Tα προβλήματα των κινητήρων FSi
Επειδή δεν έχω διαβάσει πουθενά, σε κανένα περιοδικό ή γράμματα σε περιοδικό (ελληνικό, αγγλικό, αμερικάνικο), για τα προβλήματα των κινητήρων FSi της Audi, πιστεύω ότι είναι καιρός κάποιος να αναφερθεί σε αυτά με εμπεριστατωμένο τρόπο. Δυστυχώς τα περιοδικά αυτοκινήτων έχουν καταλήξει να είναι διαφημιστές των καινούργιων δημιουργημάτων της αυτοκινητοβιομηχανίας, και η πραγματική κριτική σπανίζει. Δεν υπάρχουν πλέον σκαραβαίοι με επινίκνδυνη οδική συμπεριφορά ή κορεάτικα αυτοκίνητα αμφιβόλου ποιότητας ή, ή… ώστε να επικντρωθούν οι κριτικές, και τα περισότερα αυτοκίνητα είναι αξιόπιστα, στρίβουν, φρενάρουν, επιταχύνουν, κλπ.
Ή, έτσι έχουμε αρχίσει να πιστεύουμε. Η αλήθεια όμως είναι διαφορετική και δυστυχώς δεν ακούγεται πουθενά από κανένα μέλος του ειδικού τύπου. Τα «τεστ μακράς διαρκείας» των 30,000χλμ πέραν του οτι σπανίζουν δεν αποδεικνύουν συνήθως τίποτα. Ειδικά αν δεν γίνεται εξονυχιστικός έλεγχος του αυτοκινήτου μετά (που ποτέ δεν γίνεται).
Ιδού λοιπόν ένα τρανταχτό παράδειγμα του πόσο λάθος κάνουμε. ΟΛΟΙ οι κινητήρες της Audi τεχνολογίας FSi (direct injection) έχουν ένα κατασκευαστικό σφάλμα που καταλήγει στην συσσώρευση καταλοίπων της καύσης στις βαλβίδες εισαγωγής, με αποτέλεσμα τη δραματική μείωση της απόδοσης του κινητήρα και την ακανόνιστη καύση (misfiring). Το πρόβλημα έγκειται στο οτι το μίγμα δεν ψεκάζεται πριν από τις βαλβίδες εισαγωγής, και ως εκ τούτου δεν καθαρίζει τις βαλβίδες. Έτσι το πίσω μέρος των βαλβίδων γεμίζει με κατάλοιπα της καύσης που κάθε 25,000 χλμ χρειάζονται καθάρισμα αλλιώς ρίχνουν την ιπποδύναμη κατά 20%! Και προφανώς τα αποτελέσματα είναι χειρότερα όσο πιό πολύ μένει ο κινητήρας ακαθάριστος. Η Toyota έχει λύσει το πρόβλημα ψεκάζοντας λίγο από το μίγμα πριν από τον θάλαμο καύσης (δείτε παρακάτω).
Ιδού μιά ιστοσελίδα με πολλές πληροφορίες επί του θέματος:
Αν έχετε όρεξη για διάβασμα παραθέτω τις ιστορίες ενός κατόχου Audi RS4 μαζί με φωτογραφίες από την τραγική κατάσταση των βαλβίδων του κινητήρα του. Αλλά προτείνω μια αναφορά στο θέμα μετά από δική σας έρευνα και δοκιμή. Τα περισσότερα προβλήματα αναφέρονται σε κινητήρες 2 λίτρων και άνω, αλλά αυτό συμβαίνει γιατί μόνο αυτοί οι κινητήρες εισάγονται στην αμερική. Θα ήταν πολύ περίεργο το πρόβλημα να μην υπήρχε στους μικρότερους κινητήρες της Audi. Μία μακροχρόνια δοκιμή ενός FSi κινητήρα κάποιου τυπικού μοντέλου που εισάγεται στην Ελλάδα ακολουθούμενο από α) δυναμομέτρηση, β) άνοιγμα του κινητήρα, γ) καθαρισμό των βαλβίδων, και δ) καινούργια δυναμομέτρηση θα έλυνε τις όποιες υποψίες.
Και όταν δημοσιεύσετε αυτό το άρθρο τότε ας συζητήσουμε και για την αναξιοπιστία των BMW X5. Και πολλών άλλων μοντέλων διαφόρων κατασκευαστών. Το χρωστάτε στους αναγνώστες σας!
