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Discussion Starter #1
Bouth my toyota previa 1999 secind hand. It's an automatic and dual fuel. I mainly drive it on LPG/GPL . One of the cylinders was caracked so had the engine and radiator replaced. Since the engine was replaced instead of doing 120 miles per LPG tank it started doing 50 miles, dropping to 35. Changed the O2 sensor, and it went up again slowly but surely and now does a peak of 80 miles per LPG tank. Checked the air filter but it's new as it was changed when the engine was changed. Took it to a mechanic and everything is fine from emissions. Called LPG mechanic to see if system needed tuning but he told me it was not a problem of LPG system. I have no engine light on but WHY, why is it doing less mileage now then when the engine was working on three cylinders! Does anyone has a clue? What do I have to do? The mechanic who control the exhaust told me to sell it. I would be so happy if it just went back to 120 miles as before. Could it be the converter? What else could it be? Please help, is there anyone out there with a similar problem? Cheers Gauri
 

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You may want to start with a compression check of the engine to make sure that all the cylinders are up to par.

At the same time the spark plugs could be checked, including for telltale signs of deposits.

Good luck.
 

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Discussion Starter #3
how do you do it? $?

Thanks for replying. We had all sparks plugs changed. The change of engine came with a full service and although I doubted their work (obviously) they did change the air filter and I supposed all the rest, plus had them changed before (long story..in fact it never seems to end but I love the car!) How do you check compression of cylinders and how much is it going to cost??
We still haven't tuned the LPG system since the change of the engine. Do you think that could be it? Although it uses a lot on petrol the same and one LPG engeneer told me that was not the problem, the people who changed the engine said it is usual procedure to tuned it afterwards. Bless
 

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Checking the compression is fairly simple with a gauge that screws into a spark plug hole, with all the plugs removed, and the engine turned over with the starter a few times. The time-consuming part would be removing the passenger seat in order to reach the engine. My guess is that in the US it would cost around 100 USD.

Tuning the fuel system may not be a bad idea. You could ask for the opinion and services of another LPG mechanic.

Cheerio!
 

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My 91 Previa gobbled gas also. Bought it in 8-2007 and sold it two months later to a mechanic at a discounted price after buying a 93 model. Wouldn't pass a smog test either without lots of expenses. Glad I dumped it quickly.
 

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Discussion Starter #6
Yeah, I finally sold mine! Miss it but too big an engine for a busy city. Now got a ford galaxy diesel but got ripped off again and it's full of problems! Never mind. Best of luck ;-)
 
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