Engine stalls when warm

[Tigmaster]

Solenoids fitted and working but unfortunately it still stalls when it gets warm.
Could it be:
Dirty throttle body
Faulty TPS
Blocked catalytic converter

[g8dhe]

It sounds like you may have a number of things out of best positions even, but I would guess the other things you list are all possibilities.
Have you been able to identify if its Temperature or Time related this might help identify the main cause ?

[Tigmaster]

From cold the problem starts when the revs drop down to about 650rpm temperature is about 1/4.
Removed throttle body which was rather dirty but not bad.
Going to check tps sensor.
Removed valve on top of plenum chamber. It’s black but wouldn’t say it’s clogged.
Giving it all a clean then reassemble

[Tigmaster]

Some good news I seem to have resolved the problem.
After cleaning the throttle body, plenum chamber valve and tps I also adjusted the rpm to tick over about 750-800 rpm.
I can now select R or D with my foot on the brake, no throttle and it doesn’t stall.
Went for a drive and after 10 minutes the hold light started flashing and when I came to a junction it stalled. Started again and drove ok.
Bit later hold light started flashing again and it was stuck in 3rd.
When I stopped at the junction it stalled.
Then it drove for about 15 min with no flashing light and used all gears.
Went for another run and had the same issue with the hold light and after it stalled it had no further issues.
Am I looking for electrical issues on the box, solenoid issues or tps intermittent fault.
Thanks Geoff for all your help and advice so far

[Tigmaster]

Dirty throttle body

[g8dhe]

Probably worth looking at the error code it will most likely be the 4-digit variety on a 2000 model it may give you a pointer as to the item(s)
There is a factsheet with the codes etc. but also worth Googling the 4-digit codes "Mazda P???? error code" will normally get you an answer.

[Tigmaster]

Gearbox error codes
1791 - TP Electrical
1715 Shift Solenoid 2

Engine codes
0100 Mass/Volume Airflow Sensor
0110 Inlet air Temperature
0120 Throttle Position Sensor A

[Tigmaster]

I just realised why i have the engine faults codes up.
I didnt reset the memory after putting everything back together

[Tigmaster]

So now I have cleared all the fault codes I gave it another run.
Within 5 minutes of leaving home the hold light started flashing.
Sure enough when I came to a stop it stalled.
Started up straight away and then I drove home 15 minutes with no hold light or stalling and gearbox seems to be working ok.
Got home and checked fault codes - only one this time P0715 Malfunction in the transmission input/turbine speed sensor circuit
Should i look to remove and clean the sensor?
Why would this come on occasionally causing it to lock into 3rd gear and then other times it is ok.
Also I have been unable to select L without it stalling the engine.

Is this going to be worth fixing? MazdaBongo.com list a sensor for £211. Thats if it is actually the problem.
Would I be better off buying a 2nd hand gearbox?

[g8dhe]

Do you have the part number for the sensor itself ? I don't recognise the generic fault name reported. Does your speedometer work and does your engine revs meter work as expected especially when the fault is happening ?

[Tigmaster]

Hi Geoff
Speedo and Rev counter work fine.
Im not sure what part it is myself.
I will get back under there tomorrow and see what gearbox I have and see if I can remove the sensors and clean them first.
I think there are 2 or 3.

[Tigmaster]

Pictures of Throttle body before & after.
There was a lot of carbon build up around the intake and butterfly valve.
This was thoroughly cleaned without removing the dark grey paint substance that is supposed to be there.
The butterfly now operates smoothly.

I also removed the adjustable valve on top of the plenum chamber.
I think this might be the air inlet to the plenum chamber for the idle.
There was a previous thread that directed me to the throttle body and this valve.
Both appear to have never been cleaned in 23 years.

With these back on and testing of the Throttle Position Sensor plus a little tweak of the idle speed, the Bongo now idles really nice and allows all gears to be selected when stationary and when warm. (Apart from L which stalls when warm)

[Tigmaster]

I removed the gearbox speed sender units today.
One was smothered in black gunge.
Checked the voltage of the wires and they were all good.
I was unable to find out how to check the senders themselves so just cleaned them and put them back in.
The Bongo now runs a lot better and i took it for a long drive. There was no holding light flashing, no stalling and also when i got home there was no more error codes.
Hopefully problem solved.

Im going to put another thread on to cover these as this might be helpful to others

Cheers again Geoff for your help and advice. Much appreciated

Sean

[g8dhe]

That's great to here, these sort of faults can be a pain where everything contributes a little to the problem rather than a single cause!