Tuning issues
Hi all,
Been busy but finally got a little time to tune. I’ve been fighting a over 4500 RPM detonation problem at full throttle in 1st gear only. I tried TTNOV pulling timing and it worked but performance really suffered so it wasn’t acceptable. The most timing I could run in the WOT spark advance vs RPM function was 21*, but I still got detonation over 4500 RPM in first gear. I got to thinking about what was going on, looking over the datalogs and nothing made much sense (looked ok). So I decided to back up a bit and remove the tweak I did to the spark advance rate vs RPM function. When I originally did this my thinking was to allow the PCM to remove timing faster. The spark advance rate vs RPM function settings I was using: 0, 0.5 992, 0.5 3008, 0.375 4000, 0.125 8160, 0.125 Versus the original of: 0, 2 0, 2 992, 2 3008, 1.5 4000, 1 8160, 1 So basically 4 to 8 times faster advance rate than stock. So when I went back to the original spark advance rate vs RPM function I am now able to run 23* in the WOT spark advance vs RPM function with no detonation. All I can think of is that the PCM can’t deal with the higher slew rates of the modified spark advance rate vs RPM function. Datalogs before and after these changes are virtually identical. Anybody have any insight here? Gt90stang, Don Engine: 306 ci w/ timing at 10*, Sterling pistons H273CP w/8.9:1 compression, FMS Harmonic balancer, Edelbrock 6037 heads w/2.02" intake valves, Explorer lower intake manifold (GT-40), FMS 1.6 roller rockers, Crane 444221 (2030) 216/220 @ 0.05" with 112 lobe separation 0.533"/0.544" lift, Ron Davis aluminum radiator, Lincoln Mark VIII electric fan, 130G alternator Tweecer RT, Performance Distributor TFI module & Scream’n Demon Coil, Denso Iridium Spark Plugs IK-20, FMS oil cooler. Fuel and Air: KenneBell Blowzilla @ 8psi with a 10# pulley, 42# FMS injectors, Edelbrock 70mm TB, C&L 76mm MAF, Stock fuel pressure regulator, 190 lph fuel pump, Stock airbox w/ K&N filter (silencer removed), 91 Octane Fuel. Exhaust: 1 5/8" JBA Titanium ceramic coated shorty headers, MagnaFlow SS 2 1/2” catback and X-pipe w/Cats. Drive Train: D&P Products 2500 RPM stall 9 1/2” torque converter w/damper, AOD w/ TransGo HP shiftkit, Earl’s 19 row transmission cooler, FMS 3.73 gears. Wheels and Tires: 17” x 9” Replica Cobra R, 555 Nitto Drag Radials 275/40ZR17 rear & 555 Nitto 255/40ZR17 front. Brakes: Front 73mm calipers from 1991 Lincoln Mark VII, Sn95 MC w/3-2 port conversion & Russell SS hoses, adj. Proportioning Valve in series with the stock Combo Valve. Chassis: FMS Subframe connectors, Energy Suspension engine, transmission and front sway bar mounts. |
21-23 degrees of timing is kind of high with your current compression ratio being that you are blown. I realize that you are running low boost but any boost will generate heat (without an intercooler) and limit your timing that you can safely run.
In my opinion you should tune no higher than 19 degrees total timing from about 4k rpm and up at WOT. If you go to a higher boost pulley down the road you will need to cut the timing back more. Aside from that, your C&L meter is not doing you any favors either |
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I have seen a few members on this site (including myself) have nothing but trouble with these meters. We use to be a dealer for them but after seeing many problems with them I made the call to quit carrying them within about 8 months and I do not recommend their meters whatsoever on any car. |
I have had nothing but luck with them.
C&L 76mm w/ 24's N/A C&L 76mm w/36's S/C - 8 psi C&L 80mm w/36's S/C - 8 psi C&L 80mm w/42's S/C - 11 psi Each time I simply changed the sample tube and adjusted the MAF curve accordingly. I am now running the 80mm with the "Tuner Tube" and it provides a super clean signal from idle to over 3000 kg/hr if needed. There aren't many meters that can do that. I would use a C&L w/Tuner Tube over any meter on the market & I love the flexibility it offered me over the years. A new injector or max. flow rate was just a sample tube away. I did a survey on a huge Mustang hop-up site a while back and a huge majority of the complaints were about ProM/PMAS meters. People can believe the bashers if they want, but all meters have issues when people who refuse to get a tuning device think they can just throw on a new meter and larger injectors and go. Then they blame the meter - unbelievable!! :devileek: |
Hi all,
Thanks for the replies. Yeah, I have both Spark advance vs ACT functions pulling 10* at 254*F, so it really only sees about 21* max and less as it heats up. Both C&Ls that I have used (73mm & 76mm) required tweeking the MAF curve with a WB02 and I now am seeing some strange pull back areas (not huge) that are noticable in the MAF, MPH and RPM plots at WOT. These are probably due to the C&L MAF. Anybody else try the tuner tube in the 76mm C&L MAF with 42# injectors? Don |
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I'm using it with the 80mm MAF - don't see why it would work differently with a 76mm. A lot of people don't even know about the tube yet. It pulls air from the bottom of the tube near the middle of the meter so it is more resistant to back-pulses and bends in the piping before and after the meter (the main problem people have with meters is they've changed the intake tubing). Even the STOCK A9L programming has several places where AFR was modified @ WOT (OL), so since even Ford with their little 60mm meter couldn't get it perfect, the idea that any meter could be perfect is some bizarre internet fantasy. If you were a mechanical engineer or had read about meters as much as I have you would realize that 99.99% of the people on the internet haven't the foggiest notion about airflow meters. |
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If it can't be cleaned up with a tuner, then the electronics are bad/got damaged/are dirty. I have two sets of electronics so I was able to verify that one set was indeed bad. Having used two different diameter tubes (76 & 80mm) and 5 different sample tubes (clear, black, red, blue, and Tuner), S/C & N/A, I can verify that the meters have no inherent issues with being tuned. If the meter has a bend immediately before or after it, then all bets are off - but this is common sense stuff. Here is a post that discusses all this stuff. I love his description of a ProM Bullet meter:
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I could point to a dozen folks who have cursed to high heaven using a ProM or PMAS meter, so examples of people who can't or refuse to tune properly or give up after 2 days are a dime a dozen... |
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