Not Boosting Correctly?

[Livid]

I recently put in 440cc injectors. I have a SFMU controlling them.

For some reason I can only boost up to about 10psi, according to my gauge, no matter how high I turn up the boost controller, and it doesn't even feel like 10psi. I can see the gauge go up but I gain barely any torque. I know I'm getting enough fuel because it always reads rich. Could being too rich be a problem? Also my internal wastegate is kind of messed up, would this also cause my car to lose boost or not get an actual 10psi like my gauge says. It just feels like im not nearly getting the power I used to get before I put in the injectors, and also I'de like to get at least 15psi out of it and I can't get there. Once I hit 5k rpm my car feels like its not releasing exhaust then all of a sudden it almost sounds like my exhaust releases all at once. I don't know where to start or how to get it to run correctly so any help would be appreciated.


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Weisco Pistons
Eagle Rods
Super FMU
440cc Mustang Injectors
T3/T04b Turbo
Full 3" Turbo Back Exhaust
FMIC
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[BigRand]

Gotta check for vac leaks. And your wastegate is a big deal. You gotta make sure its working properly, ( I don't know too much about internally gated systems) And see if you can't get somone to read out your Fuel pressure on the SFMU under boost (I don't think that is the problem, but it would be good to know)

Also make sure your vac hoses are all the same sizes. Not to big either.

 

[Livid]

My mechanic told me it's probably because my wastegate is messed up, but I don't understand why if my gauge says 10 psi I'm not getting the horsepower? From 3-10 psi I feel no difference. I can understand the WG making it spool slowly or making it not reach 15psi or higher like it should, but I don't get the the issue with me not feeling the real psi. My boost gauge reads from the vacuum line in the intake so doesn't this mean 10psi of air is going through my engine? If so shouldn't I get the hp/torque no matter what the wastegate is doing?

 

[DSMcrazy3]

I had the same problem. Slow spool up, no power though it would read on the gauge I have it at times...I don't know the cause of it reading, but not actually being there. But my problem was my Exhaust manifold gasket was done for. Make sure all of the bolts holding the exhaust manifold on are tight as can be. I believe spec is 17 ft. lb... Anyways check for an exhaust leak there too you can probably hear it if you have one, you can def. feel it too. put your hand around the edge of the manifold to see if you can feel that air getting out. It was the bottom of mine that was toast and I definitely wasn't going to put my arm down there, since the car was running... Here's a quick pic of how bad my gasket was. It WILL kill your boost.

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[Livid]

Could too much fuel cause this problem? Like if my engine is getting flooded? My SFMU hasn't been adjusted since I got my 440's put in. So I think that it might be using the wrong fuel curve and when I boost it is raising the pressure too much causing it to run WAY rich. Could this be my problem?

 

[baxsom]

are you getting black smoke?
are the tips of your plugs black
what is your afr saying

do a vacuum leak test
so you can rule out a vacuum problem

i had a problem getting my boost level past about 10 as well and it turned out i had an air leak at the throttle body

there is a write up on the boost leak tester in the tech section
basically pvc and a schrader valve hooked to the turbo intake

 

[cs82685]

Could too much fuel cause this problem? Like if my engine is getting flooded? My SFMU hasn't been adjusted since I got my 440's put in. So I think that it might be using the wrong fuel curve and when I boost it is raising the pressure too much causing it to run WAY rich. Could this be my problem?

IDK if this is your problem, but what do you mean not adjusted, do you still have the same disk/ring combo in as when you had stock injectors?
here's one of the setup suggestions for 440's with sfmu and no afc, 2.72 ring and disc along with the silver spring. I am going to set my idle pressure at around 20psi (some say even lower like 14-18) with a little searching you can find a bunch more, you may need a bleed valve too but i'm not sure, let us know how it works out b/c I am planning on going to 440's soon

 

[clipsit]

Does anybody know what size disk I should replace in my fmu if I have RC 550c's, SARD fpr, safc, 255 fp, instead of the 12:1? I talked to Rand about it, but I am not exactly sure. So to anyone who could enlighten me and others on this subject more clearly. I hope there isn't a thread about this already, sorry if there is...

 

[Livid]

I adjusted my SFMU with the 2.47 disk at around 19-20psi of idle fuel pressure and it runs great. This was definately my problem. Now I just need to adjust my wastegate since it will only hold 11psi right now.