Guest |750| Posted June 1, 2012 Report Share Posted June 1, 2012 Hi, this is about something that's been going on from day 1 of getting my motor running but I'm finally getting around to asking. I'm running a V44 and when at part throttle (loaded OR unloaded) right at 2k rpms my motor stutters/stumbles/hesitates. I spoke with the shop I purchased through and they had me clock the TPS so it read the maximum voltage/percentage at idle it could, after doing the tps setup with it reading the minimum voltage/percentage. Meaning at closed throttle it reads about 16% throttle. This made it WAY better, and almost completely livable. But cruising/part throttle I still get a stumble/hesitation when driving around. That and I can't use DFCO. My engine is a 2.0l Toyota 3S w/variable cam timing. It is running ITB's and the throttle sensor was purchased brand new. Andrew Quote Link to comment Share on other sites More sharing options...
lekonna Posted June 1, 2012 Report Share Posted June 1, 2012 Hi, this is about something that's been going on from day 1 of getting my motor running but I'm finally getting around to asking. I'm running a V44 and when at part throttle (loaded OR unloaded) right at 2k rpms my motor stutters/stumbles/hesitates. I spoke with the shop I purchased through and they had me clock the TPS so it read the maximum voltage/percentage at idle it could, after doing the tps setup with it reading the minimum voltage/percentage. Meaning at closed throttle it reads about 16% throttle. This made it WAY better, and almost completely livable. But cruising/part throttle I still get a stumble/hesitation when driving around. That and I can't use DFCO. My engine is a 2.0l Toyota 3S w/variable cam timing. It is running ITB's and the throttle sensor was purchased brand new. Andrew Well, i had the similar problem with my 2jz. the root cause was that you need to calibrate the tps with the car powered, other ways it shows different numbers than when the car is turned on. This results to the situation when you are running with low load on the street, the TPS reads too low and the overrun fuel cut cuts the fuel. (you can also disable this feature to check if it is the cause, under fuel tab -> overrun fuel cut). Messing with the throttle calibration so that tps shows 16% when closed just seems bit silly to me. what an strange advice from a shop. Quote Link to comment Share on other sites More sharing options...
Jason Posted June 1, 2012 Report Share Posted June 1, 2012 what happens when you re-calibrate the TPS when it's in the new adjusted position? Quote Link to comment Share on other sites More sharing options...
lekonna Posted June 1, 2012 Report Share Posted June 1, 2012 what happens when you re-calibrate the TPS when it's in the new adjusted position? well, in theory you would loose some resolution from the sensor since you are not exercising its full range of movement. in practice, i don't know if it matters or not. The question is, are you now hitting 100% from the sensor earlier than your throttle is really fully open ? Quote Link to comment Share on other sites More sharing options...
assassin10000 Posted June 6, 2012 Report Share Posted June 6, 2012 Well, i had the similar problem with my 2jz. the root cause was that you need to calibrate the tps with the car powered, other ways it shows different numbers than when the car is turned on. This results to the situation when you are running with low load on the street, the TPS reads too low and the overrun fuel cut cuts the fuel. (you can also disable this feature to check if it is the cause, under fuel tab -> overrun fuel cut). Messing with the throttle calibration so that tps shows 16% when closed just seems bit silly to me. what an strange advice from a shop. Powered as in key on/engine OFF or as in Key on/engine ON(running) ? When I do a TPS set with key on/engine off it shows the same 0% as it does when the engine is running. DFCO is turned off currently. I also tried setting the TPS while a battery charger was hooked up so it was seeing the same/similar voltages as when the engine is running. I agree, somewhat strange advice. But the shop had come across a similar situation and this is what they found kinda 'worked'. what happens when you re-calibrate the TPS when it's in the new adjusted position? Right back to the original problem. That was one of the first things I tried. The question is, are you now hitting 100% from the sensor earlier than your throttle is really fully open ? Yes, I hit 100% on the TPS axis when the throttle is actually only open about 84%. Not a huge deal on a multi-throttle engine... from what I understand. Andrew Quote Link to comment Share on other sites More sharing options...
assassin10000 Posted June 7, 2012 Report Share Posted June 7, 2012 No one has any ideas? I do know the newer style TPS on the throttles doesn't use an idle pin like the older TPS did. Instead the second output pin puts out a voltage just like the first, but its in reverse scale as the throttle opens it drops from 4-5v down to 0v. Where the normal pin goes up from 0-5v as the throttle opens. This 2nd TPS output is not wired to anything so it shouldn't matter. But I'm wondering if maybe it has a fluctuation or something that's causing the ECU to flip out. The TPS voltage looks steady when I watch the screen which is why I've not really done much thinking about this, that and even though I rotated & repositioned the TPS a few times the stumble/pause/hesitation stayed at the same 2k rpms. Andrew Quote Link to comment Share on other sites More sharing options...
