[Jeroen]

Get it hooked up to a proper OBD analyzer and don't do anything or believe any advice from the internet until you have checked for error codes

[ajmat]

I would heed Jeroen's advice but a gut feel would be that the heat causes some connector or relay not to work

[Jeroen]

Originally Posted by ajmat

I would heed Jeroen's advice but a gut feel would be that the heat causes some connector or relay not to work

This is the problem: The Internet has already come up with the following advice:

- Fuel Pump Relay
- Vapor Lock
- Coolant Sensor
- Coil
- Starter motor
- coolant temp sensor and relay
- some connector

You could be busy for several hours, of having to pay somebody and not have found the problem. When trouble shooting it’s always good to try and use some logic. Logic dictates that on any modern car with problems, always hook it up to a good analyser. Even if it doesn’t give you error codes you can at least disregard a number of potential problems and concentrate on bits that won’t show up on an analyser.

If I have to go by gut feeling / experience alone, I would say coolant temp problem, sensor, connector, crank sensor or otherwise electrical. Very difficult to trouble shoot unless a visual inspection shows damage. You can do some simple measures with a multimeter, but if it is any of these you have a 95% chance it will show up on an OBD analyser. Otherwise it’s rip and replace and see what happens.

Good luck

Jeroen

[Sutripta]

Originally Posted by VW2010

Please ignore ignition coils.

Where do we stand on vapour lock as a cause?

@g_g - Going by 'simplest job first', use Iftex D for two tankfuls first.

Regards
Sutripta

[Jeroen]

Does your car have a rev counter. Does it move when you crank the engine but won't start?

[headers]

Originally Posted by Jeroen

Does your car have a rev counter. Does it move when you crank the engine but won't start?

Interesting point. What does the rev counter moving / not moving while cranking indicate?

[Jeroen]

Originally Posted by headers

Interesting point. What does the rev counter moving / not moving while cranking indicate?

Actually, my question should have been a bit more specific. Do you see a difference on your rev counter during cold and warm (i.e.) the failed starting.

On diesel some rev counter go off of the crank, some off the flywheel (or another gear), some off the alternator. There are even one or two other option too.

In some cases the rev counter gets disabled during starter. So cold or warm start would not show anything different. Sometimes the scale is such that you simply don't get a reading during cranking. But if this was a case where the rev counter does move whilst cranking it would be interesting to hear if there was any difference observed in how much difference between cold/warm start. If it turns slower it could be an indication of a problem with the starter motor. Starter motor have higher impedance when they are warm, normally not a problem, but as they get old this sometimes could get worse.

If normally the rev counter shows some rpm and now with a warm start not at all and it still sounds like it making sufficient revolutions, depending on how its wired up you might have an inclination where to start looking. If it's signal comes from say the crank sensors, I would say that would warrant further investigations etc.

On petrol engines its somewhat different. A lot of rev counters take their signal from the main coil. If the engine doesn't want to start and no revs displaying during cranking where normally it would, better check the coil.

Again, you really need to check per engine how/where the rev counter gets its pulses from.

Jeroen

[Aravindpn]

Hi All,

Had a tough experience last week. My Corolla (2006) broke down 300 meters (thankfully) from my home and that too when I was taking my 1-year-old daughter having 102 fever to cloud 9 Jayanagar. The vehicle was cranking and immediately rpm came down to 0 while pressing accelerator and dies off. Got a mechanic from a comparatively new but big garage near home and they asked for towing the car to the garage. After checking electrical, fuel pump etc., they zeroed in on ECM of the car. They asked for my approval to repair the circuit board of ECM yesterday and confirmed me that it was done by an outside guy and the repair cost of ECM has to be paid only if car starts. Just now got a call from them that car has started and it was indeed ECM mal functioning. They will observe the car and will run it for 50-60 kms to confirm everything is fine. Now my questions/ worries here:

1. I used to give the car to service only at Nandi Toyota, Bommanahalli. Since the place is far from my residence and towing to Nandi on that day looked cumbersome (rainy day also) I
took the help from nearby garage.
2. Nandi wont repair circuit board of ECM. They will just replace it (as per call with known service personnel there). He also confirmed that people repair this outside.
3. The car is very sparingly used. Only 78k done over last 11+years.
4. Any reason for ECM malfunctioning? Will it happen because of less use? Sometimes car is not started for 2 weeks.
5. If anyone have an experience with ECM circuit board repairing, how reliable will be this? Should I later on change ECM module in Nandi? My conservative estimate will be more than
50k for this job at Nandi. Please validate.
6. What all points I should take care when I drive the car now? Mostly when I take out the car it will be with full family and long drives. My mind is getting worried about the car getting
into ECM issues in middle of highways.

Experts, please help me with your inputs

[Jeroen]

Originally Posted by Aravindpn

.
4. Any reason for ECM malfunctioning? Will it happen because of less use? Sometimes car is not started for 2 weeks.
5. If anyone have an experience with ECM circuit board repairing, how reliable will be this? Should I later on change ECM module in Nandi? My conservative estimate will be more than

In my experience it is very rare for the ECM to have any problems. A lot of so called electronic problems tend to be related to what I would call more electrical and or mechanical issues. A sensor gone bad, a wire broken, a connector got dirty, poor grounds etc.

