KO4 Upgrade Question

[rweir]

I have just had my S4 upgraded with the KO4 turbos, miltek exchaust, downpipes, fuel pump, injectors etc ... I think it is about 1.6bar at the moment.

My question is this, the car pulls fantasticly now and very smooth, but, at higher speeds and more so from 4th to 5th or 5th to 6th I sometimes get a 'jolt' forward and I feel the car has lost boost, it gets it back ok. Has anyone any ideas how to overcome this problem while driving?

Thanks,
Rich.

[Prawn]

Hi mate,
Good move, nice ain't it [img]images/graemlins/jump.gif[/img]

May be worth checking the DV's.
Who did the conversion for you ?

[rweir]

Yes, very nice, it is like a new car!! But getting used to allready, never thought that would be possible!!

Hopefully getting my old DV's back so might swap them over to check it ...

Had it done by Scotts Mototune and SKN. I take it yours has been done as well? Who did yours? I have still to get it on the rolling road to see the final bhp ...

r

[jeffw]

I have still to get it on the rolling road to see the final bhp ...

[img]images/graemlins/shocked.gif[/img]

You're not serious.....you've had a KO4 conversion and it hasen't been on a rolling road to be mapped...I'd be very worried if it was my car....

[rweir]

It's been mapped, but on the road as opposed to a rolling road ... The car runs fine actually (appart from that wee issue above!) but other than that I am chuffed

[jeffw]

My K04ed S4 doesn't display the symptoms you describe....maybe you need a rolling road session to see if there is a fuel/boost problem.

For you info my S4 makes 395BHP & 473 lb/ft on a very hot day at AmD.

[Nige_RS4]

There are a number of S4 owners in the US who are running KO4's with Stg 2 KO3 software without problems ???

Sure, a remap gives you optimum performance, but as long as you keep an eye on your engine (esp fuel mixture) with vag-com, what problems do you forsee Jeff ?

[rweir]

Not sure how possible this is since it was done in Germany by SKN. I am assuming it would need to be remapped by them?

Unfortunatly I do not have the VAG program, worth purchasing the gear to keep an eye on things??

Thanks,
Rich

[jeffw]

A KO4ed S4 which hasn't had the Fuel Pump, Injectors, MAF and Air Filter Box changed for the RS4 equivalent components is going to be marginal on fueling. I believe that these are all part of the MTM upgrade and have been recently introduced by AmD as an optional part of their upgrade. Mine doesn't have these extra parts and there was some discussion as to the effect this would have long term as the Injectors are likely flat out a lot of the time and this could result in the car running lean due to a lack of fuel.

If your car is doing is surging since the KO4s where fitted it suggests that you are have either got a split TBB, defective DVs, that your MAF has gone faulty or that the remap is suspect. The only way to know if it's correct or not is to get it on a rolling road with a specialised Audi tuner....if you don't it may cost you another pair of K04s. Did you have the Catalysts changed when you fitted the K04s ?

Stage 2 K03 software is not designed to run K04 turbos and there is a danger (I assume I'm no expert) that it will could cause a failure in the turbos .....

[Dippy]

Jeff,

I'm not expert either but I seriously doubt that there would be any problem with K04s and a stage II K03 remap, other than the potential of the K04s would not be achieved.

Remember that a K04 is actually a 'go-faster' K03, meaning that it can just handle a higher airflow and hence be used to produce a higher boost, especially at the top end.

Now think about what the ECU map is doing - in simple terms it is adjusting fuel and timing for engine revs, MAF and boost. Boost is close-loop controlled and the wastegates would open completely within the K04 envelope. MAF would not be affected.

In fact it seems to me that running K04s with K03 software would simply give K03 performance.

Anyway, back to the original question, I note that the stated boost is 1.6 bar. This is in highly tuned RS4 territory. I would therefore agree that the fuelling system will be run to its limit and there would be a serious risk of overheating. Not good news in the medium to long term.

I wonder if the surging is in fact due to lack of fuel - does this happen at high revs?

[rweir]

I had the fuel pump and injectors changed also. Along with the Miltek exchaust and hi flow cats. The MAF and air box where not changed and are still stock. TBB should be ok since I put a new samco one in a while ago (but I will check!) and I am going to change the DV when I get my old ones back.

The problem with car is basicly it seems to have lost power when I try to move between 4/5 and 5/6 and this is only sometimes, and we are talking near the top of the rev range when I am changing ...

I have tried this a couple of times and it seemed to work, if I keep my foot depressed on the accelerator when changing, (it nearly gets to the limited before I have selected the next gear), but no issues with the loss of power if I do that ....

[Dippy]

In that case maybe you need a new MAF if it can't handle the extra airflow (same result = lean fuelling). However your cure to the problem suggests otherwise. The DV system does not appear to be perfect anyway. Nevertheless logging MAF on VAG-COM might give some clues.

Also I would seriously suggest that you dispense with the TBB altogether. There have been reports of problems with the Samco too. Fundamentally at full boost, especially your boost, a flexible TBB will baloon out putting stresses on the joins. It will always be a weak point. The alternative is either the RS4 parts or the APR bibipe.

[RobK]

I used to get the same sort of thing on my K04 S4 before the remap was properly sorted. I think it was down to the turbos producing more boost than expected and the ecu getting confused and going into limp mode. I used to find that if I took my foot completely off the throttle and then pushed it down to the floor a couple of times it would return to normal and I'd get the boost back. It was finally sorted when AmD changed the map to give less mid-range boost and more top end (it was normally at about 3-4000 revs in a higher gear when I got the problem).

[rweir]

Thanks for everyones input.

I am not going to do anything about this right now, since I was out today, and it really is above 140+ that the issue takes place, the 4/5 gear did not happen, but I did not let the 4th gear go very high before changing ... still, decided that those speeds only happen at very rare times so no real need to worry about it ....

I have a new question ... so, guess new post ..

r

[Nige_RS4]

I personally wouldn't ignore it - clearly something is amiss, and whilst you may not notice it at lower speeds it will probably still be affecting something on your car - Best case, your fuel consumption. Worst case, you're making our turbos work harder than they need to - and you don't need me to tell you what *might* happen then.

Get a check done by someone who knows there way around an S4 - stick a boost gauge on yourself and watch what happens to the boost - check or replace the DV's, check or replace the TBB and finally, get your MAF checked using VAG-COM or similar.

Good luck.