Resets - or are they?!?

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itguy
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Resets - or are they?!?

Post by itguy »

Hi all

This is a bit of strange one really - bear with me.

Ok, I've got MS I v3.0 PCB running latest MSnS-E, fuel and sparks using ford edis4 coilpack via 2xVB921s.

Earths are to the engine block as well as direct to the battery.

MS log shows NO resets recorded.

When I'm driving the car with my MS connected to the laptop and I'm running MT with autotune and datalogging, if I stamp on the throttle it randomly resets (or thats what it seems like). The laptop bleeps like the MS has been disconnected and the engine stutters like its had a fuel/spark cut then comes to life again after 'spiking' my shift-lights (I presume a reset/initialisation routine).

Thing is, I can't think what would cause this as the earths are all good, and I'm using resistor plugs (as I've previously used no problems with a Lumenition ECU).

I've got the datalog here if its any use to anyone but it doesn't show the resets (if thats what they are) :(

My first thought was Dwell for the coilpack, and I've got it set to 4.6ms with 0.5ms minimum discharge period - however these figures are guess, anyone with anything concrete that works for my coilpack (Std Ford Zetec 1.8ltr EDIS4 coilpack pre 1998)

The only other thing I can think of is my plug leads - they are standard Motorcraft ones (came with the standard engine) - could they be leaking EMI somewhere?

Its certainly feels RPM / MAPdot / TPSdot dependant as I can drive the car for hours doing short-shifting using 50% throttle and no problems what so ever....

By the way, when it does have the problem stated above it usually lets out a massive bang from the exhaust (unburnt fuel I assume) sutters for about 2 seconds (during which TPS is 100%) and then it all comes back to life.

Any thoughts / suggestions would be fantastic, as my fuel / ign maps are really starting to take shape now and the car is feeling fantastic apart from this irritation!

Thanks

Will
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Post by TV Super Bee »

You have a reset problem! It can be caused by many things. I had a reset problem too. I was getting spikes on my tach input. to solve this I had to remove XG1/XG2 jumper, run a wire from XG1 to pin 6 (tach shield) and then ground the shield near the distributor. If you already grounded the shield...you have created a ground loop as the shield IS grounded at the db37 connector. This loop could also be your problem. You can also try the "dave cap" this will also reduce tach spikes. These are olny some remidies and certainly not all the causes. The jumper wire worked best for me. Good luck
1969 Dodge Super Bee
383 EFI dual 65mm throttle bodies, 36lb injectors
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itguy
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Post by itguy »

Ok, I'll start paying attention to the grounding stuff again.

I can't understand why they aren't showing up in the log as resets though??

Jus to be clear, when you talk about the 'shield' are you talking about the wire shield on my two-core cable to the VR pickup sensor?

If so, then my shield is NOT grounded at either end at the moment, I'm using some low-loss / high insulate microphone cable with twin cores / individually screened from VR sensor to two inputs on MS. - Are you suggesting that I connect the shield to the -ve VR on the DB37 and then earth then other end at the block?

XG1/XG2 jumper - need to get the build manual back out again to check out what is being suggested here
TV Super Bee
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Post by TV Super Bee »

XG1/XG2 jumper supplies ground to the opto isolator. By using a jumper to pin 6 and grounding pin 6, you send a seporate groung to the opto isolator. This mod can help with spikes. Have you looked for resets with the data log viewer? They will show up as a vertical red line accross the screen. If you do have a tach spike you should be able to see it in excell in the tach collum. I would deffinetly ground your twin-ax shield. Ground it to the same place as the ecu. All grounds for all your sensors should also come from this same spot. I would watch out with grounding at the engine AND the battery at the same time. If your exhisting engine ground has more resistance than MS, the MS ground will start providing ground for your spark plugs. I would ground the ecu to a bare metal part of the body of chassis. Then send a new ground wire, 8 gauge or larger from the battery to the engine block and to the chassis. If you run a MSD or other type of CD Ignition, route your MS wiring away from the MSD box and coil. I hope this helps.
1969 Dodge Super Bee
383 EFI dual 65mm throttle bodies, 36lb injectors
"AS SEEN ON TV"
www.moparalley.org/gallery/hollywood
itguy
Helpful MS/Extra'er
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Joined: Thu Aug 12, 2004 11:03 am

Post by itguy »

Hi there

I'm using the VR trigger (36-1 wheel) so does the XG1/XG2 still apply? I didn't think it did?

I don't have any tach spikes in my log file, thats the weird thing.

I'm also now wondering if this could be something to do with PWM on my low-impedance injectors as it only seems to occur when the duty cycle is high...

Will
itguy
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Post by itguy »

Ok, I've now grounded the shield in the VR sensor cable, no joy

It actually now appears that its not just limited to high revs, but also can be replicated by large TPSdot from almost any revs. I can replicate the resets by just sitting with the car in my garage.

Grounding for the MS / VR sensor are all to a central bolt that has then a medium sized wire straight back to the battery - no other earth connections.

Can't do bodywork connections at this is a fibreglass body..

I think I'm going to try some new plug leads next, maybe some new plugs too, even though my current ones are correct (resistor type), they are of unknown age.

I know I should'nt get frustrated but this is really taking the shine of a great first MS experience!!
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Post by jsmcortina »

I've had similar to that with incorrect accel enrichment. If I was sitting at a junction at idle and stomped on the pedal misfire,reset, pop, bang off we go.
With AE tuning the problem has gone -I forget when it last happened.

With Ford coilpacks and VB921 I have my dwell set at:
6.0 crank
3.5 run (maybe a little higher than needed)
0.1 min discharge

Note that dwell numbers in MS1/Extra will not always correspond to MS2 dwell numbers due to calculation and implemetation differences.

James
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itguy
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Post by itguy »

Very interesting - I wonder why incorrect AE would cause a reset?!??

Anyway, I'll be back out there this PM to try some more things - got some new plugs / leads to try too but I'll try tuning the AE first :)
itguy
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Post by itguy »

Been out for another run.

New plugs - no difference
New plug leads - no difference

Ok, tried some AE tuning and did'nt really make any difference until I set the TPSdot threshold to 25.5v/s to switch it all off and then it would reset nearly every time I tried to snap the engine into revving. Switched it all back on again and altered the settings a bit, not reseting quite as much as with it switched off but its still there.

From then I saw where I could predictably get the unit to reset and when it jumps to 95kpa @ 2500rpm, so I decided to weaken the mixture on the map a bit there and see what happend. Did this and make it obviously too weak (18-19afr) but loads of resets. When I ramped it back up again, less resets.

So - is it possible that the MS can reset when it misfires due to incorrect mixture settings? If so, I wonder if thats whats happening to me???

Will
itguy
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Post by itguy »

Ok, sorted it (I think).

Didn't have the 330ohm resistor in the supply line to either of my VB921's.

Fitted it, now don't get resets - just been out for a very pleasurable 1/2hr drive and try as I might I couldn't get it to reset - stamping on the throttle everywhere in the rev range, its now a REAL pleasure!

Ok, that problem down, now onto setting up the ICV and knock sensor :)

Thanks for all your help - I'm now a VERY happy man!
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