Fuel pressure q's...

[paanta]

FPR is brand new Sorensen (a brand that seems well trusted among the Volvo + Saab folks). I replaced the old one because of a slight gassy smell in the vacuum line, but it didn't change anything.

36 PSI at idle up to 44 PSI at tip in, then back down to 36 psi once it stabilizes at a higher engine speed. It seems low, but the FPR does limit it to precisely 3 bar with the fuel pump relay jumped and the car off, rising to 4.5 with the return line pinched, which is what the Bentley spec says. So I think the FPR is ok.

If the FPR were bad, I'd expect it to run poorly more consistently, not just for a few seconds after startup. Even running poorly at idle, it has a distinctly electrical problem-esque thing going on...if you can get the engine over about 2500 rpm, it'll clear its throat and suddenly run fine until the engine speed drops back down to near idle. And yes, I've tested the throttle position sensor. And the alternator+battery.

I could start throwing parts at the problem, but I've been there, done that. No desire to blow through $500 trying to track what's hopefully a simple issue.

I keep coming back to thinking it might be a problem with the ECU itself or maybe a bad coil, though neither one can be tested real easily. Maybe the AFM pot is dirty? That's one thing I haven't tested yet. Weird values could throw the mixture off and give me that error 1222 I suppose. I'll check that tonight...

[angusbn]

Faulty/Dirty Idle Control Valve?

[Bill R.]

vane on the AFM is binding or sticking shut... so that you have to create quite a bit of manifold vacum before it pulls open... Pull it off the car and let it sit overnight then push the vane open by hand when its cold and see if its stuck.

FPR is brand new Sorensen (a brand that seems well trusted among the Volvo + Saab folks). I replaced the old one because of a slight gassy smell in the vacuum line, but it didn't change anything.

36 PSI at idle up to 44 PSI at tip in, then back down to 36 psi once it stabilizes at a higher engine speed. It seems low, but the FPR does limit it to precisely 3 bar with the fuel pump relay jumped and the car off, rising to 4.5 with the return line pinched, which is what the Bentley spec says. So I think the FPR is ok.

If the FPR were bad, I'd expect it to run poorly more consistently, not just for a few seconds after startup. Even running poorly at idle, it has a distinctly electrical problem-esque thing going on...if you can get the engine over about 2500 rpm, it'll clear its throat and suddenly run fine until the engine speed drops back down to near idle. And yes, I've tested the throttle position sensor. And the alternator+battery.

I could start throwing parts at the problem, but I've been there, done that. No desire to blow through $500 trying to track what's hopefully a simple issue.

I keep coming back to thinking it might be a problem with the ECU itself or maybe a bad coil, though neither one can be tested real easily. Maybe the AFM pot is dirty? That's one thing I haven't tested yet. Weird values could throw the mixture off and give me that error 1222 I suppose. I'll check that tonight...

[ahlem]

If you exhaust all the other options, you can pull the fuel pump and check for bronze metal shavings associated with a fuel pump bearing failure in the bottom of the fuel tank. There are two tabs that hold the plastic ring that holds the fuel pump. You squeeze the tabs together and the pump and ring come out. I noticed that when I changed my fuel pump. I started getting hesitation at serious acceleration and it got progressively worse and the check engine light started coming on until I feathered the throttle. It was a bit hairy a couple times on freeway on-ramps. Checking the fuel pump like this is mostly time consuming until you have to buy one at $285.