I've had an issue for the past few days thats only seem to have gotten worse. At first it was warm starting, it really didn't want to start up warm, where prior to my MS install it would fire up right away, as it did for the very begining of have the MS installed. Now it is down right difficult to get started. I am wondering if this could be bad plugs ? I've just replaced my fuel pump and my fuel seems to be good. I did flood it a couple times during the MS install on my current plugs is it possible they've gone bad ? I raced on these plugs last weekend is it possible running them with too much boost has caused the to die ? I was working on my front mount intercooler yesterday and when I went to start the car after sitting for 6 hours it wouldn't fire, not even stumble.. very simular to being flooded but after cranking with my foot to the floor it started.

I know this isn't really an MS question per say, but im wondering if my cranking settings could be an issue here. Or if it is a tuneup issue, the odd part is that it seems to have been a progressive problem that is now to the point of being very bad.

Sean.

 

it could be any or all of the things you mentioned... although the fact that it started with your foot on the floor makes me think you're flooding the engine somehow.

if you used my cranking settings on a TII, that could be part of the problem... as those settings assumed smaller injectors.

 

Could the minor flooding during starting cause the plugs to fail over a 2 week period ? Also how much should I lower the settings since I am using your figures for your 460cc ? n/a injectors.

 

From my experience with MSing a rotary - work the cranking, ASE, etc., from the lean side up. You can always add fuel to a too-lean start situation without hurting anything. High load VE bins should be (IMO) worked from the rich side down. If you're fully warmed up (as you should be) and venturing into high load areas you're unlikely to foul a plug. Logging is your friend and don't make the mistake of mistaking a rich misfire as a lean misfire, as the WB systems will report due to the excess O2 in the exhaust. In my experience, when you rich-foul a plug it's done and needs to be replaced. I've chased my tail several times chasing wierd problems until realizing that a new set of plugs cured the problem. Of course, YMMV! (literally...)

-Mike

 

460/whatever your injectors are. Ex: 920cc injectors (twice that of the 460s) would work out to 460/920 - or .5 the original values. This assumes that your opening time is in the ballpark. .8-1.0 ms works OK for Mazda injectors in my experience.

-Mike

 

I adjusted my cranking settings to .84 of what muy had for his example and its starts better, I still suspect my plugs need replacing but making these adjustments definetly helped.

 

I've replaced my plugs and still hard start, now I noticed yesterday the first time driving since the weekend and noticing the hard starting that I'm getting knock at low boost? I haven't changed a thing settings wise in MS. What seems odd to me is when the knock occurs 20 - 30 kpa my AFR's are very rich so it would appear its not leaning out how can I distinguish between a lean and rich misfire ? Im not getting misfire persay but definit knock. I am starting to suspect my fuel pump as I bought it 2nd hand.

 

There is definetly something wrong, I am going to pull my UIM and look at my FPR and injector seals, also going to put my old fuel pump back in and go from there.

 

it appears now that my knock problem is being caused maybe by a short, as its intermittent. One minute I can run up to max boost, the next knock at low boost. I am going to change out my fuel pump today and see what that does, then start looking at my injector connections.

 

if your AFR looks good, then the fuel pump shouldn't be what's causing your problem.

I'd look around at the ignition side of things. Maybe some noise on the CAS signal? That can cause both hard starting and knock.

 

also, keep in mind that you can't always see this kind of noise in the datalog.

On the ae86 with the 20v 4age, I've got some tach noise that happens at 6800 rpms on the dot every time (caused by electrical noise from something turning on or off... probably VVT, I'll have it fixed tonight weather permitting, but that's beside the point). Sometimes if it's really bad, I get a nasty spike or dropout of the tach signal, but often even though I feel an ignition miss, nothing shows up in the datalog at all.

 

what gets me is how intermittent it is, if I run throught the gears, the first run is OK, then the next has the knock. I don't see any tach noise in MT the tach seems steady and my datalogs show steady rpm's. What is the best way to try to identify the noise ? should my sheilding on my CAS line be grounded on either end ?

 

no, the shielding should be grounded at one end only.

I'm not saying your problem is definitely noise. I'm saying it's something to consider.

Like I said, It might not actually show up anywhere.

It could also be an intermittantly bad plug wire somewhere, or your leading coil doing something weird.... All I'm saying is that if the MS is causing knock, the source will be some kind of electrical noise.

You might try adjusting the hysteresis potentiometer on the megasquirt board, and if you're using error*'s board for the second trigger lm1815 circuit, turn the potentiometer there too.

The VR sensor conditioners are very sensitive to noise, and like I said, it won't always show up in the datalog (usually only shows there if you get really bad spikes).

The reason noise can cause knock is because noise will cause the MS to count more teeth than there are, and count them sooner than they should be... meaning it times its sparks too soon, causing too much advance intermittantly.

You only hear knock under load or boost (NA or Turbo) because this kind of thing will just cause misfires at lower loads... you probably wouldn't even notice them.

 

I hear you, my wires are 2 weeks old NGK, plugs are new as of Tuesday. I don't see any tach spikes, but i've been having problems with my trailing ignitor I think my LED16 ? may be on the way out, its been behaving strangly, it will go dim but if you move it will go bright again, ive resoldered all the connections and its been fine for the past few days. Im using the proto area for my 2nd VR. Is there any method you suggest to adjusting the pot ? Like I said I can't see any tach spikes, I thought I had them all out when I redid all my grounds and replaced my CAS cables. My CAS is NOT grounded on either end but up until last weekend I noticed nothing wrong with how the ms was running. I will check my wiring today and see if I can find anything out of place, other than that I can try adjusting the pot but without knowing what to look for while adjusting them if there is no obvious noise present im somewhat stuck there.

 

first, I'd suggest grounding the CAS wire shield to the MS... only on one end. That could very well be the source of any noise you might be seeing.

Only adjust the hysteresis pot... it's the one closer to the bottom.

Just keep adjusting it clockwise... if your tach signal starts getting intermittant, adjust it back the other way a little, and call it a day. If you shut the car down after adjusting it, and can't get it started again, adjust it back counterclockwise again until you get a stable signal on cranking.

Sometimes noise won't cause the tach to spike either depending on how it happens, and what conditioner is picking it up. Noise on the G sensor or wires will show up as nasty tach spikes, but noise on Ne might not show up at all... The lm1815 has built-in adaptive sensing, so it's pretty good about throwing out any random noise, but the built-in vr sensor conditioner needs to be manually adjusted to filter noise.

Ken