fuel management unit

[blown89]

this is what im told is the problem with my car...i just had to replace the maf sensor and now my car idles somewhat but my problem is that it just doesnt feel like im getting all the power i got. and i want to get it dyno tuned but the said that it cant be done w/o the fmu. im not sure if my timing is off (14 degrees), or it needs to be tuned. but any info would really help on this cause its making me mad.

thanks
cory

[Greg@GLD]

Can you be a little more specific about your combo and the problem you are having with it Cory? An FMU would not be the cause of idle problems in most cases, it only comes into play under boost conditions, unless it's hanging up somehow, but a fuel pressure guage would show higher than normal FP if this were the case.

As far as the dyno tune, that's kind of backwards from the norm- Some guys forgo the FMU for larger injectors and a custom tune.

What size injectors do you run, and is the FMU properly calibrated for them?

[blown89]

alright here is my setup...i run 6lbs of boost off a powerdyne silent drive w/ 24# injectors and thats the thing im not sure if my car has a fmu...and how would i tell if it does??? any help with this would be great greg,
thanks
cory

[MAT88GT]

look for something like this....it looks like a hockey puck and will have a vac line and a return like leading into/out of it. Exactly as Greg said, the fmu does nothing during off boost situations such as idle
http://www.superchargersonline.com/images/productimages/paxton_fmu.jpg


I assume the maf is calibrated for the injectors? does the eec show any codes? when was the last time you cleaned the iab/egr? whats the timing at?

[Greg@GLD]

The Powerdyne kits came in 6 PSI and 9 PSI. The 6 PSI kit did not have a boost bypass valve but it did have an FMU. Also, the pix Mat posted might confuse you only because of the colored billet aluminum- On your Powerdyne the FMU is going to be black or aluminum. It is typically mounted over on the passenger side fender near the hood hinge. It will have a vacuum line attached to it and two fuel lines- This should be easy for you to spot- Look at the fuel rails on the intake, and follow the lines back to the firewall. One of the lines will be connected to the FMU- then from the FMU to the distribution block.
Does your car have a fuel pressure guage? If it has an FMU, then under boost you will clearly see quite a spike in fuel pressure if you have 24 Lb. Injectors, I believe the guage would read somewhere around 65 PSI at full boost.

[blown89]

alright yea i seen it...i had to unbolt it off the fender to get my maf sensor in, i was wondering what that was...thanks man, and the timing is set at 14 degrees and no i do not have a fuel pressure guage. i started and took it for alittle spin today and i think my computer is reading correctly now, idled just fine but the loss of power is still there, any ideas on what that would be??? any ideas would be great, thanks alot guys

cory

[Greg@GLD]

It's hard to diagnose these things on the internet man...
Do you have a boost guage? Maybe all you need to do is tighten your blower belt a bit? Also Powerdynes have been known to have the belt break, but this is more common on the 9 PSI units, not the 6 PSI.

Is all your ductwork secure and tight? Perhaps a clamp has come loose. Did you check all your vacuum lines Cory? Under boost they can pop off. It's a good idea to secure them with zip-ties....

So many things could cause loss of power...

[blown89]

actually i went out and worked on it for awhile tonite and i checked the vaccum lines and they are already ziptied...as for the ductwork, the hose that runs from my maf sensor to the back of the blower was pretty beat up. i took it off and checked it over...there were some small holes and tears...so i customized with some electrical tape...now its nice and shiny black and i also tightened up all the the clamps. i wanted to take her out and see how shes running but i just cleaned my k&n tonite so ill have to wait til tomorrow...ill let you guys know how she goes

thanks alot guys,
cory

[Greg@GLD]

Ok Cory, good luck...

[blown89]

alright update...took her out and she ran better...alot better but still not all there but i found a guy that is an instructor at uti and he said to just bring it in and he'll figure it out for me so hopefully by next weekend i might actually be able take her out cruising

[blown89]

well now today i took it out and now shes running better than ever...and my tach is now working, i swear this car has a mind of its own, but im still getting it looked at on friday...ill let you guys know how it goes