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The MAF limiting out is not an issue. The EZK has individual cylinder knock detection and individual cylinder timing retard. People who are thinking that something like the current knock detection on the Megasquirt is going to work great on their 928 engine, and save it if detonation occurs, are in for a surprise.

 

What are you? Some kind of know-it-all?

 

Pay no attention to the man behind the curtain

 

Two guys are getting ready to go hiking in the woods when the first one notices the second guy putting on track shoes, so he asks why. The second guy responds saying that the track shoes are in case they encounter a grizzly bear. The first guy kind of laughs and says "A grizzly bear can run faster than a horse. You can't out run a grizzly bear." The second guy calmly continues putting on the track shoes and says "I don't have to out run the bear. I only have to outrun you."

I don't have to know it all. I only have to know more than you.

 

 

The stock maf output is an issue....

You need to modify the maf to reduce signal spread based on mass air flow....in other words, change the ratio of the sample tube to the diameter.

One way to do this is alter the id of the MAF itself...we cut out the sample tube and electronics and use a 4" tube....there are the obvious other methods also. this how we mad ethe 550 rwhp using the stock system and custom intake.

Mike you were at a devek days when I tried the other...but without sharktuner, it never worked..but now, with the ST we can probably make that work also.

Cheers

 

See ya soon Andrew.

 

Guess I should say something, but I doubt I'll change anyones viewpoint. I started my engine rebuild (later turned into a whole car rebuild) project about 5 years ago. At the time, there were few aftermarket ECU choices. There was Motec which was completely unaffordable for me, and still is. A few which didn't work all that well and didn't have the features I thought I needed. I'm not sure where MS was at the time or if it even existed in a usable form. There was no John Speake Sharktuner. No others I knew of who had gone before with experiments with really high hp other than Marc Thomas and before him Bob DeVore. No developed supercharger systems. The problem of the LH/MAF combo limiting at higher hp levels was known, but not exactly why. It was known that longer cam duration than the GT cams would cause reversion flow in the intake and cause idle mixture problems due to the MAF measuring air flow in both directions. There was no affordable coil-on-plug units available. The engine characteristics I wanted dictated cams with more duration and lift than GT cams which then lead toward the ITB intake system I made. A big goal for the engine work was to tidy up the normal snarl of wires and hoses all 928s have. One way to accomplish that is to use direct ignition without the distributors. I used the DTA P8Pro ECU because Marc Thomas had experience with those and it was supposed to do all I needed. It was affordable and I bought one from Marc.

Fast forward a few years to the present. I like to think I learned a little bit along the way. The first thing you understand about programming your own ECU is that it is a lot of work. Do not believe the marketing about how easy the automatic tuning of mixture can be. It's not. I do understand that having the longer duration cams makes idle and up to about 20% throttle opening extremely difficult due to wildly erratic mixture readings from the wide band O2 sensor. With S4 or GT type cams it would undoubtedly be a lot easier and probably the closed loop mixture control would work better at those low power settings.

People seem to think that getting rid of the MAF is the way to go. That should take some careful thought before coming to that conclusion. The MAF is a wonderful device which automatically compensates for changes in air density due to atmospheric changes, or boost, and air temperature. It measures the exact mass of air the engine is using at any instant. That makes determining how much fuel to use relatively easy. Without the MAF to take care of those changes, you must use air temperature and air pressure compensation tables. Air pressure compensation doesn't seem too difficult and the standard gas density formula does well. I find the air temperature compensation really hard to pin down correctly. I think much of the reason is that the air temperature, therefore density, of the air that is ingested into the engine changes so much between the time the temp gets measured (for me that's inside the air box) and when it gets into the cylinder. At idle and low power the actual air temp will be closer to the engine temp, not necessarily the air box temp. The air gets heated by the throttle bodies or intake manifold on it's rather slow progress into the engine. Conversely, the air temp will be very close to the ambient air temp under high power conditions when the velocity is high. The DTA doesn't have any way to correlate those differences. I should have mounted my air temp probe right inside the throat of one of the Throttle bodies close to the throttle plate for a better reading. I may have to do that, but who wants a big air temp probe sticking inside the throttle body? There should be some further compensation for the cooling effect of the fuel sprayed in as well, but there isn't. The Autronic is the only ECU I know of that comes close to offering a way to help with this dilema. With a MAF you don't even worry about all that.

Bottom line for that is don't toss the MAF just because you can. The MAF could save you a lot of headaches and tuning time and undoubtedly result in a better running engine. The much maligned Bosch MAF isn't inherently unreliable. The bulk of 928s using a MAF are 15 - 20 years old with more than one hundred thousand miles on them. Some probably failed with less than that time and miles, and some of those have been abused to failure too. That length of time and miles of service is really quite good. Figure on a MAF replacement when you do the WP/TB service and you'll be good.

The '87 and later LHs are unreliable until they are rebuilt. John Speake has figured out how to replace the troublesome internal module with an updated version. The rebuilt ones should be bulletproof. For a ~$500 upgrade, it can't be beat. The LH is slow by current ECU standards, but entirely adequate for most 928s. As was demonstrated a short time ago, a supercharged 928 made 540 rwhp using the stock LH/EZ-K and sharktuned for not only great performance, but perfect stock like street driving too. The updated ones have full fault/diagnostic storage the same as the latest GTS models. The sharktuner Autotune feature works very good and most mixture tuning can be done that way with some manual touch up required. That's far better and easier than most aftermarket ECUs. Yes, it would be nice to have more RPM columns and control over the RPMs of those columns. What is there is adequate.

