Date: Sun, 22 May 2005 22:35:55 +0100 From: Colin Stamp <col.dustbinnospamp.plus.com> Subject: Re: Replaced my DI cassette. Now getting misfire on 4... Help!
On 22 May 2005 14:13:53 -0700, "Hoov" <jhoovennospamter.net> wrote: >Colin Stamp wrote: >> On 22 May 2005 12:31:32 -0700, "Hoov" <jhoovennospamter.net> wrote: >> >> > >> > Long story short: Card died on the highway, I replaced my ID >> >cassette, used properly gapped NGK Resistor plugs. It now runs but >no >> >turbo boost. Engine light comes on and the DTCs (P0304 & P1304) >> >indicate misfire on 4. >> > So I took apart the old DI cassette and what do you know? The >> >cylinder 4 coil was covered in oil and there was actually a cracked >> >buldge next to it in the housing. >> > Any ideas? ... at all? I'm lost. >> > >> >Thanks very much, >> >John Hooven >> >> Most likely the new cassette was duff. Send it back for a >replacement. >> I assume it's not too obvious that you've had it apart? >> >> Cheers, >> >> Colin. > > I don't think it's the cassette. I took the OLD cassette apart and >the Cyl. 4 coil was gone. With the new cassette in, the DTCs report >misfire on Cyl 4. So I figure somthing (Trionic?) caused cyl. 4 to >misfire and that is what caused the cassette to go in the first place. > I have a local independant Saab mechanic who comes highly >recomended. I guess I'll have it towed to his place. :-( > Oh, I see. I thought you'd taken the new one apart. Doh! In that case, Maybe you were unlucky enough to have the old one blast the ECU as it failed. The dumbed-down diagram in the manual makes it look like the ECU outputs directly drive thyristors in the DI cassette without any buffering, so if one of those failed, it could have sent 400V back up the ECUs output. I'd say you're right. It's time to admit defeat and get the car looked at by someone with a box of bits to swap in and out to pin down the problem. Incidentally, does the car feel like it's mis-firing when off-boost? If the ECU output is knackered, number 4 would never fire, so it would be quite noticeable. Cheers, Colin.
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