I though I had the surging issue licked. I was wrong.

2.2 I5 20v turbo - 230bhp
4.2 V8 32v Naturally Aspirated - 326bhp
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AndyH-R6S
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I though I had the surging issue licked. I was wrong.

Post by AndyH-R6S » Wed Jan 23, 2008 7:16 pm

Hi all URS4/S6 Users again.
After changing out all the old ignition kit for the high output ‘034 Motorsport’ kit, new Bosch spark plugs torqued up correctly, replacing all of the vacuum tubes , replacing the turbo to intercooler to plenum hoses and odd bits ‘n’ bobs, I though I had the surging issue licked. I was wrong.
Although the car is most definitely more responsive, the hesitation between ‘1.2 to 1.7’ bar and around ‘3250 rpm’ still exists in top gear, as I found out on the motorway today on a longer run. (Not apparent in lower gears!!??!!) It cannot be the ignition system or the induction system as it feels like someone is blipping the brake/misfiring (Not smooth like it should be) under acceleration and it’s all new. I would actually say, based on previous experience that it’s almost like the engine management system cannot react quickly enough to a rapid change of acceleration. The car is running ‘MTM’ phase 1 engine re-map (2.2/2.3 bar max instrument gauge pressure on full boost), RS2 exhaust manifold, K&N filter, Stainless steel free flow cat (200cpsi Cats, )exhaust, plus all the above already mentioned changes.
I have spent a couple of hours researching the issue again this afternoon and it might turn out to be the actual ‘MTM’ ecu conversion!! (I hope not as it was not cheap) Especially since it did not do it before the conversion!! Numerous URS4/S6 owners that have done similar upgrades to my self, which includes the ‘MTM’ conversion, report similar issues. Even to the point that similar issues have been noticed on other Audi S and RS models!!.
So if it’s not the coils as the original stuff has been replaced with better and less kit, it’s not the induction system, as all the tubes & hoses have been replaced, its not the spark plugs as they are all new and torqued up correctly, what is it???
It does not hunt, it does not do it when cold, it does not do it all the time and sometimes if you floor the pedal to the metal it does not do it!!!!! And pulls like a train.
I am going to replace the boost control valve for the ‘034’ Motorsport’ bit, as it appears to be not the correct one, as the turbo input hose does not sit on it correctly plus its old and may be the Oxygen sensor as well, as it old too. Apart from that I am at a loss with this one!!
Why would a car tuner not be able to correctly set my car because it’s an automatic??? I some times wonder if a tuner who can set up the car correctly, even though it is an automatic, might get rid of the issue but I might be pulling at straws here, as my current tuner/service garage cannot fault the car but it cannot be set up well because it’s an automatic??? Even though he has a rolling 4WD rolling road?? (Waist gate set up, etc)
Constructive comments please if you had a similar issue and you sorted it?? (UK/England Car)
Lastly, Ha anybody done a conversion similar to the MTM phase 1 but by a different manufacturer and had similar problems or no problems at all?? :( :( :(

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AndyH-R6S
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RE: I though I had the surging issue licked. I was wrong.

Post by AndyH-R6S » Thu Jan 24, 2008 5:06 am

I had the boost pressure checked previously when I first noticed the issue after the ECU mod’s and it was all OK and the same person said there was no error codes to suggest a fault! (How can I get at theses error codes without Audi or a tuner getting involved? If I can get at the codes, where would I find out what they mean? Many thanks)
It has been suggested that it might be a week fuel pump and/or cannot supply the fuel quick enough, etc? (Some times plays catch up, if you know what I mean.) I must admit the car is 10 years old now and running more boost than stock, so all the kit that looked past it or was defective in some way, I have been working my way through. (1 bit out, 1 bit in) To systematically work the issue out of the car. I must admit, the fuel thing might have something in it, as if you slowly go through the rev range and boost, the issue is not really apparent. So, if with more boost you need more fuel pressure to keep the fuel mixture to the correct proportions, am I getting fuel starvation to the injector rail, putting a higher output pressure pump in and the associated bits might be worth while, especially if I do more stuff like a ‘RS2’ turbo and injectors. I just wanted to cure the issue before the next modifications.

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AndyH-R6S
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Posts: 52
Joined: Sun Mar 26, 2006 7:58 pm
Location: Welling

RE: I though I had the surging issue licked. I was wrong.

Post by AndyH-R6S » Thu Jan 24, 2008 5:53 am

So, has anybody done any mod’s to their cars ECU and had to change the fuel pump and associated bits to sort out a similar issue?
************************************************************************************
And just to answer a few questions from other forums:
It did it after the remap but was not totally obvious like now.
The original coil packs had cracks to the cables all over the show and I found two plugs wet on the outside. Replaced all the kit and new Bosch plugs, torqued them down correctly (2nd time a 100 miles later (Cleaned the oil out of the plug holes first) and in this department all appear to be OK))
Waistgate had been worked on after the ECU mod, new diaphragm, spring, etc. (I do think it needs setting up though. As it was adjusted to get try and get rid of the issue.
Boost jitters around when the issue occurs but eventually goes to ‘2.1, 2.2, sometimes and 2.3’. Boost slightly slower to rise after the tuner adjusted the Waistgate setting. It had been pointed out by the tuner, that I should have an instrument cluster gauge boost of around ‘2.4 to 2.5 bar’ but in the intake system the boost was correct. (Possible low set cluster gauge)
How can I get at the ECU codes with out expensive bits of kit and what do they mean?
The car was not particularly behaving it when I first got it a few years ago and it potentially might have done the issue before but was not obvious. But it did have odd chips and wires disconnected that was all put back correctly during the mod to:

270bhp Modified MTM motronic computer with 3 bar map sensor.

Many thanks to you all.
Now bed time for a few hours.

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AndyH-R6S
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Joined: Sun Mar 26, 2006 7:58 pm
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Post by AndyH-R6S » Sat Mar 01, 2008 8:48 am

I replaced the wastegate top cover for an unmolested version where the anti-tamper cover is still fitted and the adjustment screw was still at factory settings compared to the previous owners attempt at getting a more powerful engine. (Old on the left, replacement on the right. No perch fitted for clarity)

What a transformation, no juddering at all in top gear and the all round drivability in all gears is far superior to what it was before. When I compared the original wastegate that came with the car to the replacement, even at the minimum setting, the spring height uncompressed, was already “13 to 14mmâ€
Attachments
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Fin Engine rd.jpg (216.51 KiB) Viewed 2596 times
Damaged Wastegate top cover.jpg
Damaged Wastegate top cover.jpg (125.71 KiB) Viewed 2596 times
WG old + New.JPG
WG old + New.JPG (129.47 KiB) Viewed 2596 times

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