Turborado 10 Posted July 7, 2014 Hi all, I'm hoping someone can give me some help and guidance here!! I have a 1.8t AUQ conversion in my rado, running QPEng plug and play system. After changing the crank sensor for an OEM Bosch one from GSF I finally have the car running again. But the new problem has arisen now. When the car reaches 3500rpm the tacho drops back down to about 1000rpm. I have had Jon from Quantum out to my car and this has left him scratching his head, and my mechanic/auto elec scratching his head too. Any help would be greatly received. Thanks Sam Quote Share this post Link to post Share on other sites
Kevin Bacon 5 Posted July 7, 2014 Sounds like the ECU is losing sync with the crank sensor. Is the QPeng an MBE unit? Could try them directly for some help? The only time I saw that happen with my DTA ECU was when the crank signal wires were reversed. You'd be surprised how often that happens with crank sensors. I would only ever use genuine with a critical part like that personally. Another thing you can check is the crank sensor distance from the trigger wheel. The 2 sensors may not be identical and the air gap could be too large. Quote Share this post Link to post Share on other sites
MarkB 10 Posted July 7, 2014 As Kev says with the air gap, also could be a dodgy new sensor or a broken tooth off the crank trigger. Quote Share this post Link to post Share on other sites
Turborado 10 Posted July 11, 2014 OK thanks guys i will have a check, im really hoping its not a problem with the crank trigger, I will post on here if/when we solve the problem Quote Share this post Link to post Share on other sites
