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Greddy turbo running lean!!! Any Suggestions?

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Old 08-19-2002 | 09:33 PM
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Default Greddy turbo running lean!!! Any Suggestions?

Ok. Here it is!

I have been having trouble with my greddy turbo kit running to lean on my 95 sohcvtec EX. I checked all of the sensors inc map,coolant,tps. Every thing checks out good. I assumed that the black or blue box that the kit comes with went haywire. I sent it back to greddy(wasn't very easy) where they took their time and informed me that the box was fine. They said they had it on their test vehicle and they even dumped a new program in it to be sure. They might be just blowing smoke up my ass but I will never know because they sent me no paper work or any thing.

When I accelerate 1rst gear is nice and rich, 2nd Gear I get to about 4500 rpm before the mixture starts running lean, 3rd gear I am just screwed.

Anyway, this is what i have:
venom intank high press high volume puel pump
venom injectors 10percent over stock flow
holley boost sensitive press regulator

pressures are good but for some reason I am not allowed to rich out the mixture

Ive tested from 40psi up to 60psi in the rail but no possitive results. Could the greddy box be restricting the flow somehow.
Old 08-19-2002 | 11:46 PM
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How much boost are you running? Is that Holley boost sensitive regulator an FMU? You need an inline pump to supply the pressure needed for an FMU to work correctly.
Old 08-20-2002 | 12:10 PM
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you shouldnt need a fmu with the greddy black box. that thing alters the fuel for the boost. how do you know its running lean?? what kind of a/f guage do you have.....

sounds like you need to get on a dyno
Old 08-21-2002 | 05:03 AM
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I am using a autometer af gauge. I can get the pressure up to about 60 psi and more so the delivery is their. After that point though the injectors start to lock up. The only reason I am going by the gauge is because it gave me a accurate reading when I knew my car was running good. Now it feels like thier is power lose and my guage is saying lean. I replaced the guage and still the same thing.
Old 08-21-2002 | 07:54 AM
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If you're running more than the stock boost level on the GReddy kit(4.5lbs or so), and are using a boost dependent FMU, you WILL lean out under boost unless you have an inline pump. Do you know what the ratio is on your "boost sensitive press regulator"? If it's 12:1, which is the ratio that is usually used for stock injectors, even at 4.5lbs of boost your fuel pressure is going to be ~94psi(4.5 x 12 = 54 + 40psi static pressure). An intank pump can put out a lot of volume, but it can't generate this much pressure, which is where an inline pump comes in. If you're running anything over the stock boost level on the GReddy kit, then your fuel pressure under boost is going to be well over 100psi, and you will definitlely run lean. You can't rely on the GReddy box will handle all your fuel needs since you can only modify the duy cycle on stock injectors so much before you start maxing them out.
Old 08-21-2002 | 01:02 PM
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I never altered the boost pressure that came stock from the kit. I am not to sure what the greddy box does so i can't trouble shoot any sensors because I don't know what to look for. The Unit that I am using is a holley boost sensitive pressure regulator. So only when boost accures the pressure is aplied. The regulator is fully adjustable. My problem is that something is wrong somewhere in my car so I am just trying to fix it by throwing more fuel into the engine.

The kit is supposed to work on completely stock motors. Which mine was for the most part. The only reason I started adding all of the extra mods is because one day all of a suddon I was running lean..... The kit ran fine for about 3 months on stock parts without any mods.
Old 08-21-2002 | 05:34 PM
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Originally posted by jfdmas
The Unit that I am using is a holley boost sensitive pressure regulator. So only when boost accures the pressure is aplied.
That's what an FMU does. You need to find out at what ratio it adds fuel pressure in relation to boost pressure. As I said, if it's 12:1, or 12lbs of fuel pressure per pound of boost, then you need an inline pump. You're right, the GReddy kit should work fine without any add-ons with just the box, but if your box has gone bad(which some have been known to do), then you need to either get a new one, or switch to a different form of fuel management. If your Holley FMU is adjustable, you need to get it up around 12:1, and run an inline pump to supply the pressure it needs. Or, you can switch to larger injectors. Anyway, I don;t need to tell you that a lean condition on a turbo engine is a disaster waiting to happen, so I would try not to boost until you get your fuel issues resolved.
Old 08-21-2002 | 07:26 PM
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If my fmu is adjustable which it is how am I supposed to know when I am at 12:1??

I have a pressure gauge right off of the filter so that I know how much psi is in the rail. How much pressure should I be seeing when I am under full boost ..... 6-7 preset wastegate.
Old 08-21-2002 | 07:28 PM
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Hey Inspyral!!!!!!!!

I really appreciate you taking the time to try to help solve my problem..
Old 08-21-2002 | 07:52 PM
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The only way I can think of to see what your FMU is set at is to dial in your static fuel pressure(with the vac off), and then run it to a given boost level and then extrapolate the FMU ratio from. To do this you would need an FP gauge mounted in the cabin though, unless you can spool your turbo in neutral(which you might be able to, since the TD04 is pretty small). If you can spool in neutral, set your static FP to say 40psi, and then spool to full boost and take the FP reading. Let's say you get 80psi of fuel pressure under boost. Take 80 and subtract 40(static FP) and you get 40. Take 40 and divide by 4.5(your boost level) and you get 8.88, which means your FMU ratio is 8.88:1 at that setting.

If you have a 12:1 FMU and run 7lbs of boost, your FP under full boost should be around 124psi, assuming a static FP of 40(12 x 7 + 40 = 124.

Again, let me stress that for any FMU setup in which fuel pressure rises to anything over 60psi, you need an inline pump. Intank pumps can flow large volumes, but can't produce high pressures.


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