Running Lean Discovered at Dyno
11-21-2005, 08:39 AM
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Running Lean Discovered at Dyno ARRRRGGG. So I take my car to the dyno for the first time..at Colvin's in Austin. I'm all excited and also trying not to let myself be disappointed...well, we get my car strapped in and hook up the A/F, guy starts to take one run, and at idle the A/F is already in the red...way too lean, so he cuts the run off at 4200 and I had 300.8lbs.ft. and 300hp, he said he heard it starting to ping and it was leaning itself out like crazy. I had my predator and hooked it up and added 5% (the max it would allow) and started another run, same exact thing showed same lean amount on idle and beginning of run, he shut it down and said that was it, we agreed we shouldnt run it again. So the thought was, my fuel pump is on its way out, then I heard about a relay that can cause this as well, i have 82k miles on the car. I thought when a relay fried that was it, wouldnt work anymore. Does this sound like a bad/dirty fuel injector? I am thinking it is the pump? BTW, what should my fuel pressure read, and 2 what should my A/F be on the Dyno?
Cliff Notes:
1. What should Fuel pressure read?
2. What should be the A/F ratio be on a Dyno?
3. Bad Fuel Pump?
Thanks
Cliff Notes:
1. What should Fuel pressure read?
2. What should be the A/F ratio be on a Dyno?
3. Bad Fuel Pump?
Thanks
Last edited by DarkAzNite; 11-21-2005 at 08:41 AM. Reason: adding cliff note
11-21-2005, 01:04 PM
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Thanks NASTYN8
one question, I really can't afford a 250.00 or up fix right now, I may get a used factory replacement, If working full capacity, the OEM should be good to at least 400hp correct?
one question, I really can't afford a 250.00 or up fix right now, I may get a used factory replacement, If working full capacity, the OEM should be good to at least 400hp correct?
11-21-2005, 01:26 PM
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That car mod-list doesn't seem like it should really
be overtaxing the stock system (in good working
order). But, things need maintenance (fuel filter?)
or can go crusty (fuel pump harness connectors,
relays, grounds).
Have you been cleaning your MAF occasionally to
remove the spooge that oiled filters can deposit?
K&Ns are a good way to drift lean and it seems
your problems start kind of where the MAF rolls on
as the primary airflow meter.
be overtaxing the stock system (in good working
order). But, things need maintenance (fuel filter?)
or can go crusty (fuel pump harness connectors,
relays, grounds).
Have you been cleaning your MAF occasionally to
remove the spooge that oiled filters can deposit?
K&Ns are a good way to drift lean and it seems
your problems start kind of where the MAF rolls on
as the primary airflow meter.
11-21-2005, 02:06 PM
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Originally Posted by jimmyblue
That car mod-list doesn't seem like it should really
be overtaxing the stock system (in good working
order). But, things need maintenance (fuel filter?)
or can go crusty (fuel pump harness connectors,
relays, grounds).
Have you been cleaning your MAF occasionally to
remove the spooge that oiled filters can deposit?
K&Ns are a good way to drift lean and it seems
your problems start kind of where the MAF rolls on
as the primary airflow meter.
be overtaxing the stock system (in good working
order). But, things need maintenance (fuel filter?)
or can go crusty (fuel pump harness connectors,
relays, grounds).
Have you been cleaning your MAF occasionally to
remove the spooge that oiled filters can deposit?
K&Ns are a good way to drift lean and it seems
your problems start kind of where the MAF rolls on
as the primary airflow meter.
I have never cleaned my MAF, I am not sure how to do this safely. Any suggestions?
Haven't really looked at any of the harness' yet or any of the grounds etc.
I picked up a bottle of Chevron Techron fuel system cleaner since I read GM dealers use this when doing carbon cleaning, mostly just a last ditch effort to see if maybe the injectors or pick-up were gunked up (seriously doubt it though
)
11-21-2005, 02:10 PM
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Originally Posted by blacktransam
a walboro is only about 100 dollars in jegs summit.. check ebay too
Trending Topics
11-21-2005, 06:11 PM
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You'll have to modify the factory fuel pump bucket a bit, and in doing so you'll loose some of the functionality of the factory fuel system. The wire harness will provide more voltage to the fuel pump.
Matt
Matt
11-22-2005, 03:26 AM
#9
Originally Posted by DarkAzNite
What kind of additional modifications are needed, fitment etc. I read about having to run a completely new wiring harness back to the alternator etc., or buy the racetronix harness set up for 100.00.
http://www.racetronix.com/RX-F99-FPKG-2.html
We encourage customers to buy Racetronix product through dealers such as Harris.
__________________
Manufacturer / Distributor of Automotive Fuel Systems, Components & Electronics
Please support a Racetronix dealer near you for personalized service.
>WEB SITE<
Manufacturer / Distributor of Automotive Fuel Systems, Components & Electronics
Please support a Racetronix dealer near you for personalized service.
>WEB SITE<
11-22-2005, 07:41 AM
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Originally Posted by Racetronix
Please read through our ad. It addresses all you will need to know to make an educated buying decision.
http://www.racetronix.com/RX-F99-FPKG-2.html
We encourage customers to buy Racetronix product through dealers such as Harris.
http://www.racetronix.com/RX-F99-FPKG-2.html
We encourage customers to buy Racetronix product through dealers such as Harris.
