Dead ECU?

All aspects of tuning,modification and repairs to the BX 16valve.
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thanuttiscotsman
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Post by thanuttiscotsman »

mechuccio, have you checked the ignition coil itself? try changing that first, maybe the sparks are just too weak? i.e they should be bright blue and highly visible, if they are orange/yellow or faint then the coil is duff. i had alot of problems with my silver 16v and alot of them were coil related. i ended up never finnishing that project car cos i couldnt figure out why my car ate ign coils at a rate of 1 every 2 months, the car starts and drives fine but for some reason, everytime after a couple months the cars just dies and the coil is fu**ed. that problem was the only thing left i had to do to complete that valver and its still in my garage lol

rossco
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Post by mechuccio »

We've tried that and it didn't help.
But this evening we've bought a new ECU and that didn't help either.
I've cheched the spark and that's good, it's a nice clear blue spark but it seems to be too early or at least not at the right time.

What happens is that when starting the engine turns and turns and turns and then suddenly stops..... and starts turning again.

When we disconnect the coil so a spark is not possible the engine just keeps on turning until the battery is empty.

Maybe there's a problem with the distibutorcap or rotor?
I honestly don't know at this point.

However I had not too much time to check other things out this evening as I had a meeting at work, and last week when we opened up the ECU it seemed so rotten that we just thought that to be the problem. I won't believe that we've just bought another dead ECU as this one looks very good and gives exactly the same problems.
You can't spell slaughter without laughter ->I just love my 16V<-
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thanuttiscotsman
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Post by thanuttiscotsman »

mechuccio wrote:
What happens is that when starting the engine turns and turns and turns and then suddenly stops..... and starts turning again.

When we disconnect the coil so a spark is not possible the engine just keeps on turning until the battery is empty.
hello again, this info of the engine turning then turning then stopping sounds very much to me like the ht leads are connected the wrong way round and the plugs are firing in the wrong order! have you double checked them? i don think they dizzy cap or rotor arm would cause the engine to fire at the wrong time. as i said before when i had car troubles in the confusion of testing, removing and refitting parts i got the ht leads mixed up and i had the EXACT symtoms ou are having now. the only other thing i think could cause incorrect ignition timing would be the crankshaft sensor, if the computers got wrong info of where tdc is then it will fire at the wrong time.

cheers rossco
1989 BX 16v ph1 Big project chipped, k+N, scorpion s/s, weber throttle body, Nitrous injection

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Post by Vanny »

As it will only retard/advance the ignition by a very small amount, i can't imagine that the crack sensor being out would give that much difference (it would run like a bag or nails, but still run). However if the crank sensor is giving no feedback then perhaps the ECU is not sending a pulse what so ever.

Out of interest have you checked the timing? Cover off, roughly line up the timing holes with the block holes. I wonder if the belt has jumped, throwing the timing out. Its an easy check and probably worth doing (you'll need to check the crank timing as well, but again it can be done visually).

While Rossco keeps mentioning it, i assume that you have checked the HT lead arrangement?
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Post by mechuccio »

Well yeah, HT lead arrangement is good as it is.

What happened is that the car stopped about 2 weeks ago, it was brought to the garage where they fitted a new distributorcap and TDC-sensor. it still wouldn't start. Then at the garage they discovered that the ECU connection was corroded. They cleaned that and the car was working fine again. 4 days later it's ideling suddenly stops and that's it.

Tonigh we'll check the timingbelt to see what's up with that.
Also I'm thinking maybe the coil isn't that good afterall, since we've only tried to fit another one that's not working at all.
This one works but maybe not good enough allthough the spark is very clear and blue.

