Testing VF,confusing results...
- Thread starter supraman74
- Start date
Lol, NP, well if possible I would try and hunt down one if you can, those are pricey new ($81.26 at champion). So it would be nice to be sure that is going to solve your problem, before you go paying that kind of price for it. 
Today I swapped out my jdm tps for a usdm tps= no change.
Thought I'd throw that out there for you.
Thought I'd throw that out there for you.
Thought I'd throw this random data log out there too. This is after the warm restart when VF starts reading. The "Accelerator" (brownish line close to middle of graph) is the input that I have tapped into the VF wire coming from the ecu. It cycles between about 1.96v & 2.33v consistantly, no matter what the afm frequency is tuned to.
Sorry, don't mind the water temp. It's not accurate and is in no way wired to the factory ecu.
Sorry, don't mind the water temp. It's not accurate and is in no way wired to the factory ecu.
^ I won't bore you with the tech details but that's normal. Contrary to popular belief Vf isn't simply a steady state voltage which can be one of five values...just that few people ever bother scoping it.
jetjock;965990 said:
Its only boring to those that either already know or have no desire to learn. :icon_bigg
I did a voltage test on my ecu and these two failed. I'm not sure if its a wiring harness issue or an ecu problem.
Voltage at ECU - http://www.supra.co.nz/87tsrm/EFI/efi38.htm
Terminals--------Condition---------STD Voltage-----Result
idl - e2-------IG on throttle open----10 - 14----------5
vta - e2-------IG on throttle full open---4 - 5--------3
I was letting you know that I swapped out a jdm tps that passed every test I threw at it, for a usdm tps that also passed all the tests in the book. I've also swapped a perfectly good ecu for another. This is just stuff I've had lying around. None of this effected the rich restart at all. Swapping your tps might help a little with driveability but I wouldn't hold your breathe on it helping your rich restart.
I'm really thinking that the car is stuck in open loop warm up mode. When I restart the car the 2nd time, it does take a short period of time before the VF starts to show in my datalogs. Like it's warming up. We need to find somebody with one of those Techtom/reg reimer ecu's that show the factory toyota maps. That could give a clue. The open loop warm up map needs to meet certain requirements before switching to closed loop. What all of the requirements are, I just don't know.
I'm really thinking that the car is stuck in open loop warm up mode. When I restart the car the 2nd time, it does take a short period of time before the VF starts to show in my datalogs. Like it's warming up. We need to find somebody with one of those Techtom/reg reimer ecu's that show the factory toyota maps. That could give a clue. The open loop warm up map needs to meet certain requirements before switching to closed loop. What all of the requirements are, I just don't know.
Buddafuco, I have same problem as you. I am going to test voltages cold and hot at ecu and post results. I drove my car for weeks with a voltmeter taped to dash showing vfs, and current behavior is NOT normal. My vf readings had always reflected my cars tune, IE, too much fuel at afpr and computer adjusts, and vfs change. No longer the case. My car was tuned for VF before, and would occasionally show 1s and 3s, no longer the case. I can crank the a/fs up to 11 by turning up fuel pressure, and computer just lets it be, with a vf of 2, instead of showing a rise toward stoich, with a drop in vf as computer pulls fuel.
Anyone have a clue on these results?
Voltage at ECU - http://www.supra.co.nz/87tsrm/EFI/efi38.htm
Terminals--------Condition---------STD Voltage-----Result
idl - e2-------IG on throttle open----10 - 14----------5
vta - e2-------IG on throttle full open---4 - 5--------3
Voltage at ECU - http://www.supra.co.nz/87tsrm/EFI/efi38.htm
Terminals--------Condition---------STD Voltage-----Result
idl - e2-------IG on throttle open----10 - 14----------5
vta - e2-------IG on throttle full open---4 - 5--------3
Idl - E2 is wrong. IDL should go to 5 volts when the throttle plate is cracked.
VTA - E2 looks a bit low but is probably OK. Although the book says 5 volts I have never seen a TPS go beyond about 3.6 at WOT and doing the math shows that's what it should be. One of many misprints in the TRSM.
VTA - E2 looks a bit low but is probably OK. Although the book says 5 volts I have never seen a TPS go beyond about 3.6 at WOT and doing the math shows that's what it should be. One of many misprints in the TRSM.
Thanks JJ, so when idl goes to batt voltage when the throttle is cracked, does that happen inside the tps or is it a voltage signal coming back from the ecu?
I guess I could run a new idl wire from the tps to the ecu and see if that helps.
I guess I could run a new idl wire from the tps to the ecu and see if that helps.
IDL disconnects E2 when the throttle is moved, completing the 12v circuit. You should see this with a volt meter anywhere on the IDL wire.
My max VTA voltage is 3.58v.
carfreek- I saw your antifreeze post. Did I read that correctly? Your car started acting up like ours after you spilled coolant into your engine harness??
Do you run a piggyback fuel computer or anything?
My max VTA voltage is 3.58v.
carfreek- I saw your antifreeze post. Did I read that correctly? Your car started acting up like ours after you spilled coolant into your engine harness??
Do you run a piggyback fuel computer or anything?
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supraman74;968237 said:
Not sure I understand the question. It's both. IDL runs from the TPS to the ECU. Inside the TPS it gets connected to E2 (ground) whenever the throttle is closed. That pulls IDL to ground. When the throttle is opened IDL disconnects from E2 and rises to 5 volts because it's connected to sensor power inside the ECU through a resistor that limits current when it's pulled to ground.
IDL function can be easily checked at any time by connecting T and E1 in the diag block and slightly pressing the gas pedal. Code 51 should come up. The engine doesn't have to be running. It can also be checked with the engine running and the diag block not jumped by watching/listening for fuel cut when slowly coming down from above 1800 rpm. If the TPS is adjusted correctly fuel cut will occur at 1200-1500 rpm
jetjock;968895 said:
My question didnt come out right but you nailed it :naughty: Thanks
I tried T and E1 in the diag block and slightly pressing the gas pedal and Code 51 does come up.
And just for shits and giggles I unplugged the tps while the engine was running but no code or cel.
I would think that would set off the cel and give me code 41.
I've done it with other sensors like the water temp and maf and those threw the cel right away.
I know thats no way to diagnose, I was just curious.
Unplugging the TPS should have set a 51 but it won't set a 41 right away because some codes don't set until the value stays out of range and certain conditions are met. Time, speed, rpm, key cycles, etc. The knock and O2 codes are other examples of this. Some codes will be set without illuminating the MIL while other codes won't be set at all depending on where the car was made to be sold. It has to do with priorities concerning emissions.
With all the talk about tps, I decided to go disconnect my piggyback's throttle wire from the VTA wire. The rich restart is still there. Back to the drawing board.
I'm thinking I may have an ecu issue. IDL is not getting the right voltage from the ecu when the throttle is pressed.
supraman74;970249 said:
Most cars don't need an ECU.
How do you know? You scoped it with voltage over time?