Dave Kriedeman Posted June 8, 2012 Report Share Posted June 8, 2012 The second output giving a voltage output from high to low (4,5 volts down to 0 volts as throttle is opened) indicates to me that this TPS is probably one used on a DBW setup. NOTE WELL**** some DBW TPS sensors will max out their voltage sweep at around 80% throttle, they will still travel past this point but not generate any further voltage climb (resistance change). You need to do a couple of things first. Confirm that the TPS scale doesnt stop at 80%. When watching the Analogue window for TPS make sure the voltage or % keeps increasing above 80 %. If it doesnt, replace the TPS with a full linear type switch. If it does have full scale try the following,,, Make sure the throttle blade air gap is sufficient enough for the engine to idle without any influence from any type of idle control (Idle Speed Solenoids and valves etc). Make sure your throttle cable is set correctly and it is not to tight stopping the the throttle from closing correctly and making sure you get WOT. Adjust the TPS sensor so that it reads between 0.5 and 0.9 volts. Aim for 0.55 - 0.75 volts, ignition on / engine not running. Carry out a TPS calibration. Go to TUNING tab, select RUNTIME VALUES, Select Analogue Tab With the ignition on /engine not running, Press the accelerator pedal slowly open all the way to WOT. Firstly watch the TPS voltage climbs nicely in voltage as the throttle is opened, if all OK Release the throttle and do the same but this time check the throttle % has a smooth transission from 0% to 100%. You are doing this to check the TPS generates a healthy signal and that it is seeing a full transition, making sure the potentiometer in the TPS has a good sweep track and contact, No jumps in voltage or loss of voltage during operation. Next drive the car and see if the fault is still evident. If the fault is still there, I suggest you look at the A/F ratio at that point Also look at the timing parameters at the given problem area and then finally your Accelerator enrichment settings. Let us know if there is any change to your issue after carrying out the above. Quote Link to comment Share on other sites More sharing options...
assassin10000 Posted June 22, 2012 Report Share Posted June 22, 2012 1. Yes, this TPS was originally used on cars with DBW. I checked scale and it was all good. But as a just in case measure I've since swapped to a non-DBW TPS that has the standard idle switch instead of a reverse scale output for the 2nd output pin. Also brand new. 2. Checked TPS, does not stop at 80% scale. 3. TPS voltage keeps increasing right up until throttle is fully opened. 4. My engine has no IAC/Idle valve. It's the butterfly's and idle screws only. 5. Throttle cable is good, not too tight and not too loose. 6. TPS reads .54v at fully closed, ignition on and not running. 7. Calibrated TPS, both running and not running. 8. Checked run-time valvues, no pauses/dips/etc. Voltage climbs smoothly all the way until WOT, and all the way back down to closed. 9. Fault is still present. When fault occurs A/F appears to be all over the place. I've taken a log if anyone wants to look at it. Unfortunately I only have an LC1 currently and I'm not too sold on it's accuracy. 10. I tried playing with the timing with no change where this occurs. Quote Link to comment Share on other sites More sharing options...
assassin10000 Posted June 22, 2012 Report Share Posted June 22, 2012 Well.... long long story short. Fixed it. Found that somehow the anti-lag was on, even though I remember setting it to 'off'. :oops: :evil: Happens to the best of us. I'm definitely not that good. But the tuner I went to didn't catch it either, and he's pretty good. Neither did the guy at the shop I purchased the ECU from. Andrew Quote Link to comment Share on other sites More sharing options...
Dave Kriedeman Posted June 22, 2012 Report Share Posted June 22, 2012 Well done on the Fix. Good to hear you have resolved your issue. Quote Link to comment Share on other sites More sharing options...
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