Can't get past 2500 rpm

[AlanJ]

Okay, now offering $100 gift card to a place of their choosing to the person who solves this problem.

[billr]

Where are you located? There may be a member nearby willing to help, even without the bribe.

[AlanJ]

Where are you located? There may be a member nearby willing to help, even without the bribe.

Phoenix, AZ lol I have called everywhere. None of the speed shops so far even know what this mega squirt thing is....

[AlanJ]

Okay, transistors Q12 and Q9 exploded. Literally.... What circuits do these control. " active flyback" is all I can find.

[slow_hemi6]

Like I said, I didn't even know how you were driving your tach, when I opened your msq the curve values were trash.
Those transistors are flyback damping circuits for the mainboard injector drivers. What are you using high Z injectors or low Z injectors? Those should only be active or "in use" with low Z injectors and PWM control.
Edit.
I just looked at your msq again and you are using INJ1 for alternator control. and nothing on INJ2. Not really sure how both could have been taken out??? Did you build your board? Were the tabs insulated from the heatsink?

[AlanJ]

I tried the alternator on both inj1 and inj2 and neither worked correctly. So I went back to the stock control box. I thought I found the problem.....

With all the setting changes and such the issue has moved to the engine dieing like a rev limit only under moderate and high map values. I can't recreate the issue while sitting in the driveway unless I mash the pedal....

I'm really not sure what the difference is between high z and low z injectors. I have the msx controlling them directly. I just realized I skipped over that part of the troubleshooting....

[slow_hemi6]

you just measure the injectors with an ohm meter. Disconnect the plug and meter across the 2 injector pins. 2 or less ohms is lowZ and 10 or more is high z. MS3 drivers are only good at driving highZ. If you have lowZ you need to have resistors in line with each injector or Peak and Hold boards.

[AlanJ]

Just checked all the injectors, they are all between 28 and 35. I thought I might have a shorted one.... Sorry ADHD moment.... That was not the problem

[billr]

You are saying all injectors are in the 28-35 ohm range? I think that is fairly unusual, I have never heard of any with that high of a coil resistance. Do your meter leads "zero" when clipped together?

[bobdion]

i had the same problem (it was cutting at 4000 rpm ) and i was able to fix it by adjusting the 2 pod r56 and r52 to lower the voltage at r54

[AlanJ]

Okay, narrowed down the problem. The injectors are high z injectors but the maximum pulse width the ms will send is 8ms to 10ms. Anything more than that seams to be truncated. Is this the circuit cutting out due to power draw or is this the injectors drawing more than the ms can put out? I found this by using a oscilloscope while full throttle. The PW only gets so big. Isn't it supposed to fire twice if it can't get it all in one shot?

[AlanJ]

i had the same problem (it was cutting at 4000 rpm ) and i was able to fix it by adjusting the 2 pod r56 and r52 to lower the voltage at r54

Did you show sync loss before the mods? I don't have any sync loss even when forcing high rpm by downshifting...

[AlanJ]

You are saying all injectors are in the 28-35 ohm range? I think that is fairly unusual, I have never heard of any with that high of a coil resistance. Do your meter leads "zero" when clipped together?

Yes, it reads 0. I ordered a new set of injectors. This time a new and not refurbished set. The original injectors are 18 ohm. Second set is 4. This set is 30.( Average for all in the set) can or has the msx been damaged by these injectors?

Edit*** I'm ordering my 4th set. The resistance is just all over the place on these last junkyard, eBay sets...

[billr]

I don't think the MS3X drivers got hurt connecting to the low-Z, the drivers are probably well-protected. MS can output injector pulses up to 65 msec, that 8-10 limit is something else; maybe even the "protection" shutting the drivers off... Let's wait until you have a decent set of (high-Z) injectors and see how they behave.

[bobdion]

i had the same problem (it was cutting at 4000 rpm ) and i was able to fix it by adjusting the 2 pod r56 and r52 to lower the voltage at r54

Did you show sync loss before the mods? I don't have any sync loss even when forcing high rpm by downshifting...

no sync loss it was cutting like a rev limiter the engine was pulling hard and cutting at 4000 rpm

[AlanJ]

Okay, readjusted pots. Sense (bottom one) is one turn CW. Histerics (one in the center of the board) is all the way ccw. There is no change. It's based on pulse width I have noticed. I can get it to do it at a lower rpm by increasing the values in the ve table.

New injectors installed all are within 13 ohms. They are 21lbs injectors. The lowest is 13.2 ohm the highest is 13.8 . still no change. I am looking for resistors for them just to see if that works.

I have confirmed the spark is okay, the timing light I have can't flash at high rpm. The oscilloscope shows its sending a negative pulse out of the ms. It's pretty regular. However the injectors are dropping out.

