BBA-Reman Forums » BBA reman forum » Problems and Solutions » Corsa Non start

Re: Corsa Non start

Andy-01 — Thu, 07 Apr 2005 11:47:41 GMT

Dave.
The sensor and plug are different connectors now (Gold contacts and different shape), so a kit would be required now.

Tony.
Yes the cam and crank sensors have a known reference point, generated by the missing tooth idea. This indicates to the ecu the position. Nothing you could check by means of a timing light.
Where am I ? A question I often ask ;D
Have a look in your emails. ;)

Re: Corsa Non start

Chuck_Wagon — Thu, 07 Apr 2005 08:58:42 GMT

Andy,

Check your private messages.

Chuck

Corsa Non start

TONY_GINGELL — Thu, 07 Apr 2005 08:58:42 GMT

Vx Corsa, N plate x14 Ecotec.

the customer has had the engine managemnt lamp on for over a year, and so far no one has been able, (Including a dealer) to get it to go out.
The car came in just before Easter with non starting, but as the recovery man was dropping it off, it started, and has been starting fist time over the last few days.
Code in memory for cam sensor, (Looks new, and code returns when cleared) Coil resistance, (also looks new, code has not yet returned) and immobliser. (Also has not yet returned.)
The HT spark does look very week on both circuits.
At one stage during the day the car did stop and was very difficult to start. No new codes recorded, and injector time was normal with a good RPM signal.
remember Andy-1 posting re-problem ECU’s on Vectra’s, are these poor also?

Regards Tony

Re: Corsa Non start

TONY_GINGELL — Wed, 06 Apr 2005 10:19:47 GMT

Andy, (and everyone else following this thread)

I disconnect the fix wire from the battery this afternoon, and connected it through a volt meater.
With the ignition on, there was only 0.02v running through it. But under cranking, which I had not checked before, there was 1.2v!
With the fix wire back on, I re-checked the coil trigger trace, and found that it was now "clean" with no noise. Also if you refer to the link in a previous post, there is a noticable "curve" to the top of the trace, this has also gone. I will try to have a look tomorrow to see if the rest of the ECU traces are now clean, but I suspect that they will be.

Andy, one last question on the cam/crank sensors. You have not yet said how the two sensors are in time with each other. Where you refering to the two turning at similar rates? or as I suspected, that the two share a common referance point? If so, with the top cover off, can this be checked with a timing light?

Also your "profile" does not even give us what area you are in, any chance of an update? (You dont have to if you dont want to.)

One thing that realy P’s me off about this job, is that if I had not lost my spark tester, then I would have been 100% certain that it was a spark problem and wasted time looking elsewhere. On the plus side, I now am more familar with my scope, I will how have alarm bells rining when I see a trace with "noise", an with Andys help I did not waste more time looking for other possible causes of the fault.

Time for a drink! S#d it! The bottle of 5.1 is empty............ again!
Glass of Glen Ord anyone?

Regards Tony

Re: Corsa Non start

Dave Hill — Wed, 06 Apr 2005 09:04:40 GMT

Andy

Thanks for that. I had a Vectra 20ltr 96 N reg come in last Saturday that we fitted a cam sensor to just over 12 months ago. The MIL lamp has come back on & the same cam code has come back.

Looking back at the records shows that we didn’t fit a sensor & wire as we do now (just the sensor). I can’t remember when it was introduced as a kit. Is it possible to replace just the harness or do we have to have the kit? Assuming the belt tension checks out that is.

Dave

Re: Corsa Non start

Andy-01 — Wed, 06 Apr 2005 06:43:47 GMT

Tony,
Glad it worked. Thats what makes this fun, when it works out. I had typed up my next bit to my cam & crank sensor piece before I saw your last post. I hope you dont mind me putting it on the end of this post, as it was done anyway. ;D

The crank sensor uses missing tooth to gain a reference point to a known engine position. It takes the previous revolutions time taken which enables it to calculate crank speed. As the missing tooths signal is received again it starts a clock sequence countdown, and all other processes are activated from this clock signal, such as cylinder 1 ignition spark. The ecu takes that signal that no1 spark is required, checks its map for speed and load input, calculates the required dwell, and then switches the signal for the coil to fire at the required clock time from the good old crank sensor. Cleaver eh ?
Now, again as you correctly pointed out, the cam sensor doesnt have a missing tooth as such, it uses one large tooth and one small, with fixed gaps between them. This is because it just needs to provide a position reference point to start the sequential injection sequence. Again when it knows were its start point is, the rest is run to a clock signal. The design also allows a speed calculation to be taken from it for data interrogatory check against the crank sensor, and to provide limp home function. Its also worth noting the cam sensor only watches one cam, usually the exhaust.

Dave.
Yes, we will always advise of a belt tension check before condemning sensors. I personally like to run the engine with the outer cover off, to see where the pointer is whilst running. It seems to differ to when checked statically.

Re: Corsa Non start

TONY_GINGELL — Wed, 06 Apr 2005 01:43:12 GMT

Andy, YOU ARE A GRADE "A" STAR!

