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Thread: RPM dancing, poor driveability, help!

  1. #11
    VR-3747 :D Not Verified Feedback Score 1 (100%) futurevr4man's Avatar
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    A misfire is a very open ended problem. Plugs, wires, coil pack, ECU, PTU, any of the wiring inbetween, fuel injectors, fuel pressure regulator, etc. etc. etc. It could be ANY or ALL of those. It's too open ended.

    The people on here are VERY knowledgeable about these cars and would definitely be able to help, but you have to rule out some of these things on your own. If you can get it to not misfire on idle or free-revving the engine, then we can start figuring out issues. Until then, you'll have to put your mechanic hat on and learn/figure out what the potential issues could be and start ruling them out.
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    I have done many tests and been mechanicing, im running out of tests, that is why i am asking for help. You maybe missed the long list of things i ruled out? Which contains many things you listed, as well as the misfire being not very frequent and only in idle, while my problem exists constantly 10-20 times a second, in all modes of operation?

    I'm not chasing a misfire, I'm chasing my engine running improperly, all tests on ignition system, ecu, plugs, wires, coils, ptu, fuel injectors, have been mentioned above.

    Fuel system may be an issue, as our 3s has no easy way to just slap a gauge on it, i haven't tackled that yet.

  3. #13
    VR-3747 :D Not Verified Feedback Score 1 (100%) futurevr4man's Avatar
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    Make sure you're getting a good signal to the fuel pump, and if you have a stock FPR they will generally overrun but I haven't heard of one under running on fuel pressure

    Do you not have a wideband gauge? 19t's, 560cc injectors... I see nothing about a wideband though. Kinda like step 1 when tuning a car. 560's are known to idle poorly too.

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    i've got a chrome ecu flashed for the 560cc injectors, not supposed to have any problems, as the latencies are programmed in for the 560cc. The problem existed before i put the new injectors in as well, on the stock injectors, new injectors were installed partially to attempt to fix this issue, the turbos will need them when tuned. This problem is existing in all conditions, i don't have a problem with an idle, i have a problem with my rpms fluctuating, this shouldnt be treated like an idle problem. This is an overall engine problem at this point.

    I don't have a wideband gauge. Have one, not installed yet until i get a new downpipe.

    stock fuel pump, with a new oem regulator. I may install a fuel rail setup that allows or has a pressure gauge on it. if I don't part the car out.

    There is afr information in the logs, not direct, i can see the rear o2 is lean. front o2 is dead so i will have to replace that, tho when it was working i was having the same problem. I broke that replaceing the crushed connector on it.

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    VR-3747 :D Not Verified Feedback Score 1 (100%) futurevr4man's Avatar
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    You respond to my attempts at leading you in a direction with "I know I have those issues, but that's not the issue I'm worried about". I'm not trying to be an ass, but you've gotta get this stuff square.

    Your RPM signal comes directly from your PTU. Look at the wiring diagrams (they are free for download on 3sx). If your issue really is "an overall engine problem" then there's no amount of internet troubleshooting that is going to help you.

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    I'm aware of the source of the rpm signal, the question is, what is causing the rpm to move up and down, I've tried swapping ptu's already and got the exact same results.

    Me saying I know the o2 is bad, but it's not the problem, really shouldn't be an issue here, i'm describing an issue in open loop, where o2 sensors don't matter.

    if its an overall engine problem, there still are ways to diagnose what the engine problem specifically is.

    I spent alot of time going over the service manual, and testing the procedures outlined in it, for all the parts i described, ptu, maf, cas, coils, wires, plugs, injectors, timing, idle, etc. And im still having the same problem, and found no problems using the factory suggested troubleshooting.

    I spent time outlining everything i've done and my conclusions, in hopes people wouldn't tell me to do obvious things over and over again.

    and no i don't have a wideband, i haven't started tuning the car yet, it's still on a base tune besides the injectors being updated to be 560cc and their corresponding latencies. wideband is planned, but im not going to dump $1000 dollars on the car smacking it with my purse, if theres serious engine problems of some sort, i'll part it out if i can't find help.
    Last edited by kruqnut; 03-07-2018 at 06:41 PM.

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    fuel pressure overrun would cause richness wouldn't it?

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    560s have known issues. IIRC they are actually closer to 590. There are threads here regarding such.

    EDIT: Thread here shows there are two different latency values https://www.3sgto.org/threads/7965-E...ighlight=560cc
    Last edited by stealthee; 03-07-2018 at 09:23 PM.

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  9. #19
    VR-3747 :D Not Verified Feedback Score 1 (100%) futurevr4man's Avatar
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    Quote Originally Posted by kruqnut View Post
    Me saying I know the o2 is bad, but it's not the problem, really shouldn't be an issue here, i'm describing an issue in open loop, where o2 sensors don't matter.

    if its an overall engine problem, there still are ways to diagnose what the engine problem specifically is.

    I spent alot of time going over the service manual, and testing the procedures outlined in it, for all the parts i described, ptu, maf, cas, coils, wires, plugs, injectors, timing, idle, etc. And im still having the same problem, and found no problems using the factory suggested troubleshooting.
    You say things like this that give me a glimmer of hope that you know what you're doing. But you don't seem to get the principle issue behind what you're saying. There are known problems but you want to overlook them. The issue is probably a small cheap one to fix, but you seem intent on us leading you to the source at this point. As I've said, you've given us an incredibly open ended issue.

    Quote Originally Posted by kruqnut View Post
    and no i don't have a wideband
    Widebands can tell you what your engine is doing, more than your narrowband o2's will which is why it's step 1.... aka not throwing on turbo's and injectors and a tune first.

    Quote Originally Posted by kruqnut View Post
    i haven't started tuning the car yet
    Yes, you have. Don't know why you think otherwise. What do you think a tune is?

    Quote Originally Posted by kruqnut View Post
    it's still on a base *map* (corrected) besides the injectors being updated to be 560cc and their corresponding latencies. wideband is planned, but im not going to dump $1000 dollars on the car smacking it with my purse, if theres serious engine problems of some sort, i'll part it out if i can't find help.
    You may as well give up then if that's your attitude. You're expecting the internet to blindly guide you to a solution. I have no idea if the engine is assembled even remotely well, much less if you know what you're doing.

    You've got some kind of airflow issue *I think*. I'd ask what your wideband is doing during idle and when you give it gas, but that's obviously not an important part of this to you, so I can't assist any further. Good luck.

  10. #20
    VR-3747 :D Not Verified Feedback Score 1 (100%) futurevr4man's Avatar
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    And like I said, 560's have known issues. But what the heck do I know, I'm some random dude on the internet.

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