Adz9

Hey guys,

im currently running a FM2 kit on my 98 NB with MS2E and 650cc injectors. It has been driving perfectly for the last 500 miles or so but has recently started to intermittently cut out under boost.

This is not like fuel cut, the car dies completely as if someone has turned the ignition. Obv this isnt good for the turbo at all as its running full pelt then having its oil supply cut when it cuts out.

Any ideas? A few people have mentioned coil pack?

Schuyler

iTrader: (1)

Overboost protection?

edit: What engine management are you running?

codrus

The oil pump is a mechanical pump driven by the crankshaft, the only way it stops is if the engine stops. When it cuts out under boost, the engine is still turning because it's still linked to the wheels by the transmission, so your turbo is still getting oil.

There are two coil packs, each driving two cylinders. It's unlikely that both would fail intermittently at the same time, so if you're losing *all* power (and not just half of it) then that's probably not the cause. Datalog the car when it happens and see what the boost level is showing. If it's higher than the configured max boost, then the ECU is probably shutting off the fuel to the injectors for safety. If the boost level looks normal on the datalog, then it's probably a loose connection somewhere, check your grounds.

--Ian

18psi

iTrader: (76)

it could be a cam or crank sensor, it could be the coils, or possibly even bad connection or wire

pdexta

iTrader: (17)

Early NB's are notorious for weak coilpacks and the first symptom you'll see is spark blowout in boost, but that usually feels similar to fuel cut. If you suspect that may be the issue you can decrease the gap on your spark plugs and it should improve the issue.

When you say the car is cutting out, are you losing power to accessories or is the car just stumbling? Does the radio cut out? If it does make sure your battery terminals are clean and tightened.

Adz9

Thanks for all the replies guys! I'm running MS2 Enhanced and have taken it out for a datalogging session.However Tunerstudio seems to loose sync with MS any time I get up I the revs. Will try again with no USB Extension on the serial cable.

It feels just like fuel cut when it happens, but the engine stops completely. I have to dip the clutch to restart it as I'm rolling. Boost gauge doesn't seem to push past 1bar and the limit is set at 240 in Megasquirt. The coil is boiling when you open the bonnet so I might look at relocating that somewhere cooler on longer HT leads.

Adz9

Earths and crank sensors are good calls too guys. I'll investigate! Is there any way to diagnose the crank sensor?

codrus

Why do you need to dip the clutch? Key off/key on doesn't get it running again while rolling?

The fact that TS loses sync makes me more suspicious of a loose ground. Check the ground on the front of the intake manifold -- mine was loose once, and it behaved in a similarly bizarre fashion, the Hydra would cut in and out at higher revs as the vibration make the ground come and go.

--Ian

Adz9

Hey Ian,

Thanks for your reply! Sorry mine is so late, work is mental!

I have a day on the car tomorrow so plan to check all earths etc. In regards to clutch dipping, once the car has effectively stalled at high RPM its the only way to restart it. Dip the clutch and turn the key. Restarting it in gear is impossible as the starter motor would have to turn an engine already turning...

EO2K

iTrader: (37)

I think Ian was saying that you should be able to turn the key from "ON" to "OFF" to "ON" to get it to go. That will effectively powercycle your ECU. Turning the key through "ON" to "START" will result in wailing and gnashing of teeth complaints from your starter if you are already in motion.

What dwell settings are you using in the ECU?

This thread needs moar logs (hint, hint)

Adz9

Ah I see what you mean! That's why I've been coasting clutch down which stops the engine spinning and allows me to turn to 'START'.

I wilk try to log more today but last time the ECU kept going 'offline' when revs got above 4k, then coming back online.

s2k_adz

Well, it's done it 5 times today and its normally at full throttle but its starting to do it at lower revs (around 5k).

I also managed to get a data log on it, though Im not sure how much help it is. You guys were right, just turning the key back to the on position restarts the car, no need to dip the clutch.

How do I post a log file?

Schuyler

iTrader: (1)

Make sure it's less than 4.81mb.

s2k_adz

You are a legend, thank you very much bud!

Should be two logs attached. It did it in both.

s2k_adz

Think I might try and get hold of some second hand sensors. Look at changing the cam, crank and coils.

Does anyone have a wiring diagram of where all the main earths are? I've checked all the obvious ones.

Adz9

Can you see anything out of the ordinary on the logs guys?

Onyxyth

iTrader: (2)

Logs are way too short to see anything. I would try getting longer ones.

s2k_adz

Still got this bloody issue guys.

Specialist has had the car 2 months. MS2 ECU was sent and reflashed and it still does the same. COT plug conversion is happening on Monday.

Does anyone think it could be MAF related? The speciallist is sure its an ECU issue as when the car cuts out, power remains on the lines to the Megasquirt but its powered off apparently.

SJP0tato

iTrader: (7)

I had something similar happen to mine shortly after installing my MS. It turned out one of the connectors wasn't tightened on all the way, and in certain scenarios would come loose just enough to cause the ecu to lose all power for 1/2 second at a time. Check that your connectors are firmly seated and the hardware is fully tightened.

sixshooter

iTrader: (12)

What are you spark plug gaps set to? If they are more that .028, gap them down.

Weak coils that aren't quite dead will have trouble under boost. So will good coils if the gap is too large or has grown too large due to normal spark plug tip erosion over time.