A9L swap, ?'s

[93cobra#3326]

Originally posted by 93Cobra2771
Bryan - you made the swap leaving the stock injectors and stock MAF in there? If so, then the car was running rich, which would explain why the during and after shifting was running better. Bad behavior during and after shifting is usually due to a momentary lean condition... Oh, and hear you go

Lee - no shift retard on 93 Cobra - didn't start that until 94 Cobra...

thanks richard :thumbsup: hehe
hey ah your comment about lean between shifts. do all eec's or just the x3z lean out between shifts? in a unchipped supercharged application this could be a real hazard! i wonder if this could be partly the cause of my blown hg. -or at least straining them...sort of speak :??:

i know the x3z vs. a9l match will always be a issue. but im still not a believer :nonono:

-bryan

 

[Lee]

Ok, I got less out of my "chip" than I thought. :??:

 

[93Cobra#2771]

Bryan - power adder guys will often get lean initial tip in during throttle transitions. There is also a 2 sec delay (on A9L) and 8 sec delay (X3Z) for the computer to change to Open Loop during high load/not WOT conditions. In other words, if you like to lug around and pull hills in 5th gear at low speeds/low rpms, and slight blower boost, then you can easily go leaner than the eec can correct (it can't make the changes quick enough). It's all about throttle tip in values. And a car with efficient h/c/i will aggravate the condition. The more efficient the combo, the more it will need during tip in.

Lee - not necessarily. Timing values are very soft on both eec's, and the cobra is hindered by its extra rich WOT settings. I noticed and immediated difference in my car when I first chipped it - much stronger on the top end, mainly due to the leaner commanded a/f.

 

[Lee]

My dyno run showed air/fuel pretty steady at 13.6. Is this about right?

 

[93cobra#3326]

what your saying does make sense now, when i think about what the car is doing while im watching the wideband. theres definently a slow transition, way too slow. i lean out bad under part throttle boosted load.
something is definently amiss with the car.installing the 42's,pro 80mm made it worse. ive seen this coming for a while now but, im at the point were i NEED aftermarket tuning. the eec just isnt cutting it by itself. and i hear so many people say they had similar problems until they swapped in the a9l. now you and i both know you cant always believe whatchya read but stilll makes me wonder :read:
-bryan

 

[93Cobra#2771]

Lee - ideal a/f at WOT is open to debate, but most people shoot for the 13.2 range. 13.6 is a tad on the lean side, but I prob. wouldn't mess with it unless you are going to change anything else.

Bryan - while the 42's are bigger, the MAF now has less "resolution" at lower rpm as well (nature of the beast, no way to avoid it).

I can almost guarantee that if you get a chip burnt using your flow sheet from your ProM MAF (ABSOLUTELY INSIST YOUR BURNER DO THIS, OR FIND ANOTHER BURNER IF THEY WANT), along with inputting your high and low injector slopes, your car will feel/drive like you've never felt before.

Think about it this way - it's a relatively cheap change compared to your other mods...

 

[93cobra#3326]

Originally posted by 93Cobra2771
Bryan - while the 42's are bigger, the MAF now has less "resolution" at lower rpm as well (nature of the beast, no way to avoid it).

I can almost guarantee that if you get a chip burnt using your flow sheet from your ProM MAF (ABSOLUTELY INSIST YOUR BURNER DO THIS, OR FIND ANOTHER BURNER IF THEY WANT), along with inputting your high and low injector slopes, your car will feel/drive like you've never felt before.

hey richard could you explain a little more about the "resolution and what affect it has? not sure if i understand. also high and low injector slopes-?? whats this about?? how do you find what mine are? etc..

Think about it this way - it's a relatively cheap change compared to your other mods...

oh i agree, now if i can just get the ol' lady to understand that :thumbsup:
thanks for any input man,
bryan

 

[93Cobra#2771]

Resolution - basically, it has to do with airflow vs. MAF voltage. Two factors affect it: Physical size of the MAF, and injector size it's calibrated for. For example:

(all numbers are hypothetical and just to describe resolution)

Meter "A" - Can flow up to 800 cfm. Calibrated for 19# injectors
Meter "B" - Can flow up to 1000 cfm, calibrated for 42# injectors

Typical MAF airflow during normal driving will range from 50-200 cfm. This is the same no matter what MAF you are using.

Now, Meter "A" flows 800 cfm at 5v. Meter "B" flows 1000 cfm at 5v. 200 cfm difference, big whoop, right? Wrong.

Now, at 1.25v, Meter A flows 200 cfm. At the same 1.25v, Meter B flows 250 cfm. Do you see the trend here? When you start getting into lower voltages/airflow levels, the bigger MAF has a harder time covering the bigger spread of airflow with the set amount of voltage available.

