Technical Mistery, serious mistery! 1.4 16v 2007. Doesn't start.

[BravoBlu]

Hello everyone. I'm new to the forum (well, newly registered they is I've been reading a lot of posts on here).

I was hoping that maybe someone could help solve the mistery of my bravo 1.4 16v 2007. Car was working fine, no problem at all. Came back home from work, parked up and decided to replace the oil and filter. Finished adding the new oil, I installed a black box that the insurance company posted to me, attaching it to the OBD connector.
After that, I tried to start the car but it wouldn't start!
Was cranking but didn't start.
I take out the black box thinking it was the culprit, to no avail.
Get out the code reader, attached to the OBD and error code P0340 was shown. I replace the crankshaft sensor, still won't start. I checked the harness from sensor to ECU with a multimeter, cables is ok. Remove battery, short + and - battery cables for 10 min, re attached battery: code show now is p0335.
Replaced now camshaft sensor and check the harness fr sensor not ECU
Still not staring , persistent P0335 error.
Now I'm at the point where I start thinking out side the box: got out the timing tools, removed cambelt, readjusted the timing (aligning the command/valve system with the pistons/crank as per Fiat e-learn manual). Still no joy
My last effort would be to order a virginized ECU and see what happens next.

Any suggestions guys? Have I missed anything?

Thank you all very much in advance.

 

[jackwhoo]

Hi,

Very strange indeed.

I am not sure which code you had first and which code second and which code now remains.

I think you wrote that you have checked the continuity of the wiring between the cam position sensor and ecu - is that correct?

With the ecu and cam sensor disconnected is there a short between the cam sensor signal wire and either of the other wires?

With the ecu connected but cam sensor disconnected do you get reference voltage at the cam sensor plug?

p0335 code is for crankshaft position sensor . Check continuity of wires between crank sensor and ecu with sensor and ecu unplugged , check the signal wire is not shorted to the other wire.

Please let us know results.

Cheers
Jack

 

[Mike1alike]

That is nasty.
Is your fuel pump still working? When you turn the key before crancking, can you hear the pump humming from under the backseats?

 

[BravoBlu]

First of all, thanks a lot guys for taking the time to reply.
jackwhoo
I checked the continuity of all the wires from both cam and crank sensors. I have tested for shortcircuit too and the wires are not touching anything else.
there is reference voltage on the cam sensor....Im not sure this is the one to blame since the code thrown is 0335 which translates into cranck sensor, but I had the cam sensor ready and replaced it anyways and also double checked the wires.
Wires from crank sensor and ECU plug is intact also, continuity checked all ok. I wish I had an osciloscope to see what signal the crank was generating (if any).

I have read somewhere that the crank pulley could somehow be "worn" and not able to induce the correct magnetic filed to trigger the crank sensor?! I have now only the ECU and the pulley to play with before I run out of ideas.

Mike1alike
Pump is working fine! Pressing the valve at the end of the injection pipe squirts petrol a long distance!

 

[Mike1alike]

You've got the codes the other way around.
P0340 is the code for Camshaft sensor.
P0335 is the code for Crankshaft sensor.
It is very normal if you get one of this codes (especially the P0335) the car not to start. There is no fuel injected due to the codes.
The obvious thing is that the problem occured after you fiddle with it. You either damage the wires somehow and when you move them to test for continuity made them touch if have a broken part inside and show they have continuity, either by connecting the black box you've managed to do a damage, the only possibility being to the ECU. Did you check all the threds of the wires? To dismiss the wires, like to be sure they are good, you should, if you can, connect another wire for testing and if still dosen't work, the wires are good.
And what did you replaced the sensors with? Are they good, reliable make or is there any possibility that the "new" sensor doesn't work as it should?
I don't know if is very good that you've ordered a new ECU, I mean be prepared to have the same result like after replacing the sensors. But do hope because there are chances to be the fix, if you damaged the ECU with the black box.

 

[Mike1alike]

Also, have you placed the sensor correctly? Is the new cranckshaft sensor the same shape as the old one? Did you placed it were it should be? There is the possibility that when you've changed the oil filter, you've pushed onto the sensor and changed it's position. I don't know what holds the sensor on Bravo, could this happen?
If the sensor is positioned on another distance, the readings it gives are all wrong, hence the codes.
And one other thing: if you got the codes wrong, is it possible that you've placed the sensors wrong, one in place of the other? Do they have the same plug at Bravo?

