Intermittent start up problem
Discussion
When starting from cold I very occasionally find the engine is lumpy as hell, no power and sounds like it's not firing on all cylinders. If I turn off; leave a few seconds and restart it is invariably fine and there has never been a problem once running correctly.
It's almost as though the MBE is picking up some duff values when it starts up.
I don't recall ever having this when starting from hot.
It's very intermittent. I'd appreciate any thoughts anyone has as to it's cause and how to diagnose.
It's almost as though the MBE is picking up some duff values when it starts up.
I don't recall ever having this when starting from hot.
It's very intermittent. I'd appreciate any thoughts anyone has as to it's cause and how to diagnose.
Hi Nick
I would have thought if it was wiring or a component then it would occasionally fail while running but the failure mode is very specific. It normally starts fine, if it doesn't then restarting clears the problem. It never fails once properly started.
I've run MBETool and can't see any logged errors, but it's so intermittent I've not managed to have it connected while the fault is present.
I would have thought if it was wiring or a component then it would occasionally fail while running but the failure mode is very specific. It normally starts fine, if it doesn't then restarting clears the problem. It never fails once properly started.
I've run MBETool and can't see any logged errors, but it's so intermittent I've not managed to have it connected while the fault is present.
non_linear said:
Hi Nick
I would have thought if it was wiring or a component then it would occasionally fail while running but the failure mode is very specific. It normally starts fine, if it doesn't then restarting clears the problem. It never fails once properly started.
I've run MBETool and can't see any logged errors, but it's so intermittent I've not managed to have it connected while the fault is present.
I've had the miss/lack of power/lumpy running at 2500~3000 rpm, nothing shown on the diagnostics.I would have thought if it was wiring or a component then it would occasionally fail while running but the failure mode is very specific. It normally starts fine, if it doesn't then restarting clears the problem. It never fails once properly started.
I've run MBETool and can't see any logged errors, but it's so intermittent I've not managed to have it connected while the fault is present.
Firstly, replaced HT leads...which was a bit of improvement. then, replaced the coil pack - which sorted it. I believe some experts can diagnose a failing coil pack from the graphical display on the diagnostics?
These intermittent problems are devils to diagnose!
Nick
Doubt that turning it off and on again would sort it if it was the NVRAM. Also it would sort itself out fairly quickly as the adaptives correct themselves over the space of a minute or two.
As an experiment try getting into the habit of pressing the throttle a couple of times BEFORE starting...just thinking if the pot is getting noisy (one or both) then it *might* get a rubbish zero point at startup...and that deffo makes the engine run like s
t (it self zeros and then the pot kinda clears up/outputs the right value leaving the engine now running in the wrong place in the map). Turning off and on again would also clear that as you'll have moved the wiper around and settled it down a bit. Just a thought.
As an experiment try getting into the habit of pressing the throttle a couple of times BEFORE starting...just thinking if the pot is getting noisy (one or both) then it *might* get a rubbish zero point at startup...and that deffo makes the engine run like s
t (it self zeros and then the pot kinda clears up/outputs the right value leaving the engine now running in the wrong place in the map). Turning off and on again would also clear that as you'll have moved the wiper around and settled it down a bit. Just a thought.^^^^ Good points raised above!!
August time(??), I thought I'd run EvoOli's diagnostics on my Tuscan.
Weirdly enough, I noticed the throttle position indications at ~ 60% with just IGN on but (Immobiliser disabled) engine not running. I too turned key on/off a couple of times and TP sensors returned to ~15%.
Later, I removed the front (blue - cyls 123) sensor, applied some contact spray to contacts and inner face and replaced. I later (mid-September) replaced the battery. Upshot, is that A) car starts much better now - even when hot, and B) I don't seem to have a repeat of the high TP values.
Without a doubt the original battery was at the end of its life...was loosing charge quite quickly even after a couple of days on the smart charger. Was apparent when cranking as the indicated voltage quickly dropped to less than 10V.
Nick
August time(??), I thought I'd run EvoOli's diagnostics on my Tuscan.
Weirdly enough, I noticed the throttle position indications at ~ 60% with just IGN on but (Immobiliser disabled) engine not running. I too turned key on/off a couple of times and TP sensors returned to ~15%.
Later, I removed the front (blue - cyls 123) sensor, applied some contact spray to contacts and inner face and replaced. I later (mid-September) replaced the battery. Upshot, is that A) car starts much better now - even when hot, and B) I don't seem to have a repeat of the high TP values.
