456M Motronic (?) problem

During my short ownership, I've three times now asked my wife if she wanted to drive with me in my "new" car. Every time I had to cancel it because it doesn't run well or have a (Slow Down) warning. She's not very impressed I think...

Status: If often runs fine, this is an intermittent error. Either at starting or during a drive, it seems one bank suddenly doesn't contribute, I need to push accelerator down a lot more to more, it's very sluggish and doesn't sound happy.
When in that state, if I pull left air flow meter wire, it almost dies but idles on, if I pull right air flow meter wire, no effect. So it seems the right bank is not contributing.
I've replaced wiring and connectors going to the air flow meters, both sides.

Any ideas? I'm not knowledgable about injection. After reading a bit, my short list is:
-Air flow meter?
-Rev counter signal?
-Intake air temp (not likely, even if temp is misread it should contribute?)
-Throttle potentiometer?
-Timing sensor?
-Fuel pump (not my guess since the problem is very on/off)

I have no Check Engine light. I do get Slow Down P0102 every time I test by pulling air flow meter wire, and Slow Down disappears when the P0102 is cleared.


What to look at first? Anything missing from my list?
1. What can I do myself?
2. What can local Bosch shop do, they can only read P0102?
3. If giving up and driving it to Ferrari, can I expect they can read out something and find the fault, or will they just replace components until they find the right one? ;-)

Help me before my wife gives up on it (and me)

 

Yes, I wrote it a bit confusing. When I wrote that there was no effect of removing the right MAF connector, I mean the connector on the RH side of the car looking forward, and yes of course, that side actully feeds the LH bank of the engine. So right now, LH bank doesn't seem to contribute

Never heard of MAF cleaner, will try to get hold of some

Air filters replaced today, old ones not in bad shape

Voltage of pin3: On the non contributing side (RH sensor, left cylinder bank) I only have 0.23V, on the opposite side I have 12.3V...

 

Some analysis.
-On RH I have the 0.23V at pin 23, 0V at pin 2, ignition on.
-had a couple of spare catalyst ECUs, not sure they work, used them on LH side, no change
-found relay U and Q, switched them and took them out, still 0.23V(?)

"look for power on the idle air controller" please explain

 

Just did most of what Aerosurfer wrote, haven't done what Qavion wrote last yet

I removed, viewed, checked for resistance on all fuses, and removed and pushed back in all relays on the left half, all the while the battery switch off, I now have 12V to pin 3, and it runs fine. Don't know what I did. Don't know if it will last, because this problem comes and goes. But my plan right now is to drive it a few times with the plate open to fuses etc, if it starts to behave badly again, I'll wiggle everything I can get to...

 

"Sorry for all the information", don't ever apologize for that, I appreciate it. I can sort through it...

Goodnight, and I'll go driving a bit now, and will let us all know...

 

Problem solved. Maybe. For a while? We'll see

So I had both banks runnng, full power, kept fuse/relay plate down, drove to local Bosch shop to replace relay U and Q, seemed like a sensible cheap thing to do. Stopped at the shop, took out relay U to make sure he had two exactly like it, got them, put in the old relay in U, started, only half power. Busy road, had to drive half a mile, stopped, wiggled the U relay, could hear it clicked, got full power, took it out, back to half power (obviously), put in new relay, full power, wiggled it, no click and still full power. It would seem the old relay was intermittently faulty. Drove 5 miles, full power.

I realise it can also be something in the connectors where the relay U sits, and it can be something else that will come back in a few days. For now, I drive test trips with fuse lid down and extra relay in glovebox...

 

"but didn't you say you swapped the relays earlier?", yes I did, that would indicate I haven't found root cause yet...

 

A side note:
I built up courage to ask my wife for the 4th time if she wanted to go on short drive with me. And we did, and it drove fine. But I don't think the car likes my wife, she couldn't get the seat belt out. I couldn't get her seat belt out either. We drove very short trip. Back in the workshop, the belt worked fine... Today's test trip (alone), passenger belt was stuck, then after driving 10 meters it was ok again. Any known issues I haven't found googling??

 

An update. I have driven 5-6 trips without problems. I bring along a piece of wire to short 30 to 87 if needed, and a spare relay. Theunissenguido has also shown me what he can deliver of fuse box, if the problem returns and therefore is not isolated to the relay I had...

Qavion, I tested the wire 4 and 5 as you wrote earlier, and now when everything works, I got 11.7V in both, ignition on, engine not running. Does that tell me anything?

Thanks so far...

 

Excuse me for answering my own question. I today took the panels of the right seat, to get to the belt winding mechanism. It's tilted slightly to the outside of the car so the belt aligns with the exit at passenger's right shoulder. But that's the problem, it's tilted.
I loosened the attaching bolt, and wiggling the mechanism 1 mm more towards me, belt can't come out, 1mm more towards center of car (more vertical), belt works perfect. I took the bracket that the mechanism is attached to, removed 1 mm material at the top, so that the winding mechanism could sit 1mm more vertical, and installed all again. It works fine now...