O/R H pipe install car is now stalling when coming to a stop - MustangForums.com


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Old 09-19-2015, 02:27 AM   #1  
trashxtrash
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Default O/R H pipe install car is now stalling when coming to a stop

2000 5 speed gt

Just got done installing a JEGGS O/R H pipe. Surprised everything lined up, the 02 sensors are placed closer to the manifolds though, right where the secondary cats used to be.
That passenger side exhaust bolt from the shorty header is a PITA. That took 2 hours and a trip to the store, after that everything was a breeze.

I do not have an MIL eliminators, I plan to make my own soon.

I started it up with everything installed, I do have a small leak on the driver side of the h pipe connected to the headers because I misplaced one of the bolts. I will fix that as soon as possible. The car idles fine initially and does not stall.

The car will idle okay, but as soon as I give it gas, or if i go for a drive, when coming to a stop the rpms go down, and they keep going down until it stalls. This means when i'm at a stop light i have to dance with the throttle to keep the rpms up.

Does anyone know what caused this?

I had no prior codes when I had the stock h pipe on,
I do have the check engine light on now, due to not having cats?

Where is this mysterious stalling coming from? Could it be from the minor exhaust leak near when the header meets the h pipe??


Any help is appreciated... I really don't want to put the stock H pipe on because that bolt was just a nightmare even with a swivel joint and impact wrench..
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Old 09-19-2015, 09:35 AM   #2  
jwog666
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any air leaks in the exhaust before the upstream o2 sensors can result in oxygen being drawn into the exhaust stream, the sensor will read this and add more fuel, this will throw off your AF ratio and may explain your concern
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Old 09-20-2015, 02:20 PM   #3  
uberstang1
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Did you unplug the VSS sensor for any reason?
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Old 09-20-2015, 10:30 PM   #4  
trashxtrash
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Quote:
Originally Posted by jwog666 View Post
any air leaks in the exhaust before the upstream o2 sensors can result in oxygen being drawn into the exhaust stream, the sensor will read this and add more fuel, this will throw off your AF ratio and may explain your concern

THANK YOU this was the exact problem. I had a big leak because I forgot to tighten one bolt on the driver side manifold where it meets the H pipe. I tightened them down as far as I could go and put some muffler sealant around the edges to make sure nothing was leaking.

I also did the spark plug fouler trick for the o2 sensors, no more check engine light

and no more stalling!

Thank you all for your help!
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Old 09-20-2015, 10:49 PM   #5  
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good to hear u got it fixed
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