The injector pulse gets so wide then dropped off (pulse missing). I'm at a loss.... I replaced all the major transistors on the heatsink now with no change. I'm limited on things I can try.

Anyone with a jimstim near here (Phoenix) I can borrow. I'm out of money now until next paycheck. Those injectors cost me a little over 700.

I am trying to get my buddy over to drive for me so I can play with the scope some more. It's a hand held one and has too small a screen to use while driving. I will post new tune and log files tomorrow. I have had all the disappointment I can take today.....

Is there an error in the ms hardware or are my injectors too close to the cut off for high z injectors? Is there a place I can test on the msx to tell if the protection circuit is kicking in? Could it be voltage spikes from the injectors coming back through the ms? Causing it to shut off?

[AlanJ]

New log and tune files.

Please notice the max pulse width in the log files. What causes that?

[billr]

I'm going to post two replies, first the simple one:

What about the PW is concerning you? Identify a specific time in that most recent log for us to discuss, and explain why the PW is an issue (at that specific time).

[billr]

My comments are in blue...

Okay, readjusted pots. Sense (bottom one) is one turn CW. Histerics (one in the center of the board) is all the way ccw. There is no change. It's based on pulse width I have noticed. I can get it to do it at a lower rpm by increasing the values in the ve table. I assume this is a Hall sensor, since it is from DIY, so set the pots per the directions and then leave them alone. You can use either the "full CCW and then back CW x turns" method or measure voltage for that one pot. However, you don't seem to have sync problems, so why are the pots being fussed with? Also, the pots have nothing to do with PW of anything, why was that mentioned?

New injectors installed all are within 13 ohms. They are 21lbs injectors. The lowest is 13.2 ohm the highest is 13.8 . still no change. I am looking for resistors for them just to see if that works. Don't add series resistors if you have high-Z injectors, that will hurt your efforts and confuse things even more.

I have confirmed the spark is okay, the timing light I have can't flash at high rpm. The oscilloscope shows its sending a negative pulse out of the ms. It's pretty regular. However the injectors are dropping out. High rpm??? You are still trying to get up past 3000 or so, correct? A good light should go well past that. Mine (which was a cheapie "back in the day") can be used from cranking speed right up to my 6400 rpm rev limit, maybe past that... If you are going to fuss with spark-ignited engine, whether EFI/DIS or carb/dizzy-points, a reliable timing light is going to be one of your prime tools. Get a decent one and move past any wonderment about the spark timing.

The injector pulse gets so wide then dropped off (pulse missing). I'm at a loss.... I replaced all the major transistors on the heatsink now with no change. I'm limited on things I can try. I admit I didn't study every instant of that recent log posted (waiting for response to my previous reply), but don't recall seeing injector PW "missing". If you are in doubt about the MX3X drivers, then do some temporary wiring and switch over to bank-firing the injectors from the mainboard drivers. The engine should be able to run quite well on those two "standard" drivers.

Anyone with a jimstim near here (Phoenix) I can borrow. I'm out of money now until next paycheck. Those injectors cost me a little over 700.

I am trying to get my buddy over to drive for me so I can play with the scope some more. It's a hand held one and has too small a screen to use while driving. I will post new tune and log files tomorrow. I have had all the disappointment I can take today..... By all means, have somebody else go ever things with you. Explain everything you have and have done in the install. You need a "fresh set of eyes" on this.

Is there an error in the ms hardware or are my injectors too close to the cut off for high z injectors? Is there a place I can test on the msx to tell if the protection circuit is kicking in? Could it be voltage spikes from the injectors coming back through the ms? Causing it to shut off? What is "shutting off"? I saw no signs of the MS resetting.

[AlanJ]

I'm going to post two replies, first the simple one:

What about the PW is concerning you? Identify a specific time in that most recent log for us to discuss, and explain why the PW is an issue (at that specific time).

899.358s is the part in question. The RPM increases the fuel table values increase but the pulse width does not. Maxing at 18.68

However it spikes huge at 895.124 it spikes to 23ms.

I adjusted the vr pots because people here said that could cause the rev limit. Even said there would be no sync loss. I'm still just guessing as to the cause of the issue. Starting at 899.358s it begins to missfire.

My tools are limited and quite frankly I'm going without a clear path. Every time I think I narrow it down it turns out not to be true. My next idea is throw a carb on it and see if it misses. I literally can not tell witch drops out anymore. If any. It just starts to miss at high loads and over 3k rpm. Very light pedal will pass 3k reving in neutral goes past 3k now. (Didn't before) but in gear with a load will not go past 3k. If forced by downshifting it's as if everything is shut off until it drops below 3k.