XJ XJ8 / XJR ( X308 ) 1997 - 2003

NA X308 needs acceleration at startup or it stalls

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Old 10-15-2020, 04:04 AM
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Default NA X308 needs acceleration at startup or it stalls

Hello all, it’s been a while since I could not solve a problem without your kind help... But here I’m lost and I’d love some ideas. My 3.2 2001 X308 needs help at startup. When absolutely cold, if I don’t accelerate right after firing up the engine it stalls. I need to accelerate about 5 mins until it gets warm before I can let go the pedal. Once warm no issue at all. Water temp sensor is 5k km old and checks good on the OBD reader, all injectors are clean, fuel filter and fuel regulator are new, and once warm there are no other symptoms or oddities. Acceleration is excellent so fuel pump must be good, idle is as it should.... And when I stop for an hour or two and restart it works great. Issue is only on a morning start. What do you guys think ? Spark plugs ? They are 16k km old. I’ll change them next week to be sure but i don’t think that’s it. Camshaft and Crankshaft sensors? Thanks!!!
 
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Old 10-15-2020, 05:40 AM
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Spark plugs won’t resolve your issue, save your money. Check for any cracks under your bellows on your intake pipe. What I would do if I were you is clean out your throttle body and maf followed by a hard reset. It’s the easiest and most effective methods. Do you have a scanner to monitor your fuel trims?
 
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Old 10-15-2020, 06:19 AM
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Intake pipe is all checked and clean, MAF is new (many parts are since the car was rebuilt last winter) and TB was rebuilt as well with new IACV and new TPS...
 
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Old 10-15-2020, 06:20 AM
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Fuel trims are good too. In the 5% range. O2 sensors are new too. Denso, not generic.
 
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Old 10-15-2020, 10:12 AM
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Even though the Temp sensor is new, the ECU is getting a false temperature reading. Check the MAF sensor connector for bent pins. Or maybe a bad wire from the sensor to the MAF. Or bad sensor.
 
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Old 10-16-2020, 09:18 AM
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Culprit was the MAF! You’re right. It got dirty fast. A cleaning with brake cleaner did the job. I wouldn’t have thought after such a short time it would need cleaning.... Amazing how you’d first think about complicated reasons when it’s very often dead simple and staring at you 🤤 Thanks for your time and wise advice. Cheers!
 
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Old 10-16-2020, 10:09 AM
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DO NOT clean the MAF with brake cleaner or the coating on the element will be destroyed.

Use cleaners designed for cleaning electrical parts such as the MAF.
 
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Old 10-17-2020, 06:14 AM
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Oh no! Ok: noted. Anyways, MAF works fine. I have a spare one if ever it fails.
 
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