hit a large puddle...

[istoo]

a fairly generla one and looking for some pointers.
I bought my urS4 in October and it felt every bit as quick as 275BHp (MTM remap, 044 pump, stromung exhaust) But i feel its never been quite right since i hit a big puddle (felt like a lake) unavoidable on a B road with a lorry coming the otherway.

A few things which arent quite right in my head.

4th gear at 30mph, put your boot to floor and the digital guage rises to 2.3/2.4, but the live gauge reads 15-16psi. But oddly at say 3500-4000 with foot to the floor, quickly take foot off the accelerator then striaght back on the live guage will rise to 21-22psi and it really goes a good bit more.

Off the mark starts arent really that fast but it really goes once your moving at motorway speeds.

I know i am getting used to the speed but it doesnt fell as punchy as it did before. Still quick but feel more like standard plus a wee bit, But does feel like it is moving when you are at the end of the rev range but not as punchy from say 2-5k

When you start or change gear the revs rise and then drop before settling, it does this through the gears going slowly as well, moves up and down about 500 rpm.

Other than the engine parts above, i have replaced the alternators, PAS, aux belts, pulley, rear track adjusters, ball joints, o/s headlight, new tailgate struts, two front tyres, two front wheel bearings, two SH rear calipers, handbrake cable.

Engine wise with help from KnightriderS2, really insightful day, replaced a few popped off hose at the back of the block, checked for boost leaks, Replaced TB/Ic hose clamps with U clamps, MAF was filthy with oil all over it, gavre it a good old clean (i half suspect this), replaced ****** coil boots (reminds me if Steve is still doing a new batch), replaced soggy K&N filter, coil packs OK.

Any suggestions as to what might be holding back the power.

[JP]

Do a compression test, not to scare monger but I have seen scenarios where water went up the intake and ever so slightly bend a rod. End result an engine that runs perfectly fine has the occasional miss and is slightly down on power. Only easy way to check if one of the cylinders is significantly down on compression as it will have a lower compression ratio in the culprit bore.

[GazzaG60]

ive hydroliced mine on stock rods and didn't ahve an issue but it can happen as mentioned.

also depends on how deep the puddle was.

id hazard a guess you are ready for 400hp

[istoo]

OK i will get as compression test done on it, that does sound entirely plausable chaps.
The puddle/loch was enough to make the car dive worse i was on full throttle, i didnt let off in fear of sooking up water tthough the exhaust. It would have been about 8-12 inches deep, enough to make the front bumer mounts snap as well. But i did have a battle with the steerign wheel to keep it on the road, not into aqua planning speeds but enough for a brown trousers moment.

Ready for 400bhp? To be frank, I have no idea. All the tweaks/upgrades were done by the previous owner. I would be happier with a car that gave me 275bhp all day long to be honest, but I believe at 275bhp i am reaching the end of what the current turbo is capable of.

It doesnt feel like its missing a beat as such, my guess and i maybe wrong is its not opening up to full boost like something isnt opening or closing quick enough ,then on second prod of throttle if does go. Does that make sense?
There isnt a stutter on it at all, if anything the reverse very smooth, it feels like its holding back moreso at lower speeds.

[GazzaG60]

these cars handle the power with ease. thats the problem. its hard to make them feel fast.

soemtimes they feel like they are getting lethargic. usually like you say its due to being used to it.

i feel 400hp is the next worthy point thats why i mentioned it. once you have hp you need a whole chunk more to make it a worthwhile upgrade.

mine did this when the n75 was poor. like it goes then drops off then goes again. maybe its a soggy n75.

[istoo]

N75 sounds like its got to be worth a go, must be an audi thing as both my 1.8T and 2.5tdi N75's failed during ownership.
N75 is also small enough bore that it could get sticky, good suggestion, please keep it coming I am very open to suggestions (car related of course!)

Ok i completly see where you are coming from, perception of speed is tough, well not that much for the S4 as I also have a E60 530d which is similarly quick, but a very different power delivery. But ont he whole I do feel its lacking a bit on the go front, certain it is actually, but then again i am a fussy git. Honestly 275 working all day long would be more than enough for me, standard would be as well, but i know the car is not standard. Thus my fustration!

[GazzaG60]

those n75 are junk.

im a 530d man too. its a great car. pretty nippy. my S2 is a fair bit quicker than my 530d though.

[istoo]

I also must say i am no mechanic, but am slowly learning care of some good folk here and elsewhere.
Wonder if i have fluid in the lines to the N75, will attempt to take them off and have a look, will be weekend before i can do anything. but here's hoping.