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need advice on a/f ratio

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Old 11-03-2009, 02:32 PM
  #11  
Derf00
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The best way is to take them off the car and put them into a flow tester that not only checks the pattern of the spray (blocked or broken pintels), but the volume and resistance of the injectors (clogged injector or shot injector).

Since it's only happning at higher RPMs it will be difficult to diagnose clogged injectors without the proper equipment. If it were at idle or low throttle it would be easier. Yes there is a way to test under those conditions but it's dangerous and not entirely conclusive. You'd be working with electricity and pressurized fuel in an uncontrolled environment.

You could run a tank of 89 or higher fuel with Techron fuel injector cleaner through it before your next dyno.

Other than that I would wait until you see the actual readings before jumping to conclusions. I'm still thinking pressure is the issue here. Get the WOT fuel pressure and a snapshot of the STFT and LTFT at the same time. Most equipment that reads that data can take the snapshot for you. Those three bits of info will speak volumes.
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Old 11-03-2009, 02:39 PM
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67mustang302
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Are you sure his a/f gauge is correct? 17:1 is EXTREMELY lean and most engines won't even run at that at part throttle. I'd be extremely skeptical of that being the actual a/f ratio without it stumbling and cutting out all over the place.
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Old 11-03-2009, 04:16 PM
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FoxGT
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What is your fuel psi when it goes lean? Probably just need tuned.

Originally Posted by 67mustang302 View Post
Are you sure his a/f gauge is correct? 17:1 is EXTREMELY lean and most engines won't even run at that at part throttle. I'd be extremely skeptical of that being the actual a/f ratio without it stumbling and cutting out all over the place.
I've ran one up to 16.9:1. Tuning them to run very lean at cruise is fine. One of mine is set at 16.7:1 at cruising load. What I do is start at 16:1 & keep working my way up 1 point until it starts to surge, then back off 2 or 3 points. You want it to run as lean as possible at cruise load for the best fuel economy. For forced induction i always aim for 11.7-12.3:1 & n/a 12.7-13:1

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Old 11-03-2009, 04:20 PM
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17.1 at WOT or near redline (even crusing) is dangerous for an engine.
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Old 11-03-2009, 04:41 PM
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i'll start with the fuel pressure. thanks for the input everyone.
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Old 11-03-2009, 05:13 PM
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What are you using to measure the a/f
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Old 11-03-2009, 05:20 PM
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it shows the a/f ratio on the dyno graph i recieved.
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Old 11-03-2009, 05:21 PM
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i will see if i can post it on here so you guys can see what you think.
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Old 11-03-2009, 06:06 PM
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Originally Posted by gideon View Post
it shows the a/f ratio on the dyno graph i recieved.
Oh ok, so it was from the dyno runs. Any leaks in the exhaust? How does the car seem to run? Did they put a bung in the exhaust and connect a wide band or did they use an exhaust probe in the tail pipe?
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Old 11-03-2009, 07:27 PM
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they connected a wideband where the oxeygen sensors where, havent noticed any ehaust leaks. my car was an automatic then i put a manual in it but left the auto computer in the car. do you think that might have something to do with it?
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