Drive by wire reliability
04-04-2009, 11:39 PM
#1
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Drive by wire reliability I have a L92 crate engine an wonder if anyone has experienced any problems with the DBW throttle setup. I'm looking for absolute reliability (not possible of course, but want to eliminate as many factors as I can) and am looking to compare cable and DBW.
Thanks.
Thanks.
04-08-2009, 09:27 AM
#5
Every LS vette has had Drive By Wire. They have a redundant sensor system on the pedal that uses 2 or 3 sensors to make logic checks to make sure the setup works correctly. Durability is no problem. There have been a few bad TAC modules before, but people normally replace them every day just because they do not understand how they work.
04-09-2009, 03:04 AM
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Actually, I doubt GM would be as concerned about ABSOLUTE reliability as I am. I'll be trusting the only body I have to the engine. GM is more concerned about the cost/benefit ratio, not absolute reliability. As long as they think something results in more $ overall, they'll stick with it even if there are a very small number of problems. Based on that, I think my question is valid.
04-09-2009, 03:07 AM
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Thanks, John. That's information I can use. I had no idea how they were built.
Every LS vette has had Drive By Wire. They have a redundant sensor system on the pedal that uses 2 or 3 sensors to make logic checks to make sure the setup works correctly. Durability is no problem. There have been a few bad TAC modules before, but people normally replace them every day just because they do not understand how they work.
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04-09-2009, 09:19 AM
#8
Actually, I doubt GM would be as concerned about ABSOLUTE reliability as I am. I'll be trusting the only body I have to the engine. GM is more concerned about the cost/benefit ratio, not absolute reliability. As long as they think something results in more $ overall, they'll stick with it even if there are a very small number of problems. Based on that, I think my question is valid.
04-09-2009, 10:44 AM
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I probably wasn't clear...I agree with you, that's why I said "cost/benefit" ratio. If the part doesn't at least provide an acceptable level of reliability, it then isn't cost effective (even if it's free), since it drives customers away and costs the company too much for warranty work. There has to be a level that's somewhere short of absolute reliability that's "good enough" though. I suspect drive by wire exists partly because of costs, partly because of drivability, and possibly partly for emissions.
Next question: what will it take to make a LS3 GMPP engine controller work on my L92? This is something I asked some time ago, but nobody had a definite answer. Is there a L92 controller on the horizon?
Thanks
Next question: what will it take to make a LS3 GMPP engine controller work on my L92? This is something I asked some time ago, but nobody had a definite answer. Is there a L92 controller on the horizon?
Thanks
Also, contrary to popular opinion, the automakers do have the interests of the end user in mind and durability in mind whenever they go to even formulating an idea for a new part. Even if they make a "cheap" part, if you have to replace that part every month under the warranty coverage, it is no longer "cheap" for them anymore.
04-09-2009, 10:50 AM
#10
The only diff really in the L92 is the fact that it uses the VVT system. If you unplug the VVt phaser then it will run fully advanced i believe. Then you can use the rest of the engine without any problems. Comp Cams also has a phaser blocker that will limit the amount of movement the cam will have, which would stop it from going fully advanced if unplugged. Then you can use the LS3 controller. I do not know of an L92 complete assy controller on the horizon, but new things happen all the time. You may want to ask Mast Motorsports, as they have alot of that tech down.
04-10-2009, 12:03 AM
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Thanks John. Another question: It sounds like failures are very rare for the DBW, but when one occurs, what happens? Does the engine continue to run with poor throttle response, or does the computer shut it down completely?
The only diff really in the L92 is the fact that it uses the VVT system. If you unplug the VVt phaser then it will run fully advanced i believe. Then you can use the rest of the engine without any problems. Comp Cams also has a phaser blocker that will limit the amount of movement the cam will have, which would stop it from going fully advanced if unplugged. Then you can use the LS3 controller. I do not know of an L92 complete assy controller on the horizon, but new things happen all the time. You may want to ask Mast Motorsports, as they have alot of that tech down.
04-10-2009, 07:17 AM
#13
I used to do ETC validation work for GM earlier in my career before I became a calibrator. The ETC system is incredibly reliable and secure. As someone said about, there are two sensors on both the throttle and the pedal. One sensor has a positive voltage vs. position slope and the other has a negative slope. They are both checked continuously against each other for rationality and will cause a fault if the values don't correlate.
If a fault occurs (of which there are about 35: opens) the system takes one of two default actions: it clamps the maximum throttle position that you can command (reduced engine power), or it defaults the throttle to a given value and manages the incoming air by shutting down cylinders (limp home mode). The second default action feels quite nasty but it will get you home. I wouldn't be concerned about using it. The only drawback is the extra wiring under hood that you'll need plus the addition of pedal position sensors.
