fast idle problems

[tommyrugrat40]

Hi Folks

I seem to be going round in circles as there seems to be too much information about this issue with differing opinions, i am just wondering if anybody has a definitive check list for me to try.

So...here is the problem.

My 2.5L diesel Bongo has for some while been experiencing problems on start up, it seems the fast idle circuit is not working, also the engine speed does not increase when the air-con is switched on, which leads me to the vacuum solenoids.

Now i have changed the glow plugs (NGK) recently and obviously made no difference, i have checked all the piping to and from the vacuum solenoids and they seem to be going to the right places and all connected. The system did work up until recently so i am not sure what is going on, i did replace the check valve (as the original was knackered) with a simple windscreen washer item as a temporary measure just to see if that was the issue but still does not work.

All the solenoids seem to click when the ignition is turned on but there does not seem to be any vacuum pressure generated?

If anybody can shed any light on this that would be great, i do know my way around a multi-meter if it is electrical.

Many thanks.

[mikeonb4c]

Hi Folks

I seem to be going round in circles as there seems to be too much information about this issue with differing opinions, i am just wondering if anybody has a definitive check list for me to try.

So...here is the problem.

My 2.5L diesel Bongo has for some while been experiencing problems on start up, it seems the fast idle circuit is not working, also the engine speed does not increase when the air-con is switched on, which leads me to the vacuum solenoids.

Now i have changed the glow plugs (NGK) recently and obviously made no difference, i have checked all the piping to and from the vacuum solenoids and they seem to be going to the right places and all connected. The system did work up until recently so i am not sure what is going on, i did replace the check valve (as the original was knackered) with a simple windscreen washer item as a temporary measure just to see if that was the issue but still does not work.

All the solenoids seem to click when the ignition is turned on but there does not seem to be any vacuum pressure generated?

If anybody can shed any light on this that would be great, i do know my way around a multi-meter if it is electrical.

Many thanks.

I sympathise. Mine hasn't worked since I head to have a new head put on the Bongo last year. I've followed advice on here but without success and I ran out of time to track it down and I'm not about to give my mechanic a hard time over it as he did a fab job on the major work and at a v good price and freely admits he's not expert on these units - he could fix it but cost might be disproportionate. In my case also it doesn't affect starting, just a slightly low tickover when first started and/or aircon is on. Luckily I bought an Eagle throttle lock cruise control for a tenner off a member many years, got it approved by insurers and had it fitted. The operating box sits on the centre console just by my left hand and can be used in any situation where you might need to set the throttle and lock it. As well as, in theory, being the most fuel efficient form of cruise control, it has proved incredibly useful whenever I need to raise the tickover. Fitting is very cheap and simple. Seems you can get get them, here:

http://www.conrad-electronic.co.uk/ce/e ... se-Control

Check insurers are happy about fitting. Also, don't rely on brake pedal kick off working reliably when using as a cruise control. The only safe position to fit the box, in my opinion, is where your left hand can instantly and instinctively reach the OFF button. Fitting it there is also the key to being able to fine adjust the throttle position when on the move. The centre console, especially if you have the optional console box/armrest, provides an ideal position. I use mine as naturally as any other control.

[Fassi]

maybe it is the temperature sensor? It seems from other threads and from my own experience with mine, is that above 50 degrees no cold start system would operate so maybe it is giving a duff reading? maybe unplugging it or shorting it would give an idea. I don't know if high or low resistance = cold start scenario.

[Northern Bongolow]

try these links.
http://www.igmaynard.co.uk/bongo/forum/ ... ds#p585176.

http://www.igmaynard.co.uk/bongo/forum/ ... +solenoids.

http://www.igmaynard.co.uk/bongo/forum/ ... ds#p574559.

http://www.igmaynard.co.uk/bongo/forum/ ... +solenoids.

ive sent you a message.

[tommyrugrat40]

Thanks for all the replies, just a quick one.... where exactly is the temp sensor, i know that the coolant temp sensor is on the drivers side at the top of the block, but is there an ambient temperature sensor that i need to check? Or is it not applicable to the vacuum solenoids.

[Northern Bongolow]

18-840c on this link, next to it is the temp gauge sensor that is in the front of the head.

http://lushprojects.com/bongopartsmk2/c ... o=.html#11.

this sensor measures the coolant temp and is connected to the ecu, which then controls all the temp related functions around the engine, like cold start knock off temps, glow plugs, rad fan trigger points, egr on off,

the temp sender is a 2 wire connection, squeeze it to remove it from the end of the sensor, when faulty the end of the sensor can wobble about a little, usually coss its been knocked.
its shown at the bottom of this page on this link. use gen mazda if poss as its such an important part and does so many things, best is best.

http://www.mazdabongo.com/catalog/cooli ... ps-sensors

[cmm303]

Thanks for all the replies, just a quick one.... where exactly is the temp sensor, i know that the coolant temp sensor is on the drivers side at the top of the block, but is there an ambient temperature sensor that i need to check? Or is it not applicable to the vacuum solenoids.

2-wire sensor is hard to see in this pic but is just visible below the obvious connector with a red wire. It is located immediately above the hose coming from the engine.