Newbie starting and idle problems please help

I bought a mazda bravo b2600 1998 model. I got it with a blown motor not running.

I replaced the motor with a reco one installed it, it has dual fuel from factory LPG and petrol, it will only fire on LPG and at full throttle.

Once it's started It will run on LPG and flick the switch and will run on petrol fine. It will rev fine while on both fuels. It how ever does idle high around 1500-2000rpm yesterday after about 10mins the idle came down.

The afm looks alright I tried turning the idle adjustment screw down with no result it will idle higher then what it is but not lower.

It has a slightly higher idle on petrol then on gas.

Anyone have any ideas please?

I have read nearly every thread on here that sounds similar.

Thanks lars

Welcome to the forum Lars,

I am guessing that your in Australia maybe? I think most of the members here are in the US and Canada and they have probably never seen the dual fuel model of the 2.6 engine........me neither!

Does the truck have a ECU (engine computer) on it? I know on the unleaded fuel (petrol to you) version here in the states it has a ECU that has 2 original capacitors that would leak acid and damage the ECU board requiring a ECU repair. Not knowing how your Bravo is set up, I can't advise you very much........but if you can take some pictures and post them here in the thread, that may help us stateside members out some.

Hey mate yeah it has the normal ecu driver side i think it is, and a lpg computer on the other side to run the lpg system.

Might pull the cover off the Engine ECU and see if there is any water damage or corosion.
Whats the best way to repair the ECU new capacitors and resolder or new board?

Since we don't have the duel fuel set up here, I don't think any of us are going to be familiar with how the computer(s) work with the dual system. If the board isn't damaged too bad, it can be repaired. I would think you have some shops down under that can do it. But sometimes the corrosion is so bad the the circuits and the components are compromised and they can't be repaired. You first step will be to pull the cover off the computer and take a look for yourself. Post some pictures. If you see anything on the board around those two caps, then they are leaking and most certainly contributing to your problem if it's not the total cause of the problem.

You might also check the resistance of the coolant temp sensor and air charge (intake air) temp sensor. When sensors go bad, they can cause some idles issues. There are also some checks we can point you to on the Mass Air Flow meter. Also, you might try unplugging the IAC valve from the main harness and see if it has any effect. It's on top or on the back side of the throttle body on our G6 engines. Yours may very. Post some pics of what you have.

This is a shot of the engine ill get a better one tonight.

Yeah thanks mate, im sure they would run the same ecu for the petrol, the lpg one runs indapendant to the petrol one im pretty sure, ill remove the ecu cover this afternoon and have a look.

What Degrees should the timing be at?
Aslo whats the firing order to double check?

Cool, looks like the same G6 we have then. The here is what he IAC is.



Just follow the harness and unplug it and see if it makes any difference.

Sweet thanks for that, i think it dies when i disconnect it, I think that is the one I disconnected. So I take the side off that has the plug on it to clean the carbon build up?

Firing order is 1-3-4-2 on our trucks.

Timing should be 5 degrees +/- 1 degree with the green test connecter grounded.