1.4 petrol twist, engine cut out when cold

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flub136
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1.4 petrol twist, engine cut out when cold

Post by flub136 »

Hi All. Hoping someone can shed some light here. I have the above vehicle (BKY engine) that is causing a nightmare when driving now. Basically when driving from cold the car will pull away and then go into a complete frantic intermittent full engine cut out and then come to life again. It's like the car just kangaroos up the road with the rev gauge bouncing all over the place. If you come to a junction it may just stall completely. Sometimes it will start immediately after this, sometimes it will have to be turned over and revved hard to get it going again. When it's warm (does not take more than a few minutes to get fully warm (90 degrees)) it behaves its self. I have started to counter this by starting in the morning 10 minutes before leaving for work and letting it idle on the drive. Usually it starts first go, even when cold, and then I just leave it to idle and get warm. Usually that is sufficient to stop the problem although sometimes I come out of the house to go and find the car has stalled on the drive after a few minutes and the battery light and sometimes the coolant level/temp light is flashing and beeping at me. obviously I have checked the level and it is correct with no leaks and the temperature is in the normal range. My friend is a mechanic and plugged in his £2.5K snap-on ODB reader/analyser and it is not reporting any codes at all. At the beginning of the summer I replaced the crank sensor to cure a misfire problem that was not to dissimilar to this but no where near as violent in the full engine cut out I get now. I also replaced all the plugs and the temp sensor at that time. I have also given the throttle body a complete clean with carb cleaner (body off the inlet manifold) and reset by disconnecting the battery for 20 minutes. Anyone with some wise suggestions? All gratefully received.
littlepolo
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Re: 1.4 petrol twist, engine cut out when cold

Post by littlepolo »

If you removed the throttle body to clean it you need to do a calibration on refit.
flub136
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Re: 1.4 petrol twist, engine cut out when cold

Post by flub136 »

That I could get my mate to do but the problem still exists same as before I cleaned the throttle body. The car still fast idles fine (runs rich like the choke is on) when starting cold but the revs drop to normal idle (680 rpm approx) within a few minutes if starting so it seems the ecu is fuelling the engine properly when cold starting. Was wondering if it may be something electrical as it is a total engine stall rather than errant cylunder misfire.
littlepolo
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Re: 1.4 petrol twist, engine cut out when cold

Post by littlepolo »

You mentioned above it takes only a few minutes to get warm to 90C which sounds very quick to me (at this time of year).

It might be worthwhile plugging in a diagnostics and monitoring the temp sensor as it warms from cold. If the signal is reading over and fueling is reduced that could explain the stall.
flub136
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Re: 1.4 petrol twist, engine cut out when cold

Post by flub136 »

Littlepolo, thanks for the reply. We did plug the reader in when the car had been left until cold and the temp sensor read 12 degrees whixh was the approx ambient temperature at the time. We didn't however monitor it after i started the car. I was thinking about changing the sensor again just in case the new one has gone faulty.
littlepolo
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Re: 1.4 petrol twist, engine cut out when cold

Post by littlepolo »

I think they usually go faulty the other way (as in reading cold leading to enrichment) but it's worth ruling out.

It does sound like you are possibly leaning the mixture leading to stalling?
flub136
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Re: 1.4 petrol twist, engine cut out when cold

Post by flub136 »

Another twist (scuse the pun). Fuel consumption has increased quite dramatically. Instead of just on 300 miles to a tank I'm getting about 220! I'm driving it no different, in fact probably not putting my foot down as much be cause of the kangarooing.
littlepolo
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Re: 1.4 petrol twist, engine cut out when cold

Post by littlepolo »

Check the condition of the plugs to determine the mixture. What brand of temp sensor did you fit? I've had fuel consumption at 250 miles per tankful (lamp on) when it has been very cold and there have been engine problems (1.4 auto) but never as low as 220. If the fueling (trims) is way off it will show on the lambda readings (via diagnostics).
flub136
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Re: 1.4 petrol twist, engine cut out when cold

Post by flub136 »

littlepolo, thanks for the reply. All plugs checked and pretty good - light tan/orange, all same colour, no sooting and gaps checked. The annoying thing is I'm getting absolutely no codes. The water temp sensor was from the local VW dealer. I have now ordered a new MAP sensor so will see how that goes. Basically I can get it to want to cut out merely by dabbing the accelerator pedal hard when cruising at 2000 revs and it will want to cut out and the revs drop like a stone unless I take my foot off the pedal. Basically if I drive it like I'm scared to put my foot down hard it behaves itself a lot more until I stop at a junction and then pull away in first and then it will just die.
flub136
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Re: 1.4 petrol twist, engine cut out when cold

Post by flub136 »

Sorry to drag this one up guys but I'm disapearing down a bottomless money pit! after changing MAP sensor, Cam sensor cleaning and re-setting the throttle body, same with EGR getting a replacement ECU (as still no fault codes come up for this cutting out problem) I still have this fault. I am now tinking about replacing the new G28 - crank sensor that I had already replced last year when I had a similar problem. This fixed it back then. It's only when I started to get the repeat of the symptoms (sudden split second engine cutout with rev counter dropping like a stone and stalling when coming to a halt or when pulling off the line) that I assumed it was a different problem. The car is running incredibly rich now as it's going through a tank of fuel in 200 miles. I am in 2 minds as whether to change the O2 sensor as well EVEN THOUGH I STILL DO NOT GET A SINGLE CODE FOR THIS PROBLEM. Any help really would be appreciated.

I have bought an autolink AL539 OBD computer and have done live reacing whilst driving the vehicle. My SHTFT1 (short term fuel trim 1) PID was fluctuating between -15 to +35! I do not think this would be a symptom of a faulty Crank sensor and I am looking at replacing the O2 sensor to see if that is causing a problem but I keep harking back that at no time do I ever find a fault code.

Any ideas guys??!...Please.
john M
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Re: 1.4 petrol twist, engine cut out when cold

Post by john M »

Crank sensor may be suspect again.
Maybe worth checking the fuel pressure regulator
if you unplug the O2 sensor the engine should run in open loop then that will rule it out if the short term fuel trim is still fluctuating wildly.
flub136
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Re: 1.4 petrol twist, engine cut out when cold

Post by flub136 »

PROBLEM FIXED......Update. Well it turns out it was the crank sensor that I had replaced this time last year. Replaced it with an NTK unit and the problem has gone! One interesting observation however is that that after monitoring PIDs on my OBD computer I have noticed that the air intake temperature is way up. This morning the ambient air temperature was 20°C but by the time I had driven 5 miles the IAT indicated 57°C! I thought that usually the IAT should hover around 10 degrees above ambient. Clearly this is not the case here.
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