Phantom Mark

If you read my other thread you will know I was at the track recently with my car.

Whilst there I had some problems with what either felt like not enough fuel pressure to feed the engine or possibly a safety pressure cut off strangling the engine when pushing really hard.

Basicaly the symtoms are like this.......

0-80 mph the car pulls hard and fast with very little sign of any problems, beyond this as the revs increase in 4th and 5th gear upwards of 3500rpm to 4000rpm the delivery starts being strangled, by the time you reach 110mph in 5th at 4000rpm the revs on the tacho are waving around and refusing to push the car on properly, when it slips into 6th gear and revs drop back to 3000rpm the car starts to pull a little better.

I am using a tuning box atm so i removed the box at the weekend and performed the same test, hey presto the problem is gone and the car charges upwards of 130mph with no glitch, anyone got any ideas what could be going wrong ? maybe something else on the car is falling down when extra demand being placed on it ? Fuel tank pump, Main fuel pump or pressure regulator maybe ? maybe a dirty fuel filter ? ( although its claiming to be miles away from needing a new one ).

I did wonder if the tuning box was demanding too much pressure and some sort of safety cut off was intervening ? or maybe one of the above points.

I don't recall this being a problem ever since I had the box installed ( over 3 months now ) and in fact with my G-Tech Pro RR I recorded 0-60 in 6.3sec, standing quarter mile at 14.7 @ 98mph ( IIRC ), so im pretty sure it was working properly at some point, that said its never been pushed that hard before because its not been to a track before last week.

Bob525D

I used a tuning box in my old Volvo S60 D5, I had it in for about a week before the car started going in to limp mode. The code I got was that there may be a fuel leak, from that point on I decided never to use one of these things again. If I want my car tuned then it'll be a proper tuning box that will flash the ECU but can also be reverted back to original settings. I think that these tuning plug ins only increase the fueling but dont properly optimise the car.

Phantom Mark

I have heard also that these cheap tuning boxes just boost the fuel pressure hence my guestimates on the likely problems im facing...........it was only a stop gap in any case, I was wondering if its just highlighting another looming problem tho ????

Nobody else got an opinion on this one then ?

paulmc

Thats all these boxes can do. Increase fuel pressure. Sound like something is getting too hot to me. EGT going through the roof maybe? does it smoke when this happens?

Without logging a run there could be a thousand things. Read the fault codes it may have stored the problem?

Phantom Mark

EGT = Exhaust Gas Temp by any chance ?

If so, hmmm dont think so mate, it wasn't like it did it after a couple of laps, it did it from the first lap when the car was a normal op temps ( well thats assuming my EGR stat works lol ), never noticed any smoke but mine has a particulate filter if that makes a difference in relation to your question.

Maybe a trip to the local RR is now ever more overdue, I cant afford my proper re-map at the moment, and im reluctant to put the box back on for the time being.

paulmc

DPF has a Hight temp sensor on it to stop any damage. Maybe far to much fuel being added. Have you tried slowly taking the car upto 100mph then booting it just to see. If it is overfueling badly the egt's can go though the roof in seconds. As can the DPF temp.

You couuld try and find out if one box fits all. If so I still have my Abrieb box off my 535d. I had my car well over 130mph with no letup in pulling power.

i am sure all these boxes will be the same i.e increase fuel presure by "X" amount, so the box maywell fit your car.