The car would not start this morning, but before I had a chance to try "Andys Fix", in came the Snap-On man.
So complete with a new 250, on "special" fuel pressure gauge kit, (My old one was obsolete) and a new "Callibrated spark" tester, (The last one went missing at Christmas.) I was all tooled up to do battle with the beast.
The new spark tester did not give a spark, (I thought that it looked week when connected to a plug) so I wired in Andys wire. Hey presto! Big spark, and car runs!

Andy I one you one! (Note to forum admin, make this man a senior member now, and put his next years membership on my tab. ;D)

If I get time this afternoon I will see how much power is going down this line, and also if it clears my "noise" from the scope trace.

Thanks once again.

Regards Tony

Re: Corsa Non start

TONY_GINGELL — Tue, 05 Apr 2005 10:53:44 GMT

Andy,
Thanks for that, as with all good "problem jobs" the DAM THING STARTED TODAY! UUUURRRRGGG!!!!

I’m waiting for it not to start, before I try what you have suggested.
The only thing that I have still not been able to check properly is the fuel pressure. The new adaptor arrived today, but is no better than the old one. I may have have to break into the line before the rail.

With referance to the cam/crank sensors, I take it that the missing tooth is the referance point for the crank sensor, but whch of the cam peggs ties into the referance point?
If a car had a timing belt fitted one tooth out on the exhaust cam, do I take it that this would throw the two signals out of sinc and cause a fault code to be logged?

Angus,
Flourescent lights? you must be joking! I have been moved into the dark depths of the workshop, lighted by gas lamps only. (It’s getting harder to find coal gas these days....)

Tim,
When the car does start, and as you have probaly guessed, there is no set pattern, either it will start with no problem whatsoever, OR, it will turn over, firing, but not quite starting, and when it does start, it’s just like clearing a flooded engine. (Ie misses.) The exhaust also smells of fuel when turning over, and the car will "kick" just like a failed amp on letting the key return to ignition.

I have been using the 100m/s time scale so that I can see two ignition firings. (I havent got the hang of the double trace yet) The duration, at idle, with a cold engine, is aprox 8m/s and the "noise" is right on the firing line, and inbetween the two recorded triggers.
The noise is aprox 6m/s in duration. Perhaps as you are more used to the scope readings than I am, I should fax it over to you.

Regards Tony
http://img.photobucket.com/albums/v225/TONY_GINGELL/corsa.bmp

I could not get the BBA link to work, but the above links shows what I have got. Please disregrd the volts scale, i am running the scope through the supplied reducer untill i am more used to it. The actual voltage is 5V.

Re: Corsa Non start

Chuck_Wagon — Tue, 05 Apr 2005 09:45:14 GMT

Andy,

It’s posts like that that keep this forum hot. Keep that sort of stuff coming, it’s great.

Chuck

Re: Corsa Non start

Dave Hill — Tue, 05 Apr 2005 09:37:13 GMT

Andy

Do you recomend that when a faulty cam sensor fault is detected, that it’s worth checking cam timing & belt tension before replacing the sensor & multi plug.

Dave

Re: Corsa Non start

Andy-01 — Tue, 05 Apr 2005 09:29:36 GMT

Hi Tony, back at last.

Right, I think I should explain myself a bit better.
Like I said, we saw a run of this a few years back. X14XE and X16XEL engines. Random breakdown and starting failures. I know it could be 101 things, but this one is jumping to my mind for this at the moment. It just happened I had one on the ramp one day in a failed state when the field engineer turned up. All checks were good (fuel,spark etc) but no go. After he had a long phone conversation with god knows who, we shaved back the sleeve on the brown wire (earth) close to the plug on the DIS, soldered a spur to it and took it straight to the negative post. Turned the key and it went straight into life. Never failed again to my knowledge. I carried out a couple more like that, but must confess, that was quite a few years ago now. The reason Im stuck on this at the moment is you said you had start/non-start when switching DIS packs around, or as I think it could be, disturbing the wiring to it.

You asked about phasing between cam and crank sensors (I believe ?). Both sensors send a sign wave input to the ecu, which then puts it through a analogue to digital converter to produce a square wave signal. (Im sure you know that so sorry if you did). They both produce speed and position data to the ecu by missing tooth technology on the pick up ring. The crank sensor provides the primary data for the ignition dwell and position mapping, along with a host of other things. The cam sensor data s used only to time the sequential injection. BUT, the ecu keeps an eye on the two position signals, if they are out of sync it knows it, assumes its a sensor failure and flags a DTC. Slack belts are very prone to causing this sync anomaly. The ecu likes to watch both, as if a crank or cam sensor goes down, it can jump the reference data to the other sensor for limp home use. A good way to see this is with an ecotec engine with the light on for crank sensor. In theory no data from the crank sensor, and it shouldnt run, but it is. Un-plug the cam sensor now, and its lost both speed signals, so it has to give up and shut the engine down.

I dont know if all that drivel is anything like the answer you were after, but I hope it helps you or anyone else who reads this post. ::)

Re: Corsa Non start

TimSims — Tue, 05 Apr 2005 08:47:58 GMT

Tony,

I keep reading through these posts!

