I get an occasional bang when cranking the car over and it's sometimes hard to start...iirc, the crank sensor was suggested last time I mentioned this.
Any other ideas?
wrinx
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I get an occasional bang when cranking the car over and it's sometimes hard to start...iirc, the crank sensor was suggested last time I mentioned this.
Any other ideas?
wrinx
If the crankshaft's sensor doesn't work the car won't start. Most possible the camshaft sensor. Is it reving nice?
%100
defective cam shaft sensor
(cam shaft socket / cable)
Interesting, mine does the same. Sometimes it pops a bit and starts a second after you have stopped cranking it.
Will clean up the plug and cable tomorrow and see if that makes a difference.
The phase sensor on mine was replaced when I got it back on the road 8 years ago. It gave very similar symptoms!
Did it stop back firing...?
Phase sensor being the Hall sensor on the right of the head?
wrinx
Yes, and yes, that's the one.
Could have been other issues too though. It was all a bit new to me then!
Typically...you can't get this from Alfa anymore :?
p/n is 7689407 (previous 60809511).
wrinx
£400!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
http://www.ebay.co.uk/itm/Phasensens...-/350420677001
wrinx
Thats got to be available elsewhere!!
Unbelievable price.
Agreed...although it's worrying that someone has bought one, perhaps they are really that hard to find :(
wrinx
A fool and his money are easily parted!
Do you have any idea who makes them?
Fiat Coupe in a breakers yard would be my choice. It should fit I think.
Mine too...I have a friend who breaks Coupes :cool:
wrinx
My car also back fire's when turning the starter. I have changed the cam's to more race spec. Do ecu need new parameter or Will this be correct when timing is adjusted
Maybe of interest - not sure about it working on a 16vT though.
http://www.fccuk.org/forum/ubbthread...Number=1348499
Checked the connector on mine today. 2 pins of the 3 quite badly corroded. Cleaned everything up and on a couple of fire ups, seems to have instantly improved it, but will keep an eye over the next week.
I was talking to my brother in law about the 155 24v V6 conversion I am just started on at present, as the 2.5 12v does not have a cam sensor, but the 3.0 24v does. I wanted to ensure that was not going to cause problems. Examination of the 2 different engine wiring diagrams reveals all
Apologies if you already know this...
The 156 V6 ECU (where my 3.0 engine originally was transplanted) has a pulse signal for each coil pack, and a signal for each injector. The 2.5 155 has a combined coil pack where spark plugs are paired up, and the same with the injectors. This means that the injection/ignition system only needs to know where TDC is because it injects and sparks every turn of the engine. On the more sophisticated later ECUs, the fuel and spark is only on the appropriate engine stroke (induction for injection and compression for spark), so the ECU needs to know when the inlet valve are open for injection, and when all valves are closed (for ignition), hence the cam sensor signal is needed as well as the crank position sensor.
The cam sensor does very little (apparently it can help fine tune injection and ignition timing) when the engine is running. To prove the point, I disconnected mine when the engine was running and it continues to run fine. But, cam position is needed for starting to get injection and ignition in the right place (curse those 4 strokes!!).
On the 12v V6, you get an injection pulse and a wasted spark every engine rotation for a given cylinder.
So if the cam sensor is starting to mis-read, you will get the popping and banging when trying to start. Again, to prove the point I tried to start the Q4 without the cam sensor connected - exactly the same symptoms as in this thread, but with no eventual start.
Interestingly, there can be similar symptoms if the earth for the engine is bad.
Sorry if everyone already knew the above. I found it fascinating, and it was coincidentally part of the discussion on how to wire up the 24v V6 to the 155 V6 ECU.
Thanks for that :cool:
I'll check mine over as it's definitely getting harder to start, although a duff battery and dodgy alarm/immobiliser aren't helping :roll:
wrinx
This is a timing problem and the phase sensor (hall sensor) controls it. It has a very simple architecture and very hard to break its internals. It usually suffers from overheated connectors and after some time passed they get crispy and very easy to get cracked, so the connectors usually don't work and we can see the engine backfiring especially on starting. Just check the cabling and go on.
The Fiat Coupe 16V Turbos use the same sensor and can be found easily but usually price is very high. I have a spare of them and will change the whole injection system and replace the ecu if both fails... Some old versions of this engine (Other Fiats and Lancias) has distributor directly attached to there instead of this phase sensor for timing.
Only Lancia Delta Evo II 16v, Fiat Coupé Turbo 16v and 155 Q4 is using this sensor on this planet. Maybe someone can find an alternative for the sensor inside of this part. Just open the 2 screws and you will see a cylinder cut horizontally about 1cm or less and a sensor creating a signal when this section comes in front of it. If we can find a replacement sensor for it it would be praiseworthy...
Check the earths as well. The tech discussion from my BiL seemed to go along the lines of:
- Bad earth robs the ignition system of energy so weak or no spark
- Once cranking stops, might get a good pulse that creates a good spark
- If there is fuel, might be lucky and the good spark ignites it and spins the engine which runs, or might be unlucky and get a backfire
The earth cables don't make the ignition system suffer only starting engine. You can feel something going wrong at anytime you are driving your car and your car's electrical controls can act meaninglessly like the windows won't open etc...