The EZ-K is really quite sophisticated with complete spark timing tuning capability (with sharktuner) as well as individual cylinder knock control. The downside of the EZ-K & EZ-F is that you can't eliminate the distrubutors. I believe I've seen ignition splitters where you can use one ignition output to drive two coils. They create a synthetic pulse that is spaced halfway between the original pulses. That along with wasted spark coils would do the trick for distributorless ignition using the EZ-K or F.

Mike Simard had a good concise rundown on his tuning experiences. I have 110 hours on my motor with at least 70 of that being tuning. While it runs quite well, there are still jagged edges that need smoothed. I spent 3 hours tuning today trying to solve a lean condition that happens within a minute or up to 5 minutes after a heat soaked hot start. Sometimes it goes lean enough to quit when coming down to idle after driving a while. Those conditions are when the ambient air temp is 85F and above. I spent many cold mornings last winter trying to get the cold start map right. It's pretty good now. Sterling Gee can give his experiences tuning his engine with the Motec. He's been at it longer than I have. I was talking with Todd Tremel a few weeks ago and he related his efforts to get his Autronic cold start map as well as the base map tuned. He'd tweak it when he started it to go to work in the morning. The car was cold again at lunch so he'd spend his lunch time trying the cold start again as well as other general tweaking. His co-workers thought he was nuts. He did get it though and his car runs very good now. It's pretty easy to get the engine to run and run well enough to use while putting up with a few quirks. It's quite difficult to get it right for all conditions cold, hot, sea level, or Pike's Peak. I used to tune piggyback ECUs on the road and did some Sharktuning on the road. Even though I live in a rural area and the nearby freeway isn't crowded, trying to tune and drive by yourself on the road is really nuts. It's still 80% nuts if you have a tuner and driver. The nuts factor goes up the faster your car is. I bought my own dyno and that works out good. There is still a small nuts factor since I buzz up to 185 mph (2.73 final drive) on the dyno in my shop. The tires don't know they are on a dyno so they have to be as good as if you were on the road. All the same safety precautions have to be taken as seriously as if you were on the road plus the dyno itself could be a danger. You'll never have to talk to a humorless cop to answer why you were doing 185mph while looking at your computer.

I took the car to Lake Tahoe for the Sharks at the lake meet in June that Tim and Cheryl Dey organized. I felt pretty good that I didn't need to pack my spare LH and MAF that I usually carry with me on long trips. I never needed them, but they were an extrat bit of security. Soon reality set in as I thought about what would happen if my DTA P8Pro quit. It's considered to be reliable as those thing go, but someday it'll fail. Then what? There is no calling Marc Thomas, or other 928 owner for help. I can't get quick service from Jim Bailey at 928 Int'l for that ECU. No John Speake help. It would take two weeks to get another one from England. That may not even be possible since the P8Pro model has been superceded by the S80. That one is somewhat compatible and is reported to work better. Should I toss the P8Pro and get the upgraded model now? It's about $1700. Then keep the current P8Pro as a spare? Be sure to have a map for it on my computer. Should I buy another P8Pro while I still can and carry that for a spare? Any other aftermarket ECU would be the same since models are being upgraded to newer, faster, better continuously. What if my throttle position sensor (TPS) fails? It's just a pot with a wiper contact. I know it'll fail someday. Better get a spare TPS and carry that. I've learned that the Ford style (MSD manufactured) 4 tower coils I use for the wasted spark are failure prone too. Better get a spare and carry that so I can keep going if the failure happens on a weekend, or a Ford dealer is far away. It won't do me any good to call Jeannie Roberts and have her overnight me a coil. She won't have one. Make a note to put Summit's phone number in my cell phone.

Hacker's right. Unless you are going fairly far out there, keep the LH and EZ-K(F). If you have an Ljet, maybe there is good justification to go to aftermarket ECU for performance improvement and more flexibility in tuning.

All in all, getting the aftermarket ECU going and reasonably well tuned (I think I'll never be really done with it) has been a very rewarding experience. If that's all you want, and you are a tweeker by nature, then go for it. Don't fool yourself with higher reliability, less cost, etc.

Here are a couple of links you might find interesting. See what sort of problems, and success, people have with various ECUs.
http://dtaforum.psycode.com/
http://efi101.com/forum/index.php

 

Thanks Louie, that's a great exposition on the general topic :-)

 

Yes there is! Mine would be overnighted to were ever you were stuck. I'll even make sure it has your tables uploaded. Keep my cell phone number handy.

Thanks for sharing your hands on experience

 

OK Marc, I thought you were eferring to the LH ECU hardware.

I am looking at ways to reduce the cost to upgrade a std MAF to SuperMAF.
If the donor MAF is in good shape there is the potential to cut the cost.

 

Well; this has been a worthy thread. I'm at present a network engineer and the first half was spent as a microcomputer engineer. If I could attach a logic analyzer to the connection points between the EZF/LH and the end nodes, I could confidently resolve whatever has been causing this little "S" to stallout. That not being the most practical scenario, I'll get it working again incrementally.

All that being said...these are cool cars and I don't depend on it. Mine made it 4k miles across the US before a hiccup. I wanted something to keep me busy.... ;-)

Mike

 

I would like to add that on a couple of the aftermarket systems like MS you can add a second MAP sensor which adjusts the mixture realtime to the environtment, so from sea level to 14,000ft it would be the perfect mix the whole time. You can also wire in a MAF at the same time to the MS box.

That being said, I am a real tinkerer and love to be able to spend time playing with it, so it works well for me.

 

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Hopefully I'd be able to overnight an LH/EZK based system off my ride. Just don't break down anytime soon.

 

Guess you'd need the harness, a mile of wire, and lots of solder included with that package wouldn't you? Never mind.