Hey y'all. Here's the setup and background info:
Setup as pertinent to issue:
- stock ecu (JDM, to account for EGR deletion),
- stock ignition system (upgraded ground wire for ignitor)
- stock AFM/TPS/ISCV
- stock injectors
- AEM 320lph fuel pump
- Aeromotive AFPR
- UNrecirculated Synapse BOV (the non-recirculation has NEVER been an issue, I cannot stress that enough)
Background of issue:
Been driving the Supra with no major issues for over a year. Burning quite a bit of oil, not sure what the cause is yet, but a month or so ago I decided to replace the valve seals to rule out one cause. Valve seal replacement went smoothly (did not fix oil burning but that is not the issue here). Drove her for several days until I took a small roadtrip and drove her around with some spirited parts. On the way home at night, the supra suddenly lost all throttle response and revs were around idle speeds and it eventually stalled out. I coasted the car off the highway and called a buddy to help with diagnostics, we narrowed it down to the CPS wires.
Got it towed home and the next day I inspected the wires and lo, the solder joints had broken in two of the four wires. Temporarily fixed it with crimps and the car drove fine for another few days, until again, it suddenly lost throttle response. This time I opted to buy a refurbished CPS, however the resistance specs of the wires in the reman unit were out of spec, almost 200ohms when tsrm dictates around 140-180. For reference, my old CPS had good resistances the entire time, around 170. With the new CPS, the car would start and run fine until op temp and some change and then the issue would arise once again, leading me to believe that when hot, the resistances in the wires were getting too high and causing bad connection.
I removed the new CPS and opted to solder the old CPS correctly. Again, resistances were fine, re-solder went smoothly. The car started, but died after about 45 seconds, this rules out resistances getting too high since the car was still cold. Second time it idled smoothly, (take note, when it runs, it runs smoothly with no issues at all) but this time, once it reached op temp, I gave it a couple small revs and it stumbled when revs dropped and stalled out. From then on out it was the same deal, start the car and it would immediately die. I performed extensive wiggle tests harness side for the CPS wires and also verified continuity to the ECU plugs. This rules out a bad CPS connection. As per suggestions from a friend, I disconnected the TPS, AFM and ISCV in turn to see if the behavior of the car would change. This is the breakdown of the response for each plug:
TPS unplugged, car would start, revs would drop and it would attempt to recover once or twice if it succeeded the first time. Note that this exactly how the car behaves with the TPS plugged in. So no change at all.
AFM unplugged, the car would start and die much quicker than before with no attempts to recover.
ISCV unplugged, upon start, revs shoot to 2k, and drop rapidly to stall out with no attempts to recover.
I also disassembled the ISCV to see if it was dirty, it wasn't. Aside from a little bit of oil/dirt build up, it was just as clean as when I first put it back together and tested it. AFM was also clean, just a small film of oil, no doubt from the PCV system.
Compression test yielded 175s and 180s across the board, not sure if it matters, but at least you know the internals are healthy.
For all of the above tests etc, throttle response was minimal. Sometimes I would be able to force the engine to catch and rev a little, but it never occurred more than twice in any given sitting.
CEL codes, only 34 which is the same code you get from fuel cut, except I never hit fuel cut. It is a hint, but with my tired mind, it's not ringing any bells.
I can't think of anything else right now, if I do, I'll edit it in and make a note of it in the comments.
Hope someone will suggest a solution that will solve this aggravating issue, and thanks ahead of time for your assistance.
Setup as pertinent to issue:
- stock ecu (JDM, to account for EGR deletion),
- stock ignition system (upgraded ground wire for ignitor)
- stock AFM/TPS/ISCV
- stock injectors
- AEM 320lph fuel pump
- Aeromotive AFPR
- UNrecirculated Synapse BOV (the non-recirculation has NEVER been an issue, I cannot stress that enough)
Background of issue:
Been driving the Supra with no major issues for over a year. Burning quite a bit of oil, not sure what the cause is yet, but a month or so ago I decided to replace the valve seals to rule out one cause. Valve seal replacement went smoothly (did not fix oil burning but that is not the issue here). Drove her for several days until I took a small roadtrip and drove her around with some spirited parts. On the way home at night, the supra suddenly lost all throttle response and revs were around idle speeds and it eventually stalled out. I coasted the car off the highway and called a buddy to help with diagnostics, we narrowed it down to the CPS wires.
Got it towed home and the next day I inspected the wires and lo, the solder joints had broken in two of the four wires. Temporarily fixed it with crimps and the car drove fine for another few days, until again, it suddenly lost throttle response. This time I opted to buy a refurbished CPS, however the resistance specs of the wires in the reman unit were out of spec, almost 200ohms when tsrm dictates around 140-180. For reference, my old CPS had good resistances the entire time, around 170. With the new CPS, the car would start and run fine until op temp and some change and then the issue would arise once again, leading me to believe that when hot, the resistances in the wires were getting too high and causing bad connection.
I removed the new CPS and opted to solder the old CPS correctly. Again, resistances were fine, re-solder went smoothly. The car started, but died after about 45 seconds, this rules out resistances getting too high since the car was still cold. Second time it idled smoothly, (take note, when it runs, it runs smoothly with no issues at all) but this time, once it reached op temp, I gave it a couple small revs and it stumbled when revs dropped and stalled out. From then on out it was the same deal, start the car and it would immediately die. I performed extensive wiggle tests harness side for the CPS wires and also verified continuity to the ECU plugs. This rules out a bad CPS connection. As per suggestions from a friend, I disconnected the TPS, AFM and ISCV in turn to see if the behavior of the car would change. This is the breakdown of the response for each plug:
TPS unplugged, car would start, revs would drop and it would attempt to recover once or twice if it succeeded the first time. Note that this exactly how the car behaves with the TPS plugged in. So no change at all.
AFM unplugged, the car would start and die much quicker than before with no attempts to recover.
ISCV unplugged, upon start, revs shoot to 2k, and drop rapidly to stall out with no attempts to recover.
I also disassembled the ISCV to see if it was dirty, it wasn't. Aside from a little bit of oil/dirt build up, it was just as clean as when I first put it back together and tested it. AFM was also clean, just a small film of oil, no doubt from the PCV system.
Compression test yielded 175s and 180s across the board, not sure if it matters, but at least you know the internals are healthy.
For all of the above tests etc, throttle response was minimal. Sometimes I would be able to force the engine to catch and rev a little, but it never occurred more than twice in any given sitting.
CEL codes, only 34 which is the same code you get from fuel cut, except I never hit fuel cut. It is a hint, but with my tired mind, it's not ringing any bells.
I can't think of anything else right now, if I do, I'll edit it in and make a note of it in the comments.
Hope someone will suggest a solution that will solve this aggravating issue, and thanks ahead of time for your assistance.
