shrike Posted July 12 Posted July 12 1 hour ago, sheepers said: No On 07/07/2025 at 06:43, sheepers said: I still can't get this thing to run right. I'm fucking pissed off with it tbh. Is the same motor and ecu that I drove into my shed with no issue in a different car and now it won't run for shit. It's got too much fuel at idle and goes lean at throttle input. Is like the fuel controller is backwards. I haven't checked the pump voltage yet because I decided to do something to actually make progress. Not trying to teach you to suck eggs I know how many cars youve worked on just thinking aloud and hopefully something helps So Im a little confused as to why the fuel pump not running less flow via lower voltage (assuming the pressure doesn't change) would cause you to run rich at idle and lean on boost I know you need more flow to maintain pressure when your at WOT and Boost/Revs and high VE etc I've never had the issue you describe when running a fuel pump at full voltage all the time, running richer yes if the fuel pressure reg can't maintain the pressure with the higher flow rate as it can't allow enough flow back to the tank to maintain the correct pressure TPS or AFM seems more likely the issue, or a leak somewhere post AFM but youve checked for leaks so its not that Fuel pressure youve said says the same checked via gauge and multiple FPR Fuel line sizing is the same as the old car, so its not a restriction to the rail or on the return side Might be worth checking what the AFM's are reading and what the TPS reads The factory cam angle sensors on these are a common failure point and could also cause you to lean out as you go up the rev range but wouldn't explain the rich at idle Assuming you've got good filtering and nothings clogged (wouldn't explain rich at idle tho) I'm assuming you haven't taken the rail off, so guessing the injectors are fine. Power FC wouldn't be running a wideband, but a narrowband O2 sensor could be reading incorrectly causing it to be rich at idle and lean on boost? How are you confirming the AFR is rich/lean or does it just feel that way? Coilpacks on RB's are also a know issue and spark breaks down on boost esp if plugs aren't gaped properly but it doesn't feel like its running lean etc. When I had my 25det neo I had a failing cam angle sensor that worked ok when it was cold but gave me trouble when it got hot. (turning the shaft by hand you could feel how bad the bearing was) How long had the motor been sitting in the other car or was it regularly run? Based on your comments about wiring, if it was me id be making sure all the sensors read correctly (AFM, TPS, Coolent temp sensor, Fuel pump has full voltage under load and cam angle is good) If they all are fine then id be guessing wiring It could be a few things that are minor on there own but combine to be a bigger issue 1 Quote
mjrstar Posted July 12 Posted July 12 Maybe it's like my honda, the tps, map, and some other thing iacv maybe, all have identical plugs and the cables are long enough to connect in any combination. 4 Quote
kws Posted July 12 Posted July 12 Surely logging or watching live data on the PFC during the times where its faulting should show up if a sensor was reading wrong. Thats how I found on my old Link G1 when my MAP sensor was full of oil, the MAP reading went on the piss when the car stumbled, same when the IAT sensor wires were shorting on a different car. 2 Quote
Popular Post sheepers Posted July 13 Author Popular Post Posted July 13 i appreciate your input guys, it all helps to try and figure out what's going on. i wasn't a good weekend in GTR land. i spent the weekend installing speakers and wiring the radio because i wanted to do something that would just work. so i did that. i was going to take the fuel pump out of the other GTR to check that off the list of "things that i have tried". when i started pulling the boot carpet out of the other car, the car my engine and ecu came out of (that was running fine with no issues at all) i discovered that the other car has had the fuel pump controller bypassed so it was never controlling fuel in the first place. the thing that really pissed me off is that ive been pretty clear on trying to get the fuel pump controller to work with the guy i bought the car off, and the guy who's car my engine was in. almost two weeks of fucking around to get it to work and they never said a thing about the tune im trying to fix not needing the fuel pump controller at all. it was at that point that i had a complete sense of humour failure and went in the house. from what i can tell by the weird way it runs the ecu is missing a piece of information (like boost for example) that it needs to correctly control fuel. every (factory) input is connected to the ecu and is showing data at the hand controller. it does have a setting for boost but there is no boost input into the ecu. the power fc has a separate plug in the side which