Dealing with lean condition after cam swap
Thread Starter
TECH Apprentice
Joined: Oct 2013
Posts: 350
Likes: 25
From: North Shore MA
Dealing with lean condition after cam swap Hi guys,
I replaced the cam in my 5.3 swapped car, and now I'm struggling with a nagging lean condition. I'll give a little rundown on what I have:
2003 5.3 DBW out of a Silverado, using the stock harness and computer
Stock GM truck MAF out of same truck, Stock throttle body
LS1 intake manifold
Long tube headers
The cam is a 228/230 .585 .585 112LSA
PAC1218 springs, stock retainers
The Trans is a TH350 with a 3000 stall
Anyways, after getting the cam installed, it ran how you would expect it too. Very rich at idle, and didn't like to be put into gear without some throttle input to keep it running. I had the computer mail order tuned (He's been great through this ordeal), but now I'm dealing with a severe lean condition at idle.
At initial startup, the AFR gauge trickles down to about 13.4, and starts climbing upward. After about 30 seconds of running, it'll be showing AFR in the 15.5-16.5 range, and about a minute later it'll peg the gauge. The o2's are showing a maxed LTFT of 25%, and the STFT is showing anywhere from 5-15%. The plugs (which are new) are showing very lean, so I think the AFR gauge is correct.
I replaced both o2s with Denso units, cleaned the MAF, checked all the wiring for the injectors, and even pulled the timing cover back off to make sure I didn't install the cam a tooth off.
Right now it's back together, showing the same issues. If you blip the throttle in park, it'll die when returning to idle. Unplugging the MAF while running results in it dying.
Any suggestions guys? I feel like I'm overlooking something stupid, but I'm pretty lost on what it could be.
Thanks
I replaced the cam in my 5.3 swapped car, and now I'm struggling with a nagging lean condition. I'll give a little rundown on what I have:
2003 5.3 DBW out of a Silverado, using the stock harness and computer
Stock GM truck MAF out of same truck, Stock throttle body
LS1 intake manifold
Long tube headers
The cam is a 228/230 .585 .585 112LSA
PAC1218 springs, stock retainers
The Trans is a TH350 with a 3000 stall
Anyways, after getting the cam installed, it ran how you would expect it too. Very rich at idle, and didn't like to be put into gear without some throttle input to keep it running. I had the computer mail order tuned (He's been great through this ordeal), but now I'm dealing with a severe lean condition at idle.
At initial startup, the AFR gauge trickles down to about 13.4, and starts climbing upward. After about 30 seconds of running, it'll be showing AFR in the 15.5-16.5 range, and about a minute later it'll peg the gauge. The o2's are showing a maxed LTFT of 25%, and the STFT is showing anywhere from 5-15%. The plugs (which are new) are showing very lean, so I think the AFR gauge is correct.
I replaced both o2s with Denso units, cleaned the MAF, checked all the wiring for the injectors, and even pulled the timing cover back off to make sure I didn't install the cam a tooth off.
Right now it's back together, showing the same issues. If you blip the throttle in park, it'll die when returning to idle. Unplugging the MAF while running results in it dying.
Any suggestions guys? I feel like I'm overlooking something stupid, but I'm pretty lost on what it could be.
Thanks
Thread Starter
TECH Apprentice
Joined: Oct 2013
Posts: 350
Likes: 25
From: North Shore MA
I've used him before and they've worked great. I really think it's probably something I'm looking over, but idk. Stranger things have happened.
It sucks though, the car has been running for 4 years flawlessly and I've racked up thousands of miles on it.
It sucks though, the car has been running for 4 years flawlessly and I've racked up thousands of miles on it.
TECH Apprentice
Joined: Apr 2019
Posts: 365
Likes: 133
From: California
Something is either pulling fuel or timing. Let your tuner know that your 5.3 is running lean with the new cam. I just got HP Tuners and from what I know it seems that commanded fuel is not adjusted for your cam.
Thread Starter
TECH Apprentice
Joined: Oct 2013
Posts: 350
Likes: 25
From: North Shore MA
We've been going back and forth, going through everything. So far nothing really stands out, but I'll keep digging.
Thread Starter
TECH Apprentice
Joined: Oct 2013
Posts: 350
Likes: 25
From: North Shore MA
Speaking of timing, I was watching the advance with my scanner, and at idle it jumps around between 13 and 25. I never paid attention to it before the cam swap, so I dont know what it was doing before.
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TECH Apprentice
Joined: Apr 2019
Posts: 365
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From: California
Yeah it should be steady at idle usually from 10 to 15 depending on your setup. Numbers like 25 to 36 are for cruising or WOT so just share this new piece of information with your tuner.
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TECH Apprentice
Joined: Oct 2013
Posts: 350
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From: North Shore MA
I've always wanted to get HpTuners, but didn't really have a reason to. I'm thinking now is as good a time as any to grab it and start learning.
