C900, running miserably...

I assume all the basic maintenance stuff (e.g. spark plugs, fuel filter, air filter, distributer cap/rotor, etc.) has been seen to?

John

on my wife's 90 900, similar symptoms (almost dying at idle) led to a new idle control valve. I believe they also wound up doing something with the volume mass meter. I think I paid around $500 for the work. If you need it, I'll pull the rct and get the gory details. Car runs fine now.

it was the air mass sensor, not volume mass meter.

i'm hoping that the guy i had look at it checked all the usual suspects. he had it for two weeks straight, after all... i'm thinking it's an air/vacuum issue of some sort, but i clearly know nothing... thanks for your suggestions!

I could be wrong, but I think an air leak would trigger a CEL. Easy enough to test...

John

John B (John B ) gurgled happily, sounding much like they were saying:

Not necessarily.

Replacing all the vac hoses with nice shiny new silicon is cheap and easy, and will solve a LOT of miserable running - especially at idle.

When I got mine, one of the hoses was a bit split at the join on the inlet manifold. Ran OK, but smelt badly of fuel. After a long fast m'way run, it spat another few hoses off various connectors - miserable idle, stalling. Still no CEL. I've just had one of the connectors on the valve cover break (previously glued), and that didn't seem to affect very much

- apart from, again, a fuelly smell.

None caused a CEL.

thanks for all the input. i just picked her up from a very reputable shop. while the poor acceleration problem was fixed (by overhauling plugs, wires, filters, etc.), it still idles rough. i'd take it back, but i'm tapped out financially. i've done no under the hood work beyond changing batteries. is replacing vacuum hoses difficult?

Nope ... just buy 5 metres of 3mm bore silicon and replace each hose in turn with a new piece of the correct length. With regard to the CEL ... on the Lucas CU powered C900s from 1990 (we got those over here in Europe ... the US continued with Bosch LH) there are a number of faults that will not throw a CEL, like "too rich" ... "too lean", etc. If that is the case for the Bosch ECU as well, then get it checked and pull any fault codes. Also, I gather until all the fault codes are read (and cleared), the engine will continue to run in a "limp" mode ... that may just be a Lucas thing, though. So, read (or have read) the fault codes, pull the battery connection to reset the ECU, replace vac lines and hope for the best.

One quick and easy way to chase down vacuum leaks is to buy a can of carburettor cleaner, run the engine up to warm and then with the engine running, spray carb cleaner onto various air hose connectors. If the engine pitch changes ... there's your leak.

HTH, Paul

charlieontheradio ( snipped-for-privacy@gmail.com) gurgled happily, sounding much like they were saying:

Couldn't be easier.

Buy some vac hose - the silicone stuff from the usual Saab specialist parts suppliers (PartsForSaabs in the UK, EEuroParts in the US) is what you want - 3mm internal diameter, about 5m length will be _more_ than enough.

Then all you need to do is go round the engine bay disconnecting one old pipe, cutting a similar length of new, and plugging it back on. Do one at a time, so you know what's connected to what...

PJGH (PJGH ) gurgled happily, sounding much like they were saying:

Mine ('90 Lucas T16, no cat) certainly ran normally when the injection temp sensor was giving CEL faults. No limp-home mode.

My 1992 900 has a Bosch LH 2.4.2 ECU, and it does indeed display faults for too rich / too lean. If the CEL is on, the codes are easy to read and clear. It's all in the Bentley manual.

John