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2003 156 JTS 2.0 selespeed cold starting problem

4809 Views 107 Replies 4 Participants Last post by  156and33
Hi
I’d welcome a few ideas on troubleshooting a morning starting problem with my old car that I need for work (done >250k klm)

Symptoms:
Used to always start first time, then took a while to fire up on first crank. It would stop cranking by itself even though the key was in the crank position (I thought this was weird). Now struggles to start first time, but cranks strongly until I release the key. Usually starts second go but sometimes not convincingly. Problem only occurs in the morning (20 Celsius), never any issues rest of the day.
Generally driving OK, no performance issues that I have detected, perhaps a the odd splutter
Battery tests ok with carbon pile load tester. Voltage drops from 12.6 to 12.3 over night. Having to keep on charger. Alternator is charging OK. Starting issues do not appear to relate to battery voltage
I know I have a main bearing seal leak and there might be oil in the bell housing… not sure if that can interfere with the crank sensor operation
No fault codes stored
Recent repairs:
Fuel rail pressure sensor replaced. Crank position sensor replaced after stalling/starting problems (last repair). New battery July 2020. Starter replaced Feb 2021. Alt replaced Sept 2017. Plugs not due to be replaced.
Cam belt due for replacement at the moment
Troubleshooting so far:
I thought maybe the fuel pump relay might be dicky and swapped the fan and fuel pump relay - no change
Ecuscan tells me the actuators and relays work, fuel pressure is regulated at ~50 bar, lambda signals from each bank are the same, battery voltage 13.7v at idle. Don’t really know what else to check.
I carefully sprayed some gas around the engine bay looking for keaks, no change in RPMs
Spark plugs were dry sooty black but that was after idling for 10 mins, electrodes OK
Sprayed the MAF with some dedicated cleaner
Thanks
Duncan
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Discussion Starter · #43 · (Edited)
OK. Nothing badly wrong there but a couple of things are a little unusual but I must remember you are in summer heat so probably mid-high twenty odd degrees.

The air temp is fairly high but somewhat expected due to heat soak.
MAF is rather low. It is lower than I've seen a 1.6TS at idle.
LTFT are leaning the mixture a little.

Your car has covered a fair distance and I'm guessing the engine hasn't been apart. I'm guessing you have the JTS hum of restricted airflow by 5000rpm. Maybe earlier?

At this point I'd definitely like to know what compression pressures are- especially when engine is cold.

If you like, you could try to get a maximum MAF sensor reading but it may need an assistant and I don't think your engine would sound nice at 6500rpm with a wide open throttle. It will probably sound like it is in its death throes.

With all the information so far, I think a temporary loss of compression is what you are experiencing. It is not unusual for direct injection engines to experience this.
Not a definite though. Just an idea.
Catching up on some residual questions………
Would have been close to 32 C ambient.
JTS runs lean until 1500rpm I believe
Not sure about air induction restrictions kicking in at 5000rpm
Pretty sure the engine still runs sweetly at 6000rpm, I could try this later after my next trip out when the car is warmed up. What is the expected WOT MAF value, and what does it tell me? Just read your linked post “full throttle at around 6300rpm should record up to 408kg/hr.” I will report back when done.

Will try updating MES if my old laptop will do it.
 

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Discussion Starter · #44 ·
The engine drives smoothly to redline and before the limiter kicked in (or gear change at about 7000rpm, 2nd gear, 100 klm/hr) the MAF reading was 375 kg/hr

Had several misfires under load today with the usual P0304 “cylinder der 4 misfire” code pending. Will replace coil pack and see how it starts tomorrow morning. I think this coil pack has been dodgy for a year as it was originally from cylinder 3 and I swapped them over a while back but seemed to fix the problem so left it to fail.
 

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Discussion Starter · #47 · (Edited)
Replacement of the coil pack made no difference to starting.
I have ordered an air filter and found a good deal on a new Bosch MAF.
Still waiting on Sparkrite testers and cam position sensor

Fruity, I noticed that your helped me out last year with a running problem that was fixed with a new fuel pressure sensor. Big thanks for your support. Seems like you do a lot of the heavy lifting for the community.

