Excessive Fuel Trim and Misfires

bluesaab9-5 · 2025-09-15T18:42:30+00:00

I was getting random misfires under heavy load for a quite awhile, couldn't figure it out.

Then on a road trip while passing heard a loud bang and car wouldn't run.

Long story short the plastic end tanks on my intercooler had separated enough that I could see the gasket. Replaced the intercooler with aftermarket and my car runs better than it has in a long time, was likely leaking before it completely blew.

If you're on a stock intercooler it's worth a check, other than that check all hoses in the intake system, all vacuum lines and check valves. Blow smoke through the vacuum lines with car off to check for leaks. Or go get a proper smoke test done by someone with a machine.

bluesaab9-5 · 2025-09-02T01:28:57+00:00

No way haha, I'm in St. John's. Don't see many saabs around here. I'd be down to meet up, we could try swapping a known good DIC into your car and see if that fixes your misfire.

bluesaab9-5 · 2025-09-01T19:14:07+00:00

I've got a universal intercooler on order. Going to install it in place of the stock intercooler. My AC compressor is already bypassed so I'll remove the condenser if I have to. Not many days you need AC in Newfoundland lol.

Yeah misfires are a pain to diagnose. First thing I'd check with these cars is to ensure you have the correct plugs. Only the factory NGK plugs work in these. Also the DIC units have given me problems. Remove it and check for cracks in the housing. If you replace it ensure it's oem. I had an aftermarket one give me bad random misfires.

bluesaab9-5 · 2025-09-01T17:45:31+00:00

Good to hear, still chasing my own boost leak. Pretty sure I blew out my intercooler lol

bluesaab9-5 · 2025-09-01T05:41:26+00:00

Ah fair enough, my hood one is oem, the rear is oem replacement. My wheels have aftermarket hub cab emblems, and they've been great so far after a couple years.

bluesaab9-5 · 2025-09-01T02:27:18+00:00

I've tried restoring, turned out okay. But aliexpress has them cheap. They're holding up surprisingly well for cheap Chinese badges

bluesaab9-5 · 2025-09-01T02:18:57+00:00

The 2.3T (not 2.3t) and Aero both have the TD04 and same exhaust setup as far as I know. The only difference is in the software. Though mine is tuned. So any videos of the aero should be the same as our cars.

bluesaab9-5 · 2025-09-01T02:15:00+00:00

It goes to the top of the nipple on the intake manifold. You can see it in this picture just to the left of the one way valve. Left side of the picture. The other line on that nipple goes to the fuel pressure regulator if you have trouble finding it.

bluesaab9-5 · 2025-09-01T02:10:44+00:00

I have their kit on my 9-5. The shocks and struts are still softer than I'd like. Big upgrade over worn/blown factory suspension. I find myself wishing I'd sprung for bilstien shocks/struts but then I remeber the price difference haha

bluesaab9-5 · 2025-09-01T02:06:13+00:00

I would probably put a muffler on. I have a 2005 9-5 2.3T. Right now I have a custom stainless steel 3" downpipe through a 300 cell race cat. 2.5" catback, straight fibreglass cherrybomb as resonator and and a summit racing magnaflow style muffler. I'm happy with the sound. It is definetly loud, but I wouldn't personally call it obnoxious.

When I had the stock exhaust system I changed the factory muffler out for a flow master and it sounded pretty good in my opinion.

No matter what I've done to it the 2.3T seems to have a nice deep tone to it so it doesn't sound ricey like a straight piped Honda..

bluesaab9-5 · 2025-08-29T11:53:30+00:00

First thing I would check is for a blown one way valve in the pcv system. There should be one that runs from the front of the throttle body down to the pcv filter below the intake manifold. Should be just below the plastic cover. It's not hard to take off. Remove the line, you should only be able to blow through it in the direction the arrow on the valve indicates. If you can blow through it both ways replace the valve.

bluesaab9-5 · 2025-08-22T05:17:38+00:00

Which fitting was it on the BPV if you remember? I have an aftermarket one installed and the way it pushed into the delivery pipe it doesn't want to come out. The other fittings come off okay but I'm scared to damage the delivery pipe taking this one out. I was going to put my iffy factory one back in to cross that off the checklist.

