pcmhacking.net

Please help determine fault.
On the log it looks like this: There are sharp jumps in RPM, KPH, VE.
It is sometimes strong stumbles occur, and sometimes not.
Is this a problem in hardware or software?
Where to look and what to check?

I'd start off with checking whatever you are using for engine speed, be it distributor, crank sensor etc.
It looks like the spike in rpm causing the ECU to look in a different cell of the VE table and than calculate fuel incorrectly. Can see a change in the injector duty cycle that lines up with rpm spike.
Starting point would be to check all connections are good and wiring not damaged, then start looking at ignition module.

Ive seen similar from bad ecu too. Once youve checked wiring etc i'd try another computer. You could test on a stock computer without comms or write wire installed with a memcal or if you write protect the nvram before moving it around and leave it protected. If it feels better then do it properly for logs.

yoda69,antus thanks for answers

But how then to explain the jumps KpH (purple line)?

Generally, it is necessary to check all - wiring, ECU, sensors...

Speed looks OK in first trace but definitely a problem on the second one.
Do you have good ground points and power to ECU as it appears to be an intermittent fault.
If all the wiring is good I think Antus is onto something with a faulty ECU.
What vehicle is it in, standard wiring or a retrofit to something?
Is ECU an 808 with COMs board or a later model ECU?

This is a standard ECU and wiring Opel Astra (European counterpart Holden Astra 1600 TBI, ECU 808). Just added MAT-sensor, bin is a $12P 111.
Ignition of the ECU is not in use, working stock (sensor - commutator -distributor).
COMs board like this:
http://pcmhacking.net/forums/viewtopic. ... 957#p58957
The coming weekend will be all checked.
Another problem - some stumbles with increasing speed.
Also, I try to make NVRAM.
My posts:
http://pcmhacking.net/forums/viewtopic. ... 287#p65287
http://pcmhacking.net/forums/viewtopic. ... 055#p67055