View Full Version : Back-firing when starting
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)
the wombat
01-06-12, 19:16
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.
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.
Mine used to do that but not now...in fact it seems to have got a bit harder to start when hot.
...so it might just be that the wiring needs cleaning up???
wrinx
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/Phasensensor-Sensore-Phase-60809511-Delta-Coupe-16VT-/350420677001
wrinx
Steve Webb
02-06-12, 18:48
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
Steve Webb
02-06-12, 19:54
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/ubbthreads.php?ubb=showflat&Number=1348499
the wombat
04-06-12, 16:45
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...
the wombat
04-06-12, 19:14
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 :)
the wombat
04-06-12, 20:30
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.
Steve Webb
05-06-12, 10:28
If you take a look at the electrical pdf http://www.berlinasportivo.com/Technical/q4manual/155Body-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.
the wombat
05-06-12, 18:03
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
What are the two heavier cables on the Hall sensor...earths???
Yes, they're earths.
Wombat, were your three pins all loose too?
wrinx
the wombat
09-06-12, 00:15
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
the wombat
10-06-12, 21:00
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.
the wombat
14-06-12, 17:14
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.
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
Have you tried starting the car with the sensor disconnected?
Yes It did, puff puff broom broom:blink:.
Nice for you that the car now starting with out problem's.
Mine's still banging and popping :roll:
wrinx
the wombat
15-06-12, 06:01
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
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
Steve Webb
17-06-12, 07:05
Last time I looked, coil packs were cheap enough so unless you've swapped them recently, I'd get them done.
Exactly my thinking, just looking at some now :lol:
Could also be leads and grounds but for the sake of £12 each (ebay) it's worth ruling them out totally.
I've got a MAP sensor in stock somewhere but have read that the pipe to the sensor can become blocked or split, so that needs checking.
Beauty of the diag is that you can replace one item and then test for errors to see if clears the fault, rather than just replacing bits and hoping....I like it!
wrinx
Mmm...the plot thickens. The Startrek developer thinks I've got more serious problems with the EEPROM and EPROM. The latter can be explained by the Squadra but not the EEPROM :?
Perhaps an ECU fault, I don't know.
wrinx
Steve Webb
17-06-12, 21:35
Exactly my thinking, just looking at some now :lol:
Could also be leads and grounds but for the sake of £12 each (ebay) it's worth ruling them out totally.
I've got a MAP sensor in stock somewhere but have read that the pipe to the sensor can become blocked or split, so that needs checking.
Beauty of the diag is that you can replace one item and then test for errors to see if clears the fault, rather than just replacing bits and hoping....I like it!
wrinx
Getting to check the leads etc on the coils is going to be the major pain, so if you are going to do that, you may as well swap them out.
The small bore air pipe comes into the MAP sensor from underneath so you can't easily see if there is a problem there. If you are still running the original type pipe, I'd suggest swapping it out for a silicon one. They stay in place much better.
Just ordered the cables to be able to connect up the laptop to the car, so I can check all these things as well.
Oh and good luck with the ecu issues.
Getting to check the leads etc on the coils is going to be the major pain, so if you are going to do that, you may as well swap them out.
Exactly my thinking, coil packs bought for £12 each and if I've got to do down *there* (under the intake!) I'm not coming back out until it's all new...might event replace the leads too!
The small bore air pipe comes into the MAP sensor from underneath so you can't easily see if there is a problem there. If you are still running the original type pipe, I'd suggest swapping it out for a silicon one. They stay in place much better.
All looked good and iirc it's silicon.
Just ordered the cables to be able to connect up the laptop to the car, so I can check all these things as well.
Yeah, good luck with that...you may find out more than you want to! :lol:
Oh and good luck with the ecu issues.
...sometimes, too much information is a bad thing :lol:
wrinx
Steve Webb
18-06-12, 07:39
Well, seeing as the Q4 is undergoing something of an overhaul at the moment, its probably best I find out everything thats wrong with it.
