what went wrong?

[viper11]

hi
I just got my charger running again with its new forged 440 twin turbo, (have a couple header gasket leaks to sort)
I have the ms1 v3 extra 29y4, I was tuning the car in my driveway in park with no load using autotune at different rpms to get my ballparks again (it was running last year and my msq is pretty close ) brought it upto about 4000rpm and the autotune was doing a good job of smoothing everything out and all of a sudden it started misfiring on one cylinder (completely dead) as i reduced the rpm it slowly caused it to stall
I tried to restart it to see if it would clear up but it wouldn't quite start, after cranking and cranking there was a huge backfire that was extremely loud
I let the car sit for a few minutes and tried again but I could barely get it started and keep it running. its misfiring, popping and clattering. I had a hell off a time getting it up the driveway into my shop, it sounds awful, not to metallic, but not all exhaust leak either.
it takes 20-30 seconds of turning over the get it to start and i can only keep it running for 2-3 seconds, all the header pipes feel warm indicating fuel and spark

where should I look for answers? it went from 1 dead cylinder to not running at all, what could cause this???
I will do a compression test first then pull the valve covers witch takes 3 hrs cause of all the piping
thanks for anyones input (I know this might not be the ms but someone may have an idea)
I will be testing the ms with my stim too
jason

[camcojb]

Originally Posted by viper11

I have the ms1 v3 extra 29y4.

what system is this? If it's not a mechanical issue then it's in the computer programming/wiring. I have never heard of the above system. Is it laptop programmable or self-tuning?

Originally Posted by viper11

I will be testing the ms with my stim too

What is this................... maybe again in English?

Too many abbreviations.................. I thought I knew efi lingo but you've got me so lost...........

Jody

[viper11]

sorry megasquirt v3 extra is the model and 29y4 is the build code
stim is the stimulator to duplicate the motor
jason

[camcojb]

Originally Posted by viper11

sorry megasquirt v3 extra is the model and 29y4 is the build code
stim is the stimulator to duplicate the motor
jason

I've used several different efi systems, but not that one. It sounds like a mechanical issue, unless the tuning software "self-tuned" itself completely incorrectly. Not a big fan of self-tuning, prefer to make the changes myself through datalogging.

Will this software let you tune? Does it have a a dash feature that shows you what your timing, pulse-width, a/f, etc. is while it's running?

Jody

[viper11]

hi
this is completely programmable by laptop with everything displayed and adjustable
my tune is very close but the autotune tweaks the fuel tables to match my preset a/f targets it is restricted to 5-10% max
everthing was going good then all of a sudden one cylinder went dead like a dead plug now I can't even start it
jason

[adynes]

I have the same computer on my car. I'm using 36# Bosch design III injectors, and I think they need a cleaning. The base tune was way too rich while trying to fire the engine for the first time, and the plugs fouled. The engine sounded much like the symptoms you describe. After changing the plugs and getting the fuel within range, it ran fine. Then, after adding spark control, I had similar problems, but I think this time the problem is a noisy tach signal, because when I disabled spark control (defaults to the base setting) it cleared up. I haven't messed with it since do to other work being done (paint, turbos, etc).

Have you checked the plugs yet? If that's not it, maybe check your ignition signal wiring for problems, or maybe the computer ground. Good luck.

[ohcbird]

Are you sure that you are 100% mechanically correct? Have you:

1. verified your timing order/plug wires
2. set base timing
3. verified your plug gaps & plug integrity
4. verified fuel pressure during all phases
5. Etc...

Given your 10% correction limit, did you see (or log) which way your WB was pushing? I'd do some solid fuel calculations before trying autotune. I agree w/Jody; I'm NOT a big fan of any autotune feature, as most of the time you'll get a real fat (rich) map. I definitiely wouldn't use it on my twin-turbo'd motor, as tuning for a specific A/FR doesn't do anything for driveability.

[viper11]

hi
since this I have narrowed my problem down, with the distributor removed and fuel pump fuse out I can hear the injectors clicking in time with the vr signal so my distributor vr signal is good
the problem is my spark is very intermittent, 1 out of every 3-4 injector pulses sometimes 7-8, I swapped coils and no difference so its either the ms or the msd6a or between the two.(remember it was running fine last year and earlier this week.
on the stim the ms performs flawlesly with the led's flashing and megatune confirms smooth operation
so how can i check the output signal from the ms to the msd??
how can I check the msd output??
jason

[viper11]

ok the tests and results so far
the msd performs flawlessly when the white wire is grounded(or ungrounded) even when i flick it as fast as possible,it has a nice fat spark at the spare plug.
the coil is good,(verified with a second coil).
the injectors click in time with me spinning my spare distributor, by hand plugged in with the fuel pump fuse out,(indicating the ms is receiving the vr signal) but the spark is very random and weak.
the ign on the stimulator works and flashes perfectly in sync with the rpm,
dwell is set to 50% fixed,
both pots are fully anti-clockwise.and tried2 and 4 turns clockwise
tsel to vroutinv.
sheilded vr wires. all wiring checked and was working fine
all grounds to engine block including msd.
was running and suddenly started by losing 1 cylinder spark.
is there anything I am missing?? if my vb921 was faulty would the stim work??
jason