[Biturbos4] 2000 S4 Running Hot

j y jimnetpa at yahoo.com
Tue Aug 30 14:22:52 EDT 2005

see my comments in RED.

Jonathan Conta <jonnyconta at yahoo.com> wrote:

First off, welcome to the group. Prepare to be infected by the do-it-yourself / tuning bug.

Here's a big catch-all FYI/FAQ type directory to answer a lot of questions from the guys at Audiworld: http://forums.audiworld.com/s4/msgs/1559248.phtml

In the meantime, a couple of quick answers since you and I are on the same page regarding preventative maintenance (I've just started down this line with my 2000, and being the third owner I'm not taking any chances on how it was treated in its previous lives).

First thing is to proactively replace some of the weak points with respect to the engine and turbos. Start with the f-hose (only on pre 2001.5 cars) and replace it with either a Samco or homemade setup like the one from Vast (i.e. Piggy): http://www.vastperformance.com/products.html. 

Only MY 2000 S4  6 spd cars have an F-hose - the intake manifolds on the MY 2000 S4 Tips were actually adopted by ALL S4s - starting in MY 2001. 

Second would be the diverter valves, which apparently have already been done on your car. The aftermarket ones are robust, but require bi-annual oiling to keep them moving freely.

The Forge DVs (aftermkt) do not require oiling. Many savy S4 owners with mods use the Bosch 710N DVs, which are OEM on the Audi TT - go figure. The 710Ns are MUCH CHEAPER ($35 ea - USD) than ANY aftermkt DV and just as robust. In fact, I dumped my aftermkt DVs because the 710Ns held boost MUCH better. Go to your local Audi dealer and ask for the Audi TT DVs - u will need TWO - the TT uses only ONE.

Third would be the throttle body boot (TBB) which again can be replaced by a Samco or the ever-popular APR bi-pipe.

After that, you'll probably want to do the after-run switch or add a turbo timer to help the engine cool down after shut-down. The 2000's also have the aforementioned smaller tubro oil lines and a host of other things that were changed in 2001.5, but I'm not 100% sure how many of these we can swap in (MAF being one).

You bring up a good point about the MAF. If RH's car is a MY2000. Then he probably has the BOSCH MAF which are failure prone, especially on CHIPPED cars. Starting in MY 2001, Audi replaced the BOSCH MAF with Hitachi whaich are MUCH less prone to failure. Problem is - U CANNOT DO A DIRECT SWAP. The MAF wiring harness (including sensor) and ECU must be changed too. The Hitachi MAF is mapped differently than the BOSCH. Most MY 2000 owners who are chipped like myself,  just purchase the remanufactured BOSCH MAFs from the local Audi dealer when the MAF goes bad. You will know when the MAF is dead - car will feel lousy from a power delivery perspective - sluggish. You should log MAF nbrs with VAG-COM (everyone should buy this diagnostic tool) to confirm. 

Given the other mods on your car, I'd be shocked if it didn't have a chip. I wish I could tell you how to figure that out from visual inspection but I'm not sure. Find a friend with a known stock S4 and do the butt-dyno test between yours and his. 

The best way to figure if your car is chipped -

Use VAG-COM to determine ECU - it will provide u with the ECU feedback

Open the hood - locate the ECU box - PHYSICALLY open the ECU and look at the chip. Aftermkt chips have the vendor's logo on them. You can also ask the dealer to do this for you - when they do the timing belt.

Good luck, and keep us posted on your progress.


r harout wrote:
Thanks! I'll check the My when I get home tonight. It is a 2000, but not sure when it was actually built.

It would be great to know what can I do to try and prevent the failure --in addition to warming, cooling, and replacing the oil with Synthetic? I've read different things re: throttle body boots, samco hoses, etc. I can check the list --I'm sure you have all answered these questions a billion times.

I notice that there are a couple of drops of oil that accumulate on the belly of the right side hose (intercooler?) after driving the car. Nothing that makes it to the ground though. Also, not sure what coking looks like, but when I open the oil cap--it looks pretty clean in there. You can see the metal and there isn't a lot of crap on the cap.

My main concern is timing belt, etc. becasue of the overheating issue. The car is absolutely fine unless you;re in traffic for 2+ hours in raging heat--but I don't want to take any chances.

The car also needs a gas guage sensor: reads empty. Not sure what this will cost or how easy it is to fix. Car also has couple of worn rear upper control arm busings that produces an annoying knocking sound when going over bumps. The car has been lowered significantly (too low, IMO) with Eibach springs and Koni yellow shocks. The rims are rather large too (18") , which causes some rubbing when turning and scraping when go over bumps. Not good. I think I will get 17s and call it a day--or have the wheel wells rolled a bit to accommodate them. I also hate the tires--Kumho Ecsta (loud as bloody hell!).

