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New exhaust, now my stroker is running lean?

ZomBrady

Chubby Chaser Extraordinaire
NAXJA Member
Location
Albuquerque
My '96 stroker with an AW4, has easily 25K miles and I haven't had a lick of problems with it. Yes, it has stock size injectors.

Running a stock exhaust the entire time, but now I upgraded the entire system to 2.5" from the header back and my computer is throwing me an error msg that says that the engine is running lean.

Could going to 2.5" on the down pipe really have freed up that much volumetric efficiency in the engine as to allow a lean condition to form even though I had no problems before now? Just seems a little weird to me.
 
SBrad001 said:
My '96 stroker with an AW4, has easily 25K miles and I haven't had a lick of problems with it. Yes, it has stock size injectors.

Running a stock exhaust the entire time, but now I upgraded the entire system to 2.5" from the header back and my computer is throwing me an error msg that says that the engine is running lean.

Could going to 2.5" on the down pipe really have freed up that much volumetric efficiency in the engine as to allow a lean condition to form even though I had no problems before now? Just seems a little weird to me.

do you have down stream o2 sensors and if so did a hole get provided for them sensors?


Flash.
 
Flash said:
do you have down stream o2 sensors and if so did a hole get provided for them sensors?


Flash.

The only bung that needed fabbing was the upstream O2 sensor, the down stream O2 sensor bung was already built into the catalytic converter.
 
downstream doesnt do anything for how the motor runs.

you were always running lean, unless you bumped fuel pressure.

now its running lean enough to throw a code, look for some ford 24 lb injectors
 
SBrad001 said:
The only bung that needed fabbing was the upstream O2 sensor, the down stream O2 sensor bung was already built into the catalytic converter.


How many miles have ya drove it, it just may need to relearn the better flowing ex.........all thow i don't thing it should have turned the check eng light on!:dunno: .....could one of your sensor deside to take a dump, from removing from the old ex to the new?


Flash.
 
tealcherokee said:
downstream doesnt do anything for how the motor runs.

you were always running lean, unless you bumped fuel pressure.

now its running lean enough to throw a code, look for some ford 24 lb injectors


that makes sense!:thumbup:


Flash.
 
tealcherokee said:
. . .you were always running lean, unless you bumped fuel pressure.

now its running lean enough to throw a code, look for some ford 24 lb injectors

Yeah, that's what I'm thinking too. When my brother and I did the build on this motor, we went with flow tested and matched injectors form Python. Supposedly, they're good for 15% flow over stock, which would put them up around 19~20lbs. Probably just enough to keep the engine from leaning out too much, but once the back pressure was relieved it went lean.

SO! Do any of you have the hookup for 24lbs injectors? :D
 
SBrad001 said:
My '96 stroker with an AW4, has easily 25K miles and I haven't had a lick of problems with it. Yes, it has stock size injectors.

Running a stock exhaust the entire time, but now I upgraded the entire system to 2.5" from the header back and my computer is throwing me an error msg that says that the engine is running lean.

Could going to 2.5" on the down pipe really have freed up that much volumetric efficiency in the engine as to allow a lean condition to form even though I had no problems before now?

In a word, yes. The stock injectors don't cut the mustard anymore so you'll need to upsize them to Ford Racing 24lb units (or their equivalent).
 
Dr. Dyno said:
In a word, yes. The stock injectors don't cut the mustard anymore so you'll need to upsize them to Ford Racing 24lb units (or their equivalent).

Well as it turns out, the computer just needed time to rest set itself to the new operating conditions.

The original injectors that I installed where 'massaged' by an outfit here in SoCal called Python Injectors so that they flowed about 15% higher than stock. Which put them up around 23~24bs. All is well now.
 
SBrad001 said:
Well as it turns out, the computer just needed time to rest set itself to the new operating conditions.

The original injectors that I installed where 'massaged' by an outfit here in SoCal called Python Injectors so that they flowed about 15% higher than stock. Which put them up around 23~24bs. All is well now.


So how many miles/days did it take for computer to catch up?

Flash
 
Flash said:
So how many miles/days did it take for computer to catch up?

Flash

Maybe about 30 miles? I don't really do alot of driving but it reset with by the third day.
 
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