dyno tune

Discussion in 'Fox 5.0 Mustang Tech' started by radimm, Oct 15, 2003.

  1. Had the car on the dyno tune today. They had to recalibrate the FMU. The A/F ratio looks lean to me. Engine has stock cam, headers and valvetrain. Why is the HP curve so choppy - uneven? Can this be due to belt slipping? Don't have the boost gauge hooked yet. :shrug: What you guys think?

    Got it - 80kb limit for pics.

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  2. hmm seems a bit chopy and kinda low numbers.

    I think the best thing, although spendy would be a custom chip.

    Im NA and picked up 20 rwhp with just a custom chip
  3. I'm thinking timing, tune...somethings not right. Possibly belt slip But I would think you'd be make atleast another 20 hp.
  4. Wow, your about 100 hp too low! That a/f looks too lean for a "tuned" blower car. I would guess you would want the a/f to be in the 11's. A few things I would look into are, a better maf (pro m 80mm) 255 high pressure pump and 42lb injectors. With the 42's, you can ditch the fmu. Then take it to a place that knows how to tune. I have a friend w/a very similar set up and he's making over 400rwhp with a very safe tune (and his car isn't 100% perfectly tuned either)
  5. I expected like 40-50 HP more than those :nonono: 312 on the dyno. It got me thinkin' - after the blover install I have the 66 code problem exactly like has GroverDill, so there is something wrong with the MAF. The A/f curve (lean) is flat all the way so if I rise the fuel pressure on the regulator say 1-2 psi it should drop to the desired 12:1 range. It is just my uneducated guess.
    But lean (from my understanding) is more power. :mad:
  6. If the belts slipping the dyno pull is pretty much worthless.

    BTW. Do you have the stock headers and H-pipe on that car? I dont see anything in the sig.
  7. Thats right stock headers. I have an 2.5 inch H pipe with cats. I don't know how to find out the belt slippage other way than to hook the boost gauge and look if it rises as the RPMs go up.
    But still even with the stock headers the numbers should be higher. :bang:
  8. The stock exhaust system is hurting you.
  9. Agreed. Even more so with a boosted car. I still agree that the number should be higher than they are.

    Get a boost gauge.
  10. I will install the boost and temperature gauges this weekend and see what boost reading is. I will also see what is the timing and fuel pressure set at And will definitely rise the fuel pressure 1psi higher. Car bucks around 2000RPMs when gas pedal is hold steady. Looking at the A/F chart the line is flat without any surges so I donn't think my problem is fuel or air delivery. More likely it is spark or timing related. But for the spark issue I have brand new wires with dividers, MSD ignition coil and NGK TR6 spark plugs (will measure the gap tomorrow) will change cap and rotor to be sure. What to look at for timing problem? The timing retard knob is set exactly between 1 and 2 from the tuning.
    When I was setting the timing back from 14 to 10 first thing after blower install i noticed the timing mark was jumping a little back and forth (about 1/4inch) is this normal?
    Need more help guys please. I hope with your help I will crack that little coconut. :D
  11. radimm, just b/c your a/f is nice and straight, doesn't mean its tuned properly. For a blower car, your car is TOO LEAN! Raising the FP 1psi isn't gonna do chit.

    As for the timing marks jumping around, you pulled the spout connector, right? If so, possible bad timing chain. Like others said above, ditch the stock exh too.
  12. Yes, you need to find out what your boost numbers are, we can see the expected power then.....you are in dire need of a good tune!!! I would get something like a Tweecer RT, its not much more than a custom chip and has 5 settings to swap to/fro.

    And WOT pulls don't tune for part throttle, the Tweecer would be ideal for this as well.

    I agree, a few more PSI of fuel isn't going to do much at all.

    @8PSI you should have a MINUMUM of 370 RWHP
  13. Well thanks for the fuel pressure tips I will not mess with it then. I had some time this afternoon to look under the hood and first think I have noticed after new bleeder valve on FMU was a white T the tuning guy spliced to vacuum line going to FMU between original T going to bypass valve and FMU itself with remaining leg of the T left :nonono: OPEN. So that means I had a vacuum leak. But car idle was normal like always. Removed the T and now car runs worse :owned: On my way home from work the engine died on me 2 times. I don't understand. :notnice:
    I will put the T back on tomorrow to see what happens. Other than that cleaned the MAF sensor with brake cleaner and also cleaned the conector pins. But the code 66 is still coming out. I will check the voltages like MSTANG said. But for that I have to disconect the connector at MAF and have key in on possition right?
  14. Ok, get rid of the stock headers, that's causing some major problems right there, and probably more then just lack of hp.

    DO NOT clean your mass air sensor with brake cleaner, it is MUCH too strong and can result in very wrong readings from now on. You are supposed to use electrical parts cleaner, which is ammonia based, which allows the liquid to vaporize almost immediately and thus leave no trace of residue on the wires.
  15. You are right the cleaning made things go worse since code 66 appears more than before so I have ordered new 80mm ProM MAF which comes with the sensor so I will see what will happen then. I have called Speed Inc. to see what they have to say about the lean tune and the T but since it was friday late afternoon the tuning guy was not in so I have to call back monday.
    Hey FordRangerFan17 I think I know what you mean. I have opened up the engine with bigger MAF -> TB -> intake manifold -> heads + started pumping more air with the supercharger but the headers are my bottleneck and all of the air pushed in hardly exits thru the exhaust. I will look into it after the maf. Thanks for the tip. :nice:
    The Tweecer is cool hardware but since I have to fork the additional money for the maf and headers I can't afford it this year.
  16. your definetly to lean.. should be around 11-11.5:1. You really need to see how much boost your pushing. Also remember once you change your mass air, your tune that you just got is worthless. the MAF parameters will be different and will require a new tune. but it looks like the tune you have isn't too great anyways. I'm not a fan of C&L meters especially with blowers so i think your on the right track with the the new meter and headers but i would retune it and get the a/f down to around 11-11.5 and total timing around 20-22 degrees and see how it responds. you may also want to look into an ignition box at some point.
  17. could a mestup clutch be the cause of that kind of "choppiness"? :shrug:
  18. I'm not exactly sure but I know a lot of dyno programs let you smooth out the curve. I assume that most dyno printouts are implementing the feature, and perhaps yours was not. So what I'm saying is maybe everybodies curves are somewhat choppy, but just smoothed out by the program ?
  19. Not likely. I can fell the car bucking when driving with like 30mph in 1600-1800 RPM with gas pedal holding steady, not accelerating or decelerating. BTW the Centerforce clutch has about 4000 miles and the problem was not there before blower install.
  20. Hmm, I never heard of it. Anybody else?