Swede needs help to solve problem with hesitating engine

[Peppe]

Hi !

Feels a little lonely here in Sweden when I get problems with my Cerbera (1 of 3 in Sweden), so I hope You guys can help me out.

Having problems with the engine on hi rpms, around 5500 it feels as if the ignition starts to switch on and of every tenth of a second. The mil light flashes but there are no faultcodes logged by the ECU.

Have been trying to solve the problem by searching around in different posts, reading workshop manual and the manual for the ECU software, but I haven´t succeded to solve the problem yet.

I have done the following as a result of what I have found here on different posts:

1. New spark plugs
2. Set up of the engine with syncrometer and computer software, the engine runs much better now on idle and slow speeds
3. Put in a new crank sensor
4. Put a relay in to feed the ECU direct from the battery, had a voltage drop of about 0.5 to 1.0 volts betwwen the battery and the ECU before, now its down to 0.0 to 0.1
5. Cleaned all connectors I have found that has to do with the engine, are a lot of them everywhere in the car I think.

Here You have a screen shot of the software, it is between 96 and 108 seconds strange things happen:



As You can see, the ignition jumps between 12 and 45 degrees, the rpm readings jump between 250 and 5500 rpm:s and the injectors jump betweeen 5.2 and 16.3. Throttlepots, temperature and battery readings are steady.

Hope someone can help me out to solve the problem.

If anyone wants to have the file to look at it in the software, please give your mailadress and I will send the file to You.

[Peppe]

Hi !

Forgott to tell the the lambda sensors are also showing a steady reading when the hesitation occurs, 1.3 on bank one and 1.4 on bank two.

Please give me some advise.

[jensena]

Peppe - It's a shame that no one has offered any help to you yet, but now that I have answered at least your thread will get pushed back to the top and someone may notice it

All I can think is that the Ignition leads may be at fault, lets hope some one else can help, with only 3 cerbs in Sweden you need our help.

[Steve_T]

Based on what you say, I'd agree it could be HT leads or it could be the coil packs breaking down.

Steve.

[Nickccc]

Sounds like mine when I had a cracked manifold.
Did the machine gun thing around 5ooorpm with the MIL light coming on.
If the Mill light is coming on I thought it would flag a fault code up. mine was showing AFR.
Nick.

[Peppe]

Hi !

Thanks for Your advise.

Have just ordered new HT leads. Hope it helps.

[Peppe]

Hi again!!

Worked with the car for a couple of hours this evening, and guess what, now everything workes OK.
Found the following in the ECU software helptext:

CRANK SENSOR
This fault is shown if the crank sensor signal is poor.If it occurs the MIL lamp will NOT
be turned on. It may however flash as a poor signal is detected, depending on the severity of the fault.

Crank sensor fault can be caused by:
- Debris on end of crank sensor (remove and clean)
- Water ingress into sensor connector or wiring Corrosion on sensor terminals (clean or replace connector terminals using only gold plated terminals)
- Damaged trigger wheel on flywheel
- Damaged crank sensor wiring (replace ONLY WITH SPECIAL CRANK SENSOR WIRE)

I started to look at the sensor wire and couldn´t find any problems with it. Started to think a little about electronics and how You should place the wires in comparasion to each other. On my car (Speed Six) somebody has put the HT leads and the crank sensor wire together in same little space behind the engine. That is not a good way to do things if you want a clear signal from a sensor.
I have now moved the HT leads into another postion and everything workes OK.

It was a little scary to do the testdrive since it is wet on the roads here in Falun tonight. Had a couple of wheelspins even though I tried to take it easy.