I went to dyno my car again locally after the Atlanta dyno day was posted as cancelled and ran into some problems.

Problem:
My car at about 6k (106mph in 4th), hit fuel cut and bucked like crazy. I had hp go from 294 at 6k to 55 at 6100 and 324 at 6200 (to give you an idea how bad it bucked)

Conditions:
Air Intake Temp - 15C
Fuel and Ignition Maps - Tim Benton's
Inj Duty Cycle at 6k - 97.8%
Boost - set at .80, hit .95
Ice on Manifold and IC out (water dripped down the side of the engine)
Peak Knock - 65
AFR - 10.5 until 6k, then it drops dramatically, don't know how low because 10 is the baseline

Solution:
Not too sure on this one, I think it's just fuel cut from too much fuel and too much boost. I took out some fuel from row 17 and it didn't do but get me about 50 rpm before it would cut again. With my mods, what's the lowest you would go on the fuel maps? I am scared of running it too lean...

Any help is greatly appreciated.

Richard

 

By the manual, if you go .25KgCcm over the boost level, you will have cut. Your .95 was very close to 1.05. Maybe enough for error to cause it to happen.


Are you trying to blow your engine? The real danger is you injector duty cycle. You hit 97.8%. That means you ran out of fuel a long time ago and the injectors were about floating open. 85% is considered the highest for continous running. I wonder when your engine achieved that mark.

 

What would be a good solution? It seems that taking fuel out seems the best solution, but I don't understand why my car is running so rich!!!! If I'm using identical maps to others who have "tuned" their Power FC, I would think I would need light tweaking, not taking 4-6% of fuel out. That seems like a lot to me.

Also, the danger in blowing the engine is there, but how bad is it actually? I'm running extremely rich and the injectors can't keep up... well I say good (until the fuel cut) because there's already too much fuel going in there.

Richard

 

The first thing you need to do is adjust your fuel with a linear O2 sensor.
Start at a lower boost like 10 and adjust the fuel map. That will give a little indication of what you maps are doing. Then go to 12PSI and do the map again. While at 12psi, observe you duty cycle.


.8kg is 11.4 psi
.95kg is 13.5 psi

If this .95 reading was on the commander, then you were really over 14psi boost.

Keep your boost down to the conditions that your mods can handle.

 

Ok, so I'm looking at spending time and money to rent the dyno for a day, right? Next, I need to find a way to keep my boost down... Can you give me a .8 primary and secondary as well as a .95 pri and sec. solenoid duty cycle, that might be my problem with the boost going too high.

Could the low AFR be due to my base maps being programmed by Ray and that be the major difference between my fuel map and Tim's? If so, the base map is WAY TOO RICH!!!!!!!!! I think I'll call Ray tomorrow as well.

The .95 being over 14 psi because the commander doesn't show the proper boost level, right? So you're saying that because my commander said .95, that I went over 1 and hit the boost limit and had fuel cut, right? I have seen 1.02 on the commander before and not had fuel cut.

I wish the Datalogit could be used, seems like tuning a fuel map with exact O2 sensor readout along an rpm line would make it a lot easier. Also, this dyno is not good at hooking up their equipment on an FD, they cannot get a proper torque reading becuase it doesn't know rpm. The guy who runs the dyno doesn't know how to read from a coil, any idea?

I appreciate all your help guys (Chuck!)

richard

 

Richard,

we had 4 cars dyno at another dyno saturday. All 4 cars had break up at 6K, 2 NA 2nd gens, and 2 modified FD's. We had the same problem as your guys, he kept complaining about getting a good reading. None of our cars bucked or anything but at 6k, crazy hp going up and down. Mine did as well, even though the past 5 or 6 runs tuning the PFC was smooth (dyno smooth) from start to finish. His pick up he hooked up to our plug wires was sitting in 1 inch deep water, that's brilliant. Bad part was it was the part that had a connector for 2 lenths of the wires. I'm just going back to Arthurs next month (feb 9, 16, or 23) but haven't set a date yet.

At to your PFC and resulting fuel cut at 6k using my maps. When you say low AFR, what were you using to get the 10.5 reading from the start of the 4th gear pull up to redline? Just curious. I too am having boost stability issues with the cold air. I'm going to stick some bigger pills in the lines and see if that helps. I'd rather be able to raise the duty cycle number to get more boost if the pills lower the boost, than to be in the situation we are in now with not being able to lower boost with the duty cycles.

What ignition system do you have? wires and plugs new? how many miles on them.

Tim Benton

 

Plugs and wires are about 3k old. I was using a probe type Wideband that the dyno provided. My boost pills are slightly larger than stock which would make my duty cycles be a bit more "functional" for me. What are the .8 stock duty cycles out of curiosity? I don't have any problems with your maps, I just think that my base map is too rich for them, I seem to be the only one running too rich with it, for the record.

Thanks

Richard

 

I'm sort of mixed up. I was pretty sure that larger pills would help you to make more boost. Or do I have that mixed up.

Tim Benton

 

a Larger Pill on the wastegate actuator line allows more pressure to pass thru which makes the actuator open the wategate more which vents more boost. The larger the pill the lower the boost.

 

I see where I got it mixed up, larger pill means larger hole for the boost to get through, lowers boost, smaller pill means smaller hole, more boost.

Simple now,

Tim Benton