lowrider Posted August 17, 2012 Share Posted August 17, 2012 I have been having trouble with my car hitting a wall that feels like the car is hitting "fuel cut". It only happens when I get on boost for a prolonged period. I'm running MS2 on a v3.57 board and what I believe to be the 2.890 code. I initially thought that it was a fueling problem due to the sudden nature of the cut-out, and the fact that if you continue to press the gas after the motor responds as if you switched it to the off position. When it does it, the AFR gauge goes instantly to the leanest reading. I changed my fuel pump/ surge tank for another pump to rule out fuel starvation, yet there was no change. I datalogged the incident happening on the way home this evening. The only peculiar thing I notice is the ever increasing battery voltage... I'm attaching that data log along with this post. If anyone could give me a few ideas that would be excellent, as I'm currently pulling my hair out with the issue. @ 3587s into the datalog is when the "cut-out" occurs. Ohh and I am really rich, and I want to get this nipped in the butt before I start tuning further. Thank you, -Andrew 8-16-12 cut out run.zip Quote Link to comment Share on other sites More sharing options...
lowrider Posted August 21, 2012 Author Share Posted August 21, 2012 I attached a fuel pressure gauge before the fuel rail and induced the "Fuel cut", the fuel pressure stayed rock solid. I'm baffled, my data log says that I have a solid duty cycle/ pulse width and I have fuel pressure. I am now leaning toward an ignition issue. I am currently running edis with a custom mounted escort trigger wheel, escort sensor, and caravan coil. Next order of business is checking the ignition components. Quote Link to comment Share on other sites More sharing options...
Zmanco Posted August 22, 2012 Share Posted August 22, 2012 I'm having a problem with java on my work laptop so can't see your log, but keep in mind that without combustion, the O2 sensor will read full lean regardless of how much fuel is present. Remember, the O2 sensor measures how much oxygen remains, and without combustion, it's all still there. I think you're headed in the right direction looking at the ignition. What is controlling EDIS - perhaps the Explorer module? I ask because that has a fail safe mode such that if it loses the signal from MS, it defaults to 10 deg adv. Hence it's not possible if it's working properly to implement a spark cut. So if you're losing spark, the problem is probably with the EDIS components and not MS. All that said, I'm not able to imagine how it would only fail when under boost ... Quote Link to comment Share on other sites More sharing options...
Zmanco Posted August 22, 2012 Share Posted August 22, 2012 I was able to look at the log. Looks like the AFR begins to rise when the bat voltage hits 15.5V. I would not be surprised if the EDIS controller had an overvoltage protection mechanism that shuts it down - although this is pure speculation on my part. In any event, you need to resolve the battery voltage rising - is it tied to boost or simply rpm? I'd guess that it would be the latter, which you may be able to verify reving the engine while parked. I'd focus on fixing that first and the rest of the issues may go away. Then get on with tuning - AFR <9 will kill the O2 sensor. Quote Link to comment Share on other sites More sharing options...
lowrider Posted August 22, 2012 Author Share Posted August 22, 2012 (edited) See, I'm not all that certain that the megasquirt's voltage read is correct. I have a voltage meter incorporated into my turbo timer which reads a solid 13.2 volts under boost all the way to redline. I had some problems in the passed with megasquirt reading spikes in my voltage, after the spikes started showing up it never read the correct voltage. I remedied the voltage spikes by placing a 220nf capacitor cross the h1 jumper. I plan on removing the alternator output and run it straight off the battery to see if the voltage still increases. Edited August 22, 2012 by lowrider Quote Link to comment Share on other sites More sharing options...
Noddle Posted August 22, 2012 Share Posted August 22, 2012 I had an issue with my Megasquirt, EDIS setup, it worked fine, but under boost, and hard acceleration, it would just "cut out" like turning it off, what it turned out to be was the shielded cable I used for the EDIS pickup, had been slightly melted, and the internal wires would flex under hard acceleration, and short , thus cutting the sensor output. it was an easy fix once I found the issue, but it took me a long time to find it. Nigel Quote Link to comment Share on other sites More sharing options...