is specifically for boost control and there was no plug in this port in the other car so if its getting boost signal its through the factory loom somehow. my understanding is that the stock ecu has no boost input and uses the maf sensors to figure all that out and that the map sensor is only used for the gauge. it probably was getting this signal in the other car somehow but asking the guys is a complete waste of time, they either dont know or have forgotten what has been done. these guys dont do any work them selves if its wiring so they have little idea of how things work. that's where im at currently. a mate of Nick the sparky's is a tuner and may have worked on this ecu in the past so im going to reach out to him today and see if he can shed some light/come and fix the fucking thing. 12 1 Quote
shrike Posted July 13 Posted July 13 Might help if you haven't found it R32 GTR Boost Readings - Apexi PowerFC - General Maintenance - SAU Community https://share.google/AuYoKkL5O395Camn0 Annoying your having these issues, anyone have a plugin link, haltech or nistune you could borrow to validate the wiring is all good? Quote
sheepers Posted July 14 Author Posted July 14 ive read that, but my problem is finding how the power fc is supposed to receive the boost signal. ill spend some more hours looking at the wiring diagrams and see what i can see. Quote
shrike Posted July 14 Posted July 14 24 minutes ago, sheepers said: ive read that, but my problem is finding how the power fc is supposed to receive the boost signal. ill spend some more hours looking at the wiring diagrams and see what i can see. From memory, I thought it was based on the airflow the AFM/MAF was reading that it calculates against Also the MAF's on these tend to die randomly as well Quote
sheepers Posted July 14 Author Posted July 14 so I'm looking at the wiring diag now and the map sensor goes to the dash only. however there is a "turbocharger pressure control solenoid" that my car does not have. im wondering if there is a boost pressure signal in this module that gets back to the ecu somehow? actually, its only two wires so probably not going to be a 0 - 5v signal from that. Quote
shrike Posted July 14 Posted July 14 42 minutes ago, sheepers said: could be. Is your Power FC D-Jetro or L-Jetro The D-Jetro setup utilizes dual MAP sensors https://www.apexi-usa.com/collections/apexi/products/power-fc-1989-1998-nissan-skyline-gt-r-r32-r33-l-jetro-maf?variant=43932592341213 This is the L-Jetro (MAF) https://www.ebay.com.au/itm/153311544187?srsltid=AfmBOopnY4QJParEqwH-MwCa4eXv5BO8FPMb6q6LqMkaEy9f1yCz_ivV Though Id be wondering how does it run if you have a D-Jeto setup and no map sensors Edit: I am assuming you are using the same MAF's that came in the car the engine came out of? @sheepers any chance of some pics of the MAF's installed/the p/n etc Quote
fletch Posted July 14 Posted July 14 2 hours ago, shrike said: Is your Power FC D-Jetro or L-Jetro The D-Jetro setup utilizes dual MAP sensors I'm pretty sure it's D Jetro. I remember helping diagnose a similar fault on this car maybe 2008 when he byilt the rb30 for it. One of those sensors had failed and it was super rich on 3 cylinders. Maybe the front 3. It was the front map sensor. At a real stretch of the gray matter, I think they were mounted above the fuel rail say between cylinder 2 and 3, and 5 and 6. 1 Quote
shrike Posted July 14 Posted July 14 1 hour ago, fletch said: I'm pretty sure it's D Jetro. I remember helping diagnose a similar fault on this car maybe 2008 when he byilt the rb30 for it. One of those sensors had failed and it was super rich on 3 cylinders. Maybe the front 3. It was the front map sensor. At a real stretch of the gray matter, I think they were mounted above the fuel rail say between cylinder 2 and 3, and 5 and 6. @sheepers if you confirm it is a D Jetro that will help track things down So I am assuming the loom on the motor is the same that was in the old car, in which case the wiring should be correct for the D Jetro Power FC, so possible the Map sensor has died or a plug hasn't been plugged in, or wiring needs to be checked? https://www.sau.com.au/forums/topic/114249-apexi-power-fc-d-jetro-install-instructions/ Quote "There are various installation methods for the Djetro Map Sensor depending on the Car Model. For example Evo Lancer CT9A do not have to do anything as the car runs a factory Map Sensor. Skyline RB26 customers must splice twin Map sensor into the Airflow meter harness wiring. Nissan S15 customers must also manually splice a single Map Sensor into the harness. Below are instructions on how Skyline RB26 customers should connect up the Djetro kit. It appears that D-jetro customers must splice the twin map sensors into the Boost Control Kit harness (or at least use the sme port) to extract positive and negative power. The signal for each MAP sensor is then connected to Cylinders #3 and #4 based on the Apexi diagram below For a more in depth diagram and guide please view the correct manual for your car's Djetro version as it will have correct Map Sensor wiring."