I cannot figure how my car runs so lean with the 24lb injectors, 48psi of pressure and MAT sensor relocator.

Amazingly, the HP curve is super flat for a LTR setup! I am sure after the headers and a tuneup, it should squeeze at least another 15RWHP and 20RWTQ.

These dyno runs were made with two burnt plug wires, four fouled plugs and a failing alternator that burned up only 13 miles from the dyno facility on the way home.

EDIT: *I did not realize the wires were burnt and the plugs were shot until a month after when I installed the headers.*

 

One of the plug wires:

 

Didnt catch any questions in your post ....... Do you want a cookie cus you dynoed your stock car that was running like ****?

 

Hey you- MOVE ON.

 

Hehe

 

LOL!!
dyno numbers aint bad...i feel ya. they could be better. i need to dyno my car again too. they were only able to pump 209 from it on the 'stang' dyno. i know my car has more to it. hoping for 220+ next time around with a fan. heres my graph. stock 305, no free mods, nada...i will be dynoing again in a couple weeks. wish me luck.

 

Mustang dyno's are really goofy. Try and find a Dynojet and I'm sure your numbers will be much better.

 

BORLAZ06: I think 209rwhp/270rwtrq is pretty good for a pretty much stock 305.

 

yea its actually not that bad..if nething normal, but i know theres more to it

 

Yes, those are VERY good numbers for a stock 305. I have seen 305's with mods that can't get over 200RWHP!

 

Probably flat because of the poor running condition.

 

Good numbers formul8!! Interesting to see what it'll do with the headers and a good tune. The Air/Fuel ratio plot on the bottom of the dyno printout scares me. 14:1 @ WOT is lean enough to worry about hurting the engine. If that's measured data from a wideband during the run I'd recommend investigating. PROM work may be in order if everything checks out mechanically and electrically.

 

Everyone watching my dyno runs were waiting for the motor to blow up!

I have an SLP stage II chip coming as a temporary band aid until I can burn my own chips. I think that might be the biggest culprit.

I have three other possibilities:

-Crapped out O2 sensor (which I replaced when I did the headers a month ago)
-MAT sensor relocator not working
-Fuel pressure regulator diaphragm is shot

The fuel pump is new, the injectors a clean and the fuel pressure was at 48psi. I am replacing the wires,plugs,cap/rotor, and cat converters. Usually, the problem is running way too rich.

Now with the headers, which have a tendancy to lean out cylinders, I really need to fix this problem.

Any ideas are more than welcome.

 

You can dismiss the O2 sensor since it isn't part of the control loop @ WOT. I don't think it's the MAT sensor either. Insufficient fuel delivery could cause you to run lean but then I'd expect the AFR to get progressively leaner through the run as the fuel system struggled to keep up. The relatively constant AFR throughout the RPM range in conjunction with all your new fuel system parts makes me think that's not your problem. Monitoring the fuel pressure at WOT would tell you for sure.

What have you done to the MAF? Descreened, removed fins, changed to Wells or other brand? Messing with the MAF can really hose the calibration curve that's in the PROM. If your MAF's under-reporting airflow then it won't issue enough injector pulsewidth @ WOT and you run lean. There's a couple of quick checks you can do if you have a scantool.

1. Record the MAF airflow readings at WOT at various points between 3500 and 5000 RPM. I'd expect them to range from say 145 CFM at the low end up to 185 CFM at the high end based on your engine combo. If they are significantly less then the MAF may be under-reporting.

2. Check the block learn values while cruising around in closed loop operation to see if they are generally higher of lower than 128. If they are consistently higher than 128 under a range of operating conditions, that's another indication the MAF could be under-reporting.

If you know someone else who has a similar car borrow their MAF to see how the results from the above tests compare. If it turns out to be the MAF and you don't want to buy a new one, then you need to tweak the MAF calibration curve in the PROM. Heck, you need to get into PROM burning anyway. It'll really help in your quest for 13.0's!

 

Mark,

Thanks for the reply. I have descreened the MAF. No MAF related codes have ever been reported and the wire filament is still intact. Maybe it is weak?

I do have a friend with the Craig Moates software that record some WOT runs. Once I get the car going in the next few weeks, I will run some data.

 

good number!! thanks for sharing them..

 

If any mis-fires at were occurring then the WB O2 reading is useless. So if those burnt plug wires were causing some misfiring. . . all that un-used O2 will show as lean on the WB.

RBob.

 

You need to adjust that chip using the injector constant and the pe vs. coolant tables and pe vs. rpm table.

The scanner data will tell you which way to go.

 

Believe it or not, with the burnt wires- the car audibly ran perfect!!! No misfires could be heard. Now, I am sure scanning would pick up the misfiring I could not hear.

I am going to try to re-dyno the car at the end of the month.

 

Mark beat me to it. If i was a betting man, i'd say your lean problem is your modified MAF.

As for your guesses, as said, O2 sensor doesn't matter at WOT. If you have steady fuel pressure, it has nothing to do with the FPR. And MAT relocation doens't do anything for MAF cars.

Also, as for the flat HP curve, that is exactly what long tube HP looks like. You never see a good peak, because by the time you are into HP land RPMs, the LTRs are choking you off.

Of course fouled plugs and burnt wires probably played some part in that as well.

 

Formul8,
I have scanning software and I think I live somewhat near you. Too bad your car isn't street ready. Let me know when you want to get into the chip burning.

tom