If a fault occurs (of which there are about 35: opens) the system takes one of two default actions: it clamps the maximum throttle position that you can command (reduced engine power), or it defaults the throttle to a given value and manages the incoming air by shutting down cylinders (limp home mode). The second default action feels quite nasty but it will get you home. I wouldn't be concerned about using it. The only drawback is the extra wiring under hood that you'll need plus the addition of pedal position sensors.
04-10-2009, 07:19 AM
#14
I love threads like this, OP asks a question then argues with a common answer. If you have your mind made up, why post?
Why do you want to disable the phaser?????? I would kill to have one.
Phaser limiters reduce the amount of retard that the phaser can adjust. No matter what, if you just unplug the phaser it will sit fully advanced in the park position. Then you have to deal with differences between cam that are made for phasers and ones that arent(big advance differences). Youll have to swap to a traditional timing chain and cover setup so you can run any aftermarket cam.
Why do you want to disable the phaser?????? I would kill to have one.
Phaser limiters reduce the amount of retard that the phaser can adjust. No matter what, if you just unplug the phaser it will sit fully advanced in the park position. Then you have to deal with differences between cam that are made for phasers and ones that arent(big advance differences). Youll have to swap to a traditional timing chain and cover setup so you can run any aftermarket cam.
04-10-2009, 10:06 AM
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Uhhhh....are you sure you read the thread? Nothing asked about phasers at all. You seem to be looking for an argument that doesn't exist. In fact, there have been no arguments at all in this thread, just some pretty good information. Thanks to all.
I love threads like this, OP asks a question then argues with a common answer. If you have your mind made up, why post?
Why do you want to disable the phaser?????? I would kill to have one.
Phaser limiters reduce the amount of retard that the phaser can adjust. No matter what, if you just unplug the phaser it will sit fully advanced in the park position. Then you have to deal with differences between cam that are made for phasers and ones that arent(big advance differences). Youll have to swap to a traditional timing chain and cover setup so you can run any aftermarket cam.
Why do you want to disable the phaser?????? I would kill to have one.
Phaser limiters reduce the amount of retard that the phaser can adjust. No matter what, if you just unplug the phaser it will sit fully advanced in the park position. Then you have to deal with differences between cam that are made for phasers and ones that arent(big advance differences). Youll have to swap to a traditional timing chain and cover setup so you can run any aftermarket cam.
Last edited by org; 04-10-2009 at 10:14 AM. Reason: typo
04-10-2009, 10:28 AM
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All true, John, but I didn't ask about the phaser, only the DBW and later the LS3 controller. We had discussed the phaser in an earlier thread and you kindly gave the info I needed then. By the way, your delivery was much better than his:-) Thanks again for the information. It's a help in deciding which way I'll eventually go. I know it might seem strange that I'm so concerned with failure modes and so forth, but this engine will be on the front of an aircraft, so I'm pretty interested in eliminating any possible failure points that I can.
04-10-2009, 10:36 AM
#18
I used to do ETC validation work for GM earlier in my career before I became a calibrator. The ETC system is incredibly reliable and secure. As someone said about, there are two sensors on both the throttle and the pedal. One sensor has a positive voltage vs. position slope and the other has a negative slope. They are both checked continuously against each other for rationality and will cause a fault if the values don't correlate.
If a fault occurs (of which there are about 35: opens) the system takes one of two default actions: it clamps the maximum throttle position that you can command (reduced engine power), or it defaults the throttle to a given value and manages the incoming air by shutting down cylinders (limp home mode). The second default action feels quite nasty but it will get you home. I wouldn't be concerned about using it. The only drawback is the extra wiring under hood that you'll need plus the addition of pedal position sensors.
If a fault occurs (of which there are about 35: opens) the system takes one of two default actions: it clamps the maximum throttle position that you can command (reduced engine power), or it defaults the throttle to a given value and manages the incoming air by shutting down cylinders (limp home mode). The second default action feels quite nasty but it will get you home. I wouldn't be concerned about using it. The only drawback is the extra wiring under hood that you'll need plus the addition of pedal position sensors.
And there are various ranges of action from simply a reduced pedal map, to managed toruqe, to forced idle, to complete engine shutdown. A walk home situation is the last option, and over all driver security is the main concern.
Sure GM may have some cost issue in mind at the higher levels, but there are real bodies doing the work. The lawyers keep us safe
04-10-2009, 10:39 AM
#19
Well that being the case, it def would make a diff. Everything is diff in the air. I would prob use a cable driven TB, take the VVT off of it and run it normal LS2 style, and run an ign controller from MSD. Thats all you need. put a carb on it and call it a day. Would be the easiest, but if you want to stay with fuel injection, then rest assured that GM has thought about what ifs, that is why they have so many checks. Use the way that will make you feel the safest.