98 S70 misfire chasing

[Cadywampus]

I'm chasing a stubborn misfire issue on a 98 S70. Actually it is a multiple misfire according to the error codes. Weird thing is it only happens when you accelerate hard, you don't feel it misfiring, and it only pops the check engine light. Driving mildly there is no problem, but get on it and bam ...check engine light. When you scan it is always a multiple cylinder misfire but different cylinders misfiring each time. Compression is fine across all cylinders, the plugs, wires, and injectors were changed but it still has the issue. I'm leaning towards the distributor cap, rotor, or coil since they older parts.....any other suggestions?

[erikv11]

I'd also check the fuel pressure, you need a pressure gauge to get any useful information. But never any lean codes, just misfire codes?

The rotor can definitely fail internally and affect all cylinders, so that's a possibility yes. I'd be looking to get a new Bosch cap and Bosch rotor, agree with that.

Bad coil is rare on these cars, seems least likely.

[misha]

Injectors?
CEL should be blinking when misfire occurs and stay solid after misfiring stops.
Bad Maf,it's wiring or connector could cause a misfiring too.

[abscate]

I'm leaning towards the distributor cap, rotor, or coil since they older parts.....any other suggestions?

Plugs and wires too!

Open up that cap and see if its full of moisture from a seeping cam seal

[foggydogg]

I'm chasing a stubborn misfire issue on a 98 S70. Actually it is a multiple misfire according to the error codes. Weird thing is it only happens when you accelerate hard, you don't feel it misfiring, and it only pops the check engine light. Driving mildly there is no problem, but get on it and bam ...check engine light. When you scan it is always a multiple cylinder misfire but different cylinders misfiring each time. Compression is fine across all cylinders, the plugs, wires, and injectors were changed but it still has the issue. I'm leaning towards the distributor cap, rotor, or coil since they older parts.....any other suggestions?

Add one for inspecting the cap and rotor; as Dr. Abscate suggests, a little spooge inside the cap can cause spark dancing.
Random cylinder misfiring on hard pulls can be diagnostic for a vacuum leak as well.

[rguzz]

Start with the inexpensive stuff, clean up cap, rotor. Next might be vacuum leak agree with last post, also not expensive. I'd go there next, inspect hoses at turbo, tcv. Replacement Bosch cap is over 100 bucks?? Not to mention wires, etc. though you just replaced them I gather, oem parts?

[erikv11]

Bosch cap under $60 at FCP Euro. Rotor $30.