gdog

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gdog last won the day on December 9 2019

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About gdog

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  1. Well, like I said, be careful when probing the ecu connectors. It can easily be done w/o damaging them. I found there was enough room to probe on the sides of the connector fingers w/o bending or damaging anything. Yes, back-probing the TPS connector (as in the utube) is fine, but keep in mind the TPS connector is not too easily accessible, and doing this will definitely disturb/move the TPS wire harness. I.e. the pressure of back-probing may make a bad connection good (temporarily). One can back-probe from the ecu side w/o touching the TPS or harness at all. And as far as measuring a circuit when there's current flowing in it, if this was a load circuit (low impedance), then I'd agree with you. But this is a high impedance sensor circuit; the current flowing through this circuit is on the order of 1 to 4 mA. I.e. measuring via a decent ohmmeter is just fine here. You certainly don't want to measure some kind dynamic load (like a motor e.g.) with an ohmmeter, but that's not the case here. And as I mentioned, probing from the ecu gives the added diagnostic of vetting the harness. What if you saw a good voltage reading at the TPS signal pin on the TPS connector, but that wire had a intermittent break in it between there and the ecu? Then that good reading at the TPS pin is not doing anybody any good, since the ecu is not seeing it. As @Zappo mentioned, the least intrusive way to diagnose this is to look at your logs of the TPS sensor!
  2. More details.. Yeah the guy in the utube is back probing the TPS connector and measuring voltage on the signal pin with key in RUN. Should see about 0.5v at idle/closed and roughly 4.5v at WFO. Give or take a few tenths of a volt. You can do that, but IMO it's easier to pop out the ECU and then probe the TPS pins at the ECU connector (key in OFF position). Here are the TPS pins at the ECU: A15: TPS 5v supply from ECU A16: TPS signal pin A18: signal reference (ground) Get an ohmmeter, two small paper clips and two alligator clip leads. Using the paper clips, carefully insert one end on the side of the ECU connector; do not damage or bend the ECU connectors. Measure between A16 and A18: should see about 1300 ohms at idle and about 3300 ohms at WFO. I'd say +/- about 100 ohms or so. Off by much more than that, and I'd suggest a new one. Can get one at pic-n-pull but bring an ohmmeter so you can check it there. If you go with new one, do NOT spend a hundred dollars on the blue box one; get that exact same part in Bosch OE. BTW: the other advantage of measuring the resistance from the ECU pins is that you're ohming out the wiring in the harness too. If you suspect bad wiring, hook up your ohmmeter at the ECU connector as described above and then wiggle the harness, especially near the TPS connector. If the readings change while moving the harness, you just found some bad wiring.
  3. FYI: if your car's throttle response is off, might want to check your throttle position sensor (TPS). Been noticing of late my car has been sluggish. Will go into more details in another post, but the more I thought about it, the engine was acting like it was not getting full throttle. So I took a log w/several WFO runs, and sure enough, it was maxing out at 60% throttle! Note with tunerPro logs, >75% is considered WFO. I.e. the ecu was never getting a full throttle signal. Pulled the intake boot off of the throttle body and mechanically it was all adjusted properly, as the throttle plate was going horizontal with the foot down. So had to be the TPS I figured. Found this guy's youtube here: https://www.youtube.com/watch?v=m_6dhZzWM54 which eventually tells you to expect about 0.5 volts at closed and 4.5 volts at WFO on the TPS signal wire/pin. I was getting slightly over 3 volt at WFO! With new TPS, it's amazing the difference it's made. Will add more details later.. Hopefully this helps someone.
  4. Lucky is in Hillsboro OR; why would he ship out of Arcata CA? http://www.ardideas.com/
  5. Wait, what? VS was down?! Who did the re-solder? I've had to do mine multiple times now. You've got to clean off ALL the old solder first, or it will just break again (ask me how I know.. ). Look at the solder joints with a magnifier; you'll see the cracks if you look carefully. Or @Matty Moo could take care of you too: www.midwest-abs.com
  6. gdog

    How Your Car Sits

    That bites big bananas!! Seeing Marlon cry makes me sad too..
  7. Not common AFAIK. What's entailed in "flashed ECUs"? Do you have anyone's mods incorporated?
  8. Good stuff! You could add instructions on how to use these channels here and on the wiki too. Yeah, a bit sad, but it's up to the rest of us to keep it going, as best we can..
  9. Interesting? I generally agree there may be ambiguous info at places in this thread (as it is wide open after all) but the standard channels that have been known to work for some time are the tank pressure and the rear O2 sensor inputs. The thing about the latter is to NOT use the rear O2 reference (ground) pin of A19 since this will cause an offset; use A18 or other known good ground reference pin instead. Has someone said the accelerometer input works for logging? Don't recall hearing about it. Not too surprised if there's some signal conditioning circuitry in there for that channel.
  10. Thanks for the reminder; every once in awhile I actually think about getting back into it (on part-time basis). It's more fun as a hobby than a business I suppose..
  11. Seems a zener would be a more appropriate solution, no? Thinking two zener diodes back to back (maybe a resistor in between) across the VR sensor leads?
  12. Awesome results! Wasn't sure what you meant by "synch loss" but then found this link: https://www.diyautotune.com/support/tech/other/megasquirt-vr/ Now I see. Good shielding on the VR sensor?
  13. @black855r I'm assuming you're going for AFR readout for petrol fuel. So looks like the 30-0300 AEM gauge has the same transfer function as mine, which is AFR = 2.375 * volts + 7.3125 // note the output units here are AFR, except for the 2nd term (2.375) which, if you think about it, is in AFR/volts (AFR per volts) units. As my old algebra teacher used to emphasize, it's very important to understand what your units are in an equation. So we need to figure out how to convert that 2.375 term above into something the ecu understands, since we're hooking up the output voltage from the AFR sensor to an A/D (analog to digital) convertor in the ecu (aka the tank sensor gauge input) which we happen know is an 8bit convertor so it has a numeric output range of 0-255 bits. Then to convert the AFR/volts term to AFR/bit, we need to multiply it by a term in units of volts/bit. That term is 5v/256bits, which is the voltage span of the A/D divided by the bit output span (i.e. 2^8 = 256). ==> 2.375 AFR/volts * 5volts/256bits = 0.0464 in units of AFR/bit (rounded to 3 significant digits). AFR = 0.0464 * x (in bits) + 7.3125
  14. Help us help you. You'll need the analog output conversion table for this gauge which will be in the instruction manual. What's the AEM part number? Various manuals can be found here: https://www.aemelectronics.com/products/instructions/download