Ok...update:
I've repaired the grounds in the ECU and replaced the MAP sensor and IAV, but it's still not starting properly; and what's worse, it's still giving exactly the same errors as before!
Unplugging the IAV when running doesn't seem to make much difference but it's a pig to idle when started without it.
Similarly, unplugging the MAP sensor causes problems.
I'm loathe to start throwing bits at it in the hope of a cure if one is causing all the problems....is it perhaps an ECU problem after all?
I need to test power and grounds to the various bits, but it's still throwing up coil 2 error, EEPROM, EPROM, VAE/IAV, MAP sensor and TPS :(
I'll be replacing the coil pack at some point, but the inlet has to come of and I'm really not motivated to do that!
wrinx
Ok...update:
I'll be replacing the coil pack at some point, but the inlet has to come of and I'm really not motivated to do that!
wrinx
may be some point, but in my previous v6 155, i had almost all of Your symptoms
i've even exchanged ECU so already have two spare ones,
ecu errors, ignition problems, cutting ignition on iddle, injector errors (replaced them also)
and guess what.... removed coil pack (very easy access) and underneath coil pack case was totally broken.
Replaced coil pack and no problems any more
so previously replaced injectors, spark plugs, twice ECU, spark cables, rpm sensor etc etc made quite big bill, and coil pack was only 1/10 of total price of this replacement
not to mention the stress and well-being that the engine is not working properly...
so my suggestion is that You will try with coilpacks as a start, not as last bit :)
regards
w
Steve Webb
23-06-12, 16:39
If it is a problem with the coil, might it be possible that the HV generated by the coil is not being contained within the coilpack and causing the other spurious errors?
Have you been getting more than the usual static shocks from the car? :hyper:
removed coil pack (very easy access) and underneath coil pack case was totally broken.
Replaced coil pack and no problems any more
Easy access :huhsign: We must be looking at different cars :lol:
Thanks for the information though, very helpful.
wrinx
If it is a problem with the coil, might it be possible that the HV generated by the coil is not being contained within the coilpack and causing the other spurious errors?
Have you been getting more than the usual static shocks from the car? :hyper:
I guess anything's possible, if the cars' not running right it'll be giving lots of dodgy readings...no electric shocks yet though :lol-030:
wrinx
Steve Webb
23-06-12, 17:41
Easy access :huhsign: We must be looking at different cars :lol:
Well maybe if you've dropped the subframe first. :rofl:
Easy access :huhsign: We must be looking at different cars :lol:
Thanks for the information though, very helpful.
wrinx
Just re-read your post and realised you're talking about a V6 :lol-030::oops:
wrinx
Just re-read your post and realised you're talking about a V6 :lol-030::oops:
wrinx
That's why access is easy :) it hit's your eyes when you open the hood :)
regards
Juan AR155Q4
09-07-12, 22:06
Try turning the camhsaft sensor "case", as I remember, you´re not with the std cams.
And the cam sensor position, has to be in a certain window.
You're correct, I've got a C&B inlet cam, but the car backfired and was difficult to start before this was fitted.
wrinx
Juan AR155Q4
16-07-12, 12:08
Anyway, try with the cam sensor case. May be it was rotated before.
Don't think so, it looks to be lined up in the correct position but I guess a play might be worthwhile :)
wrinx
Were all your problems solved regarding this or still the same?
I have this issue now on one of my cars, have checked all cables and wiring, new spark-plugs, measured and checked the leads.
Still back-firing when starting and more likely starts when I stop cranking..?
grateful for any tips or info regarding this..
Still the same on mine but I have other problems to solve before I can confirm anything.
These include coil packs and the aforementioned wiring.
wrinx
the wombat
20-10-12, 18:35
Starting just as it stops cranking, and popping and banging on start up sounds like the discussion we had a couple of months ago on dodgy cam sensors.
I think I mentioned I changed the plug on mine as it had bad connections.
Symptoms sound like they were similar.
