Turns over wont fire help please

Turns over wont fire help please

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cris654321

Original Poster:

233 posts

159 months

Friday 4th November 2016
quotequote all
mechanical guru's please help my girl friend needs to get to work on Monday frown

vw polo 1.4 petrol 2005

turning over wont fire

fuel pump whirring when turn key

checked fuel rail pressure, not got a proper gauge but spurts out fuel then stops with just ignition on not turning. I haven't tested while turning over, should I?

tested one individual coil pack wasn't sure which terminal was which, so tested all 4, 3 had nothing, 1 had 12v with just key then dropped to 6v when spinning over (not sure if thats correct or not.... the fact there is power there at all rules out crank or cam sensor????)

I would like to look at a spark plug while turning but dont have the right socket to remove the spark plug

the oil is right level decent colour no leaks I can see no oil or mayo in the coolant coolant is clean

battery is not flat but boost pack on anyway and no difference

cambelt was changed a year ago iv looked at the belt all looks tight and right

have tryed plugging a cheap OBD reader in but says it wont connect this may be the reader at fault although it is quite new

what else can I test or try??

thanks in advance for any help

Chris

GreenV8S

30,150 posts

283 months

Friday 4th November 2016
quotequote all
Diagnosing a modern engine without the right tools or any knowledge of how it it supposed to work is going to be extremely difficult. Without any disrespect to you, the best advice you can give your GF is to take it to somebody experienced and equipped to diagnose this sort of thing. That might mean calling out your breakdown service (if either of you have one) or finding a friendly local mechanic.

stevieturbo

17,229 posts

246 months

Friday 4th November 2016
quotequote all
It really does sound like that.

No experience, no tools, no knowledge.....not sure how anyone is going to help you here.

But back to basics, check for spark, check for fuel, and ensure air is available.

Edited by stevieturbo on Friday 4th November 22:11

Steve H

5,224 posts

194 months

Friday 4th November 2016
quotequote all
Two tests that you should do next -

To check for a spark remove a coil and put a bolt or short metal rod into the end where the spark plug would go. Rest the coil against the engine bock so the end of the bolt is around 5mm from the head (wiring plug still connected to the coil). Crank the engine and you should see a spark.

To check if the injectors are being triggered hold a long screwdriver to the body of one of the injectors and (get someone to) crank the engine while listening to the end of the screwdriver. You should hear a sharp ticking noise coming from the injector body. Yep, really, I st you not.



Chances are one or both of these things will be missing, report back.

trickywoo

11,704 posts

229 months

Saturday 5th November 2016
quotequote all
Could be something as simple as a duff cam or crank position sensor but unless you want to throw parts at it the best thing to do is read the faults.

Simply checking for fuel and spark on a modern engine won't get you very far.

cris654321

Original Poster:

233 posts

159 months

Saturday 5th November 2016
quotequote all
Steve H said:
Two tests that you should do next -

To check for a spark remove a coil and put a bolt or short metal rod into the end where the spark plug would go. Rest the coil against the engine bock so the end of the bolt is around 5mm from the head (wiring plug still connected to the coil). Crank the engine and you should see a spark.

To check if the injectors are being triggered hold a long screwdriver to the body of one of the injectors and (get someone to) crank the engine while listening to the end of the screwdriver. You should hear a sharp ticking noise coming from the injector body. Yep, really, I st you not.



Chances are one or both of these things will be missing, report back.
Thanks those sound like logical things to try I will do them today and update later.


GreenV8S said:
Diagnosing a modern engine without the right tools or any knowledge of how it it supposed to work is going to be extremely difficult. Without any disrespect to you, the best advice you can give your GF is to take it to somebody experienced and equipped to diagnose this sort of thing. That might mean calling out your breakdown service (if either of you have one) or finding a friendly local mechanic.
I know I sound like a moron on here but I do understand the very basic processes of an engine just not really done any diagnostics before. I have done alot of work on my own cars. I just like learning how to do things. Getting someone else to do it is the easy way ha ha, teach a man to fish and all that wink

stevieturbo

17,229 posts

246 months

Saturday 5th November 2016
quotequote all
trickywoo said:
Could be something as simple as a duff cam or crank position sensor but unless you want to throw parts at it the best thing to do is read the faults.