Without a doubt the original battery was at the end of its life...was loosing charge quite quickly even after a couple of days on the smart charger. Was apparent when cranking as the indicated voltage quickly dropped to less than 10V.
Nick
Good news, of a kind, it's failed with MBETool running. The obvious thing I can see is lambda1 never getting above 0.2. At time stamp 421 I try to hold the engine steady at about 1200 RPM and its hunting. You can see the adaptive 1 and injector 1 cycling.
At timestamp 871 I stop and restart the engine, and lambda1 immediately goes to the correct value.
What could cause that? I thought it might have been a heater fault but clearly it's getting to temperature.
At timestamp 871 I stop and restart the engine, and lambda1 immediately goes to the correct value.
What could cause that? I thought it might have been a heater fault but clearly it's getting to temperature.
I'll try that as an experiment. It's the adaptives that I don't understand. On a good start they both remain at 0.4 for about 40 seconds before changing. On the bad start, adaptive 1 is all over the shop immediately. What set of input conditions could cause the MBE to start altering that?
Glad I've come across this as I've been having the same symptoms for years, and have just got used to warming the car for 5 mins or driving round the flat spot on light throttle when cold.
OP do you notice a difference when the ambient temperature is much higher on first start? Mine is always better.
The other thing which sometimes works is to start with a touch of throttle as the engine catches.
I've exhausted the mechanical things to change so will be keeping an eye on this thread.
Any chance of moving to the Speed Six thread in case it affects anyone else.
OP do you notice a difference when the ambient temperature is much higher on first start? Mine is always better.
The other thing which sometimes works is to start with a touch of throttle as the engine catches.
I've exhausted the mechanical things to change so will be keeping an eye on this thread.
Any chance of moving to the Speed Six thread in case it affects anyone else.
All I need now is a small child I can send down the footwell to change it for me. I'm pretty certain I can't get down there without taking the steering wheel off and removing the drivers seat.
It's not happened often enough for me to correlate it with ambient temperature. I'll report back what difference it makes when the chip is installed.
I didn't know there was a separate speed six forum! I'll check it out.
It's not happened often enough for me to correlate it with ambient temperature. I'll report back what difference it makes when the chip is installed.
I didn't know there was a separate speed six forum! I'll check it out.
non_linear said:
All I need now is a small child I can send down the footwell to change it for me. I'm pretty certain I can't get down there without taking the steering wheel off and removing the drivers seat.
It's not happened often enough for me to correlate it with ambient temperature. I'll report back what difference it makes when the chip is installed.
I didn't know there was a separate speed six forum! I'll check it out.
The one and only time I've accessed it I was let's say a little more flexible! It's the narrow opening angle of the door that gets in the way most, on a Tuscan anyway.It's not happened often enough for me to correlate it with ambient temperature. I'll report back what difference it makes when the chip is installed.
I didn't know there was a separate speed six forum! I'll check it out.
As long as the subject titles in the Speed Six forum are detailed enough you can narrow down a search for what you want. The audience and contributors will be wider but those who've answered here really know their stuff.
non_linear said:
When starting from cold I very occasionally find the engine is lumpy as hell, no power and sounds like it's not firing on all cylinders. If I turn off; leave a few seconds and restart it is invariably fine and there has never been a problem once running correctly.
It's almost as though the MBE is picking up some duff values when it starts up.
I don't recall ever having this when starting from hot.
It's very intermittent. I'd appreciate any thoughts anyone has as to it's cause and how to diagnose.
Mine had similar symptoms after a 12k service at specialist dealer #1, may have been a coincidence but afterwards anything under 1200 rpm the firing was uneven and trying to stall irrespective of ambient temperature, took it to specialist dealer #2 who sent the engine Ecu away for testing and it came back as serviceable, no fault found, still the problem persisted but more intermittently, took it to specialist #3 who diagnosed the problem as the engine wiring harness from the bulkhead to the engine bay, this finally resolved the problem and not too expensive to repair. It's almost as though the MBE is picking up some duff values when it starts up.
I don't recall ever having this when starting from hot.
It's very intermittent. I'd appreciate any thoughts anyone has as to it's cause and how to diagnose.
Can only assume the Ecu was being sent duff or no input data from the sensors in the engine bay
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