No Codes Diagnostics

At Gotboost we are often asked to ‘plug in our diagnostic machine’ to find a fault with a vehicle. We are always keen to remind people that true diagnostics do not consist simply of plugging in an OBD scanner, seeing what code is there and then changing the parts mentioned in the scan. This approach does not accurately diagnose issues, and in many instances does not fix the problem. There is also the issue of faults that do not flag up any codes, especially in a world where it is becoming more common to see garages remapping cars with code delete maps, which in some cases merely stop the engine’s ECU from being able to see that a problem exists, and does not fix an issue. So…how do we fix these? 

Here at Gotboost we have access to some of the best diagnostic equipment available, including hardware to return a vehicle with code deletes to stock software to see what is being masked. We also follow a tried and tested pre planned diagnostic structure to test for faults beyond the scope of an OBD scanner.

This month we have had an instance of a 2010 Audi A3 which was going into limp mode, but was not showing any lights on the dash or codes in the scan. The car had been to other garages and had been used for target practice by the parts cannon. The customer had spent thousands of pounds on “maybe’s” but to no avail.

We started with our customer questionnaire to find out exactly what the complaint was, how often it occurred, when it occurred, and what work had recently been carried out on the vehicle. 

We heard how the customer had spent money on all kinds of parts, and even a remap to get his performance back out of the vehicle. The OBD scan did indeed show no codes to work from, but the diagnostic session did not end there. The scanner stayed plugged in, and we drove the car using it to record a datalog of various parameters within the engine, showing us that the vehicle was incapable of producing the turbo boost requested by the ECU. We then were able to read the maps in the ECU to find that the remap had been incorrectly done with a page of A4’s worth of codes deleted in an attempt to solve the issue, some even had an effect of the ECU being able to communicate with the ABS system! This map was then removed and replaced with one of our tried and tested maps from Quantum, allowing the ECU to react to issues. However, the fault remained, but we could be certain it was not caused by the map, and the ECU could now communicate with other systems on the car. The turbo actuator on this vehicle is often prone to internal failure, not allowing a vacuum to be held, however, once checked with our vacuum pump and gauge, no fault was found, with the actuator able to hold vacuum and move the actuator arm. Boost control valves can also be problematic, but this was tested electrically and physically and found to be within spec. Diagnosis then moved to the vacuum being produced by the pump on the engine itself. This was tested at various parts of the vacuum system and was found to be next to zero at the boost control solenoid. The ‘Columbo test’ (one more thing, to confirm our suspicion) was then carried out. Running vacuum straight from the pump to the boost control solenoid, and…..Eureka, the car now produced boost, drove as it should, and did not go into limp! The vacuum system was then tested for the source of the leak, at the EGR control valve, and then fixed.  

This series of tests was all carried out within our ‘Diagnostic Assessment’ package, showing the difference between a quick plug in and a proper diagnostic assessment.