Have i got a "Bent" 1.6 FSI

BuzzB said:

Hi Peeps
Having got the "Fizzy" firing on four, a worrying issue has reared its ugly head. Driving in fifth gear at 3200 rpm I am only doing 60 mph and 3800 rpm = 70 mph ish. Im getting Paranoid now that i may have a 1.4 gearbox or engine or Both?
I have cut in a Cone air filter in the front of air ducting, using air flow directly from beneath with original air filter in place. (Still growing up) Lol,
Its got 151000 miles on the clock so it might be a goner. also where is the rev limiter set to?

Any Ideas or Comments would be gratefully received, Thanks.

Click to expand...

Those figures don't seem that far out.

The FSI should rev to 6,000 and slightly beyond.
The1.4 petrol around 5,000
and the 1.4 TDI around 4,000

The log book will show the engine capacity but there are several cosmetic differences that will make it easy to spot the difference.

Steve B

From recollection 70 is approximately 3000 rpm in 5th, so I would say this isn't right. Does it have rear disc brakes?

thanks for the response, the answer is yes to disc brakes

thanks for the information.

The rear disc brakes are a good indication in the petrols that you have the FSI; 1.4s have drums. Some retrofit the axle so it isn't a cast iron guarantee. It does sound a touch high, almost like you are still in 4th. I'm no mechanic, I'm sure others will offer counsel, but it does sound like it warrants further investigation.

Are your wheels and tyres standard?

Theycan affect the ratio if they are undersized tyres (diameter wise)

Steve B

yes my wheels are 17" with 205/40/17. the a2 alloys that are prone to warp.

Hi,

Don't know why but remembered your first post from Tuesday when doing 70mph on a local bypass yesterday. Looked and it was a steady 3200rpm. My A2 is also a 1.6 FSI, 72k which I believe has an engine in good order.

Andy

BuzzB said:

Hi Peeps
Having got the "Fizzy" firing on four, a worrying issue has reared its ugly head. Driving in fifth gear at 3200 rpm I am only doing 60 mph and 3800 rpm = 70 mph ish. Im getting Paranoid now that i may have a 1.4 gearbox or engine or Both?
I have cut in a Cone air filter in the front of air ducting, using air flow directly from beneath with original air filter in place. (Still growing up) Lol,
Its got 151000 miles on the clock so it might be a goner. also where is the rev limiter set to?

Any Ideas or Comments would be gratefully received, Thanks.

Click to expand...

Hi,

the 1.4 and 1.6 petrol gear boxes have the same gear 1 - 5 ratios but a different final drive ratio. The 1.4 has 66 : 17 = 3.882 where as the 1.6 has 59 : 15 = 3.933.

The overall 5th gear ratio of the whole box from engine to drive is 3.156 for the 1.4 and 3.197 for the 1.6.

My 1.4 petrol engine is doing about 3150 RPM for an indicated 70 MPH on the speedo. Given the above difference, the 1.6 engine should be doing few more revs indicating around the 3200 RPM mark on the dial.
As the 1.6 engine has a much higher red line than the 1.4, the slightly different gearbox ratio makes more use of the revs, although before I just worked it out I had thought the difference was more.

Given Andrew's comment of 3200 RPM at 70 MPH on his 1.6 that all sounds about right.

1.6 FSI gearbox ratios:

Final drive 59 : 15 = 3.933

1st gear 38 : 11 = 3.455
2nd gear 44 : 21 = 2.095
3rd gear 43 : 31 = 1.387
4th gear 40 : 39 = 1.026
5th gear 39 : 48 = 0.813
Reverse 35 : 24 x 24 : 11 = 3.182

3800 RPM for 70 MPH sounds odd as that's too high for 5th and too low for 4th. Perhaps there is a problem with the instrument dials or the speed reading? Indicated speeds are not affected by the size of wheels or tires.
Reading the RPM and speed via VCDS or another OBD tool will tell what the computers think the speeds are (rather than what the analog dials are actually reporting).

regards

Andrew