I have read this. would rather buy a Racetronix kit, just can't afford 250 bucks right now. So will most likely just get a rebuild kit, or buy used.
Thanks
11-22-2005, 01:44 PM
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Originally Posted by jyeager
Why are you buying new parts based on an assumption? Did you measure fuel pressure during the pulls?
What else could it be? Maybe fuel injectors are clogged/dirty?
11-22-2005, 02:22 PM
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Could be the MAF. Someone mentioned this earlier in the post, but the K&N filters often coat the maf wire with oil unless you are very sparing on the amount of oil you use.
There's also a fuel press. regulator somewhere in the back of the car, on the return line.
One or more clogged/malfunctioning injectors?
There's also a fuel press. regulator somewhere in the back of the car, on the return line.
One or more clogged/malfunctioning injectors?
11-22-2005, 02:56 PM
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Originally Posted by jyeager
Could be the MAF. Someone mentioned this earlier in the post, but the K&N filters often coat the maf wire with oil unless you are very sparing on the amount of oil you use.
There's also a fuel press. regulator somewhere in the back of the car, on the return line.
One or more clogged/malfunctioning injectors?
There's also a fuel press. regulator somewhere in the back of the car, on the return line.
One or more clogged/malfunctioning injectors?
Where is a good place to get a fuel pressure gauge?
Is the regulator an item that can be replaced?
Also wouldnt a faulty injector generate a SES code?
Last edited by DarkAzNite; 11-22-2005 at 02:57 PM. Reason: add question
11-22-2005, 03:56 PM
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You should be able to get a pressure gauge at the local auto parts store. You might even be able to rent/borrow one. I know the local autozone often loans out DIY tools. This just screws on to the test port on the end of the fuel rail. You'll need to be measuring under WOT and near red line though, so it will only really give you good info on the chassis dyno.
Is fuel pressure one of the sensor readings available with ATAP? If so, you could just read it with a laptop while driving on the road.
I'm not sure if any solvent cleaner (say carb cleaner) will work for cleaning the MAF, or if you need something special. But cleaning it is the first thing to do.
The regulator can be replaced. I remember there being a lot of info 1-2 years ago about how the stock regulator often fluctuated pressure output quite a bit under high demand. There was a lot of interest at the time in a better aftermarket unit. I don't have specifics though, try searching the archives. (but you should find this to be the problem first before bothering).
If possible, any dyno tune session should be logging your A/F ratio with a wide-band and plotting this alongside fuel pressure.
Is fuel pressure one of the sensor readings available with ATAP? If so, you could just read it with a laptop while driving on the road.
I'm not sure if any solvent cleaner (say carb cleaner) will work for cleaning the MAF, or if you need something special. But cleaning it is the first thing to do.
The regulator can be replaced. I remember there being a lot of info 1-2 years ago about how the stock regulator often fluctuated pressure output quite a bit under high demand. There was a lot of interest at the time in a better aftermarket unit. I don't have specifics though, try searching the archives. (but you should find this to be the problem first before bothering).
If possible, any dyno tune session should be logging your A/F ratio with a wide-band and plotting this alongside fuel pressure.
11-22-2005, 06:15 PM
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Thanks,
I was able to borrow one tomorrow from a buddy at work. I will check out my pressure tomorrow and gonna clean my MAF with some electrical contact spray. I dont really have the $$ for a tune or wideband analysis right now so I guess first will take pressure reading under idle and blip of throttle, maybe take it to 4k or 5k for a split second and see if I still have 47lbs?? I think that's what it should be, forgot exactly think it was answered in earlier post. If it drops or sputters, then will look into the check valve option, then i guess replace the pump.
Thanks
I was able to borrow one tomorrow from a buddy at work. I will check out my pressure tomorrow and gonna clean my MAF with some electrical contact spray. I dont really have the $$ for a tune or wideband analysis right now so I guess first will take pressure reading under idle and blip of throttle, maybe take it to 4k or 5k for a split second and see if I still have 47lbs?? I think that's what it should be, forgot exactly think it was answered in earlier post. If it drops or sputters, then will look into the check valve option, then i guess replace the pump.
Thanks
11-23-2005, 10:02 AM
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The first thing you need to do is measure fuel pressure...if its dropping down significantly under load then you know it is either the fuel pump or the fuel sump screen on the fuel pump assembly. Is it noisy? If fuel pressure stays consistent under load then check the MAF for oil. Just spray the wire throughly with a good electronics cleaning spray that does not leave a residue. You can get some at Radio shack. Just make sure it states for electronics and non-residue.
11-23-2005, 02:51 PM
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Originally Posted by cantdrv65
The first thing you need to do is measure fuel pressure...if its dropping down significantly under load then you know it is either the fuel pump or the fuel sump screen on the fuel pump assembly. Is it noisy? If fuel pressure stays consistent under load then check the MAF for oil. Just spray the wire throughly with a good electronics cleaning spray that does not leave a residue. You can get some at Radio shack. Just make sure it states for electronics and non-residue.
it is not noisy at all, on the dyno my AF read that it was lean even at idle, I tried to richen up with the predator and it had no effect. I will check the pressure and clean the MAF and see where it stands.
