LS3 - MAF Frequency Fail High Setting
Thread Starter
Staging Lane
Joined: Apr 2024
Posts: 53
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LS3 - MAF Frequency Fail High Setting My new LS3 (700 miles on it) is swapped into a rear engine vintage Porsche. This morning after a good startup and long cruise, I stopped and went into an auto parts store. When I came out and re-started the engine, the idle entered into a cyclical loop (sine wave) and the throttle was unresponsive. After several wait-and-restarts, idle resumed normal procedures. When I got home, I ran a scan and detected a P0103 DTC, which meant that the MAF sensor triggered an error. Cause --> With wrapped headers, and running a higher than normal IAT (I don't have cold air intake), as soon as the engine stopped and there was no air movement, heat rose and caused a heat sink on the MAF - so at startup the ECM threw a P0103.
Right now, the MAF Frequency Fail High is set to 0 Hz. Can I set it to e.g. 14000 Hz, which is above the max Hz I'll ever see?
Right now, the MAF Frequency Fail High is set to 0 Hz. Can I set it to e.g. 14000 Hz, which is above the max Hz I'll ever see?
Last edited by lep; Yesterday at 01:58 PM.
You need to post the tune, but if the MAF fail high frequency is set to 0, you are not using the MAF at all. Your problem likely lies elsewhere, and may be tune or mechanical related.
Thread Starter
Staging Lane
Joined: Apr 2024
Posts: 53
Likes: 10
FYI - I just noticed in earlier tune files, when I didn't experience limp mode when re-starting after heat sink, that the MAF Frequency Fail High was 14,500 Hz.
Here's the tune file. The cycling idle RPM (like a sine wave, 1000-1500) occurred again yesterday after a long cruise, shut down, then restart 10 minutes later. I think it's called limp mode caused by heat sink, which can occur after brief shut down when hot, and then attempting restart maybe 10-30 minutes later. During restart and heat sink, all the hot air from the block, headers, transmission rises to the intake and MAF sensor. Sucking in that hot intake air at startup causes the ECM test to fail - since several parameters don't correlate.
I know there is a test conducted at startup at 1.0 seconds to check for the MAF sensor and IAT, so is the solution to delay that to 3 or 4 seconds, when cooler air is sucked in?
Last edited by lep; Yesterday at 02:34 PM.
Thread Starter
Staging Lane
Joined: Apr 2024
Posts: 53
Likes: 10
First I would ask your tuner why they decided to switch to speed density from the MAF, they may have had a very good reason to do so and I wouldn't just go making changes. Looking at the tune file it certainly looks intentional on the switch to SD. However they missed a few things that need to be done if they are running it in speed density on this computer, like the Speed Density Air Mode patch. Also, when it goes into limp mode it's likely to throw a code which will give you more information on why.