\\ D-Jetro link https://www.apexi-usa.com/products/power-fc-1989-1998-nissan-skyline-gt-r-r32-r33-d-jetro-map?variant=44318035443933 Someone who sold a complete kit back in the day (help to confirm you have everything) https://www.sau.com.au/forums/topic/404653-apexi-power-fc-d-jetro-to-suit-r3233-gtr/ Some very bad instructions on how to install the Power FC D Jetro with dead pics https://www.gtr.co.uk/threads/apexi-power-fc-d-jetro-install.78356/ Harness option on ebay probably cheaper to make your own tho https://www.ebay.com.au/itm/233738570551?srsltid=AfmBOopkoyW61FGCxFRTSE2IgHv-9CB9dEVR0_izrExs8_FWjBtUyAOU Factory Maf plug looks like this and you would have 2 as the RB26 runs two Mafs, a note the factory RB26 IAT on the plenum isn't meant to be very good and has issues with heatsoak, a few people have commented that is worth relocating https://www.sau.com.au/forums/topic/411652-rb26-air-temp/ Typical Wiring: Pin 1 (No Pin): N/C Pin 2 (Red): 12V power supply. Pin 3 (Black): Ground. Pin 4 (White): Signal wire, sending data to the ECU. Pin 5 (Brown): Not used (N/C) Edit hope this helps 2 Quote
sheepers Posted July 14 Author Posted July 14 right, so just to recap, the engine, gearbox, ecu, AFMs, entire intercooler pipework, coils, coil pack wiring, crank angle sensor, oil pressure gauge, turbos and alternator all came together off the running car. things that are different are, engine turbo side loom, engine cold side loom, lots of wiring inside the car under dash etc, fuel pressure reg (tried two different ones) boost controller (it now has nothing, just inlet pressure plumbed straight to the gates) and the BOVs vent to atmosphere rather than being plumbed back and both the recerc holes in the intake have been welded up. the fuel pump is different but probably the same (don't ask....) and its wired to run at full 12v all the time, just like the car the engine came out of. i have checked, all coils have power and continuity to the ecu, so do all injectors. injectors all click with voltage. MAFs are showing correct info at the hand controller, as are inlet air temp and water temp. it reads the revs right on the controller, TPS and idle switch both function correctly according to the controller. 1 Quote
chris r Posted July 14 Posted July 14 You've probably checked but is there any way of supply and return being mixed up on the fuel rail or pressure regulator? Is there any display for coolant temp? If that sensor has randomly shit the bed or reading wrong it can cause stupidity with mixtures. Seen it heaps on stock Nissan's when I was on the tools, coolant temp sensor shits the bed and ecu thinks its negative a million degrees and dumps fuel in for cold enrichment Quick and dirty test for maf sensor(s) is to unplug them and see if it behaves less badly when ecu is in limp mode or not using the maf sensor inputs. 2 Quote
shrike Posted July 14 Posted July 14 1 hour ago, sheepers said: right, so just to recap, the engine, gearbox, ecu, AFMs, entire intercooler pipework, coils, coil pack wiring, crank angle sensor, oil pressure gauge, turbos and alternator all came together off the running car. things that are different are, engine turbo side loom, engine cold side loom, lots of wiring inside the car under dash etc, fuel pressure reg (tried two different ones) boost controller (it now has nothing, just inlet pressure plumbed straight to the gates) and the BOVs vent to atmosphere rather than being plumbed back and both the recerc holes in the intake have been welded up. the fuel pump is different but probably the same (don't ask....) and its wired to run at full 12v all the time, just like the car the engine came out of. i have checked, all coils have power and continuity to the ecu, so do all injectors. injectors all click with voltage. MAFs are showing correct info at the hand controller, as are inlet air temp and water temp. it reads the revs right on the controller, TPS and idle switch both function correctly according to the controller. If you check the P/N on the Power FC and confirm if its a D Jetro (MAP) P/N 414-N035 or an L Jetro (MAF) P/N 414-N034 that will rule some things out If you've changed looms and its a D Jetro Power FC (Map) then it won't work correctly with the MAFs as it needs the map sensor kit to work (I would be surprised its running though if its a Map sensor power FC as they aren't meant to work with Mafs at all) If its the L Jetro (MAF) power FC then that rules some things out but if its the D Jetro that might be your smoking gun, the loom you replaced did you copy the loom that was in the original car or did you use factory harnesses? BOV venting to atmo on a MAF sensor car can cause issues but doesn't explain all the ones your describing Quote Google explanation below A MAF (Mass Air