regulating as it should sadly :laughing:.

I sprayed around the intake and found no vacuum leaks.
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That sounds good. Someone earlier in this thread posted an adjustable TJ regulator too, might be worth taking a look at.

Your call but I'd still replace that gasket, cheap insurance and all.
 
TanTJJim said:
That sounds good. Someone earlier in this thread posted an adjustable TJ regulator too, might be worth taking a look at.

Your call but I'd still replace that gasket, cheap insurance and all.
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My current pumps regulator doesn't seem to be replaceable. I have seen the style that is. They have a hold down strap over the top. Mine does not.
 
The pump is installed is rated at 60psi.

I am just going to run a bulkhead fitting next to the old regulator from the pump.
 
Its better, but the miss, persists.

Plugs/wires maybe.

I spent a bit of time this morning checking live data on the OBD reader.

the MAF sensor was within spec at idle and 2200rpm

The 02s seemed to be within spec with their ranges.

I do feel the motor seems to idle a touch low. I believe it was in the 580-600rpm range this morning seems low but also seems to be in spec according to Google.
 
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Gravy said:
Being temp related, I would suspect the temp sensor, is there a way to diagnosis or plug into to see temp recording
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I havent explored that yet.

The Jeep has, what I believe to be too large of a radiator. It is aluminum, and pretty good size.

In the summer, I may reach 190. In the winter, 160.

It also has a thermostat controlled electric fan. It still will cycle when the Jeep is parked/off. People ask me often if I left the Jeep running. :laughing:
 
From the videos you posted and the symptoms you described the problem doesn't sound ignition related to me. That being said, new plugs/wires are never a bad thing especially if you don't know how old the ones you have are.

You have that handy dandy scan tool. You could always look at various readings and compare them when it's running well to when it's not and see if something sticks out to you.

Out of curiosity, did this ever run well?
 
TanTJJim said:
From the videos you posted and the symptoms you described the problem doesn't sound ignition related to me. That being said, new plugs/wires are never a bad thing especially if you don't know how old the ones you have are.

You have that handy dandy scan tool. You could always look at various readings and compare them when it's running well to when it's not and see if something sticks out to you.

Out of curiosity, did this ever run well?
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It ran well before the trip, except for wonky low/erratic idles at times lately.

I have not had any issues with missing since buying it almost 2 years ago. That started on the way home a few weeks ago and hit hard.

I did blow up the AX5 though... :lmao:
 
Trashman said:
It ran well before the trip, except for wonky low/erratic idles at times lately.

I have not had any issues with missing since buying it almost 2 years ago. That started on the way home a few weeks ago and hit hard.

I did blow up the AX5 though... :lmao:
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That's good to know. Let us know if that scan tool data shows anything.
 
All old plugs looked used but good on the tips, one did have a cracked lengthwise in the porcelain.

One old plug wires had a good crack by the boot that plugs into the spark plug.

Another wire had a burned spot/cracks.
 
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