Starting just as it stops cranking, and popping and banging on start up sounds like the discussion we had a couple of months ago on dodgy cam sensors.
I think I mentioned I changed the plug on mine as it had bad connections.
Symptoms sound like they were similar.
Yes I have read your previous discussion thoroughly.
I have rebuilt this engine myself during the summer, before it started just perfect but was leaking oil (hence the rebuild) when in parts everything was of course cleaned that was oily but this sensor was not one of the oily or dirty bits, so no excessive cleaning with though chemicals or anything was used on that one..
I have also changed to my other cars cam-phase sensor (which runs and starts very well but as it is my summer car sits in the garage for the moment) and the problem still exists I don´t see that the sensor is the problem
all the connections look fine and the cables as well, the spark plugs are new leads worked fine before the rebuild and the engine runs smooth and fine after the popping and banging (and I stop cranking) starts her up.
Getting desperate as I need to rely on this car and I suppose the battery will take it´s toll after a while from all the cranking? anything else that may take damage of this?
Hello guys, I am afraid I have stuck on this problem still..
Need your help now!!
I start from the beginning, due to many oil leaks and finally a blown headgasket I completely (standard-)rebuilt my engine this summer with new gaskets and sealing all the way, new piston rings and bearings, completely renovated head (by a enginerebuild-company, not by me), renovated the injectors with new filters and so on (by a company who does these things, not myself), new sparkplugs (BP6ET, are these right/Ok?) you get the point no expenses spared, altough keeping it standard as I intend to use it as my daily driver. now to the problem:
After the rebuild the car backfired when try to start and started when I stopped the cranking in the beginning, I have doublechecked all connections and cables that I can think of, exchanged the camshaft-phase-sensor, tried with the crank-position-sensor tried with the starter motor, tried changing the ignition module and the ignition-coil packs and nothing has even made a difference, I have doublechecked the cambelt fitting
Now I am left with 2 non-working cars, the black one is stripped to take parts from to try on the red one to get it running, as the other one anyway stands in the garage during winter no biggie..
I have also left the car in desperation to a local "Alfa-specialist" (that actually knew what car this is, he runs a dyno-shop with usual customers ferraris and lamborghini and many alfa) to adjust the timing and look at the start-problem, he did the same tests as I have done and three weeks later he calls me and says he won´t continue as he is overbooked and I have to come and get the car, when I come to get it he says "that´ll be 1100 EUR", the car still wont start and it is exactly the same as when I left it there, although I now have new earth/ground cables between the battery and the chassis and engine to chassis as he thought it could be "earth/ground-problems"..
my wallet are now much lighter but the same problems still and have escalated into now not starting at all with the ignitionkey, runs well if you tow it and put in gear (don´t know the english word, jumpstart? no thats with cables)..
the car is fitted with an immobilizer system, can this be causing the problems somehow, during the dis-/reassembly the chassis only stood outside my work, nothing changed there.
another info is before the rebuild the immo-system could come off during a drive and the red indication light came on and a long (2min) beep could be heard and sometimes shut down and sometime left on until I parked the car and then stopped a minute after stop, but the car could also die during running and then be a bit cranky to get started again but not backfiring like now.
any ideas would be greatly appreciated
Solved the back-firing issues I have had for some time now, It all was the hole way a "broken" misfiring ignition lead for the 3rd cylinder.. You would think that a workshop that charge you 1100 Euro would have already checked those =P
now all is well
Merry Christmas to you all..
You would think that a workshop that charge you 1100 Euro would have already checked those =P
You would indeed, have you thought about complaining?
wrinx
Steve Webb
22-12-12, 16:54
Shocking behavior from a so called specialist
I've just read through all that David, its pretty despicable behaviour from a specialist who supposedly knows what they are doing.
I suppose they have charged you for the time of one of their mechanics, but if I ran the company I wouldn't have the gall to charge a customer that much if I hadn't fixed the problem.
I guess you won't be going back there again will you.
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