 

[Mike1alike]

I have read somewhere that the crank pulley could somehow be "worn" and not able to induce the correct magnetic filed to trigger the crank sensor?! I have now only the ECU and the pulley to play with before I run out of ideas

Yes, that can happen as that is how the sensor works. The pulley has a piece of metal (or actually I think there are more of them, 3 or something in specific places) on one side and that runs right in front of the sensor when rotates. When is next to sensor, the sensor sends different voltage signal to the ECU, so it knows the pulley is moving. If that piece of metal is worn out the sensor do send wrong signal as it "reads" the metal by magnetism and not having the metal where it is designed to be, there will not be correct reading.
It's true you cand do an exact reading only by an oscilloscope, but you can test the sensors with a multimeter. Here is a youtube video on how to do that, it is for a camshaft sensor but the same goes for the Cranckshaft sensor as well.

 

[BravoBlu]

Tomorrow I have the morning free and will do some more tests. You are right, and that's my line of thought too: either the insurance black box killed the ECU or there is something (from the crankshaft pulley passing through the sensor and wires ) that is not right. I will try to run a new pair of wires from the sensor directly to the ECU (bypassing the original harness, or in parallel to it), will attach the multimeter in AC mode to the sensor terminals and try to start the car to see if there is any reading.

The sensors I replaced were brand new, even if there is the small chance of being defective out of the box. This morning I did have a look at the crank pulley and in fairness it does look a bit "old", worn.

Ill see what results I get from the tests tomorrow and let you know.

Really appreciate the help!

 

[Mike1alike]

With the pulley: even if is dirt on that spot it gives you a different reading. So check it to be clean, you will notice it as it runs right in front of the sensor (and maybe do a count if is one ore more metal points).
Good luck and get a not expensive fix and soon.
PS: for the wire testing you should run the new pair of wire bypassing the original, as if the original has a shortcircuit, you'll have it too with the new one connected in parallel.
And I see I forgot to post the link. Here it is:
//youtu.be/cB1VEfjGz1c

 

[BravoBlu]

The sensors (cam and crank) are different, can not be swapped by mistake (cam is Hall effect 3 pins, crank is induction 2pins). The crank sensor is indeed very close to the oil filter that I replaced but while you make sense saying it could have been knocked out of place, this sensor is bolted to the engine block (and I have fitted a new one anyways).

What a mess!!! I miss the good old days when we used to have no electronics at all in the engines.....every problem could be diagnosed with a test lamp and fixed with some wires as tape

 

[Mike1alike]

That is true about the old days and easy fixes.
But the electronics do bring some good things too. Problem is there are kind of a lot of electronics and there are not unity in all makes of cars, everyone uses something different again and again.
The good part is that this forum is a very good platform to help you become the best mechanic for your Fiat.
You will get to the bottom of this problem and will be able to fix it.

 

[Mike1alike]

Here is how to test the crank sensor, kind of the same, but it being induction does not need to be powered, it produces it's own voltage:
//youtu.be/RvuzZJqQDf4

 

[Mike1alike]

The sensors (cam and crank) are different, can not be swapped by mistake (cam is Hall effect 3 pins, crank is induction 2pins

I thought you have them both Hall effect. My mistake!
Here is another way of testing the crank sensor, this is better than simply mesure it with the multimetre because you can hear if the injectors opens. So you test not only the sensor but the functionality, if the sensor is good (mesured by multimetre) it means the problem is with the ECU or the wires
//youtu.be/LaTEPhB1_C8
This is also very easy to do and I think this is made for you. You have to use wire and a lamp

 

[BravoBlu]

so.....good and bad news.

Main issue was a faulty new crank sensor! I spoke to the local shop and they will refund it since I got a new one online. Measuring the AC on the sensor while cranking the engine was giving less than 1v with the faulty sensor, whith the new sensor it generates about 2.5v.

Replaced the sensor, ready to test if the car would start: turn the ignition and after a few seconds a metalic noise and a boom. I forgot to tighten the cambelt tensioner the belt slipped and I think some valves are now bent

I have now re done the sync and this time I made triple sure the tensioner was tightened properly (whilst cursing myself in my head of course).

Now when I try to start the car, the crank turns with pops and booms but does not start.