Maybe you guys can clue me in on some of the other mods: This car has AWE downpipes, which I understand are expensive and difficult to install. Since I have never driven an S4 before I bough this, I can't tell if they make a difference or not. From what I understand, they make the turbos louder. You can only slight make them out at low speeds--they sound like cops or like Curly from the 3 stooges!

The exhaust is stock..which is interesting. It also came with a set of Baileys diverters. Any thoughts on whether or not these are good to put on? I don't know if the car has been chipped or not-- is there a way to tell?

All in all, I knew I would have to do this stuff anyway. Considering what I paid for the car, I think I'm in reasonably good shape. I'm hoping to get everything taken care of and have it (hopefully) be a nice driver that won't blow up on me and will be a relaiable and more vesatile sports machine than my sorely missed 911. It's not a garage queen or 'cream puff' but it sure is fun!

You guys have been great--thanks for the help and advice!


j y wrote:

I mentioned in my msg to you last night - ONLY THE EARLY S4s (like mine) had the risk of catastrophic turbo failure. It had NOTHING to do with the TYPE OF OIL USED - It had to do with a POOR turbo design (the oil inlets and ducts were too small thus restricting oil flow and its cooling ability) that was corrected in the MY 01.5 (2001.5) S4s. So, early S4s that experienced catastrophic turbo failure under, or just beyond the warranty period, were given UPGRADED (K03) replacements by AOA. 

YOU NEED TO FIND OUT WHEN YOUR S4 WAS BUILT. The build date should be on the side of the driver door. The build date on my S4 was 11/99. It was sold as a MY 2000 S4. I CLEARLY own an EARLY S4. There is no need for you to purchase K04s unless you plan to siginificantly modify the power, like I said in my msg to you. I hope this helps clear things up for you.

r harout wrote:
so let me ask a question (nervoulsy)

How likely is it that I was have catastrophic turbo
failure if the car has only run with regular oil--but
chnaged frequently?

Inevitable? What are the signs? I will use Mobil 1
moving forward, but the owners before me did not.

Maybe I should order the K04s now so I get them in
time for failure!

--- Grant wrote:

> Agreed. Cool is actually not good. The only
> regular failures I know 
> of are turbo-related failures in which the oil
> coked. Coking takes 
> place WAY above 200deg. If you find differently,
> please contact the 
> steel industry - they want your technology badly. 
> As to "how hot"? 
> the flash point for mobil1 is >400deg (F).
> Admittedly, the hot underhood temperatures
> contribute to this, but I'm 
> nto sure how much it improves things to extract the
> heat to the 
> radiator, which then blows the heat through the
> engine bay, which .....
> So who's had a turbo failure that ran synthetic,
> cooled down after hard 
> runs, and warmed up in the cold?
> Anyone?
> And who's had a ring job under ANY circumstances. 
> Anyone?
> Grant
> On Aug 29, 2005, at 2:53 PM, costco wrote:
> > A lot of research has been performed with regards
> to cylinder wear vs.
> > coolant temperature in the 70's and 80's amongst
> the automakers.
> >
> > 192 degrees F is actually optimal in most engines.
> More or less is
> > application specific. I would never put a 160
> degree thermostat into an
> > engine that prior had a 180 degree thermostat. In
> many EFI systems that
> > alone could cause the engine to run in open-loop
> "warm up" mode, 
> > running
> > excessively rich and ignoring the oxygen sensors
> for short and long 
> > term
> > fuel maps.
> >
> > I know the biturbos run 'hot' but IMO effort would
> be better spent 
> > finding
> > a way to get more hot air out of the engine bay
> than trying to get the
> > thermostat to open earlier. The biturbo RS4 has an
> extended bellypan 
> > that
> > covers some of the transmission-- this bellypan
> section is obtainable 
> > from
> > the dealer for around $120. It wouldn't take much
> to get it to bolt up
> > behind the stock bellypan, and I would definitely
> give it a try as I
> > wanted to before getting rid of my B5. I never got
> around to doing it.
> >
> > The low pressure area there will probably greatly
> help pull air through
> > behind the front tires.
> >
> > If you have a little more money to toss around I'd
> consider 
> > retrofitting
> > the RS4 oil cooler into the system.
> >
> > Next I'd eliminate the foglights, elongate the
> slits in the front
> > wheelwells to promote more air through the
> intercoolers, and replace 
> > some
> > of the front lower center grill area with
> something freer flowing yet
> > would still provide some protection from rocks
> hitting the a/c 
> > condenser.
> >
> > - Keman
> >
> > On Mon, 29 Aug 2005, Greg Amy wrote:
> >
> >> efficient. After all, we're not talking about
> mid-60's
> >> muscle cars here; these things run fine on 180F
> >> thermostats.
> >>
> >> GregA
> > _______________________________________________
> > Biturbos4 mailing list
> > Biturbos4 at www.audifans.com
> > http://www.audifans.com/mailman/listinfo/biturbos4
> >
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