The whole issue is that fuel (and it’s cleaning agents) do not hit the back of the valves, hence the accumulation of carbon over time. The Audi corporate book calls for clearing fault codes lights, pouring the fuel additive, driving 60 miles and returning the car to the customer. When (not a matter of ‘if’) the faults come back, only then do they do the cleaning. Luckily, the guy I deal with knows people up the ladder so he pushed my clean without having to go through the minutia.
Yiannis, my car barely just hit 25K miles. Sadly CB is not a function of mileage (although the more mileage the more accumulation you have), there are plenty of people that have had the CB clean at 5K miles (including some good friends). And this wasn’t preventative, they had the whole host of lights, CELs, EPLs, limp modes, etc.
Sadly no dealer will cover you beyond the 4yr/50K miles. Heck, they give you a helluva hard time to get it done even under warranty. There are independent shops that charge anywhere between $550-$850 per cleaning. I love this car so much that I’ve chalked this up as ‘routine’ maintenance every 15-20K miles L
Here is what a 4.2FSI engine looks like 14K miles after cleaning!
There is really nothing an owner can do to prevent it. We logged countless hours for surveys, there is no clear pattern what makes CB accumulate faster or slower, it is simply there do to an inherently bad design by Audi engineers. Here is what the folks at Lexus/Toyota have done to remedy it (they’ve added port injection on top of the DI):
You can read more about their solution here.
You have heard me telling you the nasty story about Carbon Buildup on Audi FSI (direct injection) engines, so here is something that will convince you once and for all, as this is on MY car! Laiker and Brandon, sorry to dim your Audi ownership but sadly sooner or later you boys will be facing it (in fact dealer said they see the highest % of cases on the 3.2 FSI engine).
Here is the ugly truth once we opened the Intake Manifold. According to the Service Manager, it is the worst he has seen in all of their cleanings! From what I have seen posted, the buildup on my valve stems really looks massive!
Car details: 2008 RS4, 28,800 miles, 5K oil changes (Euroformula Pennzoil paid out of pocket in between the factory paid for Castrol), Shell V Power 93 virtually 100% of the time, Audi Fuel additive used religiously, no short in-town trips, yada yada. Yet this ugliness…
Note that I never got a formal CELs/EPCs (though hidden misfire codes were present, but for the 3 yrs I have owned the car I have yet to see a CEL/EPC light on the dash), the dealer really worked with me to get this authorized through Audi of America (a 10r extremely manual process at $150 per hour, so a significant out of pocket expense otherwise). Tech that performed the scrub (over 3 full days) took all of the photos below (had left my camera in the glove box). Basically, one of very few dealers who didn’t take the Audi AG corporate line, acknowledged it is a huge issue and over a few months built a case with the head office to get this through. By far the best, if not THE best, dealer in my area.
Was hoping to ‘get away’ with CB cleanings every 25K miles, but seeing this nastiness, it looks like those need to be done at 15-20K mile intervals. There really is nothing one can do to prevent it, short of…not driving the car!
Off to the dyno in a couple of weeks and will give you the update. On the same dyno, under very similar conditions over the years, I got 324whp when car had 15K miles, 317whp when car had 20K miles, barely cracked 300awhp last month (302whp) when I had 25K miles. When new, car should be making near 350 awhp (420 hp at the crank but Quattro has big parasitic drivetrain losses). Audi just released a new software ‘fix’, which I had to get as part of the CB cleaning, but we all know that will do nothing as this is a design flaw issue (Tech went as far as saying that if anything, the software will likely raise the threshold of the CEL light being triggered, so yeah, basically Audi puts the skeletons back in the closet).
