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Thread: 1jz wont rev past ~2500rpm *SOLVED*

  1. #1
    Yay! I'm an Automotive Encyclopaedia Hydra's Avatar
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    Angry 1jz wont rev past ~2500rpm *SOLVED*

    Hey guys,

    I'm stuck! I can't get my 1jz out of what would appear to be limp home mode. It's sparking OK, but I hooked up a duty cycle meter to the injectors and it would hit about 4% (just above idle) and die in the arse. It's like hitting a fuel cut. If I let off the throttle after this cut occurs, the engine springs back to life. It's just anything more than a little throttle and/or 2500rpm kills it. If I open the throttle fairly quickly it just stalls.

    The Fuel system is working as far as fuel pumps go. What puzzles me is that the duty cycle on the injectors hits about 4% and goes no higher at all, no matter what throttle I dial in.

    This has lead me to think that the TPS may be either faulty, or not getting power at the right places. Does anyone know what pins should have what power/signal?

    The MAP appears to be getting power - no error codes are getting recorded either. As far as I know everything is hooked up the way it should be. There are no vacuum leaks to speak of.

    I'm really stuck here - I need help figuring this one out!
    Last edited by Hydra; 27-07-2008 at 03:27 PM.

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    Default Re: 1jz wont rev past ~2500rpm

    Quote Originally Posted by Hydra
    would hit about 4% (just above idle) and die in the arse
    I mean, it stays at 4% - never goes above that.

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    Toymods Pimp Chief Engine Builder Norbie's Avatar
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    Default Re: 1jz wont rev past ~2500rpm

    Sounds like a MAP sensor problem to me. This is the primary means of determining engine load, not the TPS. Make sure the sensor is getting a clean vacuum signal and check the output voltage is in the correct range.

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    Default Re: 1jz wont rev past ~2500rpm

    Ok, sounds like a good place to start! What range should I expect?

    The MAP is connected to the intake via some adaptor thing - is this the correct place?

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    Default Re: 1jz wont rev past ~2500rpm

    Here's a pic - the black thing that bolts in:


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    Default Re: 1jz wont rev past ~2500rpm

    FWIW, I just tried the MAP sensor on a few other vacuum points - still no go.

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    Default Re: 1jz wont rev past ~2500rpm

    intercooler pipe/ hose ?
    i dont have a funny or cool signature.

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    Hopefully soon a 5S-GTE Chief Engine Builder MWP's Avatar
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    Default Re: 1jz wont rev past ~2500rpm

    Is the map sensor reporting correct values?
    Correct values are listed in the Toyota Mechincs Guide.

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    Default Re: 1jz wont rev past ~2500rpm

    Doubt it'd be the intercooler pipes/hoses - MAP shouldn't be affected by that.

    MWP - got a link to it by any chance?

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    30DET... The only way. Carport Converter Kyosho's Avatar
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    Default Re: 1jz wont rev past ~2500rpm

    Check your cooler pipes as mentioned.

    I run a MAP, and when I blew the cooler pipe that goes between FMIC and Throttle, my engine displayed the exact same symptoms.

    Have you also reset the ECU?
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  11. #11
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    Default Re: 1jz wont rev past ~2500rpm

    Disconnect the battery for a while (10-20 mins) so the ecu resets and try again, if that fails try manually resetting the ECU by using the Diagnosis pins!
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    Default Re: 1jz wont rev past ~2500rpm

    ECU has been reset many times since the engine was put it. The car sits there with the negative disconnected while i'm at work since it's up on stands.

    The pipes are fine, no leaks that I can find.

    No diagnostic codes are showing - I wish there were so I could just fix the damn thing!

  13. #13
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    Default Re: 1jz wont rev past ~2500rpm

    Found the mechanics manual thigo:

    http://www.autoshop101.com/forms/h35.pdf

    Off I go to test...

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    Default Re: 1jz wont rev past ~2500rpm

    Seems to be working OK - it was sitting around the 2.4-5V mark on the PIM pin while the engine was off, 1.3-4V while the engine was idling. Revved the engine, it hit the 2.4-5V mark as the engine started it's rev-cut thing.

    So I can only conclude that it knows how much air is going in... but that doesn't help.

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    Default Re: 1jz wont rev past ~2500rpm

    I did pull the cover off the ECU early on - I didn't notice any form of leaking or corrosion from the capacitors thankfully. I am setting this aside as a potential problem for the moment...

    Something that would be very awesome would be a pin-out for the ECU with the voltages to expect on each pin. I've seen this before in TSRM's but I can't find one for the 1jz-gte anywhere.

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