Thread: OBD2 data logger/black box device...

Originally Posted by Stump

I've played with a few OBD readers, if your going to datalog I'd use this one
OBD Link MX+ https://www.obdlink.com/products/obdlink-mxp/
Uses its own app
You can get them of Aliexpress

Not cheap but very high refresh rates
Cheaper ones have slower bandwidth and results in a chonky chart.
This ones rated quite highly and is chalk and cheese when compared to the likes of a $30 vgate.
if your just reading & clearing codes the vgate is fine.

Couple of good apps for logging is torque & Carbit

Also pays to have a dedicated device plugged into car full time for logging, PITA reconnecting BT everytime you jump in.
Now the fuel issue with air in the fuel return line...is their air getting in on the suction side of the pump? worn/ cracked hoses, loose fuel filter fittings (water sensor on bottom is a culprit), hoses all the way back to tank in good nick?
Dongle logging might show signs with SCV duty% going up and rail press going down with air entering on suction side.

Oh and not the first time I've heard of dealers loading the parts cannon....

Hi, thanks for that will try the MX+ unit (was looking at it already so your comment just confirms that one is the one to try). Cheap enough vs close to NZ$8K for replacement parts that might not fix the thing... I'll definitely check out those two apps as well, I think it's going to be a pesky fault like an intermittent loom issue or a sensor getting overheated and reading erratically - one of those great faults that doesn't make sense until it's found.

And you're right on what we are thinking with the air leak - when the independant checked the return fuel for aeration with the clear line it wasn't excessive, just the usual foaming after depressurizing when it comes out of the common rail piping. I'm suspecting that the fuel system is heat-soaking and it's getting a seal that is opening up after a period of time when the temp gets up or something like that - with the mechanics unit on it in live data mode, the commanded pressure and delivered pressure to the fuel rail were fine only a minor amount of variation, RPM sensor and fuel temp were all AOK. Fuel temp didn't get over 39degC in 3 hours of driving so no apparent issues there at all, nowhere near the 85degC needed to trip the ECU into self-protect mode.

The independant mech reckons the injectors and injection pump are fine, no telltale tiny shiny's in the fuel dropped off the filter and it starts and runs better than the one that has just had the heads done and all new injectors pump and radiator and was back in for it's check over and retorque. So I dunno - feel like the dealer really couldn't be arsed in actually diagnosing the thing. Doesn't make me happier with their service, actually right out the other end to be fair (kind of like I'd be dead before I take a vehicle back to them and it's not because I think they are too dear like most people go on, they actually aren't. It's all down to quality of the job).