I am not sure where to go from here and have no idea why the battery drain problem just disappeared.

Is there anything else I can check or recheck (do better) that will assist?
 

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I'm still having a think about this one. It is no doubt quite a difficult one to solve.

The data you have provided suggests that the management system is working correctly. In other words, it is possibly not electronic. That doesn't rule out an electrical issue but I'm not wishing to narrow thoughts on a whim. That said, can you get a voltage (ideally whilst running) for coils and injectors? Just 1 of each would do rather than the whole lot. The fault appears to affect all cylinders so 1 of each should be representative of voltage to others. If I was to do it, I'd probably just do no.4. That way you could have engine running on the other 3 and not have fuel or spark for a single cylinder whilst testing.

My thinking is it is not just 1 cylinder. That should rule out cylinder specific components.

Just to recap; one the engine is started it is mostly OK.
It has trouble cold starting but once the engine is warm, it starts OK for the remainder of the day.
The initial start-up is not very convincing. It perhaps need the engine speed lifted for a few seconds before it returns to a good idle and response.
Does all that agree with what you have experienced?
 

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Discussion Starter · #49 ·
I would say that it runs as well as I can remember on the road. Perhaps the lean idle maybe a bit rougher these days but who can remember back 19 years!
Has never started first go of the day since this post began. It is as if something does not wake up until the second go.
On the first start it would crank until the battery dies. Feels like no spark or no fuel injected.
I don’t smell any obvious unburnt fuel at the exhaust pipe. Not sure if temperature has anything to do with it as the nights are 20 Celsius.
Engine idle is in spec
Typically starts second time but not always as easily as it might during the remainder of the day
It appears to start normally thereafter during the day.

I have back probing pins so voltages could be checked while running but have not done so before and I would have to find a pinout diagram for each

I don’t think it is a cylinder head problem - some valves would have to be stuck open initially wouldn’t they?
If there is spark and fuel and compression, and authorisation to start, how could the timing be completely off just for the first start?
 

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Cold, dry compression figures are good.
You did not state but I assume these are pre-start figures. That should rule out valves not closing fully.

Timing is not so issue. If it was, performance would be impaired, as would idle etc.

You gave high pressure fuel pressure. It was not completely clear but I assumed you measured the fuel pressure before even cranking the engine for the first time of the day.

Is the throttle valve and body clean? It may be worth taking the throttle body off to do so.
 

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While you wait.

Say you have a slightly leaky injector. Overnight the system drains down into the tank. When you crank you get ‘fuel’ pressure, but it’s pressurised air in the rail and because there is no excess fuel return system it has to bleed out through the injectors, which takes a long time because all the pipework and filters are full of air.

You could try cracking the nearest joint to the injectors which is accessible and repeatedly priming the system until you get fuel only coming out. Then tighten the joint (while the pump is running if necessary to prevent the fuel running back), and try starting.
 

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Discussion Starter · #53 · (Edited)
I have not touched the fuel injector system for fear of all that plastic breaking.
Crack the system- which side of the high pressure pump?
Where could this leak occur - injector o-rings or elsewhere? Could I hear a air leak with a stethoscope?
Does this hypthesis fit with the fact that I can crank the engine for as long as I like on the first go and it does not start - wouldn’t any air have plenty of time to be purged from the system?
What is the lifespan of these injectors? Are there any reliable aftermarket or refurbished injectors available?
If the injectors ever need replacing does the ECU need to be supplied with any specs as I read that each injector has different performance ?
I also read on another forum that injectors could be a culprit for these symptoms but there was no conclusion.
If I pull the plugs after the failed first start might I see anything (eg wet plugs)?
I have routinely used Liqui-Moly injector (petrol system) cleaner once a year or so.
 

