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Turbo Woes

Discussion in 'Turbo Cobras' started by lilsilverponey, Mar 23, 2017.

  1. lilsilverponey

    lilsilverponey Member Established Member

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    Hello all,

    I've been doing a turbo build on my cobra for quite some time now. Unfortunately problems keep popping up (stupidity of purchasing a used kit). Now I have a problem I haven't encountered before and was hoping some Cobra gurus on here may be able to shed some light.

    After replacing the turbo with a new one, whenever the car sees any load it shuts down and won't restart. It just turns over. My guess it's an electrical problem. Something is getting hot and the car won't restart till whatever overheated cools off.

    Components I have already cleared as potential problems:
    - ECU
    - Alternator
    - Battery
    - Tune

    Anyone have any idea what it could be? I have attached a video of the car doing it on the dyno. My next plan of action is to start checking grounds.

    http://vid1154.photobucket.com/albums/p533/SuperCruise12/IMG_0741_zps5rxbelk6.mp4

    th_IMG_0741_zps5rxbelk6.jpg


    Thanks guys.
     
  2. static74

    static74 in the 9's Established Member

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    No codes present? Judging by it breaking up there is something wrong with ignition or fuel, I'm guessing fuel. What's the fuel setup? What's the pressure when it shuts down?
     
  3. lilsilverponey

    lilsilverponey Member Established Member

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    Fuel is Lethal Budget Return setup with Walboro 465s. It's throwing codes for 02 sensors and the IAT II sensor (going to order a new one today). I haven't had the opportunity to check the codes after the car shuts down (have been reloading the tune to get it to start). I need to make it shutdown and check the codes, just haven't because it's very tricky where I live considering the car becomes inoperable anywhere from 1 hour to multiple hours thus leaving me stranded.

    One thing I forgot to mention: When the car shuts down I can't reload the tune. I get error messages consistently till whatever causing the problem cools down. Then the tune will load. I'm using a SCT X4. I don't remember the specific error message that shows up on the tuner.

    I haven't been able to check the fuel pressure as the shutdown happens but it looks good when idling.
     
  4. Eatonualive281

    Eatonualive281 Well-Known Member Established Member

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    What do the plugs look like? Can you log the coolant temp, what is it? It sounds like you car is thinking it's very very warm and almost going into a limp mode.
     
  5. lilsilverponey

    lilsilverponey Member Established Member

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    Plugs look fine, I pulled them all and did a compression test. Coolant temp looks fine via the gauge (we know how good the stock gauges are). I will run the car a bit this weekend and datalog the coolant temp. I think it will be fine though.
     
  6. Juiced46

    Juiced46 I love being Blown Established Member

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    When the car does not start, what is fuel pressure showing?

    Reason I ask is. I have seen where people did not set the correct pump depth in the Lethal Fuel hat. OR someone bent the center of the gas tank a little when removing/installing it. What was happening was, when the car was driven for about 30-45mins, it would get hot, the pumps would suck against the bottom of the tank and run dry, fuel pressure would drop until it cooled down, then back to normal. I have seen this a few times on botched installs. Sounds exactly like what is happening in your case.

    However, the thing that does not add up is when it happens you cannot load a tune. How did you establish it is NOT the ECU?

    Also, do you have good ground from the driver side block to the frame?
     
  7. lilsilverponey

    lilsilverponey Member Established Member

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    After it goes into "Limp" mode and I turn the car to the ACC position to let the fuel pumps run the gauge at the regulator shows 40psi as it should. I have watched the fuel pressure while someone was trying to start it and the fuel pressure stayed at a good PSI. I did have clearance issues when I put the pumps in the tank. I had to pound out the center of the tank to gain clearance (guess one of the previous owners used a jack in the middle to drop the tank). But the funny thing is, when I had the bad turbo on the car (just replaced), you could wind it out to 6k plus rpm no problem.

    I established it wasn't the ECU by replacing it with another good ECU and seeing if the problem persisted. Which it did, the car ran smoother with the new ECU but the main problem remained.

    I need to double check the ground to the frame near the block. I know I hooked it up originally but maybe something has snagged that wire.

    Thanks for your input!
     
  8. MG0h3

    MG0h3 Well-Known Member Premium Member Established Member

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    Man problems like this blow...we change so much stuff its easy to chase your tail.

    I know were talking about something getting hot>shut down>unable to load tunes for XXX amount of time for cool down. Not sure if thats adding up for me.

    What doesnt make sense is that it didnt do it before the new turbo. Sure you didnt stretch a harness or something so that when the motor moves (under load) you are shorting/disconnecting something? Id think the MAF is a possible culprit because that got moved for sure (harness likely lengthened and probably disturbed during turbo swap).
     