You say that you have a spark even when the engine will not go. So what is happening at the fuel end? Is there any fuel being injected? On the occasion when it didn’t start, how did the engine run once it started?

I am glad to here that you have the pico scope- what a fantastic piece of kit. what voltage range are you using when seeing the "noise" 0f 25ms frequency.

Cheers,
Tim

Re: Corsa Non start

TONY_GINGELL — Tue, 05 Apr 2005 01:41:00 GMT

Andy,
I have checked for voltage down the power and earth lines of the coil, but this was with the engine running. I will try again when it stops. Most of the time when it wont start it will be firing, but just wont go the extra little bit to actually start.

When I get time I will try it with the altenator drive belt off.
Regards Tony

Re: Corsa Non start

Andy-01 — Mon, 04 Apr 2005 11:29:32 GMT

Tony
Had a run of this a few years back. Splice another earth wire from the brown wire at the coil and take it straight to the battery. Let me know what happens ?
Will post tommorow night when I have a bit more time. ;)

Re: Corsa Non start

Angus — Mon, 04 Apr 2005 11:16:26 GMT

Tony

Could this 40Hz "noise" be generated by faulty diodes in the alternator? Or, if your scope is sensitive enough; is it picking-up the mains-frequency [50Hz] EMF in the air that is always there - in varying strength.

Try scoping the wires with the engine off to see if it’s still there. If it is: try turning your fluorescent lights off.

Re: Corsa Non start

TONY_GINGELL — Mon, 04 Apr 2005 09:31:51 GMT

Andy,
Well the dam thing would not start this morning. But I did have in an 8 valve 1600 Astra on an "N" with the same design of coil. As soon as it was fitted it started, but after the fitting of a new coil it would not.
I had a closer look at the coil trigger traces, and found some "noise" Whist firing, and also between fires. (Which I took to be from the second section of the coil firing.) So I faxed a hard copy to BBA (Mike) who forwarded it on, and came back with it COULD be the ECU, but only by having it off the car could "noise from another sorce be ruled out.
I then had a look at the other traces, and found the same noise on nearly every wire you check. (Plese note that I am new to the Pico scope) What I cant make out is why the noise is at regular 25ms intervals.
The signal from the cam sensor looks good to me. (Except for the small amount of noise) I am getting four traces of 5 vlots, of varying durations.
I will have to try to get them transfered onto the home PC so I can post them.
One last thing to note, the vehicle had a new coil fitted by us in June that cured a mis-fire, so a spiked ecu is a possibility.
Regards Tony

Re: Corsa Non start

TONY_GINGELL — Sun, 03 Apr 2005 09:37:17 GMT

Andy,
I spoke to the customer on Saturday, and she said that the engine management lamp had been on for the last 5yrs!
I see on another thread that you refer to the phasing of the cam/crank sensors, are they both suposed to be "in time" with each other? Or just give the same waveform output?
Like you, I am sure that this is not the cause of the fault now, but it would be nice to see how the two are linked.

I still dont like the look of the spark, so will check it better tomorrow, whilst it is running, and compare it with when it stops.

Regards Tony

Re: Corsa Non start

Andy-01 — Fri, 01 Apr 2005 08:30:45 GMT

Ok. A few things spring to mind here.
You say the cam sensor looks new, but as you didnt replace that do you trust it ?
Please check the belt timing is 100 percent spot on.

If the code is not getting set until cranking/running, its passing self test at ignition on, so this should rule out short or open circuits. Its the data stream from the sensor that the ecu doesnt like. If its not the ecu its self it must be getting interference in the loom. Does it look ok. Are things like the leads original ? It would be painful, but you could try separating the cam sensor wires from the loom and shielding them. (remembering to earth the shield). Years ago now we had to do a lot of loom changes on Cavaliers for cam and crank codes, due to interference problems.

All that said, the cam sensor is responsible for timing the sequential injection only, so this in its own right shouldnt cause a breakdown. I would be keen to know some more when its in a failed state. The cam sensor code may be responsible for the light coming on, but I dont think its causing your cut out/starting concern. ???

Re: Corsa Non start

TONY_GINGELL — Fri, 01 Apr 2005 06:30:43 GMT

Andy,
The cam sensor code will only return once the engine is started. I have not been able to check the fuel pressure, as my adaptor keeps fouling the altenator bracket. All I can tell is that there is fuel there.
The week spark is worrying me most at the moment, I will see how strong it is with the engine running, and compare it when, (IF) it stops.

Regards Tony

Re: Corsa Non start

TimSims — Fri, 01 Apr 2005 02:12:16 GMT

Hi Tony,
Just a quick question:

If you had a stronger spark, what do you think it will solve?

Tim
Ps-I wouldn’t be worrying about the spark yet. Unless your answer to the above is a good one.

Re: Corsa Non start

Andy-01 — Thu, 31 Mar 2005 10:43:37 GMT

Tony
Sorry but no known history of ecu faults on these. Fuel pump relays were a bit weak though.
So are you saying the cam sensor code is present, even without the engine running ?