Simply checking for fuel and spark on a modern engine won't get you very far.
How wrong you are.

If you do not start with the basics first....then you'll never get anywhere.

Ignoring whether the engine has the vitals it needs to run will never get you far.

Boosted LS1

21,165 posts

259 months

Saturday 5th November 2016
quotequote all
stevieturbo said:
trickywoo said:
Could be something as simple as a duff cam or crank position sensor but unless you want to throw parts at it the best thing to do is read the faults.

Simply checking for fuel and spark on a modern engine won't get you very far.
How wrong you are.

If you do not start with the basics first....then you'll never get anywhere.

Ignoring whether the engine has the vitals it needs to run will never get you far.
Unless you intend to push it :-)

GreenV8S

30,150 posts

283 months

Saturday 5th November 2016
quotequote all
cris654321 said:
I know I sound like a moron on here but I do understand the very basic processes of an engine just not really done any diagnostics before. I have done alot of work on my own cars. I just like learning how to do things. Getting someone else to do it is the easy way ha ha, teach a man to fish and all that wink
You may be able to fix it yourself eventually, but it is likely to involve a lot of learning and trial and error and time and money.

If your goal is to provide your GF with the quickest and cheapest fix so she can go to work on Monday, take it to an expert. Trying to diagnose it yourself will involve you spending time and money fixing things that weren't broken, may well involve you breaking other things along the way, may take a long time to finally fix the problem and may even turn out to be beyond you. Unless you think your GF is happy for the car to be off the road for a few weeks while you figure that out, consider that by trying to fix the problem for her you aren't actually doing her any favours and the best help you can provide is to help her find a reliable local garage and make sure they don't take advantage of her mechanical ignorance to rip her off. From what you've said it's clear that you would be able to follow the garage's explanation and know if they were trying to BS you.

If it's a simple problem it will be quick and cheap to have diagnosed and fixed. And if it is a complicated problem, well it's unlikely that you were going to fix that yourself in any case.

Sardonicus

18,928 posts

220 months

Sunday 6th November 2016
quotequote all
Might be nothing more than flooded (easily done if shunted about) these drive by wire throttle systems can be hard to flood clear at times, agree with mentioned already fuel and spark check essential

Steve H

5,224 posts

194 months

Sunday 6th November 2016
quotequote all
Given that the car was needed for tomorrow but we've heard nothing from the OP since yesterday morning I'd guess that either

a) It's fixed
b) It's going somewhere to get fixed
c) It's not gonna get fixed by tomorrow.

trickywoo

11,704 posts

229 months

Monday 7th November 2016
quotequote all
To all the people saying to check fuel and spark he already says he has fuel so what would you suggest the next step if he has:

1) Spark

2) No spark

On a modern breakerless ingnition system their aren't many causes beyond physical damage for no spark.

I really think anyone saying that checking spark and fuel is better than reading the codes on a modern ecu controlled engine is behind the times.

Spark and fuel are the first things I'd do on a carb and points ignition system and do on my non-starting mower / 2 stroke garden machines but on a modern car I think you are wasting your time. Happy to be factually educated however.

rev-erend

21,404 posts

283 months

Monday 7th November 2016
quotequote all
Take a few test spark plugs (any type) and disconnect each plug lead and inset extra plugs .. rest each on something metal ..

Then turn over engine to see if they have a spark..

Does it have an alarm / immobaliser ?

stevieturbo

17,229 posts

246 months

Monday 7th November 2016
quotequote all
trickywoo said:
To all the people saying to check fuel and spark he already says he has fuel so what would you suggest the next step if he has:

1) Spark

2) No spark

On a modern breakerless ingnition system their aren't many causes beyond physical damage for no spark.

I really think anyone saying that checking spark and fuel is better than reading the codes on a modern ecu controlled engine is behind the times.

Spark and fuel are the first things I'd do on a carb and points ignition system and do on my non-starting mower / 2 stroke garden machines but on a modern car I think you are wasting your time. Happy to be factually educated however.
No he did not say he has fuel. He said he can hear the pump prime on key on. That is absolutely not the same thing.