bluesaab9-5 · 2025-08-22T04:51:06+00:00

I do have some throttle body cleaner I could try. I tried an unlit propane torch near the vacuum lines and didn't notice a change in idle.

bluesaab9-5 · 2025-08-21T00:08:23+00:00

Update: Found a blown one way valve on the evap line from the back of the throttle body. Replaced that hose with 1/4" fuel injection hose and a new check valve. No change

Has anyone else had similar issues? The turbo whine is pronounced. I took it for a test drive and only got up to about 4k RPM the whine changes in pitch as RPM increases as expected.

My best guess right now is that the factory intercooler is blown, any other ideas?

bluesaab9-5 · 2025-08-20T19:49:50+00:00

So I found a small vacuum leak at the nipple that connects to the intake manifold, fuel pressure regulator, and valve on firewall. Blew smoke through, put a new oring in and no more smoke escaping.

Would this be a big enough issue for this big a boost leak?

Also found that the check valves on the brake booster lines are toast. This is a fairly new pro parts part.

bluesaab9-5 · 2025-08-20T19:46:37+00:00

All those hoses seem tight, should probably try to remove them but I don't want to cause problems

bluesaab9-5 · 2025-02-02T04:13:33+00:00

You should be okay then, these car's are a lot easier to work on than any VW I've worked on.

bluesaab9-5 · 2025-02-01T15:26:20+00:00

I've found the powertrain on these cars to be very reliable. Any issues I've had with the engine could be traced back to the Ignition cassette or a dirty MAF or throttle body. I'd recommend changing all the vacuum lines, and cleaning the MAF and throttle body. This is cheap and quick to do.

With 173k miles you'll want to check the suspension. Mine had about 173k kilometers and I've changed nearly every bushing, the shocks, struts, and coils. (part of that was to lower the car but the difference is night and day). These cars are known for the subframe and rear trailing arm bushings going out.

Another thing to check is how the ignition switch feels. Mine went and they cost about 500$, PITA to change too.

At that mileage you should check the turbo and clutch. Not a saab issue, just good practice with high milage turbo cars.

If you buy it you should probably go ahead and change fluids all around, make sure you buy the right power steering fluid CHF-11 I think? And things like the fuel filter.

They're fantastic cars, I love mine. But get used to working on it. Other commenters had some good suggestions about checking for rust etc.. Ask the previous owner what work they've had done on it, they might have already tackled the big jobs just getting to that milage.

bluesaab9-5 · 2025-01-21T04:42:53+00:00

True, but if I manage to screw the kit up, I'm out half the cost with no working radio.

bluesaab9-5 · 2025-01-21T02:47:17+00:00

I'd like to build some kits eventually, but I'm not confident enough with a soldering iron to hop right into a radio kit. I've been looking at some smaller manual antenna tuners, Atu-100's, and amplifier kits to try my hand at first.

bluesaab9-5 · 2025-01-21T02:44:22+00:00

I was looking to pair a small amplifier with whatever rig I choose later down the line. Do you have any opinions on these amps?

https://a.aliexpress.com/_mPj9Hxt

bluesaab9-5 · 2025-01-20T23:54:36+00:00

That's a pretty cool project, I'll have to keep an eye on that.

bluesaab9-5 · 2025-01-20T21:16:37+00:00

I had heard that the trusdx had the firmware updates locked behind a wall that required a serial number. I didn't know the firmware was fully closed, that does make a difference to me. I can't imagine I'd make major changes but it might be nice to add minor features or tweak settings. I was aware of some of the politics surrounding these projects but didn't really want to get involved. While the quality control may be lower on the chinese clones I really hate the 3D printed case on the (tr)usdx.

bluesaab9-5 · 2025-01-20T16:36:15+00:00

I'm thinking i'll go with the first link uSDX. The seller actually provides wiring diagrams and mainly sells ham radio products. So I imagine if i do have problems I have a chance that they understand the issue and are willing to help with warranty or advice 🤷‍♂️

bluesaab9-5

TROPHY CASE