Mazda Project Idle Surge

[TheArete]

Alright so it’s been about a month working on this idle surge problem to little avail so I’m admitting I’m missing something that’s probably right in front of me.

Topic

[djdevon3]

So someone put on the cams in the wrong place and then made their own timing marks? How does that even work if the ignition timing is electronically controlled? Sorry I’m not understanding this because I’m so used to working off factory specs. Didn’t even know it was possible to set timing any other way. Would love to see some images and better explanation of it all. Whole thing confused me. B:*)

[TheArete]

You’re thinking of Ignition timing which the PCM/ICM control. I’m talking about Valve timing, the actual mechanical timing of when the valves open and close relative to the crankshaft rotation (piston position) which can only be adjusted via Advancing or retarding cam position, which in turn means irrelevant of when the spark occurs the valves will open or close a little sooner or a little later.

I know some enthusiasts out there mess with Valve and Ignition timing, especially with programmable PCM’s/ECU, for performance gains, my valve timing however was just human error.

You can create your own timing marks using a degree wheel on a crankshaft and a piston stop if for say… you have a crank sprocket/gear without the timing marks on it like a lot of older British cars do with their timing chains. All you need to do is find TDC manually and mark it and you now have new Timing marks. Same is true with Cam sprockets that have markings or are put in the wrong key. Simply manually find TDC of the valves (multiple ways people go about this, the least of which is “eyeing it” or using a straight edge on rocker assembly single valve set ups), make the mark on the cam shaft and an aligning marking on the engine housing (or as FSM has, on the other sprocket) and Voila. New timing. That easy… not really lol, you have to know what you’re doing and a little theory behind it (where the cam lobes are positioned relative to the valve lifters at TDC on the compression stroke) and I guess a little trial and error…. Hell some people do this and take it to have it dyno’d. Each microadjustment they go and look at either the gains or decreases and then adjust accordingly.

Anyways I don’t really know enough to go into great detail, a power enthusiast would probably do a better and more accurate job of explaining it, but in short… my valves were at the wrong position because the sprockets were at the wrong position. Pics and Vid’s forthcoming to help illustrate what I’m saying… or at least…. I hope it’ll be helpful. lol.

[EricTheCarGuy]

DON’T remove the IAC when doing the test I suggested just try putting your finger over the inlet hole but leave a little room for air to get in or you will choke the engine.

[TheArete]

I hear ScannerDanner in my head now telling me that 5 volt references are used because they that can be consistent whereas battery voltage is not… lol however Ford has been known to not include 5 volt references on some of their vehicles where this is done internally in the MAF. This particular car is a Ford/Mazda hybrid as it was put together in the States but the engine was built overseas.

-My MAF is a Hot Wire type MAF that heats up the wire to 212

[EricTheCarGuy]

Yep that will do it, so often mechanical causes are overlooked for a more ‘complex’ explanation however if the engine isn’t right, nothing is. Thanks very much for your updates and for using the ETCG forum.

[Author]

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