  9. lilsilverponey

    lilsilverponey Member Established Member

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    Yes, it's incredibly annoying chasing a problem like this down. What's crazy is this problem didn't happen before I replaced the turbo and all I did was change the turbo, didn't mess with anything else. The MAF is literally brand new (SCT BA5000). I'm pretty certain the IAT2 sensor is bad on top of the intake. The car is idling funny and after it warms up, it idles very lean. I'm not sure how to check this sensor through data logging but I plan on ordering a new one in the next day or so.
     
  10. MG0h3

    MG0h3 Well-Known Member Premium Member Established Member

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    Malcolm V8 had a weird issue that turned out to be a corrupted tune. Can't remember all the details; think he thought it was black goo from e85 so maybe search under that.

    So you can't communicate with the ECM after this happens?

    As far as the iat sensor, you can usually google some tests for it. Likely need a volt ohm meter. I'd be very surprised if that's causing the shutdown and no restart but always gotta replace known failures.








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  11. lilsilverponey

    lilsilverponey Member Established Member

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    Initially I thought it was the tune. Took it to my tuner (very well known and knowledgeable) and discovered it wasn't the tune, which led to the possible thought of a short in the ECU. Also checked the crank sensor while it was at the tuners.

    If I try to load the factory tune when the car is down, an error comes up on the tuner (forgot the exact code as it's been a few weeks since I messed with it). I think it's a high voltage code.

    I don't think the IAT2 sensor is causing the shut down but hope it fixes the idle problem I am also having.
     
  12. MG0h3

    MG0h3 Well-Known Member Premium Member Established Member

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    If you hadnt have said "high" voltage I would think your ECM is losing power. You cant load tunes and can actually damage the ECM while transferring files and the batt dies.

    Have you checked for power at the ECM while the failure is occuring? Not sure if the OBDII port is powered on the same circuit as the ECM; Id check at the harness.

    Whats weird is it sounds like the problem corrects itself. PCBs can get hot and fail but Id look for something simpler. Relay or not sure if there is a circuit breaker on the ECM power circuit?

    Another thing Im curious about; it only does this under heavy load? If its heat related, you should be able to stop and go in traffic and recreate it.
     
  13. lilsilverponey

    lilsilverponey Member Established Member

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    Now that I've recreated the problem a few times I have noticed the following regarding the actual shut down:

    1. The colder the car is, the longer it makes it/harder I have to push it to shut down (about 75% throttle, shut down around 4k rpm when it starts to see boost).

    2. The warmer the car is, the easier it is to shut it down. I have gotten it to shut down around 40% throttle around 3k rpm (No boost, close to 0 vacuum).

    It doesn't take true "heavy" load to shut itself down however so far it hasn't shut itself down while babying it around.
     
  14. MG0h3

    MG0h3 Well-Known Member Premium Member Established Member

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    I could see a fueling issue like juiced mentioned causing this, but you have fuel at the rails during the crank no start.

    If it were my car I'd log as many pids as I could and watch it during the failure. It may at least point you in a certain direction.

    Still, the extended no start that suddenly corrects itself hours later does suggest some sort of thermal shutdown.

    Remember, poor connections cause heat and increased amperage draw. When the engine torques it could be causing a poor connection to worsen. I really wouldn't be surprised if the ecm power circuit had a breaker.


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  15. NastyNate420

    NastyNate420 Member Established Member

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    Yeah.....id be looking closely at your ECM....
     
  16. lilsilverponey

    lilsilverponey Member Established Member

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    Care to elaborate? I am retarded when it comes to electrical problems (such as this).
     
  17. MG0h3

    MG0h3 Well-Known Member Premium Member Established Member

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    I don't know if it has a breaker in the circuit. I'll google a bit when I get home. However, you could simply test for power at the ecm while the failure is occurring.


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  18. lilsilverponey

    lilsilverponey Member Established Member

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  19. MG0h3

    MG0h3 Well-Known Member Premium Member Established Member

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    Damn man nice work finding that.


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  20. lilsilverponey

    lilsilverponey Member Established Member

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    Well, not sure what I did but I looked a few things over and took it for a spin to datalog this weekend. Made two quick small pulls near the house trying to get it to shut itself down and couldn't get it to do it. First pull I only ran it to 4300 RPM in second gear, second run (didn't datalog) I ran it up to about 5,500 RPM and hit about 12lbs of boost. The A/F is fluctuating and there is a slight misfire up the RPM range. Pretty certain it's a bad MAP sensor. I have a new one on order. Once it arrives I will start driving the car again and see how it does.
     

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