I might have to bite the bullet and cut my loses. Too much has been spent already and I dont think its worth the cost of replacing valves.
The gasket set alone is around £100 then the cost of however many valves would need replacing. That if I try it myself, to send the cylinder head to be engineered I suppose would cost around £200.


The road ahead of my brave Bravo II is looking bleak guys.

 

[Pugglt Auld Jock]

BravoBlu you have my most sincere sympathies. It's all to easy to do something like this when you're working with several components at one time and I can tell you it gets worse as you age! sometimes I find I can't find a spanner that I was using just 5 minutes ago!

Was your faulty new sensor a "big name" component or a "cheapie"? We all tend to assume that a new component, especially if it's cost lots of money, is going to be perfect and factor it out of fault finding.

Is the rest of the car in good order, especially bodywork? Fixing it up might still be a better option than spending lots of money buying a newer vehicle which you know nothing about? If it's looking like bent valves I think I'd be taking the head off for a bit of a look see before I made a final move. Good luck for the future and do let us know how things finally turn out.

 

[jackwhoo]

Firstly ..I'm so sorry to hear your bad news :-(

Secondly a good used cylinder head form a dismantler may be cheaper than replacing valves- if you can find one.

Very good luck

Jack

 

[Mike1alike]

I'm so sorry too, to hear about what happened.
But I would advise you not to let yourself discouraged. These things happen, but it's fixable and might be the best outcome to fix it, as Jack said.
I'll tell you what I've been through: 3 years ago, winter, snowy road, a big truck kept riding my tale, I got snow under the right side and slid right into the end of guardrail. Full frontal, right in the middle, broke the front of the car: headlights, bonnet, radiator, AC condenser, engine mount, the metal part where radiator stands, the one between semi-rails and so on. I said I will fix it and got to work. Found at a guy striping a pretty decent shaped Punto, same body and bought what I needed. A friend of mine did the work, welding and so for a reasonable price.
When he was done and we tried to start the engine: no luck. Then we discovered that that metal front part hit de engine, right on the camshaft pulley, through the plastic cover, just cracked the plastic but totally damaged the pulley and broke the belt. Also, it turned out it ripped the engine mounting bolts from cylinder head. I was strongly advice if I want to fix it, to get a new engine or at least a new cylinder head, I was told that by the look of it at least 2 valves are destroyed. But the valves are really really cheap, changing them is a bit tricky.
Anyways, I didn't believe any valve was touched (turned out I was right) and I choose to rebuild the cylinder head. Took it off, all was good inside except it needed valve seals replacement, so good thing I got it off, did that. And I took it to an aluminum welder guy, welded the broken parts were bolts stand, put new thread to it and it was better because the treads we did, we did them to all the length of the bolt. The original ones are weird, although there is space, bolt being long enough, the tread in cylinder head is just about 15mm towards the tip of the bolt, than no thread all the way down to the very tip of the bolt, just space. Later on a mechanic friend told me that for that reason, without any accidents, he have seen on multiple Fiat cars having treads in cylinder head being damaged and could not sustain the engine on.
I am very please with the fix I've done, the car works fine and I did some service that it needed but I wouldn't hurry to do, like replacing valve seals and head gasket.
So what I am trying to say is don't give up on your car, see it from another angle. You will do unplanned service repairing. Like those on mine: valve seals and head gasket, maybe something else. It is a bit expensive, as you've not planned to do it, so maybe you feel forced to do it, but if you can afford it do it, cause it's a service that needs to be done and you don't do it everyday.
And remember: the valves are really not expensive at all, so you didn't do too much damage (cost wise). How you replace them... that's another matter.

 

[Pugglt Auld Jock]

Just a wee word of caution if you do decide to start replacing bent valves. Take a very careful look at the guides. I've seen them cracked by a valve being bent. Also, of course, it's likely that large forces will have been transmitted to the valve train - followers and cam lobes etc - so they need to be looked at very carefully too. Lightly "dimpled" pistons where the valve heads have made contact is usually of little matter but heavy contact may have done all sorts of hidden damage - not just to the piston crown but maybe to the ring lands (potentially jamming the top ring) I've read also that it's possible that con rods may have been bent/weakened and big end bearings damaged. I've done half a dozen or so with bent valves over the years and I've never seen this though. In our workshop we were very keen on just getting a used head from the breakers if we were repairing a customer's car but that was mostly because it kept labour costs to a minimum