Problems with boost [Archive] - SaabCentral Forums

: Problems with boost

Janne Selinummi
21st March 2004, 07:19 AM
When I got this car, it was running fine up to 1.0 bar of boost, but now the engine starts coughing when I reach 0.8 bar. This is odd, but it would seem like the engine's not getting enough fuel. I checked the fuel pressure and it was OK, but then it is possible there's a fault at the RRFPR. I'm confused really.

I did swap the OE intake pipe between turbo and AMM to a bigger alloy one, 3 inches in diameter. But surely this couldn't affect the AMM's readings? I mean, the same amount of air passes the AMM anyway. I also doubt this improved intake pipe could help so much more air flow that the EFI couldn't cope. So can anyone help me?

Willy Wonka
21st March 2004, 12:10 PM
A few things come to mind. You've probably done them but here goes. 1) All the electrical to the AMM should be checked; 2) Air pressure leaks to the FPR; 3)When checking fuel pressure, pressurize the FPR; 4) Check/bypass the ground to the fuel pump relay from the ecu; 5)last resort - Check the gap of the points/ oops, Check the plugs for the right color for your engine once you know it's fuel starvation Then put back the original pipe to the AMM, if it goes away then the air flow has something to do with it. Since at boost you're probably under a fuel map rather than lambda, start looking for leaks on the lines to the intake pressure sensor. The most directly affected items would be the AMM and the bypass valve. Fuel pressure does not equal adequate fuel at all times.
You know all this - from your previous posts. Good luck

21st March 2004, 02:28 PM
too much water ? does it do the same without waterinjection ?
check the ignition timing, change the igntion wires, change the spark plugs...

21st March 2004, 02:52 PM
guess - blocked injector ?

22nd March 2004, 02:49 AM
I would try putting the 1st pipe back on. If this cures the problem then it is likely that the additional airflow through the new pipe is upsetting something.

If the problem persists then check that all pipes are properly connected and that you didn't disturb something during the fitting.

Janne Selinummi
25th March 2004, 11:04 AM
Problem solved - the spark plugs had worn out, even though I just checked them a couple of days before. It seems that platinum plugs go out fast when they do.. I think I'll keep a spare set with me from now on.