However, ECM can of course and do go wrong on occassion. It depends a bit on what type of ECM it is, but broadly speaking there are two kinds of problems:

1) A component (e.g. resistor, capacitor, etc) goes wrong
2) A mechanical problem such a soldering point coming apart.

It really depends on the skills and competence of the individual to what extend he/she can carry out such repairs. The more modern the ECU is, the more difficult it becomes.

My Alfa spider has some of the first series of ECU's from Bosch. Very simple electronics. Easy to open up, easy to inspect visually and do some basic electronic checking as well.

On my 2002 Jaguar there is a well known problem with the ECU and BCM. The soldering over the years becomes a little to brittle and starts cracking. Resulting in all sorts of vague problems. The solution is very simple, you just resolder every connection on the PCB. Again, you can do this on these units, because it's simple to open them up and stick a good soldering gun into it.

On moderen ECU it might be a problem just opening the damn thing. Multilayer PCBs dont lend themselves to DIY type of repairs.

So it really depends, the more modern/advanced ECU, the more advanced workshop and skills you need to fix it. If possible at all.

Jeroen

[Aravindpn]

Thanks Jeroen.

Yesterday had a test drive after ECU correction and felt that refinement has increased and also temperature gauge which consistently was on middle in last few years dropped a bit. Will get the car after the elaborate checks by tomorrow.

Again, if someone here had done the ECU repair for similar segment, will appreciate their observation over the period of time.

Also, asked them exactly what has been done with ECU. The input was, no component has been changed, just remapping of circuits has been done. Not sure what they mean by this. They will check with ECU guy again.

[Jeroen]

Originally Posted by Aravindpn

Also, asked them exactly what has been done with ECU. The input was, no component has been changed, just remapping of circuits has been done. Not sure what they mean by this. They will check with ECU guy again.

Remapping means they put new settings/parameters on the ECU.

An ECU is just like any other computer. It has a number of programs that control various functions on the car and engine in particular. For instance how much fuel gets injected when you press the throttle. The ECU checks for instance, temperature, RPM, how far did you press the throttle and then commands extra fuel. All of these correlations are set via parameters. Remapping means they have put a new set of parameters in. They might also have updated the actual software on the ECU (akin to your operating system on your PC).

So yes, when a remap is done the car might feel a bit different. There are several threads on the forum on ECU remapping. It is the easiest way to improve on engine performance without evening opening the bonnet! All done through software settings/parameters.

good luck,
Jeroen

[wooka]

Team, I need your help desperately. I've just picked up a Swift 2010 K series from the family, and it has the writings of a breakdown in the middle of nowhere all over it!

The engine will die out after cranking (ignition does indeed happen) if I don't tap the accelerator. Once on, it can run a hundred miles. This happens mostly (90% failure) with a cold engine though happens with a hot engine (40% odds) as well. I recently had these parts changed with a hope I could nail the weakest link - engine oil (now synth), transmission oil, fuel filter, air filter. The car throttles freely and I can do good speeds in it easily.

Kindly turn on closed captions!

https://youtu.be/W2YbEgp75M4

Help!

[hserus]

Originally Posted by wooka

The engine will die out after cranking (ignition does indeed happen) if I don't tap the accelerator. Once on, it can run a hundred miles

Fuel pump / pump relay? Ignition coil?

[Aroy]

It is either loose contact with ignition coil, or clogged fuel filter. Get both checked.

[great_guns]

The mystery deepens

The story so far
1) Excellent first crank startup on cold start and no start in hot condition.
2) successful workaround of keeping accelerator pressed while cranking - engine starts in 5-6 crank attempts
3) checked battery. No issue found.
4) checked relays. No issue found.
5) diesel filter found clogged. Replaced. Issue not resolved.
6) fuel pump found to be intermittently working. Replaced. Issue still not resolved.
7) hooked up to service center scanner and found 2 error codes (G40 CAM sensor and G28 engine speed sensor).
8) hooked up to external garage scanner. No errors found.

What else is left to explore? :( Fuel tank has lots of debris floating around which will be cleaned in my next visit but can't imagine that's the primary cause of this peculiar problem.

Any pointers?

Originally Posted by great_guns

I've been facing a peculiar problem since the past 2-3 weeks. My car starts perfectly fine in first crank in the morning or after staying unused for a few hours. If I shut off the engine after driving for a certain period of time and then shut it off, it won't start again until the engine cools down. The cranking is stable but the engine doesn't catch.

To me this looks like a possible case of vapor lock or a failed Crank sensor. I read that in modern fuel injected cars the chances of vapor lock are minimal.

I tried a hack that I read somewhere on the internet which is to keep the accelerator pedal pressed while cranking which I guess floods the fuel line getting rid of the vapor. When I tried this trick, I was able to start the car when hot but after 10-15 cranking attempts.

So basically all this points to vapor lock but could anyone here suggest alternative problems that I should get investigated? I'll be taking this in to a garage anyway but am looking for some pointers on what we should investigate first.