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From the articles I found I would expect this to read 9v at full open. I can see two groves on the connection track. Makes me think I should adjust the arm to get a better connection. How else can I tell if the AFM had other adjustments made? |
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To lean the mixture, one just increases the spring tension for smooth engine RPM acceleration.
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little help for you
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1985 911 with original 501 761 miles...807 506 km "The difference between genius and stupidity is that, genius has its limits". Albert Einstein. |
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When air leaks are the problem, the mixture becomes lean! The OP's 1st post states the mixture is TOO rich and has to bypass the temp sensor to allow improved starting.
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Hope the brain trusts are working on a modern replacement for this 40 yr old electromechanical marvel. |
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The nice part of having an AFM is that one can easily move the AFM wiper, without adjusting the spring, and determine whether the AFR is too rich/lean based on how the engine reacts.
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Redo the vacuum check. It's quick, immediate results, no tools required, and highest frequency cause of problems on these cars.
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It still won't explain why the engine is running TOO rich!
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Did you measure it with a AFR, or with your calibrated nose?
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Haha, just the sniff test for me. The mechanic at the shop that put the motor in said it is running lean. He also suggested is was just the idle control switch, or the need to clean the ICV. So who knows.
They had the whole intake manifold off to replace some leaking fuel lines. They said they inspected and replaced the gaskets. I’m sure they didn’t vacuum test it. |
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You, like some, failed to read/understand the OP's first post;
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It doesn't get any easier than that! Tests like that are why the 911 3.2 is very easy to troubleshoot. Hey guys, get with it, this isn't a CIS engine!!!!!!
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Dave Last edited by mysocal911; 03-23-2024 at 09:09 AM.. |
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When you say you jumped the CHT sensor, you mean you shorted (with a paper clip or whatever) the sensor connector terminals on the harness side, right? Not on the sensor side (this wouldn't make sense).
In that case I wonder why this makes the engine run richer, since shorting the CHT sensor input to the ECU simulates a warm engine. The CHT sensor is a NTC. The lower the resistance, the higher the temp. Shouldn't it be the opposite?
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Dave Last edited by mysocal911; 03-23-2024 at 09:15 AM.. |
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Date, post #30: "It only starts running rich when I jumped the CHT sensor. It’s a bit on the lean side when the sensor is plugged in."
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As I said up-thread, time for another DME ECM!
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Dave Last edited by mysocal911; 03-23-2024 at 09:25 AM.. |
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There're too many unknowns at this point for any productive troubleshooting;
1. DME ECM chip type 2. Injectors being used 3. Fuel pressure 4. FP/Damper leaks into intake via vacuum lines 5. AFM incorrect spring tension 6. Throttle enrichment switch shorted to ground
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I took the ECU out to hopefully test it in a friends car soon. Figured I would open it up to see what chip is in it. Clearly it had been opened before. Chip has a sticker on it, PAE i8. I did a search and couldn’t find a reference for that.
I had also opened up the AFM and noticed the spring was moved one notch towards the lean side. ![]() |
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I posted the chip and AMF spring settings. To my understanding these are OEM injectors that had been cleaned and refreshed. It does seem like it might be a fuel pressure issue. I took the vacuum lines going to the FP damper and regulator off, they weren’t wet, but they smelled of fuel. |
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