Well yea, unless the previous owner took out some s3 injectors and replaced them with standard ones before selling the car, it's been running lean its entire life. When I bought it the multiplicative trim was at 18% already. Only about two months ago I fixed the problem by replacing the FPR with a 4bar unit. HOWEVER, the car never once overheated since in my possession, at least on the temp gauge.

Fuel, since I have it, was only 99+.

The boost is another issue, I don't really know what to say. It's running 1.6 overboost and holds 1.4-1.5. But I know a few people running this on the S3 209 and 225 engines and they are fine. Those engines should basically be the same as the AUQ right?

Hang on .......What car/engine is this I'm :confused::confused:

Octavia Mk1 RS AUQ, K04, S3 MAF, 4bar FPR, FMIC + SMIC, cams

If its holding 1.5 bar boost to the end then its probably too high for the car.

Edited 12 June, 200917 yr by Beretta

Octavia Mk1 RS AUQ, K04, S3 MAF, 4bar FPR, FMIC + SMIC, cams

You got me worried because I assumed your engine was standard! The 210 and 225 1.8T engines are more different that you'd think. I believe the block is strengthened etc., might explain your cracks. I guess the AUQ can't handle all that extra pressure.

On another note, the '98 Passat head won't do. It won't have VVT. Get the large port head if your getting a new one, may aswell seeing as you've done a fair bit to it already!

I would be looking into fuelling issues. I have been a VAG techie for many years and never seen a 1.8T with a cracked head in standard or tuned trim. My old ibiza was 366 BHP and the head was fine. My octy is 455 BHP and is fine also

Sounds to me like its getting hot, where was it mapped? worth getting it on the rollers to check fuelling.

From what i remeber the passat head will fit, you just need to put your original cam chain tensioner on, but you would need to double check this.

I remeber on the VW T4 vans the 2.5TDI in particular, when replacing the head gasket 99% of the heads were cracked between the valves, many calls to VW technical about this, and they said this was perfectly normal and the head should not be replaced. They always ran fine.

My advice to you is get it repaired with a replacement head if needs be, i would also fit supertech 1 piece valves, if its getting hot the last thing you want is to drop a valve, because that would be expensive.

Matt

Edited 14 June, 200917 yr by cupra_matt

It was mapped by dupre motorsport in germany, by the previous owner. And yea, there were fueling issues, I wrote about them in a post above.

As for other cracked heads on 1.8T, they happen: a friend has a 209 s3 (chipped) and had the same problem. It was also welded and seems to be ok so far.

The head repair guys are taking a look on monday, I'll keep you posted.

i would have a look around the water pump they aint the best:thumbup:

Do you know what duty cycle the injectors are running?

Above 90% last I checked.

The repair shop quoted about 300 euro for the repairs: 6 cracks welded, all exhaust valves and seats replaced, all sealing rings (or whatever they're called) replaced etc. And they give 6 months warranty for the job. Thinking about it...

You run into a prospect of lean running when the duty cycle gets that high, which could explain the cracking.

Right, and this was also supported by the high multiplicative trim value. But now, with the 4bar fpr, it should be fixed. Unfortunately the car ran 7 years like that :(

Update: head is done... don't know how well until it's up, but looks cool, shiny & stuff . Cost: 280 euro :(. Company that did it looks pretty cool also, they do around 50 heads a week

nice one, now get vag-com and log the AFR.

Yea, as soon as the head is back on the car, which should be next week sometime. Still, I'll probably be driving around "normally" for a while, no high revs, and will just look at the multiplicative trim. Back when this was out of whack I seem to remember the AFR was around 14 at low revs, started to drop as the revs went up to about 11 and then at 4500-6000 went back up to around 13 (probably because of lack of fuel).

yeah 13:1 is too lean for the higher revs.

Ok, new head is up and after 3 days it looks ok. I'll see how it behaves during the next few weeks.

I've still got one small problem though (which was there before the head thing): misfires on cyl 4. Today I swapped the coils first, no effect, then the plugs, no effect. It's not a stored fault or cel, but looking at block 016, the counter goes up slowly, like every 4-5 seconds, then resets and starts over. Car runs absolutely fine, with a slight revs flicker at idle. Any idea what it could be? (note: the cracks in the head were on cyl 1 and 2, so I guess that's not it).