97 XJ 4.6L running lean

Performance mods and Advanced Stroker discussion.
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Enzosrock
Posts: 9
Joined: May 12th, 2022, 2:29 pm
Stroker Displacement: 4.6
Vehicle Year: 1997
Vehicle Make: Jeep
Vehicle Model: Cherokee S

97 XJ 4.6L running lean

Post by Enzosrock »

I am hoping to get some advice on my lean condition. We just recently built a stroker and completed the cam break in with the stock injectors, changed oil and filter. I then put Bosch 161 12 hole injectors on that I had purchased before the rebuild along with the AEM wideband. Now I start the vehicle and within 30 seconds of it running the wideband is reading off the charts lean. So I shut down engine to prevent damage. Any idea on how to fix? Would larger injectors fix the problem I dont want to spend a few hundred again to now fix the lean condition. Thank you for your time!



Heres the list of parts changed in the rebuild.
Bored .030 over and decked the top
Scat 4.2L crank
New flexplate
Scat Bushed rods
18cc inverted dome Racetec pistons
Melling oil pump and pickup
New crank bearings
New cam bearings
Comp cams 68-235-46
Rollmaster double roller
Johnson lifters
9.060 pushrods
Harland sharp 1.65:1 roller rockers
Full ported Russ 0720 cylinder head w larger valves
Horseshoe intake
Bored TB to 62mm
Stock intake
Banks revolver exhaust manifold
New Mopar Crank position sensor
Mandrel bent full 2.5" downpipe with no dent lol
New cat and muffler reducing to 2.25" tailpipe
AEM wideband 30-4110
HP Tuners MPVI2+ will arrive soon
TJBUD
Where's the "any" key?
Where's the "any" key?
Posts: 27
Joined: April 20th, 2022, 9:32 am
Stroker Displacement: 4.7
Vehicle Year: 1998
Vehicle Make: Jeep
Vehicle Model: TJ

Re: 97 XJ 4.6L running lean

Post by TJBUD »

Enzorock,
I had exactly the same issue with my 4.7 stroker and AEM 30-4100 in October. Good news for me was the engine was not really running lean. AEM tech support (excellent help on phone) walked me through how to test the setup, which concluded a bad LSU4.9 WB sensor. They sent a new one and i’m still running with it today. If you send me a PM we can chat on the phone or email, especially if AEM tech support is after hours.
TJBUD
TJBUD
Where's the "any" key?
Where's the "any" key?
Posts: 27
Joined: April 20th, 2022, 9:32 am
Stroker Displacement: 4.7
Vehicle Year: 1998
Vehicle Make: Jeep
Vehicle Model: TJ

Re: 97 XJ 4.6L running lean

Post by TJBUD »

Typo-mine is AEM 30-4110 also
TJBUD
Where's the "any" key?
Where's the "any" key?
Posts: 27
Joined: April 20th, 2022, 9:32 am
Stroker Displacement: 4.7
Vehicle Year: 1998
Vehicle Make: Jeep
Vehicle Model: TJ

Re: 97 XJ 4.6L running lean

Post by TJBUD »

Enzosrock, Did you solve the lean problem?
I dug up my notes from debugging my Wideband and thought you or others might find thus useful.
AEM 30-4110 full lean reading:
Upon startup the gauge goes through a flashing sequence ending in P00 then the gauge displays about 14.3 for a few seconds before tracking the A/F mixture. If after about 20 or 30 seconds the gauge slowly migrates up numerically to full lean, follow these steps:
1) On a cold start it is unlikely that after a few seconds the engine would run smoothly if at all at full lean. Remember when we used a choke to richen carburetor mixture at startup? Is the engine running well at startup when the gauge goes full lean? If yes go to 2.
2) Do you see about the same behavior when turning the key to “on” (not run)and waiting about 20-30 seconds? The gauge will migrate to full lean if the engine is not running. But, If the sensor is installed as instructed and pegging lean with the engine running, the gauge or sensor is not working properly. Go to step 3.
3) With the WB O2 sensor removed from the exhaust but still plugged into the gauge wiring, have someone turn the key to “on” (not run) while you carefully hold the threads of the sensor between your fingers. It should get warm to the touch within a few seconds (<30). This tests the gauge and sensor wiring for the sensor’s pre-heat. If not warming, the wiring or the gauge is the problem. If the sensor gets warm move to step 4.
4) Perform this test after fully cooling sensor, exhaust, engine, etc to avoid fire. Lightly moisten a rag with gas and then wrap the rag around the sensor, including the tip. Turn the key “on” (not run). The gauge should begin the same, near 14.3, but migrate down numerically to full rich. If not, the sensor is bad.

It looks like a great stroker build-I hope you like it as well as I like mine.
TJBUD
Enzosrock
Posts: 9
Joined: May 12th, 2022, 2:29 pm
Stroker Displacement: 4.6
Vehicle Year: 1997
Vehicle Make: Jeep
Vehicle Model: Cherokee S

Re: 97 XJ 4.6L running lean

Post by Enzosrock »

TJBUD wrote: February 12th, 2023, 2:13 pm Enzosrock, Did you solve the lean problem?
I dug up my notes from debugging my Wideband and thought you or others might find thus useful.
AEM 30-4110 full lean reading:
Upon startup the gauge goes through a flashing sequence ending in P00 then the gauge displays about 14.3 for a few seconds before tracking the A/F mixture. If after about 20 or 30 seconds the gauge slowly migrates up numerically to full lean, follow these steps:
1) On a cold start it is unlikely that after a few seconds the engine would run smoothly if at all at full lean. Remember when we used a choke to richen carburetor mixture at startup? Is the engine running well at startup when the gauge goes full lean? If yes go to 2.
2) Do you see about the same behavior when turning the key to “on” (not run)and waiting about 20-30 seconds? The gauge will migrate to full lean if the engine is not running. But, If the sensor is installed as instructed and pegging lean with the engine running, the gauge or sensor is not working properly. Go to step 3.
3) With the WB O2 sensor removed from the exhaust but still plugged into the gauge wiring, have someone turn the key to “on” (not run) while you carefully hold the threads of the sensor between your fingers. It should get warm to the touch within a few seconds (<30). This tests the gauge and sensor wiring for the sensor’s pre-heat. If not warming, the wiring or the gauge is the problem. If the sensor gets warm move to step 4.
4) Perform this test after fully cooling sensor, exhaust, engine, etc to avoid fire. Lightly moisten a rag with gas and then wrap the rag around the sensor, including the tip. Turn the key “on” (not run). The gauge should begin the same, near 14.3, but migrate down numerically to full rich. If not, the sensor is bad.

It looks like a great stroker build-I hope you like it as well as I like mine.
TJBUD
TJBUD

Thanks for getting back to me. I do love the build. I just want to get it running smoother. To answer, yes i did have a faulty wideband which i had to have a new sensor sent out. once that was in i did verify that i was NOT running full lean. Then I started tuning with the HP tuner and it is great. I just need to get more comfortable with the software.

regardless of that i am having a rattling sound in the valve cover, pulled it off to find every one of my rockers is contacting the valve cover oil baffle... didnt want to shim but that may be the only optin because aftermarket covers dont have the oil baffle.

Thanks again!
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