Auto gearbox slow changing up

Technical questions and answers about the Mazda Bongo

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helen&tony
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Auto gearbox slow changing up

Post by helen&tony » Thu Jun 10, 2021 3:37 am

Hi
I have an issue with the auto changing up from first and second when cold, or when left a while whilst out. The first to second goes with a thump, but once warm it seems fine. The fluid level seems fine as far as I can see, but , as usual , it's a nightmare trying to read it. The colour is good, and no smell. Any ideas?
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Helen
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Re: Auto gearbox slow changing up

Post by Ian » Thu Jun 10, 2021 8:06 am

Hi Helen, don't know if this helps but I found it in the archives.

Q: I’m having problems with my gearbox. It doesn’t always seem to know which gear it should be in, especially at greater speeds. So, starting from cold, it changes gear OK, sequentially, up through the box without any particular clunkiness, and finally moves into top gear. However, if, say, I was then cruising along at 60mph in top gear and driving circumstances in front of me required me to back off of the throttle, with a resultant loss of, say, 15mph, reapplying the throttle would cause the gearbox to appear to be uncertain about which gear it should get back into. What’s the likely cause? And will I need to take it to a tranmission specialist? (Andy from Battersea)

A: Identifying and fixing auto-box problems can be time consuming and expensive. So before you go down that route try the following. Not all gearbox problems are actually gearbox problems at all. Lots of things affect when the gearbox changes, including the fuel filter, banjo filter (top of the fuel pump), throttle position sensor, and turbo pipework leaks. All these can fool the gearbox into conflict.
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helen&tony
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Re: Auto gearbox slow changing up

Post by helen&tony » Fri Jun 11, 2021 3:29 am

Hi Ian
Thanks. I had wondered whether the TPS (Throttle Position Sensor) was an issue, but I don't have much knowledge on it's symptoms of failure. I do get a feel of the throttle wanting to decrease engine speed of it's own accord, so that's what made me wonder. The vacuum solenoids have been replaced, and are functioning, so it might seem to indicate the TPS. I wanted to rule out shenanigans in the transmission. It's rather slow on gear changing at all speeds, and likes to stay in gear when , previously it would have changed
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Helen
In the beginning there was nothing , then God said "Let there be Light".....There was still nothing , but ,by crikey, you could see it better.
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Re: Auto gearbox slow changing up

Post by Doone » Sat Jun 12, 2021 4:22 pm

Hi Helen. Allan says the TPS can be adjusted. Undo the screws that are holding it on. Turn it just a gnats whisker. Try anti-clockwise. See if that helps. If it doesn't, go 2 gnats whiskers clockwise. But mark its normal position with tippex or similar before you adjust.
Repairing Bongos since 2003, in Plymouth, Devon: http://www.allansvehicleservices.co.uk
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Re: Auto gearbox slow changing up

Post by helen&tony » Sun Jun 13, 2021 4:43 am

Hi Allan
Thanks very much...I'll try
I have just done the side seals on the fuel pump, and I'll see what happens. I'm replacing the pump as part of ongoing maintenance soon, so it's a temporary fix. I have a long trip to France next year, so I'm replacing a lot of parts
Cheers
Helen
In the beginning there was nothing , then God said "Let there be Light".....There was still nothing , but ,by crikey, you could see it better.