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Thread: Bad tps?

  1. #1
    Join Date
    Jun 2012
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    Nanaimo, BC
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    Bad tps?

    Smallport engine. When I put the motor into my car I never touched the tps at all. It ran good and had good pep. But it had the urky jerky thing going on at low rpm with light throttle input. So I adjusted it clockwise slightly and it cured the jerkiness but it doesn't have as good of power and fuel mileage is poo compared to before. I've tried multiple times to set it in a spot where it's not jerky and runs good but no luck. Does this mean it's no good? Anyone have any tricks to setting these things properly?

  2. #2
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    Easy to set up with a multimeter and the FSM instructions. Should be able to google those specs.
    1JZ 1984 Celica GTS
    1UZ 1981 Corolla sedan
    ? 1972 Celica race car

  3. #3
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    Jun 2012
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    Alright. So I went and bought a multimeter and feeler gauges to set up my tps properly. I used this as a guide, http://www.matrixgarage.com/content/...tps-adjustment, but after setting it to the spec with the feeler gauges I ended up with over 1 k ohm when i should be at 0.2-0.8 k ohm with vta and e2 connected. So I tried my spare tps and same thing but at 0.9 k ohms. How important is it to be within that spec? It's way to jumpy to drive at low rpm's with the tps set where it's below 0.8, but it seems to have more pep.

  4. #4
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    What is "too jumpy to drive"? Like it's too sensitive? When I got my stuff sorted, it was way more sensitive and it's awesome! What is your idle set at anyways? Mine used to do some strange things at low RPM, so I upped it to around 1100 and it was fine.

  5. #5
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    more likely bad setup than bad unit. the spec is for the idle contacts to open and close as the throttle is at idle and just off idle. this will allow you to set base timing properly.
    - Brian


  6. #6
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    Quote Originally Posted by Blade7 View Post
    What is "too jumpy to drive"? Like it's too sensitive? When I got my stuff sorted, it was way more sensitive and it's awesome! What is your idle set at anyways? Mine used to do some strange things at low RPM, so I upped it to around 1100 and it was fine.
    What I mean is when I'm crawling along at very low rpm and very light throttle it will suddenly cut fuel then surge back up again. Which is majorly annoying when crawling along in slow moving traffic or through a parking lot.

    Quote Originally Posted by Brian View Post
    more likely bad setup than bad unit. the spec is for the idle contacts to open and close as the throttle is at idle and just off idle. this will allow you to set base timing properly.
    I realize that the spec is to set the unit so it cuts out of idle mode at the lightest touch of the throttle. That's where it is set. But for some reason my ohms are higher than the spec says it should be. It drives very smoothly but seems to lack a bit of power. My timing is set at 10 degrees in diagnostic mode. But when I take it out of diagnostic mode it goes to about 12 degrees even tho everyone says it should go to about 18 degreesp

  7. #7
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    Jun 2012
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    So I just did an experiment on the tps that came with the motor originally since it's off the car and I'm running my spare. I found a write up about taking an mr2 tps apart and cleaning it. So I tested, then cleaned, and retested my tps. The results were interesting. Before cleaning the tps, when it was set right at the perfect spot to disengage the idle switch I would get a reading of about 0.9 k ohms with vta and e2 connected. Which is out of spec. So after cleaning the tps and setting it up properly again on my spare throttle body I now get a reading of only 0.6 k ohms. Which is nicely within spec. I could definitely see some grime on the q-tip after cleaning it. I'll get it installed in my car and see if there is any improvement in how it feels to drive

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