2.0 Twinspark down on power. With Dyno pics
I have a 147 2003 2.0TS with only 65000 miles on the clock, recent oil change and plugs within last 10k
I love the car, it handles well, since changing the brake fluid the brakes are good and it sounds great.
Thing is it seems slow, especially at the top end. Plenty of pantomime and great noise and rpm but the car just isn't going anywhere. So I did some testing.
The dyno is not the most professional but it has proven itself very repeatable on many other cars and with surprisingly accurate figures taking into account air temp, rel humidity, air pressure etc etc. From its real dyno comparisons in the past I have a lot of confidence that it is useable.
I have also over estimated drive train losses so these figures are also slightly generous and may well be worse.
I made multiple runs for each test and picked the average of each.
One set of initial runs,
one set with a cleaned maf,
one set with a replacement maf from another ALFA
one set with maf disconnected
It seems like the torque is almost bang on the manufacturers figures however above around 4500 rpm the power just feels limp, the acceleration drops away and it just feels slow. The BHP is showing only around 130 instead of the 150 it should have. I want to tune the car but don't want to do so until I can start with the bhp that the car should have as standard.
To drive the car it only feels like it has 120/130bhp at most. I have owned several other ALFAs and many other cars and have a good feel for this thing.
I apologise for the poor photos as the dyno system runs on an old computer that was tricky to get screen shots from so will try to put up better ones up soon.
My investigations led me to look at the MAF and try to eliminate it as a lot of people say that is what causes top end power loss. How do I know if the variator is switching or if the intake is switching over?
First clean run as is to see the problem.
So where to start looking for that lost approx 20BHP? Remember with lower transmission losses it could be more like 30bhp loss?
The best quote I ever saw after a review of the 164 QV, was "From now on I am only going to buy cars powered by Alfa V6's"
Mmmmmm The noise, the noise...................
Last edited by Dom B; 22-10-13 at 18:22.