Sudden tach dropout when getting boost.

[Thelittlefatguy]

Hi everybody!

I have a volvo 240 with a B23E+T+MS2 v3.57
I MS'ed the car about 6 months ago, and the car has driven perfectly until about a month ago. I was experiencing like hitting the revlimter at about 5200-5400 RPM while my limiter was set at about 6000 RPM.
Now the car stall comeplely when i get boost, about 2400-2500 RPM, and then the car "Reboots" a second or 2 later.
Looking at my log, there is a complete dropout in RPM, reboots, then dropouts again, then reboots again, and my AFR gauge starts the heating procedure agains.
Looking at my oscilloscope, there is no sudden loss of signal after the VR conditioner circuit ( measured at VRout J1 jumper).
I'm using a new stock VR sensor btw.
Thanks in advance!
Log attached.
Feel free to answer in swedish.

[Erikk]

Störningar från tändsystem kanske? Utslitna tänddetaljer, rotor fördelarlock, tändkablar, stift? Kan ju vara helt vanliga slitdelar som felar

[Johan Lindberg]

Can't read the figures on the small pic but, are you running high boost and/or rich? sounds like the spark blows out. Try smaller gap on the sparkplugs, I run 0.35-0.4mm on mine. And of course check ignitionwires and the distributor

[Thelittlefatguy]

Störningar från tändsystem kanske? Utslitna tänddetaljer, rotor fördelarlock, tändkablar, stift? Kan ju vara helt vanliga slitdelar som felar

It's worth a shot.

[Thelittlefatguy]

Can't read the figures on the small pic but, are you running high boost and/or rich? sounds like the spark blows out. Try smaller gap on the sparkplugs, I run 0.35-0.4mm on mine. And of course check ignitionwires and the distributor

The gap is fine. I'll fix another photo.
0.8 bar is full boost.

[Thelittlefatguy]

I cant get the picture better.
Check out my post on msextra:
http://www.msextra.com/forums/viewtopic ... 411da02c4f" onclick="window.open(this.href);return false;

[Thelittlefatguy]

I've uploaded a log on msextra.
Use the same link as above

[Johan Lindberg]

is the afr meter connected to the MS? The afr looks rocksteady around 14.6? (except when the cut is) but at that boost, 0.5bar in the log. you should run a little bit richer, right? Way to lean gets that kind of cut, just thinking if it is broken and doesn't show a sudden leaning due to some fault in the fuelsystem, bad pump, filter etc.

[Thelittlefatguy]

Yes it is connected. That depends on how much pedal i give during boost.
I''m still tuning the bottom of my VE table.
At full boost ( 0.8 bar) and 100 % TPS, my AFR is about 12-12.5

[youask]

We had problems of that kind using 60-2 triggers and ms2. Went back to ms1 and the problems disappered

[Thelittlefatguy]

Changed from Falling to Rising egde. No problem now.
But we have about 20-30 cm snow here atm., so i cant floor on a long road, which mean i cant get over 0.5 bar without going completely sideways.
I'll update when i find an open road.
One thing i dont understand is that, the last 6 month i driven the car perfectly, on falling edge.
Why first misbehave now, if thats just it?

[Benny Steen]

I had the same problem. I'm using coil on plugs, bosch 115R and have no sparkplug wires.

After changing the sparkplugs to resistor type, in my case to NGK BCR8ES the problem disappeared.

/b

[Thelittlefatguy]

It's funny. I tried to move the the jumper from J1 3-4 to J1 5-6 inverted signal , and the problem came back.
So changed back to J1 3-4.
I know it's not the solution, but a least it's running.

[Thelittlefatguy]

I had the same problem. I'm using coil on plugs, bosch 115R and have no sparkplug wires.

After changing the sparkplugs to resistor type, in my case to NGK BCR8ES the problem disappeared.

/b

But i'm not using COP.
Spark plug is new stock for 244 TIC
My destributer cap is a new OEM and wires OEM, and bought last summer