Harley Posted November 7, 2021 Report Share Posted November 7, 2021 Hi guys pretty new to the aftermarket set up, got an RB25 neo in my patrol with a link G4+ ecu, had it wired up mostly by a shop and had it all running last break, doesnt have an o2 or iat installed yet as im getting it running to drive it to the workshop i can use to install that haha, ran last break obviously a bit rich and smoky being the base tune without those sensors, wired up thermos the other day (twin AU fans), with only 1 of the relays being triggered through earth on the FP speed output which was a loose wire in the harness (aux 5), had the fans working fine but when i fired it up the idle seemed to be all over the show and it completely dies in the ass when i go to take off, can move the car if i give it lots of revs and ride the clutch which i didnt need to do prior to wiring up the fans, it did sit for about 5 weeks between the first drive and wiring up the fans though. i have noticed the TPS signal was only ranging from .10-.20V from closed to WOT and it popped up with MAP limit activated, noticed the MAP and MGP were reading a bit inconsistant, spiked up to 400kpa and cut out completely. ive attached a log which i hope will have the right information but being my first log im not sure if ive done it correctly haha. tested the TPS and the signal output was as the log says 0.10-0.20V but the resistance tested from 2.5Kohms to 5.5Kohms ish on a S1 rb25 TPS. any help would be much appreciated Log 2021-11-6 6;36;13 pm.llg Quote Link to comment Share on other sites More sharing options...
Adamw Posted November 7, 2021 Report Share Posted November 7, 2021 Something wrong with the map sensor or its wiring in that log. It slowly drops down to 5kpa with the engine off, then jumps back up to 100kpa all by itself (should be ~100 with engine off). The ECU is reporting the 5V output is still ok so the problem is possibly a loose connection or bad sensor. Quote Link to comment Share on other sites More sharing options...
Harley Posted November 8, 2021 Author Report Share Posted November 8, 2021 had a check today and noticed the MAP reading was fluctuating a little and when i wiggled the wires on the plug it went crazy so i think you are on the money there, the resistance between power and earth and earth terminals on the MAP sensor seem to fluctuate as well when tested out of the car, heading back to work this week so going to order a new MAP sensor so it should be here by the time i get back to test so will keep update when i get back. Tested the TPS while i was in there and the sensor it self seemed to test fine, 2.5kohms closed and goes through up to about 7kohms smoothly to wide open on the pedal, is it normal for the voltage range for the signal to only be .10-.20 volts? the TP main % doesnt doesnt change then jumps up to like 75% and only changes when pretty much flat to the floor. Quote Link to comment Share on other sites More sharing options...
Adamw Posted November 8, 2021 Report Share Posted November 8, 2021 56 minutes ago, Harley said: 2.5kohms closed and goes through up to about 7kohms smoothly to wide open on the pedal, is it normal for the voltage range for the signal to only be .10-.20 volts? the TP main % doesnt doesnt change then jumps up to like 75% and only changes when pretty much flat to the floor. That doesnt really sound right, you would usually have near 0 ohm and one end and max resistance at the other. Quote Link to comment Share on other sites More sharing options...
Harley Posted November 8, 2021 Author Report Share Posted November 8, 2021 would explain the tiny voltage reading coming out of the TPS, might be worth looking at a new sensor, seems strange that both would go out at the same time but stranger things have happened, ill see if i have another TPS floating around someone to test with Quote Link to comment Share on other sites More sharing options...
Adamw Posted November 8, 2021 Report Share Posted November 8, 2021 Im not sure it explains the low voltage either. A change from 2500-7000ohm should give something like a 2V change. Quote Link to comment Share on other sites More sharing options...
Harley Posted November 8, 2021 Author Report Share Posted November 8, 2021 do you think it could be an earth issue? with the 5v supply being ok would a dodgy earth mess with the signal going back to the ecu from both the MAP and the TPS? not sure if an earth problem would cause the MAP reading to fluctuate when wiggling the wires at the plug though? also seems rather strange that the signal voltage gets higher as i open the throttle which increases the resistance in the sensor Quote Link to comment Share on other sites More sharing options...
Adamw Posted November 8, 2021 Report Share Posted November 8, 2021 13 hours ago, Harley said: do you think it could be an earth issue It could be anything from a pinout issue, sensor issue, 5V issue, Gnd issue, or other wiring issue such as a bad crimp. You need to eliminate what you can logically. Obviously 5V and ground are easy to check. The factory service manual will give you expected resistance and or voltage for the TPS. 13 hours ago, Harley said: also seems rather strange that the signal voltage gets higher as i open the throttle which increases the resistance in the sensor A TPS has 3 wires, the resistance increases between 2 pins and decreases between the other two. Quote Link to comment Share on other sites More sharing options...
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