high idle, glowing red headers and occasionally sound like its knocking
02-01-2013, 02:30 PM
#1
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high idle, glowing red headers and occasionally sound like its knocking Need help bad! I have a LQ9 408 that wants to take off soon as I lift my foot off the brake pedal. The headers glow red after about two minutes of idle, plus sometimes it sound like its knocking when i give it gas; that's in park that is.. at idle I don't here any abnormal noise... I'm disgusted
02-01-2013, 02:38 PM
#2
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I have no vac leaks, no cats and just changed O2's. Car have a speed density tune, I changed pcm from another SD tuned setup, and the same thing happened???????
02-01-2013, 03:21 PM
#3
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Sounds like too much air (high A/F ratio) or way too much fuel that is maybe collecting and burning in the exhaust. Maybe idle air control valve not operating properly. Maybe MAF not metering correctly. TPS sticking or getting bad signal? If you have a meter you should be able to check a lot of these things with voltage and resistance readings. I cant remember if there is anything in the Haynes manual for those readings but might be able to find them on here. Best to start with the small things.
02-01-2013, 03:37 PM
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Was just reading through some other threads and had a thought. Do you have a secondary air in jection pump or not? If so, make sure it cycles off and doesnt run constantly which would pump air into your exhaust and heat it up.
02-01-2013, 03:51 PM
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No pump, last time I was in the car it pulled freaky hard in 1st & 2nd then fell off in third! 30 mins later I noticed the headers glowing
02-02-2013, 07:38 PM
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Having no MAF, cats or air pump makes me start to think something with the various sensors on the throttle body or something going on with the tuned not allowing enough fuel in for the amount of air going in. Typically air is what will drive your temps up. Do you know your A/F ratio?
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05-11-2014, 04:38 PM
#11
430 LSX block, -28cc pistons, Callie's crank, afr 235 heads, fast 102 intake and TB, dynatech 3/4 heads to dynatech power cats to borla cat back.
Brand new motor just built and put it. Front 02 sensors, speed density tune
Hope this helps I'm gonna pull a plug and see if she is running rich or lean. Last I checked she was rich. I also removed secondary air and EVapp.
Brand new motor just built and put it. Front 02 sensors, speed density tune
Hope this helps I'm gonna pull a plug and see if she is running rich or lean. Last I checked she was rich. I also removed secondary air and EVapp.
05-12-2014, 10:02 AM
#12
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It could be from running very very rich. You can try removing all plugs cleaning or replacing them, gap them smaller (which shouldn't be an issue with how low your compression is, is your build boosted?), and see if that fixes the issue temporarily.
If it doesn't it's most likely a lean condition, if it does then it could be from being way to rich. Being overly rich can screw those cats up is a hurry.
It could also be something I'm not thinking of either, like is the cam degree'd correctly?
If it doesn't it's most likely a lean condition, if it does then it could be from being way to rich. Being overly rich can screw those cats up is a hurry.
It could also be something I'm not thinking of either, like is the cam degree'd correctly?
05-12-2014, 11:31 AM
#13
ok so here is where I am at so far. I have my rear 02`s turned off and had the wires criss crossed so that is fixed. 02`s now read correctly as they should.
however prior to resolving the above I realize that bank 1 and bank 2 were swapped. We addressed the above and all good.
Now during that time i pulled a bank 1 spark plug and found it was lean, I also pulled the same spark plug on bank 2 and saw it was rich.
That being said I have gone over the injectors but wouldnt mind going back over them to make sure they are all firing.
Would the criss crossed 02`s cause the lean condition in bank 1?
I have check around the intake etc with carb cleaner for a vac leak as well and found nothing. Please let me know if the 02 would cause the lean condition in Bank 1 only, and if not what your thoughts are.
This is a return fuel system as well, utilizing the Nasty Performance Pro Touring tank, magnafuel FPR, magnafuel y block, FAST rails, and ID 1000cc injectors.
Thanks!
Thanks!
however prior to resolving the above I realize that bank 1 and bank 2 were swapped. We addressed the above and all good.
Now during that time i pulled a bank 1 spark plug and found it was lean, I also pulled the same spark plug on bank 2 and saw it was rich.
That being said I have gone over the injectors but wouldnt mind going back over them to make sure they are all firing.
Would the criss crossed 02`s cause the lean condition in bank 1?
I have check around the intake etc with carb cleaner for a vac leak as well and found nothing. Please let me know if the 02 would cause the lean condition in Bank 1 only, and if not what your thoughts are.
This is a return fuel system as well, utilizing the Nasty Performance Pro Touring tank, magnafuel FPR, magnafuel y block, FAST rails, and ID 1000cc injectors.
Thanks!
Thanks!
05-12-2014, 12:26 PM
#15
TECH Addict
Yes, criss crossing your O2's can cause that condition.
For example, if your O2 senses that bank 1 is rich, it'll lean it out. But if they are cris-crossed it'll lean out bank 1, but because bank 1 is reading bank 2 it'll notice no effect on bank 1 O2 and try to lean it more, but simultaneously it'll notice bank 2 O2 is running lean now so it'll richen it up. And the cycle continues until both correction factor limits in the PCM are maxed out both ways.
Fixing the swap should resolve your issues. But, I'd also have the tuner go in the PCM and fix the split fueling issue anyway.
For example, if your O2 senses that bank 1 is rich, it'll lean it out. But if they are cris-crossed it'll lean out bank 1, but because bank 1 is reading bank 2 it'll notice no effect on bank 1 O2 and try to lean it more, but simultaneously it'll notice bank 2 O2 is running lean now so it'll richen it up. And the cycle continues until both correction factor limits in the PCM are maxed out both ways.
Fixing the swap should resolve your issues. But, I'd also have the tuner go in the PCM and fix the split fueling issue anyway.
Last edited by hrcslam; 05-12-2014 at 12:32 PM.
