Ok, I FINALLY got my Megasquirt installed. It seems that I have it wired up correctly (I think). I can plug my laptop in to it and fire up Megatune get values for RPM, MAP, CLT, IAT, etc....

However, It will only run for about 5-8 seconds, if you try to push the gas pedal, it chokes off and backfires. For the short time it does run, its VERY rough, loping idle

Specifics of my setup:

91 Miata
1.6L motor
Firmware version 029q
FUEL ONLY (at this point)
GM CLT and IAT

Here is my .Msq

http://members.***.net/dsmautox/mega...0607031716.msq

Any help is appreciated!

 

How much have you played with your VE table? Generally when an engine is backfiring, it is too lean. Are you using the stock injectors? My VE numbers are about 15% higher than yours on an all stock motor.

 

I had a look at your .msq (but I am running a different version of MSnSE and had 51 warnings so I may have seen a few scrambled settings).

I'm seeing your Required Fuel as 13.3. That looks a little high for a 1.6. Try something a little lower (say 13.0 and then maybe 12.7) and see if that helps.

I'm also seeing your acceleration/deceleration set up as running from the tps. Do you have a throttle body from a 1.6 automatic with the variable tps? The standard 1.6 throttle body has a tps that acts like a switch so having your car set to tps for accel/decel could make the MS freak out as there ain't no variable signal. You probably should try the mapdot settings instead.

Try those changes and see what happens.

You could still have some wiring issues that are causing your problems, but we can work on those later if none of the .msq fixes actually change anything.

 

Ok, I do not have the TPS input hooked up to the funky 1.6 TPS, its grounded. I will have a 0-5 TPS when I install my IRTB's. I didnt realize I had it set to TPS, I'll change that.

This is my first shot at the VE table, could you take a screen shot of your VE table for me?

Thanks guys for all the help, its greatly appreciated! I hope to be able to return the favor to others down the road. This has been a HUGE learning experience!

 

My fuel table is leaner than yours at low map/low rpms and my car goes just fine.

The fact that it's starting and running for a few seconds doesn't automatically mean that it is the VE table. The ASE settings will kick in for the first 20 to 30 seconds, then the warmup will kick in after that. Only once the car is warmed up will it be relying on the VE table.

Req Fuel plays a far more important part within the first 5 to 8 seconds than the VE table does....

 

Hmmm, now it wont start at all, except on the very first shot after sitting for awhile I also have a faint gas smell and some bitchin' backfires

Sounds like too much fuel, I backed ReqFuel down to 13, I may back it down somemore.

Thoughts?

 

That sounds like too much fuel.

Try setting your required fuel down to 12.7 and see how that goes.

 

I keep backing it down but it still does the same thing

 

Ok, what exactly is happening?

Is it starting easily?

Have you checked through your .msq to make sure that everything is consistent?

Have you wired up your injectors properly? (ie are they in the correct groupings?)

Try using my Cranking settings from the Settings Sticky (post #14) and see if they make any difference.

 

I hop into the car, hook up the laptop to the MS, turn the key "ON", wait for the beep from Megatune so that the MS is powered up. Turn the key to crank. It fires up the first time, idles for like 5-8 seconds, and dies. Then it wont even try to start again until I let it sit for 10-15 mins.

I have checked it and its as exactly like yours

On a whim, I switched the injector wires, same results.

I am using your settings.

While cranking with Megatune running, I get data for CLT, IAT, RPM, and MAP.

 

If it's starting ok then chances are your req fuel is ok, and your cranking settings are ok as well. 5 to 8 seconds is while the ASE is happening, and according to my scrambled view of your ASE settings, they seem to be fine as well.

One option could be to download MSLVV or MegaLogViewer from the msefi forum index and do a data log of one of your starts.

Do you still have the AFM connected? If it isn't jumper the two pins that I mentioned in my install to get the fuel pump working while ever the ignition is on.

 

AFM is still connected.

I will run a log on a start tomorrow.

Thanks for the help so far.

 

No probs at all mate.

Don't get down on yourself about the current situation. Your car starts FIRST go which is a hell of an achievement in itself.

You will get your car running reliably on the MS, these type of teething problems are something that everyone goes through.

Keep up the great work, and before you know it you'll wonder what all of the fuss was about!!!

 

If you PM me your email address, I can send you my .msq file if you're interested. I used Aussie's as a baseline and have worked from there. I have a 1.6 with a header, 230cc injectors, and am using the stock CTS, GM IAT sensor. I haven't spent a great deal of time tuning, but I really love the way it runs, I can't keep my foot out of it!

 

Thanks for the kind words. I was a bit down on myself yesterday, everyone always says that "Fuel is so easy".

Anyhoooo.... I went to msefi.com and looked at the sucess stories of Greg Salt and Nate Sully, both of them have their Req Fuel at 6.8. I may give that a shot when I get home from work.

 

I felt the same way. These guys say they struggled, yet the only posts of theirs I can find are like, "So I just put it in yesterday and it's running fuel and spark pretty well....." : ) No long posts like mine screaming "I MUST BE AN IDIOT!!!" Read my thread and see how long it took me to get to where you are! But OMG is it rewarding!

Anyway, 6-8 for required fuel? Guys, does that seem real low? That part of the manual did not seem very clear to me. I'm running 11.6 with a 1.6 with 230cc injectors.

 

Yeah, 6.8 for Req Fuel is way to low for a stock injection system. I'm almost certain that Nate is using DSM stuff which is why his is so different.

 

Alright, I double checked all my settings and fixed my VE table to match Aussie's EXACTLY. I also changed my Req Fuel to 11.6

No Change :( The first time I try to start it, it will start very briefly, then die. The it wont do anything but crank over for 10-15 mins.

Im gonna re-open the case and make sure I have everything jumpered right.

Here are some issues:

-I did NOT remove Q6 and Q8.
-My resistors for getting the CAS to read are the old 1K values

Im also gonna check to make sure I havent fried anything.

 

FWIW:
Doublecheck the board.. I may have had a similar problem, it turned out to be missing R57.

Nates using DSM 450's..

 

Ecugrad my car was doing the same thing. I would start for about 5 or 2 sec and then die. To fix this I ended up having to greatly increase the amount of fuel I was using. I was able to verify this was the correct answer because I also have a WB O2.

I could be wrong about you situation, but that is what worked for me.