can a motor blow up with perfect a/f and egt?

im going to get a haltech e8 this month

 

Absolutely, I've done it. Ignition misfire due to poor RPM signal.

 

do you guys stab the CAS so that your pickup for the 2-tooth-wheel is lined up with the 3rd tooth ahead of one of the 2-tooth-wheels teeth?

that may have been the most confusing sentence i've ever written, but it was my 4th attempt at wording it simply...but i think anyone who has re-stabbed a CAS correctly will know what i am talking about.
i was using MegaSquirt and that seems to be the well accepted way to stab the CAS...is this how it is stock...for the rest of this post i will assume that it is.

correct me if i am wrong, but it is stabbed like this becasue the ECU will know the exact angular position of the engine when the 2-tooth-wheel passes it's pick-up. every millisecond that passes after that, and there is a higher margin for error. with this in mind, it is better to know exactly where the motor is when it is at a degree of advance close to (but not below) the maximum advance of the motor. so when your advance is near its maximum value, your timing needs to be as accurate as possible, so you stab the CAS in such a way so that your 2-tooth-wheel passes the pick-up at 20*BTDC (for example). in doing this, the ECU will know for sure when it is at 20*BTDC.
i was under the impression that this is why the CAS is stabbed until i thought about something...the sparks fire every 90* of CAS rotation, and if my previous statements were true, Mazda would use 4 teeth on the upper CAS wheel, not 2 teeth. i am clearly missing something here...why is the CAS stabbed like this?

this may seem off topic, but after 'classicauto' mentioned that bit about a poor RPM signal causing a blown motor, i started to get worried about not only the RPM signal (24 tooth CAS wheel), but also the angular position signal (2 tooth CAS wheel).

 

The CAS should be stabbed in a stock location for any standalone, unless otherwise instructed.

You can stab the thing nearly at any angle you want as long as you can change the trigger angles (Haltech, Megasquirt, etc.) but if you can't (Microtech) then it must be stock.

The ECU knows where the engine is because it counts the triggers. It doesn't just fire when there is a trigger.

A bad RPM signal is a sure way to toast an engine. These are generally recognized by spikes in the signal. They may be very brief, and undetectable if your ECU has noise filtering. Turning off the noise filtering and checking the cleanliness of the signal is a good place to start.

 

i dowloaded some Haltech software and was looking over several sets of maps for various 13b hardware configs.

the common trend i noticed was that after around 3500 rpm, the spark maps were the same curve all the way up to redline. these were "base maps" intended to help people get their motors running. should i assume that the commonality of these advance curves has just not been tuned yet?

also, what sort of AFRs do you guys typically read when you start your engine "cold" on a warm day (25*C)? something like 9:1 ?

 

most ignition maps are laid out like that because their conservative. Once tuned they generally just flatten out after torque peak, perhaps advancing a bit if you're really after all you can get.

On a cold start my car runs at ~12.5:1. 9:1 is ridiculously rich for any area of the map.

 

so if you assume we are close to stoich (14.7:1) during "normal" idle, then when you are starting off around 12.5:1 you have a TOTAL enrichment of 17.6% over normal required fuel (or in other words your injector PWMs are %117.6 instead of %100 at stoich)

based on what i have been seeing on these enrichments tables in the haltech, that seems about normal for a warm day, i guess i was thinking of the enrichments when it's cold outside. in that case do you think you would get AFRs near 10:1??

 

You car probably won't idle very well at stoich. Most rotary engines start to falter under idles leaner then about 13.8.

 

Hey me and my friend had that problem so we compensated by looking at your level of boost by that RPM and made corrections by adding fuel at the amount of pounds you hit by that RPM. The problem occurs because the secondaries haven't kicked on yet. They usually don't until around 3500 to 3800 RPM. The manual for the rtek 2.0 tells you this. I think the manual gives you a smaller range but this will help. I don't know if they are that informative with the 1.8.