And there can be many causes for no spark...presumably you've never diagnosed too many cars ? And in this instance...he didnt even have any means or ability to check for a spark.

And if you think blindly reading codes is a fix for a non starter...once again, clearly you've never diagnosed and actually repaired too many cars.

Steve H

5,224 posts

194 months

Monday 7th November 2016
quotequote all
trickywoo said:
To all the people saying to check fuel and spark he already says he has fuel so what would you suggest the next step if he has:

1) Spark

2) No spark

On a modern breakerless ingnition system their aren't many causes beyond physical damage for no spark.
Not the case at all, there's more different reasons than with points or standalone electronic ignition.


trickywoo said:
I really think anyone saying that checking spark and fuel is better than reading the codes on a modern ecu controlled engine is behind the times.
None taken laugh.

The trade is full of robots who reach for a code reader and ignore the basics, I'm the guy they call in when that doesn't work so I'd like to think I'm reasonably up with the times.

trickywoo said:
Spark and fuel are the first things I'd do on a carb and points ignition system and do on my non-starting mower / 2 stroke garden machines but on a modern car I think you are wasting your time. Happy to be factually educated however.
Trouble solving on modern motors is all about cutting the options down.

So, if I have a spark I know the following -

The ECU is powered up
The ecu is seeing at least some form or RPM signal and is reacting to it
The coil(s) are powered and working

It's a 20 second test that tells me a lot of information.

Checking the injector triggering covers a lot of the same information but if I had spark but no injector trigger that might mean something different to injector trigger but no spark etc. Either way by the time I've done those two simple tests I'm zooming in on the possibilities of the failure.

Code readers are great but they often don't give the answers and they are not the first thing I reach for on a non-starting car.

GreenV8S

30,150 posts

283 months

Monday 7th November 2016
quotequote all
Steve H said:
Either way by the time I've done those two simple tests I'm zooming in on the possibilities of the failure.
This is why you take the car to an expert who knows how to do this sort of diagnosis.

Somebody without the tools and expertise to make these tests safely and accurately, and without the background knowledge to understand what the test results tell them about the state of the engine management system, is at best wasting their time and more likely going to make the problem worse.

Steve H

5,224 posts

194 months

Tuesday 8th November 2016
quotequote all
I suspect that this ^^^^^^^ is what the OP decided as well yes, in this case a bit of guidance could have been given to an enthusiastic amateur (at least for the first couple of stages of investigation) but I agree he's probably better off just getting it done professionally.

Penelope Stopit

11,209 posts

108 months

Tuesday 8th November 2016
quotequote all
Steve H said:
I suspect that this ^^^^^^^ is what the OP decided as well yes, in this case a bit of guidance could have been given to an enthusiastic amateur (at least for the first couple of stages of investigation) but I agree he's probably better off just getting it done professionally.
You gave good guidance further up this page so the OP did have a good direction to head in
As you have commented, code readers are only an aid, many years ago I became pissed right off with the direction the auto service and repair trade was heading in, my opinions have now been confirmed, there are too many people in the industry that are not skilled enough to be there, the whole situation has got way out of hand, the governing bodies in the service side of the automotive industry are a major shambles
Most skilled people that really do know the ins and outs of diagnostics have moved on to better things and those that are now made out to be the skilled ones are in fact semi-skilled at best because their is a free for all, training programmes are nothing like they used to be
I appreciate that there are still some gooduns about but.....What a feckin mess it all is

stevieturbo

17,229 posts

246 months

Tuesday 8th November 2016
quotequote all
For a problem like that...code readers are usually the first route of choice for fools...because they have this naive expectation that code readers fix all problems.

Obviously experience would tell people who know...there are more appropriate ways to diagnose and fix problems.

Code readers have their place....a very limited place I might add vs proper diagnostic scanners though. But for a non start like that, proper work needs done.

trickywoo

11,704 posts

229 months

Tuesday 8th November 2016
quotequote all
stevieturbo said:
But for a non start like that, proper work needs done.
We won't know if OP doesn't come back but I'll bet a virtual pint that its a duff cam position sensor which a simple plug in would tell you in minutes.

No need to get your hands dirty until you've eliminated the simple stuff. Just pulling the plugs on some modern stuff can take you a good while and for little gain.