Misfire ? Gearbox issue on 95 Aero

[drfrank]

Dear All,

The SAAB 95 aero I recently bought has possibly developed an issue.
Under hard acceleration/kick down, the car judders as if it's misfiring or failing to select the correct gear, it sorts itself out but I'm not sure what it is. The engine warning light can on and flashed for a couple of secs but went off.

Could it be...

1)- misfire prob
2)- fuel delivery issue
3)- low quality fuel (last filled with sainsburys)
4)- gearbox issue

I was planning to try decent juice in it and I'm planning on a gearbox flush and fluid change.

Any other suggestions ? It was recently serviced by SAABTECH in Wellyn and was given a clean bill of health. It still pulls well and accelerates smoothly when the right foot isn't stamped on the go pedal.
All help appreciated

Drfrank

[morgrp]

Could be an overboost problem and the car is electronically cutting back the power. Check the turbo pipe work for leaks. Wouldn't hurt to flush the box and rule it out too

[drfrank]

Thanks for the reply. On hard acceleration it now not only judders but belches out white smoke. On gentle acceleration it accelerates well and pulls nicely.
Any ideas ??

[drfrank]

Had it at a high street garage near work who put it on their diagnostics and no code came up.
They suggested it could be the fuel rail ??
Taking it to a specialist diagnostic centre next week so hopefully will have it sorted.

[DavidY]

Misfire is very likely to be DI Cassette, known weak item, this will often kick management system into safety mode, then all bets are off on how the car will function.

You need to get to a Saab specialist with an OBD2 reader, the generic readers do not show up all the faults.

If the gearbox issue persists, then change the gearbox oil, Saab say that it is lifetime oil in these boxes, but I wouldn't trust that. I changed the oil evry 90k in my 9-5 Autobox and it was still going strong at 230k miles.

[drfrank]

I told them that the DIC pack is a weak point but they said it would misfire all the time if it was the case and not only under 'load'.
The SAAB Indy is a bit of a tonk so will see what this auto diagnostics place come up with, are there any telltale signs of DIC failure ? I've seen that they do crack, is it worth taking it out and inspecting it ?

Thanks

[DavidY]

I had two replacement DI cassettes in my time with my 9-5, and second one failed as you described (failed under load), I used to keep it in the boot as a get you home DI Cassette in case the replacement completely failed.

The first one failed with a misfire all the time, car in limp mode permanently!!

I'd try a different garage!!!

You need to sort out what is sending the car into limp mode first, and then see how many other problems remain.

[drfrank]

Update:
Car started to idle quite 'lumpy' and was taking longer to start. It now will not start. Battery is fine and everything seems to be turning over, just no ignition.
I'm fairly certain it's the DIC but have a mobile chap coming out tomorrow to give a diagnosis.

[moustache]

Remove the DIC and check the underside for cracks. Cracks indicate failure and mean it needs replacing. Very common problem.

[bakerstreet]

drfrank said:

I told them that the DIC pack is a weak point but they said it would misfire all the time if it was the case and not only under 'load'.
The SAAB Indy is a bit of a tonk so will see what this auto diagnostics place come up with, are there any telltale signs of DIC failure ? I've seen that they do crack, is it worth taking it out and inspecting it ?

Thanks

How many times have you used them? SaabTech are probably one of the best Saab specialists out there. They really know their stuff. They are pricey though.

Your issues do sound like the DI unit. Really common issue. Mine has been replaced on my car. I just can't remember when.

[DavidY]

There's two things your should carry in the boot, a get you home DI cassette and a get you home CPS. These two items fail in random ways.

[paulmachin]

Just resurrecting this as my MY04 9-5 Aero manual has a similar problem – juddering on overboost – and coincidentally my garage has diagnosed a slight oil leak into the gearbox. Is this more likely a problem than the DIC?