sml

as per post above ... next step is a quick switch-out with a replacement DME unit to test. find access to someone so you can borrow their DME for 30 mins.

m3vs911

both me and the mechanic have already done it but the issue is still there..

m3vs911

update:

the mechanic said he is ordering some bits including the ECU, he suspects the ECU is causing the DME relat turning on and off and causing the stalling and misfiring problem.

I want to ask, if my ECU is gone, the car should not be to drive anymore, how could I drive my car for 2mins before the problem occur?
before the problem occurs, I could do a full throttle to 6000rpm and change gear. after that, things happened.

Ken D

When others referred to swapping out the "DME" for a known good one, they were referring to the ECU (not the relay). Did your mechanic swap out for a different ECU before ordering you a new one?

m3vs911

I think what he meant is he could return the ECU if the ECU doesn't sort this problem, but is that mean the chip is faulty or I just literally destroyed the ECU while I open it ...?

Ken D

Since you swapped out for the factory chip and it didn't solve your problem, then it seems the chip isn't the problem.

Could be bad solder joints in the ECU, which is most easily determined by swapping out the unit for a known good one. More difficult is opening the box and looking for bad solder joints, your mechanic should be familiar with pcb boards and electronics before attempting that one.

Could be faulty engine speed sensor. Could be faulty wiring, or (related) to the corrosion in the fuse box you previously. Could be a bad ignition switch.

Whatever it is, it is probably also related to your post from last week (before you chipped the car) where you thought your distributor belt was broken due to intermittent poor running.

Assuming your mechanic is a Porsche specialist, then he should be able to make these determinations and test properly. I'd be a little concerned that he would order up a new ECU without even swapping the old one out for a known good ECU, it makes me think he doesn't have Motronic boxes on hand and may not be a specialist.

m3vs911

that makes a lot of sense. Yes, he is a porsche specialist but I doubt that he has a motronic box on hand tho. I think that's why he needs it to test my ECU is faulty or not..

He told me that he has checked all the ignition system and they are fine.
I think what he told me today about sourcing the ECU will not be taken from my wallet yet, of course if it is the ECU problem , I don't think I would have other option to go for , which is quite a expensive way.

However, if that's the case , I just don't understand why since I've followed the instruction properly to replace the chip.

and I could drive my car before this happened me

sml

please re-read my post #6 above.

sml

he doesn't have another 964 in for a service where he could ask the owner for a favour?

my mechanic had just done a motronic install and had a spare DME/ECU laying around.

find a friend nearby with a 964. ask here maybe.

or for $20 just drop off the DME/ECU to a TV repair dude to check solder joints.

Amber Gramps

THAT Bosch hammer drill.

m3vs911

hi guys, I have to say my garage works really slow on this repair and however he cannot completely gives conclusion about this yet. He didn't manage to replace a ECU to the car yet, as he has not got a spare one.

Rang him today and he told me that since there is misfiring in the engine, so if he disconnect one of the distributor coil module (he said it has 2 of them), that means the engine running with only 6 spark plugs, the car runs fine and no problem.. He tried the other way around, the problem would comes back and he said he has never seen this before and this is quite tricky.

I want to share this to you if you are reading this so I hope someone could share their views.
He said the distributor itself is fine and the belt is tight, so it is not the distributor problem.

I am fed up with this and hopeless about he can fix this by the weekend.

PS. I think it is ridiculous at some point BUT if someone could have a spare 964 ECU to lend to me in UK (I am in Nottingham) so I can let the guy to test it out immediately, my garage said he does not have 964 there and do not want to remove someone's ECU to test it on my car, of course if I don't mind to keep one for spare he can order it under my name... I am wondering is there any "pay and borrow" available out there as well...

Sire

I believe you live in in the UK there is Ninemeister give them an call. They know 964 verry well.

swftiii

Look at post #3 - this sounds exactly like what my problem was. Have him replace both coils. My wrench replaced the bad one and then I had the problem again and after some additional research he replaced the second and the problem is 100% resolved. He now suggests that when 1 coil needs to be replaced it is wise to replace both.

This fix doesn't take a significant amount of time nor is it overly expensive.

THanks and good luck.

Skip

m3vs911

Thanks for your advice Skip, I am curious that what happened if it is a "bad coil"? would it be just not working instead? I've told him to check the ignition system before however he said it is fine.

did you mean if one of the coil has gone, the car can still run but performance will be tuned down? for a "bad coil" the ignition timing would just gone wrong and misfire all the time?

sorry for being so ignorant on 964...

swftiii

I'm not knowledgeable enough, but I believe it can, but not well. I can't seem to remember really well the symptoms, but what you are saying as your symptoms seems to be very familiar. My wrench, who is awesome, diagnosed that one of the coils was bad by running on 1 at a time and when the bad one was used it stalled or was very rough. The other one seemed to be fine until he replaced only the bad one then the other old one wasn't at the same level of performance so the car ran rough and had the christmas tree issue and stalled. I limped it back to the shop and he replaced the 2nd coil and all was good from there. I think I'm remembering that correctly...he also did some swapping of the coil wires to check them as part of the diagnosis as I was concerned that might be part of it.

Good luck,

Skip