While I plan on keeping the RS for a while, it is fair to say no Audi FSI is in my future (and if I win an R8 in the lotto I’ll be sure to trade it in after 1st month of ownership ;-o)…
———- Forwarded message ———-
From: Boyadjiev, Constantine <firstname.lastname@example.org>
Date: Tue, Feb 1, 2011 at 9:45 AM
Subject: Carbon Buildup Cleaning gains
To: Yiannis Tsiounis <email@example.com>, Zac Moseley <firstname.lastname@example.org>
As promised, I got the RS4 dynoed this Saturday, and as expected, the gains from the CB cleaning are huge! Just like my carbon buildup ;-o) The gains were a whopping 44awhp (i.e. as measured at the wheels, not the crank)! Given Audi’s/Quattro’s notorious 23+% drive train loss, that equates to nearly 60 crank HP. So sounds like I was driving an S4! Here is a pic of the dyno results (3 pulls, each one showing improvement). I need to play around with DynoJet’s software (WinPep) on my arcane HP Windows laptop (as the software is not Apple-compatible and I’ve been using a MacBook for quite some time now), will superimpose my 4 dyno plots over the last 2+ years and see visually the losses due to carbon buildup. As a reminder, when car was at 15K miles I got 324awhp (i.e. was already built up), when she was at 20K miles I got 317awhp, and last month when she was at 25K I barely cracked the 300-mark (302awhp). [This is on the same dyno, with the same gas, tires, operator, strapping method, ambient conditions, etc. – so an apples to apples comparo]. The one on Saturday returned a very healthy 346awhp! Notice also the 5500 RPM spike in power is back, and it was a flat line before (a characteristic of this engine, almost like a turbo-kick, you should be feeling it as it is noticeable on a clean car). Sad part is, it is all downhill from here as there is nothing one can do to prevent the CB coking up the valves of the high-strung FSI engine 😦
BTW, as part of my CB clean (under warranty), Audi had me load their new software ‘fix’ for CB. My tech openly said it does little to nothing, other than to increase the threshold level for triggering a CEL/EPC light! Great job Audi of locking the skeletons in the closet. I may have told you already, but I checked with a well know Audi/Porsche software tuner (European Performance Labs), he had analyzed the new software and the news is even worse: according to him, the new software flashed by Audi AG is intended to reduce cam overlap which will reduce EGR and vapors circulating inside the heads. While Audi claim it improves cold start misfires, that is simply a way for them to get it covered under an emissions banner…. so they can push the update without the customer’s consent! So yeah, you can imagine how I feel right now about owning an Audi going forward…
The natural question that is probably going through your mind is: “do our cars have it?”. Don’t like being the bearer of bad news, but every Audi FSI engine has it, and it seems the worst is the 4.2FSI on the RS4/R8 as it has the most aggressive cam overlap. As an example, on the RS4 the Intake valve opening angle is 230 crank angle degrees – Exhaust valve opening angle is 220 crank angle degrees. The Q7 4.2FSI has a lot less – 200/210. While the Q7 cokes up less, it builds up nevertheless. So if indeed Audi’s new tune adjusts these intake/exhaust crank angles and makes them less aggressive, we are closer to riding the 4.2FSI engine of the Q7 than we are for what we paid for…
So there are a few ways to check (not if, but) how bad of a CB you have in your engine:
1. Run the Vag.com diagnostic tool (you can buy from RossTech, by far the vest $250 you can spend on your car), check for shadow fault codes (there is a certain minimum number of misfires/errors/faults that need to occur before you see a formal CEL/EPC light come on, so the fact that you don’t have a dash warning does not mean you are free and clear of fault codes).
2. On said Vag.com tool, run various tests, most notably air flow readings so you can gauge how much airflow is coming into the chamber (if you have built up valves, you will naturally have less airflow). Ditto for timing readings, if your timing is retarded, boom – you know you are coked up.
3. Hop to your nearest dyno and do some pulls. Dyno’s never lie. In fact, I may be best to hit the dyno I went to, there are about 15 RS4s and several R8s that have been tested there, so it should give you an accurate comparison what how your car is performing and where it should be (as an example, I organized a group RS4 dyno day in December, we had 7 cars, range was from 280 to 330, so that gives a very good relative perspective of which cars are healthier and which ones aren’t)
4. Of course easiest may be to pull aside another RS4/R8 on the West Side Highway and just gun it, not the option I’d recommend for obvious reasons ;-o)
BTW, I after all the dyno runs were performed, I installed a set of Milltek downpipes (basically the pipes coming out of the engine headers, which eliminate one of the 2 cats, and the sole remaining cat is a much higher efficiency 200-cell cat, see attached picture). We re-dynoed again, had some very interesting results (second dynograph attached)! Gained some meaningful power down low (as much as 12 awhp), but lost 4awhp up top, indicating a software tune is in order (to richen out the fuel mix and advance timing after 5500 RPM). Pretty cool if one is into car tuning and modification!