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[QUOTE="156and33,
Does this hypthesis fit with the fact that I can crank the engine for as long as I like on the first go and it does not start - wouldn’t any air have plenty of time to be purged from the system?
[/QUOTE]

Only if there was an anti-flooding function in the ecu that turned the injectors off after a certain time cranking; but that is speculation. I’m afraid I know little about the JTS, mine is a diesel. Fuel draining back seemed like the most likely cause of your symptoms and when I saw in elearn that there is no fuel return system I thought that could explain why it took so long to start the engine, despite fuel pressure showing in your graphs (the slow pressure rise in graph two might be the air being compressed?)

The outlet port of the HP pump might be a good place to open the system? It would still leave some air to purge but hopefully the difference would be noticeable. Elearn indicates that the lift pump pressurises the whole system up to the injectors so you should get air/fuel coming through the pump.

I suggested an injector leak because if it was further back I assume the engine would fire a few times as the fuel in the rail was used (there is a thread where this symptom happened but that was not resolved either). I’m not sure if a stethoscope would find a leak, if you can eliminate background noise: perhaps?

If you get fuel wet plugs after the first attempt then the problem isn’t fuel or at least not lack of fuel, but spark/compression, so that would be a good test to do.

Time to sleep here.
 

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Good points. One of the standard checks I always use is how does a non-starter go with ether spray? If it coughs and nearly catches, or starts and runs, your problems are likely in fuel delivery.

Some hard-to-start Pugs I’ve seen are casualties of a “paint pen dot” timing belt job, without confirmation of mechanical timing - they can be out most of a cam tooth. Usually though, they present a cam sensor fault so the workshop change the sensor without need. If problems persist, confirming mechanical timing might be a good step.
 

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Discussion Starter · #56 · (Edited)
Thanks Guys
Throttle body has been cleaned several times while ai have owned the car - will have a look when I replace the MAF.
When I do the belts I use cam locks so unless it has skipped a tooth while running, it should be OK, maybe.
Not sure why MES 4.8 also gives me no SPKADV data, maybe my OBD interface cable is crap?

Here is some more data:
First crank parameter trace: no start, not sure why the fuel pressure does not rise to 50 bar during cranking
After first start: pulled three plugs. Could smell fuel and the tops of the cylinders looked wet.
Second crank parameter trace: fired up OK

Wood Rectangle Font Parallel Pattern

Rectangle Font Wood Line Parallel
 

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not sure why the fuel pressure does not rise to 50 bar during cranking
The last petrol car I worked on delivered a measured 2.5 times stoichiometric air/fuel ratio* during crank, which may be more than the HP pump can deliver since when running only about 1.1 times would ever be required. Apparently the engine is designed to start from lift pump pressure, which presumably is why it is comparatively high.


Started second go but that was not very convincing as if the engine was flooded (3-4s).
only 375kg/hr looks rather restrictive when you should see 460kg/hr at 6400rpm for the JTS.
You have fuel going in (wet pistons) so spark or compression. I can’t explain why it would only affect the first start attempt but maybe try a throttle body self-learning procedure in case it is starving the engine of air?

* That was port injected, direct engines might need a bit less?
 

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Compression was measured prior to cold start up (I'm sure) and seems ok so it seems not to be carbon holding valves slightly open.
AFAIK, fuel pressure was also checked prior to initial start up and it seems good. That seems to rule out fuel pressure regulation.

The symptoms suggest all cylinders on initial cranking are affected but from diagnostic measurement, the engine cranks at around 300rpm. The coils should therefore be operational but this has not been verified as spark testers have not arrived.

My current thoughts extend to 2 things. Are the coils operating as they should? I suggest checking supply voltage and earth. The 4 wire coils have inbuilt ignitors. These appear to operate from ECM as they should. A high resistance somewhere in supply which limits voltage from ECM (common to all coils) could be a possibility.

The other question I have is about fuel volatility. I was told it is OK due to the car being used recently but I still question fuel volatility. If it was my car, I'd have already rigged up a supply to feed in fresh fuel so I could be sure the next morning start up is on completely fresh fuel. It is the only way to be sure though and would be rather awkward doing so.
 
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