Thread: D2 TD5 surging full acceleration issue

Hi John,

Was the old manifold leaking a lot? Could be getting more exhaust gases to the turbo now making it over boost?
Sounds like it's fuel cutting due to over boost? But you should get an over boost fault on the Nanocom if this happens?

A few things to check

Waste gate modulator and the three hoses all connected to the correct locations and no holes?
Sticky waste gate or actuator? How many thread are between the nut and smooth part of the rod? I think factory is 11, maybe 13????

MAP and MAF sensor, remove and give a good clean with MAF cleaner.

Can you do an input fuelling log with the Nanocom and post up the file?

Cheers Lemo

Originally Posted by Lemo

Hi John,

Was the old manifold leaking a lot? Could be getting more exhaust gases to the turbo now making it over boost?
Sounds like it's fuel cutting due to over boost? But you should get an over boost fault on the Nanocom if this happens?

A few things to check

Waste gate modulator and the three hoses all connected to the correct locations and no holes?
Sticky waste gate or actuator? How many thread are between the nut and smooth part of the rod? I think factory is 11, maybe 13????

MAP and MAF sensor, remove and give a good clean with MAF cleaner.

Can you do an input fuelling log with the Nanocom and post up the file?

Cheers Lemo

Thanks Leno. I’m working the next 3 days, so I’ll get a chance to do that Thursday morning all going to plan.

Couple of questions:

A) where can I get MAF cleaner? I use carby cleaner followed by compressed air to do the ECU. Same stuff?
how do I do an input fueling log?

I'm not sure about your fault code on the transmission. Might or might not be related given a different area. If you clear it does it reappear? If so, immediately? After driving for a while? After heavy acceleration only? etc.

MAF cleaner is available from auto parts stores such as Repco. It's not cheap - more than normal electrical cleaners/degreasers, etc. but for the cost of the MAF better to be safe than sorry although I suspect it might just be a rebranded electrical cleaner.

Being a 15p Euro 3 model and with your boost pressure so mucher higher than factory I would be suggesting that your running beyond the MAFs capabilities. I had this issue years ago on my D2a shortly after purchasing and bringing to Tasmania with the stock turbo at only around 18psi as adjusted by the previous owner. Some technical information is available at The Mysterious MAF Patch | DiscoTD5.com I think.

You can try to identify this by driving with your Nanocom Evolution connected on Discovery 2 / TD5 / Input Fuelings and then I think it's page 3 that gives you the MAF readings in "g/hr" at the bottom. If, at WOT or heavy acceleration, you see this figure going beyond 650 then your pushing the limits of the standard MAF sensor and ECU calibration. If its going from these high numbers to 0 then it's definitely gone beyond its ability to read.
To do Input Fueling log in CSV file format, hit the blue floppy disc button, choose save location on the SD Card and file name, drive while it records, when done, and before you turn off the engine (depending on your Nanocoms setup), click the blue floppy disc button again to save it and write to the SD Card.

Another method to test or confirm is to just unplug the MAF sensor and test drive. On the 15p/Euro3 motors though the MAF sensors readings do seem to also effect other systems such as automatic transmission so there may be some other abnormalities with it disconnected.

The easiest solution is to wind down the waste gate rod so that you get back to stock boost levels (I think this is around 14psi so your running significantly higher at the moment). If the problem goes away great. If it solves it but you still want to increase the boost for the extra power then there's a few options such as electronic trickery (boxes and modified MAFs) and software tuning (perhaps TRS may consider modifying their remap for you to suit) discussed in Increased power TD5's - what have you done to solve the MAF issues?

Good luck. I solved my issue with it back in 2012 era and it's resurfaced now as the electronic trickery box has gone and failed on me. This time I'm looking at the ECU tune solution as it seems to be a superior solution in terms of vehicle operation and ongoing reliability.

Surging will be over boosting.

Either the WGCM is faulty
MAF going out of range
Waste Gate needs a small tweak backwards

I've had the same issue for a long time, but I recently resolved it by replacing:
The vacuum hoses to the to the waste gate with SAE30 rated fuel line. This is reinforced so it doesn't blow up like a balloon, gives a more consistent (responsive) boost to the waste gate.
Boost modulator. (The boost modulator can cause this issue too, it fills with oil - sometimes cleaning it can help)
Clean the sensor in the air box (D2a's have one - not sure about D2's)
Check the wires going to the boost modulator sensor are OK, mine were not making a great connection and have since been re soldered.
Cleaning the MAP sensor in the intake manifold may also help and is worth doing anyway.

As twr7cx mentioned page 2 of the instruments screen on Nanocom will give you the MAF reading, when it surges you might find this drops to 0 or goes out of range.

Cheapest and easiest thing to do is replace the 1/4" hoses, considering they've recently been disconnected it would be a good place to start.

Mine was not the TPS, probably don't go down that path first. Best of luck as it is frustrating, i know.

Thanks guys. Looks like I’ve got heaps of things to do. I’ll get back after I’ve had a play with it.

agree with above , did you remove wgm before moving the air con compressor?, if not it could get damaged , the surge can happen if your right on the edge of overboost and not log a fault . I'd back the rod off by a turn especially as between not having an exhaust leak any more and the weather getting cooler it might have been only just overboosting

Originally Posted by discorevy

agree with above , did you remove wgm before moving the air con compressor?, if not it could get damaged , the surge can happen if your right on the edge of overboost and not log a fault . I'd back the rod off by a turn especially as between not having an exhaust leak any more and the weather getting cooler it might have been only just overboosting

No. All I did was undo the hoses and the exhaust manifold and exhaust pipe bolts and removed it. I didn’t move the air con.