Saab Tech Talk (STT)

Workshop for classic Saab models => Classic Saab 9-5 (MY 1998-2010) => Topic started by: sgould on 10 May 2026, 10:56:23 PM

Title: Bad misfire?
Post by: sgould on 10 May 2026, 10:56:23 PM
I went down to Swedish Day, and back today.  140 miles each way.  Half way down I used full throttle to clear the way for traffic entering te dual carriageway, and the engine gave two big "hiccups" before continuing normally.  I found that I could get the engine to repeat this on the rest of the trip about 50% of the time when hitting full throttle.  No engine light.  Otherwise ran normally.  I will be looking at varios readings tomorrow.  But any thoughts?  DI unit?  It's only three months old and one of the new design.  But I would have thought a P13** code.   Fuel pump?  Not sure, but after the first hiccups it accelerated OK even when keeping my foot on the floor.  

I'll look for pending codes etc. tomorrow.
Title: Re: Bad misfire?
Post by: carrera on 11 May 2026, 09:03:19 AM
Hmmm

See what codes you have, does it seem like plug fouling, which would be strange if the car is up to temperature & being driven normally.

Is boost / MAir behaving as expected & achieving expected values
Title: Re: Bad misfire?
Post by: Audax on 11 May 2026, 09:38:04 AM
My brother has apparently got through 3 of the new design DI units in less than 2 years... he did mention something about no codes or the wrong codes being generated for DI failure.
Title: Re: Bad misfire?
Post by: carrera on 11 May 2026, 09:43:52 AM
My Dame Edna has been running on a DI cartridge which occasionally generates the usual 1312 / 1334 DTC's when the car starts in wasted spark mode & hot for about 6 years. Sometimes the CEL even clears itself.

Might be worth putting the old DI back on for diagnostic purposes, at least