Kinda like fooling with the "mouse" speed on your computer. Set it up to as fast as it goes, and you can easily move from side to side on the screen with a flick of the wrist. Try to select a single letter in a text document at the high speed, though, and it's a whole new ball game. The amount of distance the pointer covers vs the amount the mouse actually moves makes it very difficult to define exactly where you want to be when it is a very small area. Set the mouse speed to slow, and you can easily select what you want.

Hopefully that makes sense.

Hi and low injector slopes - the eec can be programmed (via chip/tuner) with your actual injector size (just as the 93 Cobra was programmed with "24"). Greatly affects drivability during part throttle conditions. Also has a big effect on idle manners as well...

 

[LEE93COBRA]

Damn Richard. I thought I was at the tweecer forums for a minute.

By the way #6 cylinder in my car is dead

 

[93Cobra#2771]

By the way #6 cylinder in my car is dead

Bummer, but I can't say I'm surprised. That much boost on a motor with that many miles, something was ready to give. Had a chance to tear into it yet?

BTW, I suspect that may be where the extra boost was going, and prob. why you were having some trouble tuning...

 

[LEE93COBRA]

I think it happened due to the horrible gas I got at the BP station across from tellicafe. I started expriencing detonation for the first time since the install when I did a high speed run against my buddy's 03 cobra on the way back to Bama that day.

 

[93Cobra#2771]

Surprised you got bad gas there (it's called the "Tellico Pride"). They go through a ton of it there...

 

[trey193]

Damn Lee I hate to hear that. Thats why I said with any supercharged motor running a descent amount of boost it is best to splash in some 100 octane or Torco. I have done that to my 03 since I upped the boost, its one helluva safeguard. Not directing this toward you in any way on the Terminator forum when I see guys bragging about making huge numbers on 93 octane I just:nonono: because its stupid with the bad 93 thats out there. I bought a 55gallon drum of VP100 and I splash in a couple gallons when I am going to beat on the car, if your car is your daily driver this could get expensive but you would have the safeguard, just a word to the wise!!! :beer:

 

[93cobra#3326]

hey thanks for the info richard, great explanation.
-bryan

 

[mustangcobra93]

If I upgraded from the stock 24 lb injectors to 36 lb injectors and matching Pro-M MAF, would I have to change to a A9L or can I keep the cobra computer?

 

[blk50cobra]

I swapped my Cobra processor for the A9L the first day I had the car in 1996. The computer was tuned by Mike Wesley using Autologic though.

It is unnecessary to change computers if you're going to use a chip. The only difference between A9L and X3Z is the program that the computer runs. If you're using a chip then you're switching the program anyway. The chip can be used on either computer and will operate exactly the same.

 

[blk50cobra]

I wouldn't expect a noticable drop, just a "leveling off" in the rate of power climb. And, the difference should be evident in your a/f - it will richen up at the same time that a degree or two of timing is pulled.

People tend to make a lot out of the 93mph speed limiter, when it is prob responsible for less than 5hp on a stock car. Course, it is prob worth more on a modded motor, maybe 10hp...

Exactly right. I tried to test this with back to back dyno pulls. For the second pull I unplugged the VSS. Comparing the two graphs, they were identical until around 90mph, then they separated slightly. With the VSS unplugged, the difference was about +1.5-2hp above 90mph. This was on a mostly stock engine. I'm not saying the difference was definitely caused by the "speed limiter", but that's the only thing that changed between pulls. Next time I will take out the limiter in the computer rather than just unplugging the VSS and compare that way.

 

[02_Lightning]

It is unnecessary to change computers if you're going to use a chip. The only difference between A9L and X3Z is the program that the computer runs. If you're using a chip then you're switching the program anyway. The chip can be used on either computer and will operate exactly the same.

Mine has no chip though. Mike took the computer and hooked it up to his lap top, and began changing things right there. The car never felt stronger... it was the best thing I have ever done to that car.

 

[93Cobra#2771]

If I upgraded from the stock 24 lb injectors to 36 lb injectors and matching Pro-M MAF, would I have to change to a A9L or can I keep the cobra computer?

Keep the stocker, as blk50 said.

Not doubting what you say, 99L, BUT he would have had to basically rewrite the code on your EEC to modify the EEC's operating parameters, which is a pretty involved process. I'll wager that your EEC has a chip on it, and you have never noticed it...

 

[02_Lightning]

What we did was remove the processor from the kick panel area. He opened it up, and hooked his lap top to the processor, and then began adjusting all of the A9L settings. We sat there for quite a while going through each item. After he was finished, I put the computer back together, and re-installed. My original Cobra processor has an ADS Superchip (that should tell you how old that technology was...) attached to it... actually it is stuck to it. I have not been able to remove that thing for years. I am afraid that I will break something if I apply too much force.