Ok I am trying to find some kind of explaination of why my car is possessed… not coming up with much. I don’t think this is the case, but does Fuel Cut have a memory?
What I mean is, once I hit fuel cut, it then will not boost at all, not even 1 pound without cutting again. Not until I turn it off, and turn it back on (the car) will it run all right again. I have not modified my electronics in any way yet, stock computer, no ems, no fcd.
My fuel cut is at 12 psi, occasionally i’ll spike to that, and it sucks, obviously. I’ll be setting it higher, however I don’t want to make more changes until I can figure out wtf is going on with the car.
i think it does. although it isnt fuel cut, it would be your ecu recognizing a deviation in boost, and putting your car into limp mode.
thats my guess, and the only reason i am uncertain is i dont know what year your car is, and i am not sure if that is something a car from say, the mid 90’s would have built in as a fail safe. but now realizing how dumb i am for thinking that, i am pretty sure your car is in limp mode from over boosting. call up a tuner that reflashes, or tunes your car, and ask if thats a failsafe that exists, and if they have a way around it.
gotta love electronic failsafe for possible mechanical failure, when all you are really trying to do is be mad fast y0.
word, and word… i just wanted to see if it was common or not. Now I also didn’t think it was in limp mode because instead of just setting boost lower it continues to cut at 0, however, i also do have a mbc on it, thus disabling the wg from opening as it should, soooo maybe that is what it does as a backup to lowering boost? I dunno, like suggested i’ll have to spend some time looking through mr2 specific forums
it is common on my car. i installed a map clamp and it solved all my ramp up problems. befor ei used to spike to 22 and it would shut me right down. now i spike to 26 and hold at about 24 and have zero issues because all the ecu knows is that it is seeing 17 psi (or whatever my tuning requests) and as long as i am not an asshat, and keep an eye on my gauge, make sure the set screw on the mbc is tight, keep my 02 voltages in check and run good gas when i run high boost, the map clamp isnt a risk.
when my car goes into limp mode (it doesnt anymore), it goes to .5 bar. which isnt 0 obviously but it may as well be. however with the mbc in line (or mbc only) the wastegates have a much more abrupt action, and so in these cases i do end up seeing 0 boost. the ramp up is enough to kill boost altogether whne in limp mode. as if a IC pipe was venting to atmosphere. but its not.
pressure test? maybe you have a leak that only rears its head at a certain boost pressure. are there any definitive mr2 tuners? call em up like you wanna buy something and work your questions in…they will help you more if they think they are selling you something in the end. good luck
that sounds exactly like what is happening, i didn’t think about how the mbc would cause ill effects on the car trying to set itself to limp mode. It does feel/act as if an IC coupling blew off, at times it will completely die… I am just going to do the FCD and see if it dissappears, worst case, it still does it and I have eliminated one more thing it isnt
sorry, but worst case is you are successful in removing the fuel cut and then you go and bust a piston from running way lean because your fuel is not tuned for those boost levels. There is a very good reason that the fuel cut is there because the stock fuel mapping tables do not go up to those boost levels. Removing it without tuning the fuel for the increased boost could result in very bad things. Joe knows the risks the hard way and takes appropriate measures to ensure he doesn’t detonate, how are you going to be sure you don’t bust your ring lands?? I’d hate to see you create another driveway sculpture because of not understanding the risks.
You need to do some more research on your particular ECU and find out exactly how and why it does that. You have to remember that fuel cut is controlled by the computer based on muiltiple readings it is getting, any of which can be the variable that triggers safety mode. Instead of just trying to circumvent the system, try to understand why it is going into limp mode and troubleshoot the engine to find and remedy the cause.
Part of the problem may be also be if you have a piggyback system like an AFC that is supposed to be “fooling” the ECU. They don’t always do a good job, even with proffessional tuning. Double check the settings on the AFC, and make sure everything is where it should be (karmen vs the other settings, etc. etc.). Also check the other parts of your turbo system and be sure that they are working properly. You may have a bigger problem trying to get free than you think.
Do you have a datalogger yet? Better go get one if you don’t. You’'re flying blind without one. If you can get one, you could monitor the parameters that affect limp mode and clearly see what is happening when the ECU shuts down. Then you would know where to look to fix your problem.
