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Discussion Starter · #1 ·
MY car is permenantly displaying the " check engine " message after an LPG conversion and gearbox in/out for slave cylinder. It did display the message briefly once before this for 4 miles and run [expletive deleted] but it went away. My LPG guy has ( at his own expense) spent alot of time trying to find the fault, to no avail. The SAAB main dealer's computer says it's the rotary air valve ( it's staying open). LPG man has swapped this over with a healthy unit but it still stays open. He then tried swapping all the sensors he could see from the donor car but fault remains. He reckons it's a sensor fault sending a wrong message to the valve. The car is now V. diff. to start and slower than normal. He has put in a manual screw in the air valve hose which at least makes the thing possible to start, but idles at 2000 rpm. Oh and my speedo and trip computer are kaput. Any (cheap ) ideas ? PLEASE. The "specialist" injection guys won't touch it due to the mysterious, magical and scary LPG stuff. & my wife won't drive it and the kids won't get to nursery and I'll be bankrupt etc etc......
Low Calibre WOW unpridictable
My LPG guy has
 

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Discussion Starter · #3 ·
Yes, Ive thought of this but even a second hand one is £205 from Two Stroke to Turbo. I'm hoping to get to the bottom of this before spending serious wedge. Electronic stuff is non - returnable. I know this because I've still got a £125 2nd hand ECU from my last '89 9000 which wasn't needed. Hey ! anyone want to buy it,? Yours for £50.
Wulbert.
 

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I have a similar problem. I believe it's down to the ECU expecting to get a certain mix of fuel, and LPG is providing - by definition - a different mix. Or at least that's what I understood my SAAB / LPG specialist to say. It goes away when I run on petrol.

With regard to performance, I have excellent performance (2.3 turbo) with neglible difference between LPG and petrol - in fact LPG is slightly better, I'd say.

Who did you use for your conversion?
 

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wulbert,
You mention your speedo and trip computer are not working and that the gearbox has been in/out for slave clyinder.
Was the speedo working before the gearbox was taken out?
Only my speedo stopped working early this year and the car became undrivable in much the same way as you describe. The speedo drive on the diff had broken and therefore without a speed reading the ECU can't 'manage' the engines settings correctly hence the starting/running malfunctions.
Wondering if your speedo drive got damaged when the gearbox was worked on?
 

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Discussion Starter · #6 ·
I used Wellside Motors in Fife . They have a web site. wellsidemotors.com
I don't think it's the LPG as it runs better on it and the fault remains even with the LPG stuff disabled. The speedo was not working when I collected my car from the LPG conversion & clutch work, it was working before it went in but I also briefly ( 4 miles) saw the "check engine" warning before I had the work done. The symptoms are similar to the problems described in the "rough engine" thread.
I do wonder about the speedo & if its affecting the ECU. Mine is the electronic kind unfortunately , not so easy to check. Any one know how to test it to find if prob is in sender or display?
Otherwise the conversion is great already my wallet is fatter as I was about £ 240/month on petrol.
 

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As far as the speed and EDU display are concerned it sounds like the speed sensor has been damaged when the LPT conversion has been done.
The sensor is located at the top rear of the gearbox above the diff. housing. Sometimes the plastic teeth which engage in the gears box break off but in your case I suspect the cable is broken somewhere. I'm not sure that the lack of a speed signal will affect the ECU or whether it is related to it but the air valve should definitely not stay open. The air valve is continually modulated by the ECU to maintain a constant idle speed irrespective of load. Suggest you get the speed sensor fixed and see if it has any effect on your other problems.

Wellside Motors used to have quite a lot used Saabs at one time but I haven't seen them with any for some time. I suspect they were unwanted trade-in from St. Clair in Kirckaldy who lost their Saab franchise a couple of years ago.
How much do they charge for the LPT conversion?
 

