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Discussion Starter #1
Ok...Today I went back to the dyno to finish up on my tuning. This time I decided to run air/fuel and I'm glad I did. I did a base run and at 6200 rpm my air/fuel went from 11.6 to 18+(wouldn't measure any leaner). I pulled my chip out and that fixed it(it stayed rich at WOT). I went to the dyno to try to get a little more power(@138.4whp/136.6wtq should be @145+whp,145+wtq)before I get my new cat-back. Back to the air/fuel...Once I get a good run with a good air/fuel mixture I started working with the cam gears. I found that when I retarded my exhaust,(I was already at int:-5,exh:-4)I was getting more hp and tq. The problem with this was that my air/fuel was going very lean(18+) again after 6200 rpm and this didn't matter whether I retarded or advanced my intake or exhaust. I would go lean with any further adjust- ment anywhere. What do you guys think is causing my car to go lean like that. Is it my fuel pump? I don't think my injectors would be the cause because I was only pushing 138 actual not corrected whp(its 130.3 whp and 132.8 wtq SAE corrected whp). My mods are listed in my signature. Any feedback would be greatly appreciated.

Roger

[ 02-19-2003, 08:12 PM: Message edited by: Jet powered go-cart ]
 

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I think the fuel pump is something you should look at. Last Sunday I was at an auto-x event and my ZX5 always stuttered at the same spot on my three runs at about 5000rpm. After talking with my local Focus experts in the 5280 forum we came to the conclusion that I probably ran the fuel lines dry for a moment since the stock fuel pump sucks! I would change it and see how the a/f ratio looks.
 

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Discussion Starter #3
I am going to try the fuel pump. Does anyone know where I can get a high flow fuel pump for a 2000 Focus. If not, where can I get the sending unit for the focus central 2002+ fuel pump. Thanks.

Roger
 

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Originally posted by Yel900rr:
The cheapest thing to try is your fuel filter. Then consider the pump or even cleaning the injectors.
<font size="2" face="Verdana, Arial">thats what i was gona say. do a fuel filter first. then if you still go lean then do a pump.
 

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Discussion Starter #7
I have a new spare fuel filter to install but, I changed my fuel filter about 5k ago. That is why I'm thinking maybe the pump. I will also try to clean out the injectors. Any more suggestions?

Roger
 

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It could be a few other things. MAF or TP sensor. I would check all of those voltages as well. It doesn't cost to check and clean things up before you start replacing parts.
 

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Discussion Starter #9
How do you go about checking the voltages on the MAFS and TPS @ 6200 rpm Without being on a dyno? That is the only time I'm having a problem, other that the fact that my horsepower is lower than it should be. I plan on taking my old MAFS with me the next time I dyno to make show this MAFS is good.

Roger

[ 02-19-2003, 10:20 PM: Message edited by: Jet powered go-cart ]
 

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It would be tough to do it without the dyno. But the TPS you can key on and open the throttle plate idle voltage should be between .950 and 1 volt and as you opn the throttle should go up to 4.9 to 5 volts. The mass air you could do on the road possibly with a scanning device or on the dyno with a volt meter. You have an aftermarket mass air it might not be reading correctly on the high side. At around 3.5 to 4 volts it could make it jump lean. Thats probably about where you are on top end.
 

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Discussion Starter #11
Okay, say I go back to the dyno to check my MAFS. How will I tell if it is causing the problem, other than putting my stock back on. Where on the MAFS will I take the reading(which wire,etc). What voltages should I be getting @ 6000 rpm and up. In other words, how will I be able to tell if it is bad, so that I could sent it back to McNews for a replacement. Thanks

Roger
 

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On some UK cars with FC 65mm TB's we've noticed the car can go very lean due to the throttle position sensor not giving the full 5v readout due to it not reading full throttle even though the butterfly is virtually all the way open.
Bending the bracket on the throttle body to make sure it gives the full 5v by opening the sensor up all the way helps.

I think it's mainly a problem on the 1.8L Zetecs though...
 
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