I'm sure I'll have a ton of dumb questions for you guys. lol
I'm sure I'll have a ton of dumb questions for you guys. lol
TECH Fanatic
Joined: Oct 2014
Posts: 1,220
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From: Virginia
Timing will jump around a lot at idle. It's how the PCM maintains a target RPM. With bigger cam setups, might be a lot. There are a ton of factors, but never a bad time to learn.
If you got questions, someone here can probably answer them.
If you got questions, someone here can probably answer them.
Thread Starter
TECH Apprentice
Joined: Oct 2013
Posts: 350
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From: North Shore MA
TECH Apprentice
Joined: Apr 2019
Posts: 365
Likes: 133
From: California
I took a look at my '01 Camaro's tune and compared it to your 5.3s tune. Your timing at idle is far too aggressive and it needs to be backed off. Take a look at your tune on the left and my tune on the right.
I also sent you a PM.
Last edited by SoCalDave; Jul 19, 2019 at 05:05 PM.
Thread Starter
TECH Apprentice
Joined: Oct 2013
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From: North Shore MA
Aside from messing with the tune (I haven't touched it yet) I'm pretty stumped. I'm running out of things to check. I pulled the intake and checked the gaskets, and they look fine. The only two things pulling vacuum is the power brakes and the transmission. Both are connected to the back of the intake and look fine. The inside of the intake is slightly oily, more so on the driver side, but nothing crazy.
The clamps on the intake tube are tight, including the ones around the MAF.
I even pulled the front of the engine apart to make sure I didn't install the cam a tooth off, and everything looks good.
I'm officially stumped. Am I overlooking something obvious? Where should I look next? I didn't see anything in the tune that would make it incredibly lean, but then again I'm still learning so I could have missed something super obvious.
The clamps on the intake tube are tight, including the ones around the MAF.
I even pulled the front of the engine apart to make sure I didn't install the cam a tooth off, and everything looks good.
I'm officially stumped. Am I overlooking something obvious? Where should I look next? I didn't see anything in the tune that would make it incredibly lean, but then again I'm still learning so I could have missed something super obvious.
Thread Starter
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Joined: Oct 2013
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From: North Shore MA
Restricted User
Joined: Mar 2014
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From: Ohio
If your IAT is in your MAF, it might create other problems.
Although, if you unplug it, the IAT will go to its coldest column in the table and likely add a bunch of fuel.
Failing the MAF and forcing it into speed density might change the idle. Try to get a datalog if possible. It may help your tuner solve the problems.
Although, if you unplug it, the IAT will go to its coldest column in the table and likely add a bunch of fuel.
Failing the MAF and forcing it into speed density might change the idle. Try to get a datalog if possible. It may help your tuner solve the problems.
Thread Starter
TECH Apprentice
Joined: Oct 2013
Posts: 350
Likes: 25
From: North Shore MA
If your IAT is in your MAF, it might create other problems.
Although, if you unplug it, the IAT will go to its coldest column in the table and likely add a bunch of fuel.
Failing the MAF and forcing it into speed density might change the idle. Try to get a datalog if possible. It may help your tuner solve the problems.
Although, if you unplug it, the IAT will go to its coldest column in the table and likely add a bunch of fuel.
Failing the MAF and forcing it into speed density might change the idle. Try to get a datalog if possible. It may help your tuner solve the problems.
I can log it, but it's not drivable. It's so lean I really dont like running it. Plus it dies easily in gear, as soon as you give it gas.
Thread Starter
TECH Apprentice
Joined: Oct 2013
Posts: 350
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From: North Shore MA
Update:
I put the stock cam in, and the original tune. Car starts and idles fine, but the AFR is still off the charts lean. Driver side LTFT is pegged at 25, although it'll drop to 10ish for a few seconds before returning to 25. The passenger side LTFT is hovering around 16.
I'm at a loss. Intake gaskets are new and look good, o2 sensors are new, plugs are new, etc etc.
The injectors are firing, I checked each one by unplugging them one by one as it was running. MAP is reading around 10.2 at idle, moving around a bit. The MAF was temporarily replaced with a known good unit. Still lean as hell at idle.
Maybe a wire is pinched somewhere?
I dunno.
I put the stock cam in, and the original tune. Car starts and idles fine, but the AFR is still off the charts lean. Driver side LTFT is pegged at 25, although it'll drop to 10ish for a few seconds before returning to 25. The passenger side LTFT is hovering around 16.
I'm at a loss. Intake gaskets are new and look good, o2 sensors are new, plugs are new, etc etc.
The injectors are firing, I checked each one by unplugging them one by one as it was running. MAP is reading around 10.2 at idle, moving around a bit. The MAF was temporarily replaced with a known good unit. Still lean as hell at idle.
Maybe a wire is pinched somewhere?
I dunno.