Flow) sensor car venting a BOV (Blow-Off Valve) to atmosphere can lead to a rich fuel condition and potential drivability issues. This is because the MAF sensor measures the air entering the engine, and when a BOV vents this air to the atmosphere, the ECU still injects fuel for that air, even though it's not entering the engine. Here's a more detailed explanation: MAF Sensor Role: The MAF sensor is crucial for determining the correct amount of fuel the engine needs. It measures the airflow into the intake manifold. BOV Function: A BOV is designed to release excess boost pressure when the throttle is closed, preventing compressor surge. Venting to Atmosphere: When a BOV vents to atmosphere, the air that was measured by the MAF sensor is released outside the intake system. Rich Condition: Because the ECU doesn't know the air has been vented, it continues to inject fuel based on the original MAF reading, resulting in a rich fuel mixture (too much fuel for the amount of air). Potential Problems: This rich condition can cause a variety of issues, including: Stalling or stumbling during deceleration or idle Rough idling Backfires If the BOV's are leaking at idle that could be causing your richness issue at idle as well (vac line to BOV leak or bov seals not seating properly) If its a MAP based car then its not an issue as the MAP will be reading at the Plenum after the BOV Quote It's got too much fuel at idle and goes lean at throttle input Can you explain the issue more? If TPS and CAS are reading fine then id be thinking MAF issue (assuming its a maf car How does it idle? not something silly like the IACV/AAC idle control being backwards and opening when it should be closing causing a leak? Assuming its still not running right at wastegate boost pressure? Quote
sheepers Posted July 15 Author Posted July 15 again, i appreciate the input but i wrote in my post that the car was running with the same ECU, AFMs etc. the power fc obviously was working with these maf sensors because i drove it into my shed like that. when i say different loom, what i mean is that both looms (as far as i can tell) are the same factory loom, but i did not take the loom from one car and put it into the other. i have checked multiple wires in the looms and they're both the same. the one in my car has been butchered and put back together but i have continuity checked every wire that has been fucked with and they all check out good. tonight I'm going to plug every vacuum port on the balance pipe and see if there is any difference to rule out any vacuum leaks. even though i have already pressurised the balance pipe with compressed air to look for leaks and i did find a leaking injector seal but i fixed that. 1 Quote
AllTorque Posted July 15 Posted July 15 1 hour ago, sheepers said: the one in my car has been butchered and put back together but i have continuity checked every wire that has been fucked with and they all check out good. Can you check voltages at each end instead of continuity? A broken wire with 1 strand still touching may have continuity and a voltage drop. 1 Quote
shrike Posted July 15 Posted July 15 1 hour ago, sheepers said: again, i appreciate the input but i wrote in my post that the car was running with the same ECU, AFMs etc. the power fc obviously was working with these maf sensors because i drove it into my shed like that. when i say different loom, what i mean is that both looms (as far as i can tell) are the same factory loom, but i did not take the loom from one car and put it into the other. i have checked multiple wires in the looms and they're both the same. the one in my car has been butchered and put back together but i have continuity checked every wire that has been fucked with and they all check out good. tonight I'm going to plug every vacuum port on the balance pipe and see if there is any difference to rule out any vacuum leaks. even though i have already pressurised the balance pipe with compressed air to look for leaks and i did find a leaking injector seal but i fixed that. Yes but if its a Map based power FC you have to modify the wiring to the Mafs to the Map sensors. If this was done in the original cars loom and youve replaced that loom with a factory loom that change may not have occurred but if youve already checked that wiring then that maybe I am on the wrong track If its a Maf based power FC then its probably fine and rules that out, im assuming exhaust/intake is all the same as well? Sorry if im not making sense or giving you a red herring, honesty keen to see this running mint for you Its odd if everything is pretty much the same, not something stupid like dodgy fuel filter or some shits been picked up from the tank and the injectors need a clean Could be a couple of different things ie mafs are making it rich at idle and the injectors/fuel filter being dirty making it lean on boost Quote
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