Zmanco Posted August 22, 2012 Share Posted August 22, 2012 See, I'm not all that certain that the megasquirt's voltage read is correct. I have a voltage meter incorporated into my turbo timer which reads a solid 13.2 volts under boost all the way to redline. I had some problems in the passed with megasquirt reading spikes in my voltage, after the spikes started showing up it never read the correct voltage. I remedied the voltage spikes by placing a 220nf capacitor cross the h1 jumper. I plan on removing the alternator output and run it straight off the battery to see if the voltage still increases. You really need to get this resolved before you can worry about the cut out under boost. If the alt output is really rising to 16+ volts, then you're going to damage the battery and perhaps other components. If the problem is with MS reading inaccurately, then you're going to have other problems with tuning e.g. PW is compensated based on battery voltage. Good luck and let us know what you find. Quote Link to comment Share on other sites More sharing options...
lowrider Posted August 23, 2012 Author Share Posted August 23, 2012 I just started back to school, so time is somewhat limited. Tomorrow I plan on disconnecting the alternator to see if that resolves the voltage issue. I plan on posting the results and possibly a data-log. Quote Link to comment Share on other sites More sharing options...
lowrider Posted August 23, 2012 Author Share Posted August 23, 2012 (edited) The problem seems to be with megasquirt. I did two runs both with the alternator disconnected. The first run was with a 47mf capacitor across the boot jumper H1, The second with the capacitor removed. Both runs' datalogs yield interesting results, all of which point to megasquirt. The first run acted just like previous ones the voltage increased exponentially with the load and rpm. The second run the voltage fluctuated from 6.5 to 21.3 volts under load with no detectable pattern. I have a 12 gauge wire straight from the battery to the relay board and a ground from the battery leading to a terminal block inside the car, which is where the relay board is grounded. I have heard of low z injector's PWM current limiting circuitry making noise in the feed line. I have yet to test this because I don't have dropping resistors. Anyways, any addition advice before I pull my hair out? Thanks, Andrew 8-23-12 47mf cap no alt.zip 8-23-12 no cap no alt.zip Edited August 23, 2012 by lowrider Quote Link to comment Share on other sites More sharing options...
Zmanco Posted August 24, 2012 Share Posted August 24, 2012 - What is CLT/MAT/Battery Lag factor set to? - Are you sure you have the alt completely disconnected? Don't mean to insult you with such a basic question, but nothing should be connected to the output stud. - I believe in the MS assembly instructions there are test and trouble shooting steps for the voltage regulator. IIRC, it's one of the first portions of the board to be assembled. You might follow the test measurements and see if that provides a clue. - What is the history of this MS unit? Did you build it? Has it ever been run successfully before? Did this problem recently begin to occur or is this a new MS install? - The Target AFR values all appear to be 100 times too large. Instead of 14.7, it shows as 1470.0 in MLV. Check the Target AFR table. Perhaps your MSQ file is corrupted? (I don't know how that would affect BATT V though). Where did the MSQ file originate? If you created yourself, did you start a new project while the laptop was connected to MS powered up? - Might be a good idea to post your MSQ and let us know which version of firmware you're using. Quote Link to comment Share on other sites More sharing options...
lowrider Posted August 24, 2012 Author Share Posted August 24, 2012 -The lag factor is 50, as far as I know that is the factory setting. -The alternator was completely disconnected, nothing on the output lug nor was the charging wire attached -I did not build the unit, it was bought pre-assembled from DIYautotune. The board is the 3.57 which is surface mounted PCB. -I have ran it successfully before with steady voltage according to one of my older datalogs. I'm not exactly sure when this started happening, some where around the time that I made my surge tank. I made the surge tank because I thought my previous fuel pump setup was running out of steam. Up until that point I hadn't tuned my top end for a while, which is where the problem rears its head. -peculiar... My afr tables in TS display the correct afr reading. -I created the MSQ myself. I honestly don't remember how I initially started the project, Its been so long. -If I'm not mistaken, I'm running 2.1.0d extra currently. 8-23-12 tuning cut out.zip Quote Link to comment Share on other sites More sharing options...
Zmanco Posted August 24, 2012 Share Posted August 24, 2012 TS displays the AFR tables properly for me as well, not sure if the x100 display in MLV is important or a red herring. I'm still curious if the voltage rises due to RPM or boost. Other than that, I'm out of ideas so would suggest you post on the megasquirt forum and/or email DIY Autotune. Matt Cramer is super helpful and hopefully will have some insight. BTW, you're running 2.1.0q. Once you resolve this, you might want to catch up to 3.x as there are many enhancements as well as some bug fixes. Quote Link to comment Share on other sites More sharing options...
lowrider Posted August 24, 2012 Author Share Posted August 24, 2012 Thanks for all of the attention and suggestions Zmanco. I went yesterday and picked up a 220uf cap to replace the 47uf i had on the boot jumper. It made a significant difference in the voltage increase under load. It increased from a base of 10.8v to 11.4v during 4th gear, however in my opinion that is just a band-aid. It's my plan to email DIYautotune later today to see if they can give any incite. I'm already a step ahead, I downloaded the software pack last night! Again, thanks soo much for the help. Quote Link to comment Share on other sites More sharing options...
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