My car started to squirt water to screen without any effort while cruising and wipers didn't work :)
Very off topic but...
Wiper earths etc are normally different earthing points to the chassis than the main engine block earth, which in most 90s Alfas was battery negative strap to gearbox. ECU was also earthed to the cam cover or plenum on quite a few cars.
I reckon washers and wipers are likely to be a separate issue with a chassis earth.
If the engine block earth is badly corroded/not making a good contact, it can be detrimental to a good spark when power is going through the starter motor. Worst case, if the ECU is earthed through the block and the main earth is faulty, might get some random ECU behaviour (never experienced that though). Correct that it is on startup, but the issue being described will be ignition related because of this.
It can be replicated, loosen off the ECU and gearbox earths. If you suspect its happening, easiest test is a jump lead from battery negative straight to a clean part of the head to bypass the suspect faulty block earth.
If you take a look at the electrical pdf http://www.berlinasportivo.com/Techn...Electrical.pdf you can see just how many different earth points the 155/Q4 has. Some of these are in dodgy places susceptible to rust, so its always good practice to make sure you've got a good earth and connections before checking anything else.
Bit more extensive testing today. No backfire when starting, but still takes a little bit of cranking to start when warm.
What are the two heavier cables on the Hall sensor...earths???
The connector and it's three pins looked in good condition although all three were very loose...is that normal?
The two heavy cables were a bit grotty so cleaned them.
Replacement battery on the car means it started on the button, so perhaps that's something which has been making it worse too.
wrinx
Pins were tight, but badly corroded. Showed BiL the plug yesterday, and when he waggled the wires, the black one (shield I think) came out of the plug.
Holding it out of the way, car really struggled to start. Holding it in the plug, car started kind of OK.
To be sure all is well, we cut the plug off and soldered a brand new one on today. No starting problems so far and no popping and banging.
So in summary, no loose pins, but plug fubarred so replaced.
On a slightly different but related topic, my cam sensor unit is actually quite noisy. Went over the engine with a technicians stethoscope today, as there is a rattle coming from cmbelt end that I can't trace, and the top end seemed noisy. Still no wiser to the cambelt end, but suspect the a/c pump clutch (needs removing altogether), but front cam sensor end is definitely noisy compared to inlet cam.
Has it got trick cams in...I forget? If not, you might have some wear on one of the lobes, the exhaust cam is known for it.
Think I might have to remove the sensor and inspect these wobbly pins...car starting slightly better, but not much and probably down to a newer battery.
wrinx
Standard cams, but new when Sub had the engine built.
Wobbly pins might suggest a bad connection in the plug/unit - yep, time to take it to bits!!!
It was a pig to start after the event today...being sat in the sun can't have helped so perhaps the air temp sensor is dodgy too :roll:
wrinx
I have open the sensor and checked all wires. They are in good condition. But after testing and turning of the sensor I saw that black wire on the plug goes to red on sensor. Red in the plug goes to green on sensor and at last the green goes to black on sensor. Is that the same for you? Strange that they don't correspond
I've just opened mine to check the loose connections...all is well despite the sloppy pins.
Didn't notice any difference in the colours, but as there's only one way it can connect it must be ok.
The earth wires felt terrible but are actually very strong, it's just the heat shielding which is hardening and breaking down with age...the three wires in each seem fine.
wrinx
I have measured that its correct as it is. Just thougt the sensor was change some time with one from a coupe or some other with not matching wires.
Anyway there is no effect on the engine if the sensor is connected or not. No effect if I turn the sensor. The only thing that effect is when you connect the plug to the sensor when engine is running, then the engine stops.
Have you tried starting the car with the sensor disconnected?
The cam sensor is to tell the ECU what position the camshaft is at when the engine starts, and in some ECUs the signal is used to fine tune spark/injector pulse when the engine is running. Generally, the engine won't start if the engine has sequential injection (i.e. each injector fires only on the cylinders inlet cycle) and the sensor is unplugged or fubar.
Just to break the good news, mine starts on the button everytime since I replaced the loom plug for the sensor.
Good to know....where did the plug come from?
I removed the rubber boot on mine and the plug/wires looked perfect...but, there was some hardening of the wire (heatshield?) where it bends just before the plug, so perhaps I have some high resistance issues???
wrinx
Mine's still banging and popping :roll:
wrinx
Its possible that the problem is the sensor breaking down, or resistance as you say. Could not even be related worst case.
The plug is a standard 3 pin ECU loom plug. BiL had a new one with pigtails lying around. He thought it might be a Kia one!!!!
Integrale, good to hear the car started without the sensor. That is quite unusual though.
Okaay, after reading my codes the cam sensor hasn't popped up, but the following have:
When cranking there's a definite TPS and coilpack error and a possible MAP sensor error.
When revving there's a definite coilpack error and possible TPS/MAP errors.
Errors for idling are strange because the codes are not listed, so I'm guessing (same as the "possibles" above) that they're made form two added together :roll: These *might* be idle stepper motor and coilpack again.
Would the TPS sensor stop it starting? I know the MAP sensor might...coilpack error could produce a weaker spark to hinder starting.
The code 3 (not listed) was there all the time the engine was running, whether idling or revving...this *might* be TPS(1) and MAP(2)...I've emailed Neil to find out :)
wrinx