mike2016 Posted March 8, 2021 Report Share Posted March 8, 2021 Upgraded to G4X from G4+ on my R32 GTR. it has NZ wiring trigger setup. It used to start like factory with G4+, now on G4X it takes twice as long to start. I was told this is normal on G4X as it needs to see 2 full revolution of engine rotation before it syncs is there any way to make the start up faster? Quote Link to comment Share on other sites More sharing options...
Adamw Posted March 8, 2021 Report Share Posted March 8, 2021 That trigger has only 1 unique event every 720 deg. The ECU will only know which cylinder to fire once the missing tooth has gone past the sensor. That could potentially be up to two crank revolutions depending on where the engine stopped. The G4+ and every other ECU on the market is the same - there is no way any ecu can possibly know crank position until it has seen that missing tooth with this trigger system. Are you sure it is not arming thresholds or fuel settings that is causing a longer start up? Quote Link to comment Share on other sites More sharing options...
mike2016 Posted March 9, 2021 Author Report Share Posted March 9, 2021 Arming threshold and fuel are sorted. Identical to the old setting in the G4+ (we did intensive trigger scope not long ago trying to sort out the g4x issue end up being swapped pins on the ecu connector) oddly enough, the G4+ started in half the time required, almost like factory Even some tuner I talked to said this is common with G4X. it just doesn’t make much sense why. all ecu see the signal the same way Tomorrow I’ll observe the trigger signal while cranking. I believe it only becomes “active” after some cranking Quote Link to comment Share on other sites More sharing options...
Adamw Posted March 9, 2021 Report Share Posted March 9, 2021 You would be best to do a Pc log of a start up, then we can see how long it takes to sync and then how much long er after Sync until it starts. Quote Link to comment Share on other sites More sharing options...
mike2016 Posted March 10, 2021 Author Report Share Posted March 10, 2021 Here's a few log files. i logged 5 different starts. the trigger is picking up RPM as soon it starts cranking. another thing that I've been trying to solve after G4X upgrade, the car would randomly fail to start. it fires up for like split second but won't continue to start. if it fails, it will become very difficult to start again ~ have to keep cranking for 5+ seconds, maybe due to flooded cylinder? you can see in the file "6:44pm Start then died". it logged a bad start, then attempt to restart that took a long time. and all the "successful start" have a little dip in RPM right after start. it's completely random, at all temperature level. I copied over all the G4+ cold start settings over, and tried the G4X base map settings, they all behave similar. tried adjusting crank enrichment / precrank prime...etc , nothing really helps. PC Datalog - 2021-03-9 6;42;14 pm.llgx PC Datalog - 2021-03-9 6;43;11 pm.llgx PC Datalog - 2021-03-9 6;44;01 pm Start then died.llgx PC Datalog - 2021-03-9 6;56;28 pm.llgx PC Datalog - 2021-03-9 6;57;07 pm.llgx Quote Link to comment Share on other sites More sharing options...
dx4picco Posted March 10, 2021 Report Share Posted March 10, 2021 I have faced the same Problem on a Subaru. Fiddling with the fuel table at low rpm did somewhat help but I wasn't able to get the instant start and reliable start of the g4+ Quote Link to comment Share on other sites More sharing options...
Adamw Posted March 10, 2021 Report Share Posted March 10, 2021 11 hours ago, dx4picco said: I have faced the same Problem on a Subaru. Fiddling with the fuel table at low rpm did somewhat help but I wasn't able to get the instant start and reliable start of the g4+ Please start your own thread and post some logs, the engine in this thread has a missing tooth cam trigger only so sync is always going to take at least twice as long as your subaru which has multiple sync points per cam rev. @mike2016 I see a couple of problems in your logs. Ill coveasy one first. The start then stall is caused by fuel settings. In the log with the stall in it you have 32% crank enrichment, but only 2% post start enrichment. When the RPM reaches 500RPM it swaps from crank enrichment to post start. It stall when this 30% extra fuel is removed, you can see lambda go to 1.3 before it stalls. Typically the crank enrichment and post start enrichment should be near the same so it is seemless when you transition from one to the other. The long start up problem is mostly due to the sync, you can see in all these logs the RPM rises quickly as soon as there is dwell, but in some cases it takes a long time before there is dwell. Testing on the bench I think it may be code related as it looks like it takes one revolution longer than I expected it should need to sync. I have passed some questions on to engineering to see what they come back with. Quote Link to comment Share on other sites More sharing options...
mike2016 Posted March 11, 2021 Author Report Share Posted March 11, 2021 Thanks Adam. didn't know post start take over that quick and would have such a big effect. i thought "crank enrich hold time" would kind of do the same... i'll make some adjustment to post start. if you see any other issues please let me know.... Quote Link to comment Share on other sites More sharing options...
Adamw Posted March 11, 2021 Report Share Posted March 11, 2021 I can confirm after some testing that the sync with this cam trigger is taking one revolution longer than it did in G4+. Note for anyone else reading, this comment only applies to this rather unusual missing tooth on cam system with no trigger 2, no other trigger types are affected. The engineers are working on a fix to improve it. Mike, you will have to deal with the longer startup for a bit longer, I will give you a fix to try when they have something ready. Confused and JeremiahJ 2 Quote Link to comment Share on other sites More sharing options...
mike2016 Posted March 11, 2021 Author Report Share Posted March 11, 2021 3 hours ago, Adamw said: I can confirm after some testing that the sync with this cam trigger is taking one revolution longer than it did in G4+. Note for anyone else reading this comment only applies to this rather unusual missing tooth on cam system with no trigger 2, no other trigger types are affected. The engineers are working on a fix to improve it. Mike, you will have to deal with the longer startup for a bit longer, I will give you a fix to try when they have something ready. Perfect! I'm glad to do whatever testing on my side as needed, just let me know. Link / Adam is the best Quote Link to comment Share on other sites More sharing options...
mike2016 Posted March 12, 2021 Author Report Share Posted March 12, 2021 another thing i thought of about the start up then stall issue, can the long cranking contribute to this? i adjusted the post start enrichment table to match crank enrichment. it improved but still stalled randomly, but less stalls. maybe due to longer cranking times, some fuel got "purged" out? Quote Link to comment Share on other sites More sharing options...
Lench Posted May 15, 2023 Report Share Posted May 15, 2023 Apologies for the gravedig, was a solution ever found? Quote Link to comment Share on other sites More sharing options...
Adamw Posted May 15, 2023 Report Share Posted May 15, 2023 The extended sync for missing tooth cam triggers that this post is discussing was fixed back in 6.20 firmware. Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.