justinde Posted September 9, 2020 Report Share Posted September 9, 2020 I have a 1995 M3 with an S50US (basically a bigger m50 vanos) with a G4x plug'n'play. Im having an issue where the engine is backfiring out the intake when I turn on the ignition and wait for the tachometer sweep. It also has a hard time starting if i attempt to start it while the tach sweep is in progress. It doesnt happen every time. Does the G4x do a spark test when the ignition is turned on? Im not sure how else this backfire would be happening, but it keeps blowing up my idle control valve hose and its really annoying and im not sure what to look for. Thanks! Quote Link to comment Share on other sites More sharing options...
Adamw Posted September 9, 2020 Report Share Posted September 9, 2020 I have had a couple of users mention this now so I have just asked engineering to take a look at it. justinde 1 Quote Link to comment Share on other sites More sharing options...
justinde Posted September 9, 2020 Author Report Share Posted September 9, 2020 3 hours ago, Adamw said: I have had a couple of users mention this now so I have just asked engineering to take a look at it. Great, thank you. Quote Link to comment Share on other sites More sharing options...
Poseidon Posted October 13, 2020 Report Share Posted October 13, 2020 The problem was also wrong ignition coils Quote Link to comment Share on other sites More sharing options...
Dandeman Posted December 14, 2020 Report Share Posted December 14, 2020 Yes - +1 Did engineering figure anything out? Quote Link to comment Share on other sites More sharing options...
Adamw Posted December 14, 2020 Report Share Posted December 14, 2020 There is a hardware mod needed on early G4X plug-ins to solve the backfire at key-on. Contact tech support for instructions on getting it fixed. Quote Link to comment Share on other sites More sharing options...
Poseidon Posted December 17, 2020 Report Share Posted December 17, 2020 The intake of my m54 engine burst. After searching for the fault a lot, I found that the original ignition coils were not suitable. Then I took the vw stick ignition coils and then it worked. The spark is also very weak with the original BMW. Quote Link to comment Share on other sites More sharing options...
koracing Posted January 7, 2021 Report Share Posted January 7, 2021 Another couple notes on this topic: 1. The G4+ did not seem to do this 2. The base map has the start prime set to fire the injectors at Key-on -- this is obviously the source of fuel causing the backfire. Since there is no start signal to the ecu to provide an alternative prime signal source, on a couple of cars with the same no-start signal pinout I've done the following: Set up a virtual aux output to engage when RPM > 0 AND RPM < 400 RPM AND Engine run time is < 5 sec. I then use this output as the activation for the Start signal digital input. The G4x has the ability to do this, but the G4+ does not it seems. Quote Link to comment Share on other sites More sharing options...
essb00 Posted January 15, 2021 Report Share Posted January 15, 2021 Hi... Since "Stop Switch" is 100% fuel & ignition cut, would something like this work? ...or maybe the "Anti Theft"? Quote Link to comment Share on other sites More sharing options...
Adamw Posted January 15, 2021 Report Share Posted January 15, 2021 14 minutes ago, essb00 said: Hi... Since "Stop Switch" is 100% fuel & ignition cut, would something like this work? ...or maybe the "Anti Theft"? What are you trying to acheive? Quote Link to comment Share on other sites More sharing options...
essb00 Posted January 15, 2021 Report Share Posted January 15, 2021 Just now, Adamw said: What are you trying to acheive? ...to stop the intake backfiring on ignition on. Quote Link to comment Share on other sites More sharing options...
Adamw Posted January 15, 2021 Report Share Posted January 15, 2021 That was a problem with some specific engines on early G4X boards. Im not sure if preventing precrank prime is going to solve that. If you get in touch with tech support you can get it fixed properly. Quote Link to comment Share on other sites More sharing options...
koracing Posted January 15, 2021 Report Share Posted January 15, 2021 A simple test would be to simply turn off pre-start prime and see if it still occurs. Quote Link to comment Share on other sites More sharing options...
Stevieturbo Posted March 12, 2021 Report Share Posted March 12, 2021 A similar issue has popped up with other ecu's in the past. A sort of fix was to wire the supply for the ignition coils via the fuel pump relay or trigger. The slight delay in coils turning on with key on, prevented the initial fire some hear/feel. I highly doubt changing anything relating to fuel injected will make any difference, although the user feeling anything probably does relate to some degree about residual fuel already left in any cylinder. Which can often be down to tuning too. Quote Link to comment Share on other sites More sharing options...
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