Idling at 450rpm

At 2am this morning, doing 40mph through some roadworks on the M1 (Interstate to you american folks!) the "Check Engine" light came on. It was accompanied by the cruise control turning itself off, and a little loss (only just noticeable) in power. When I pulled over to gather my thoughts, I noticed it idled very lumpy indeed, at 450rpm! I eventually drove it 80 miles home at 1800rpm (damn it took a long time).

I've checked the DI unit by swapping one in from another car and it made no difference so I suspect something else. When I switch the ignition on, I get 9 loud ticks (like a relay), then a quick whirr from what I suspect is the stepper motor. I thought the stepper motor always did that when you turned on the ignition?

Anyway, any ideas what this could be, or any diagnosis/trouble-shooting I can do which might save me a hefty garage bill?

Many thanks, Steve :)

Reply to
sda100
Loading thread data ...

in article snipped-for-privacy@o13g2000cwo.googlegroups.com, snipped-for-privacy@gmail.com at snipped-for-privacy@gmail.com wrote on 15/08/2005 18:27:

Yuk! Sounds like a vac pipe might have popped off. What car do you have? I know the M1 ... There's certainly a few of your countrymen here, but yes, our "little" M1 could be called an interstate :)

... Just a thought ... Your oil filler cap is on nice and tight, right?

DI? Okay, so not a C900, unless you've retro-fitted the good stuff :)

The clicks/ticks could be the APC solenoid, or perhaps just aircon clicks that you might not have noticed before.

Check over all your air pipes. An overtight jubilee clip might have sheared one of the larger pipes, or one of that smaller ones might have rubbed a hole ... Or just popped off. Check them out first.

What year/model do you have? Hopefully someone with the same car will be able to home in on more specific information.

Paul

1989 900 Turbo S
formatting link
Reply to
Paul Halliday

Thank you very much for your reply Paul. I took it to a dealer this morning, apparently the throttle housing is at fault, and the cost to replace... the equivalent of $1500. Needless to say, I declined the repair!

I don't suppose you know if it's a serviceable part? Or if I took it to pieces and cleaned it myself, would it go back together again? Do you have cheap used parts over there I could ship to England?

Many thanks, Steve :)

Reply to
sda100

Sounds quite odd; it's not a component with heavy wear. What exactly is the fault of the throttle housing?

Vacuum leakage (elsewhere) is a likely problem, but this will normally increase idle rpm, unless a sensor overcompensates. Check also electrical sockets for the various sensors.

Ask what they think is wrong with the throttle housing.

Reply to
Johannes

Thanks Johannes,

I did ask what they thought was wrong. The chap said the fault code from the ECU said it was faulty, and they just replace them. He said it could be something to do with one of the steppers motors contained within.

When I turn on the ignition, a relay ticks 9 times. Perhaps that is the ECU trying to adjust something in the throttle housing that won't move?

Thanks, Steve :)

Reply to
sda100

If it's such an expensive component, I would want to see the fault before replacing it, or you could just go round in circles. There are many other more likely sources of poor idle.

But in fairness, cases of poor running can be difficult to trace, even for a mechanic. My car also had a mid life crisis of poor running, but in the last many years it has been perfect.

Reply to
Johannes

in article snipped-for-privacy@o13g2000cwo.googlegroups.com, snipped-for-privacy@gmail.com at snipped-for-privacy@gmail.com wrote on 16/08/2005 10:37:

Try for a comparative price.

Anything is possible. Grab a Haynes manual and see what the procedure is. I suppose once you have the throttle in bits, replacing any faulty parts would be a lot easier. Better than replacing the whole thing and I'm sure there are people here who will know how to test each part.

Buh! Now I'm confused :) I'm over here in Blighty, too.

If you can give us an idea of what model your car is and where you are in the country, people will be able to point you to nearby SAAB Specialists which would no doubt give a different price, if you know what I mean :)

Paul

1989 900 Turbo S
formatting link
Reply to
Paul Halliday

I didn't think there was a Haynes manual for the 9-5... I must look again.

I think I got you confused with someone from another group, in the US - my apologies.

My car is a 9-5 SE Auto (lpt), 1998 S.

I've managed to find a breakers yard that will do me a used throttle housing for 130 inc. or a new one for 275 inc. The used one has a 3 month warranty and the new one a 1 year warranty. Should there be anything wrong with a used one with limited warranty?

I have been told I will need to get the ECU fault code reset, but the SAAB specialist who gave me the original quote of =A3625 + vat, for the throttle housing hinted that it would also require some reprogramming of the ECU.

Many thanks again, Steve :)

Reply to
sda100

Hmm. The ECU fault code eventually resets itself after a few starts with no engine faults.

Reply to
Johannes

I bought a used throttle body housing and went to fit it, but it didn't fit. On mine, there is a moulded channel in the actual housing that fits over an opening in the inlet manifold, but on the one I bought, the housing has no opening, but instead has a pipe protruding from the side.

What is the purpose of this air channel, or can I simply block it off?

I found out how the limp home throttle is actioned, and put it back, but as soon as I switched on the ignition, it put the limp home thing one again. I suppose either the fault needs to be reset or the throttle body housing is just downright faulty. Is it difficult to take the electronic gubbins off the end and swap just swap that part over?

Thanks, Steve :)

Reply to
sda100

Don't know. It could be anything, e.g. a smaller pipe leading to a sensor. The air channel is probably there for a specific reason.

But have you pin-pointed the original fault, or is it just trial and error? The limp mode is triggered because of incompatible sensor data. As soon as the problem is fixed, the fault code will reset after a couple of starts.

Reply to
Johannes

You could always remove your part, taxi over there and get them to match it visually. (Well, sometimes you can get lucky!) Cheers

Reply to
hippo

MotorsForum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.