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Blu's 1995 Contour SE 3L build thread

I did a few WOT's this morning to see what the A/F was reading. On all 4 "pulls" the gauge reads pegged rich from 3k all the way to rev limit :shrug:. 2 pulls were in 2nd gear and 2 pulls were in 3rd gear. It runs good and it kinda sounds like I might have an exhaust leak but it kinda mimicks what LAURA posted about in troubleshooting, just a "woosh" sound and only occasionally.

Still no CEL's, temp is good, everything works, etc..
 
blu_fuz said:
I did a few WOT's this morning to see what the A/F was reading. On all 4 "pulls" the gauge reads pegged rich from 3k all the way to rev limit :shrug:. 2 pulls were in 2nd gear and 2 pulls were in 3rd gear. It runs good and it kinda sounds like I might have an exhaust leak but it kinda mimicks what LAURA posted about in troubleshooting, just a "woosh" sound and only occasionally.

Still no CEL's, temp is good, everything works, etc..
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that is great to hear. it also confirms that the SE PCM is setup to run basically pig rich as I saw with the first dyno I did on my car. above 3krpm it went below 10 to 1 at the tail pipe :shocked:

try checking for pending codes to make sure there is noting hiding waiting to pop up.

so do you like the added torque of the 3L?
 
The TQ is yummy :)
It feels like I am probably about 180hp & TQ at the wheels right now. There is someone I know with an '99 T-red SVT and I am going to call him up so I can drive his to see how much different mine feels.
It has basically been about 11 months since I have driven my car.
I parked it in Nov. of '07 for winter. Drove it again to Pole's to have the powder coated bits put on. Drove it 1 more day like usual and then about 3 days of babying it due to the oil filters blowing..... so I have kind of forgot what it feels like.
 
air/fuel ratio of 10 to 1. meaning there is a lot of fuel. for a stoich reaction you need 14.7 parts air to one part fuel. like my car currently runs at 12.5 to 1 which is alot of fuel. 10 to 1 is a lot of fuel ...
 
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BrApple said:
air/fuel ratio of 10 to 1. meaning there is a lot of fuel. for a stoich reaction you need 14.7 parts fuel to one part air. like my car currently runs at 12.5 to 1 which is alot of fuel. 10 to 1 is a lot of fuel ...
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other way around. 14.7 air to 1 fuel, thats why 10:1 is rich, less air per fuel
 
blu_fuz said:
is it worse to lean out or rich out?
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both can be equally bad.


to much fuel and you can wash the cylinders down. this removes the oil needed to lubricate the pistons. can lose compression also.

to lean and the engine pops. although you do get more power when its learned out some. again you want it to be 14.7:1 in an ideal situation.
 
blu_fuz said:
is it worse to lean out or rich out?
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Rich just kills power and possibly catalytic converters. Lean can kill your engine.

BrApple said:
that is great to hear. it also confirms that the SE PCM is setup to run basically pig rich
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The full-rich fuel strategy is a failsafe. We know that because it happens at different times under the same circumstances. If the PCM doesn't see a problem, full-rich won't be initiated. I was never able to confirm positively what fault it was that my PCM was seeing that caused it to command full-rich, but everything suggests detonation.

BrApple said:
too much fuel and you can wash the cylinders down. this removes the oil needed to lubricate the pistons. can lose compression also.
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This would only occur with a prolonged no-start problem, or ignition miss on a given cylinder.
 
awesome info, thank you
So the PCM is pushing my injectors over the 80% duty right now because it knows I would be lean otherwise.

This is what I am gathering:

17# @ 80% = 13.6# (stock '95 SE)
17# @ 95% = 16.15# (3L w/ '95 SE LIM & injectors)
17# @ 90% = 15.3# (3L w/'95 SE LIM & injectors)
19# @ 80% = 15.2# (stock SVT injectors and LIM)

So basically my 17# injectors riched out by the PCM is actually better than a 19# running a stock injection at 80% duty.

Even only at 90% duty on a 17# I am at what the 19# puts out for 80%.

So why not just leave what I have? Just to take the load off the injectors? Sounds like too much work for so little based off the math....
 
I think that you are looking at the duty cycle wrong. it doesn't relate to how much the injector can flow but how long it sprays fuel.

yup ....

The fuel injector duty cycle (IDC) is the percentage of time the injector is supplied with power.
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http://www.stealth316.com/2-calc-idc.htm


What do the terms “static” and “duty cycle” mean?
An injector in an engine turns on and off very quickly to control the amount of fuel delivered. The amount of time an injector is turned on and delivering fuel is known as the duty cycle. This is measured as a percent, so 50% duty cycle indicates that the injector is held open and held closed for an equal amount of time. When the engine needs more fuel, the time that the injector stays on (its duty cycle) increases so that more fuel can flow into the engine. If an injector stays on all the time, it is said to be static (wide open, or 100% duty cycle). INJECTORS SHOULD NOT GO STATIC IN A RUNNING ENGINE! If an injector is static in a running engine (open 100% of the time), that injector is no longer able to control fuel delivery. It is just “along for the ride”. This could be an indication that the injector is too small for the needs of the engine. Injector duty cycle should usually not exceed 80% in a running engine at any time.
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and

If injectors should not exceed 80% duty cycle under operating conditions, why do manufacturers rate them at 100% duty cycle?
A test at 100% duty cycle is used to determine the maximum amount of fuel that will flow through an injector in a given time. This test is useful for determining whether an injector’s internal fuel passages were machined properly, but it does NOT check an injector’s ability to cycle on or off. It is usually NOT recommended to run an injector at more than 80% duty cycle under actual driving conditions. This 80% duty cycle operating limit is taken into account to make sure the injector will be large enough to feed the engine under ACTUAL OPERATING CONDITIONS and will not starve the engine for fuel.
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from http://www.injector.com/faq.php
 
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Just when I think I am catching on WHAMO! I get hit right in the mouth.
Duty cycle is length of injection NOT the amount of fuel put out by the injector.
It is like dumping buckets of water. 1 gal of water (17#) poured fast or slow is still less than another bucket with 2 gal of water (19#) poured... Right?
 
using some online calculators I am getting that a 3L needs 18.75# injectors to not be over 80% duty cycle. So 19# injectors seem to be a minimum to make sure the injectors can safely fuel a N/A 3L engine.
 
blu_fuz said:
It is like dumping buckets of water. 1 gal of water (17#) poured fast or slow is still less than another bucket with 2 gal of water (19#) poured... Right?
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I think so. A 19# injector will flow more fuel then a 17# injector at a given duty cycle.
 
blu_fuz said:
So basically my 17# injectors riched out by the PCM is actually better than a 19# running a stock injection at 80% duty.
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Right now, your stock injectors are your only viable option IMO. Until you get a tune or an SVT PCM, leave your 17lber's in there. If you put larger injectors in without getting a tune for them, the computer will have no way of knowing that you've put in larger injectors and it will be injecting fuel as if you've still got your 17lber's in there. You'll throw over-rich codes shortly after you pull the car out of your garage and you'll get probably 7-10 mpg if you actually drive it around that way.
 
Apexi cheating! :eek: never. Another thing to throw money at and don't know if I need it - I need people to borrow me some things:
-Apexi
-Wideband 02
-19# injectors
-svt lim
-svt return fuel rail


I will return what I don't need ;)
 
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