I have certainly put time into making sure what I plan on doing is safe. From any and all instances the stock fuel system, and stock fuel delivery is safe for what i plan on doing (keep in mind I have only adjusted my boost controller 3 pounds). I am not doing any 7 psi stock, and running 2 bar. It is going in to limp mode/fuel cut because it is supposed to cut at 11 psi. I am currently running 10, but on occasion, or cold days it will spike to 11. I plan on keeping it at 10, but increasing fuel cut to 12 or 13 just to avoid the problem on spikes.
I am aware that you need to make sure you’re not running overly lean, however through time and trial people have safely run well over what I do (15, 16 or even 20 psi) with stock fuel delivery. I would not ever run that high, for a few reasons, but that is neither here nor there. I am not blindly just turning the knob on my boost controller and hoping that it works.
The reason i ask the question is that recently I have had ignition problems (even with the boost controller out). The symptoms I am experiencing could possibly be FURTHER ignition problems, however it could also be results of car going into limp mode, but experiencing harsh liftoff problems due to the boost controller. I wanted to see if it was acting the way it is because of the controller, and as Joe had stated it sounds like that may be the case.
Should I have some sort of engine management, absolutely, and in due time it will go in, however I don’t have the resources to do it yet, and I do not want to put in a piggyback system because they are not reliable, as Rick mentioned. However the levels I am running are not anywhere near the danger zone.
edit also: I really do not see what my past project has to do with this…
How a bout a brief summary of the original ignition problems, and what you did to fix it (assuming it was fixed)?
Another thing I hate to use is manual boost controllers. Is it me or do they always seem to do weird unexplained stuff at the most inopportune (sp?) times? Maybe I’ve just had too many bad experiences with them :shrug:
it wasn’t about anything in the past, it was about the chances of something happening in the future. This is tech, not OT, so there is no drama implied. I’m just trying to help based on the info you provided and make sure you understand the risks, too many people drop a boost controller and FCD on their cars and then act surprised when they blow their stuff up. Without knowing what you have done or know about the setup, people who are trying to help can only be cautious and assume that you don’t have good info until you prove us wrong.
An EGT gage would be a good way to keep an eye on the situation also.
just so you know, the only things to ever blow up on my car were manufacturing error, nothing having to do with a modification/tuning decision i have made.
things to blow up on my car:
turbos (they cant handle stock boost much less chipped)
flywheel- non0recessed dowels in the outer ring of the flywheel came out, and thus went THROUGH my trans and clutch
clutch- manufacturer used a refurbished clutch that had excessive wear on the finger of the pressure plate. that combined with larger pilot bearing for lower engagment left no room for clearance issue.
i tune my car, but i have never had to learn the hard way about the ins and outs about it. after my turbos blew and set my life into a flat spin, i make sure to do my research.
i hope you dont think i blew my motor or something :eekdance:
yeah, just clarifying. i didnt take what he said as an insult, and i wasnt trying to be brash. just making sure he knew that i didnt blow anything up. that way next rally trip he manages he will let me do more than sweep the van out
Well, pretty much everything had some minor problems, and step by step it got better and better. Changed plugs, misfire lessened. changed plug wires, misfire lessened. changed coil wire, missfire lessened, changed cap and rotor, missfire lessened. changed coil, missfire went away. Probably was a chain reaction of a bad coil passing through good parts and ruining them, but either way I was sure the problem was licked. Then going back and reinstalling the MBC, started generating problems that initially I thought were ignition (since they had many of the same symptoms). Lowering boost, I still have yet to experience it, so I think I am correct on it being a boost cut/fuel cut issue, controlled by the stock ecu, but having amplified effects from the controller.
EDIT: Also, the problem is so intermittant that I may not know if lowering boost out of the max. range before limp mode has actually taken care of it, and I may not know for a week or two. So i’ll be running at a lower setting for some time before I am confident it is not continued ignition problems.
Sorry, it just came across as condescending, if i missinterpreted your intentions I appologize. I also was just trying to explain where I was basing my intentions from, not to argue.
i didnt take what he said as an insult, and i wasnt trying to be brash. just making sure he knew that i didnt blow anything up. that way next rally trip he manages he will let me do more than sweep the van out 