Maybe I'll just mount his coil in my car tonight too, see what that does.
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Post by mechuccio »

Well, she's up and running again.
I removed the distributorcap and found the rotor loose in it.
1 of the three screws was missing and a couple of pieces where broken off the rotor. But I refitted it anyways and she started brilliantly immediately.
Now just to buy a new rotor and forget this has ever happened :D
You can't spell slaughter without laughter ->I just love my 16V<-
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thanuttiscotsman
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Post by thanuttiscotsman »

mechuccio wrote:Well, she's up and running again.
I removed the distributorcap and found the rotor loose in it.
1 of the three screws was missing and a couple of pieces where broken off the rotor. But I refitted it anyways and she started brilliantly immediately.
Now just to buy a new rotor and forget this has ever happened :D
excellent news dude! just bloody typical of garages though! they always break something eh!

rossco
1989 BX 16v ph1 Big project chipped, k+N, scorpion s/s, weber throttle body, Nitrous injection

1990 BX 16v ph2 (now scrapped)
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Post by mechuccio »

Yeah you're right!
Well this isn't my car it belongs to a good friend and it's the one we've bought in november with the broken timing belt and 14 bent valves.
As I've never before remoced and refitted a cilinderhead I'm allways worried about this particular car, but when driving she's brilliant. She did about 10.000KM since we've fitted the new cilinderhead so I guess everything for that part is in order but still, when somethings wrong I always worry :D

However this problem is absolutely due to the garage, I was in The Hague at the time she broke down so my friend brought it to the garage and they renewed the TDC sensor and distributor cap and cleaned the ECU's connections. It's very bad that after the car came back it just worked for less than 4 days and worse that this was the problem.

You would suspect that a good garage when fitting a new distributorcap checks if everything is in order behind it. I just won't believe that all three screws came loose in the three days the car was working again.

The bill my friend got was allmost EUR 400,- but he's not going to pay for a rubbish job obviously. Tomorrow he'll call the garage to explain everything that has happened.

His father buys all his cars at that garage so my guess is that they'll do something with the bill. Allthough they've spoken to his dad about the 16V, telling him that it's a hobbybob car which will allways cost a lot of money because it's old and unrelieable.
My ass it is, tightening three screws is not so expensive in my book and my own 16V has done over 350.000KM's allready, and up to now it has cost me around 400 euro's per year on maintanance.

But anyway I'm glad the car is working properly again, that's the most important for now :D
You can't spell slaughter without laughter ->I just love my 16V<-
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thanuttiscotsman
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Post by thanuttiscotsman »

mechuccio wrote: when somethings wrong I always worry :D

You would suspect that a good garage when fitting a new distributorcap checks if everything is in order behind it. I just won't believe that all three screws came loose in the three days the car was working again.

But anyway I'm glad the car is working properly again, that's the most important for now :D
hiya, thats natural, these things only happen just after you have adjusted something or sprayed wd40 on a door hinge :lol: . i would strongly suspect they did remove the rotor arm and probably cleaned it too, the stupid error was probably made when re-fitting it. i work as a mechanic in a garage and know well that most garages are the same, there are very few good garages around these days that are honest and do a good job. but at least its going again, having a broken valver is like getting the worlds coolest new toy then being told you cant play with it till tomorrow. :lol:

rossco
1989 BX 16v ph1 Big project chipped, k+N, scorpion s/s, weber throttle body, Nitrous injection

1990 BX 16v ph2 (now scrapped)
mechuccio
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Post by mechuccio »

That's absolutely true about the garages.
The Citroen dealer in the village my parents live is fantastic for that matter.
The owner is about 70 years old and when having a problem usualy he's the first one to dive under the hood. And the mechanic that has been working there for the shortest time compared to the others is still working over there for more than 12 years. I would trust them blindly, if they say there's a problem than they're right. I'm glad i'm able to do everything myself though, if I haven't done something yet I still start working on it, with the proper tools and the Haynes so far I've allways been able to fix up my own problems on my valver. I had to because she was a wreck when I bought her, I just had to have it though!
And it's an absolute truth that having a broken valver sucks. So far in the pas 3 years I had two breakdowns where I couldn't drive it, although I allways have a spare BX which is usualy driven by the mrs. there's just nowthing compared to the violence a valver has to offer.

A couple of days ago somebody came to pick up a front fender with headlightsprayers of a scandinavian GTI, he had never experienced a valver so offcourse I was obliged to take him for a short sprint. while driving 190KM/h with my hands loose off the steeringwheel and still going straight forward without any vibrations in the car he was stunned, then when I shifted to 6th gear at 205KM/h his eyes opened up even wider :lol:
I'm wondering how long it will take him to buy a valver too :twisted:
You can't spell slaughter without laughter ->I just love my 16V<-
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