Engine running rough when plugged into laptop?
Discussion
Hi!
I've got a bit of a strange issue that I haven't seen anyone mention before.
I've always struggled to get the engine setup and running smooth, even with the adaptive readings identical just below 0% on both banks, the throttle pots identical on both banks at 19%, the link rod balanced and the lambda sensors are brand new and reading correctly.
Now with the laptop plugged in, even with no software running, it runs rough, idling jumps between 1200rpm and 1000rpm, it can also drop to less than 900rpm when the fans kick in and the engine stalls. It's misfiring and clearly not happy. I unplug the laptop for a couple of minutes after resetting the adaptives to get the new adaptive readings, then when I plug it back in I can make the adjustments.
As soon as I unplug the laptop, it all runs smooth at a steady 1050rpm... I even took her for a drive yesterday and she drove an absolute dream. Perfect right the way through the rev range.
The laptop seems to cause interference with the ECU. The laptop is 5 years old and is pretty high spec.
My car is a 1998 4.2 which is running the original MBE ECU.
Has anyone else experienced this? It's rather annoying having to unplug the laptop all the time and makes the job even longer and more tedious.
Thank you!
I've got a bit of a strange issue that I haven't seen anyone mention before.
I've always struggled to get the engine setup and running smooth, even with the adaptive readings identical just below 0% on both banks, the throttle pots identical on both banks at 19%, the link rod balanced and the lambda sensors are brand new and reading correctly.
Now with the laptop plugged in, even with no software running, it runs rough, idling jumps between 1200rpm and 1000rpm, it can also drop to less than 900rpm when the fans kick in and the engine stalls. It's misfiring and clearly not happy. I unplug the laptop for a couple of minutes after resetting the adaptives to get the new adaptive readings, then when I plug it back in I can make the adjustments.
As soon as I unplug the laptop, it all runs smooth at a steady 1050rpm... I even took her for a drive yesterday and she drove an absolute dream. Perfect right the way through the rev range.
The laptop seems to cause interference with the ECU. The laptop is 5 years old and is pretty high spec.
My car is a 1998 4.2 which is running the original MBE ECU.
Has anyone else experienced this? It's rather annoying having to unplug the laptop all the time and makes the job even longer and more tedious.
Thank you!
There's a few reasons why this can happen but a common one is an earth loop via an in-car power source. It took me absolutely ages to work out in the early years of cerb diags why on some cars the tune changed with the laptop plugged in .. it was a long time before i realised it was only with a power source plugged into the lighter socket that it happened ...
Unfortunately I haven't got the right cable to plug it into my phone but I will try my girlfriend's laptop instead later and see if that makes a difference.
I don't have anything plugged into the cigarette lighter. The only thing I can think of is I replaced the radio with a newer one last year. Do you reckon that could have affected something?
I don't have anything plugged into the cigarette lighter. The only thing I can think of is I replaced the radio with a newer one last year. Do you reckon that could have affected something?
If you've not got it powered off the car (cig lighter or direct from battery) and it still changes when the laptop is plugged in then you will probably need the mbe mapping lead with the inbuilt resistors. This lead is only normally required when the live mapping is enabled in the ecu and puts the fuel ign and boost trims in their default position ..sounds like you may be using a std serial lead (no issues with this in 99.9 percent of cases) and the laptop connection is applying a trim to the map.
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