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Discussion Starter · #8 ·
Thanks for the tips folks,
Derek, I wondered about the valve and whether it is simply an on/off affair but you are saying it will constantly be adjusting its opening during normal running?
This would explain something I noticed with my old '89 9000 s ie, that say , stuck in heavy traffic you can cruise along at very low speed in 2nd or 1st gear and gently use the break to slow down without stalling. The enginge will produce a fair amount of torque just on idle , with no throttle. It's a bit like having a mini auto box. This was useful in snow for getting up hills where you can actually let the clutch out on zero throttle and allow the idle speed to gently pull the car uphill. My new car won't do this , it stalls.
The LPG conversion cost me £1200 + VAT. The cost seems fairly fixed , Jim, the owner, saying if it takes a little longer to get a car set up he will absorb the cost.He allows 4 days for the work and can supply a Volvo 740 Est. courtesy car , making you glad you bought a Saab. I've got the car booked in for yet another £70 diagnostic on 14th Nov.
 

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Discussion Starter · #9 ·
The speedo was working before theLPG/ clutch work was done on the car but I doubt it being bust could affect starting as the car is stationary anyway? The speedo on my ( '93 K , 2.0 LPT)car has a transducer on top the diff. with two wires leading out , I assume they go to the speedo which counts pulses, read off the gearbox output shaft or somesuch.
Gassy, I've been very pleased with the performance of my new car coming from a plain vanilla 2.0 litre. I think I'm in love with the" someting for nothing" aspect of turbo power. The 2.3T Full Monty must be very pleasant indeed . My car cost £1400 with 176k miles up, seems an OK price but the ongoing " check engine" saga and expensive slave cylinder work make me wish I'd spent another £500 and got one with less miles on. My reputation as ace bargain car buyer is shot... " serves you right for buying one of those costly big Saabs, I've read about them in Which? Magazine " says Mr Peugeot 205 owner smugly. It makes me mad.
 

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Wulbert,

You did well getting a conversion at this price. Mine cost £1900 inc VAT. But I have got a 90 litre tank. I reckon to save £5 per 100 miles, so I will get payback eventually.
 

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I had a similar problem with speedo and poor performance. When the speedo was broken the ECU could not manage the engine, it would cut out if the load was suddenly removed eg when approaching traffic lights the engine would stall. In addition the idle speed was would vary up and down from 750 to 2500 rpm when engine started from cold. Also on open road boost would not to to "top of yellow".
The teath on the plastic gear at the gearbox were worn off. When replaced the car worked like new !
 

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The speedo is electronic, being driven from pulses from the sender unit (sensor). The sender unit, as I described above is located at the top rear of the gearbox above the diff housing. It is held in place by a single bolt which has to slackened or removed ( I can't remember the details) It is accessable from under the car but a bit awkward because of it's position. And yes it does have teeth which engage with something inside the gearbox, presumably on the crown wheel. The gear in the sender is spun round and generates a pulse, possibly from a hall-effect device, which is sent to the speedo, cruise control and probably the ECU.
 

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Discussion Starter · #14 ·
It's now fixed. Cost me £250 though.
The electronics expert traced fault to a dodgy multi pin cable connector between the engine compartment & front bulkhead. Possibly precipitated by gearbox work but I suppose it must have been on the way out / corroded in any case. The previous owner enjoyed cleaning the engine bay with a jet wash, probably not a good idea.The " check Engine" light does stil come on when running on petrol after gas. Sods law, it didn't show when I tok it back to injection man.The speedo ( and trip computer) is now working again as it is driven from the same ECU pin where the fault was. Ho Hum , maybe WD40 would have been cheaper. Thx 4 all the help People. wulbert.
 

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Discussion Starter · #15 ·
The "Check Engine " warning was finally cured by replacement of the Lambda Sensor. This was testing OK for resistance but a dynamic check on the LPG guys computer hook up showed it was stuck at one value instead of constantly changing. Cost £ 40.
Car is faster and more efficient as well.
Wulbert
 
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