Engine stops in heavy stop/start traffic
Discussion
Something (I think) is overheating, what's the most likely thing for it to be?
I did a track day earlier in the day and the car was perfect - but driving past Oval at rush hour and abruptly I am having to push it into the bus lane and wait 10 minutes for it to cool down before I can drive the rest of the way home.
This is what I would characterise as sub-optimal, all helpful suggestions gratefully received.
I did a track day earlier in the day and the car was perfect - but driving past Oval at rush hour and abruptly I am having to push it into the bus lane and wait 10 minutes for it to cool down before I can drive the rest of the way home.
This is what I would characterise as sub-optimal, all helpful suggestions gratefully received.
Stevieturbo - a lot of changes, rather too many to point the finger at one I suspect:
- Aircon compressor clutch shimmed so it now works for the first time in my ownership (electromagnetic clutch that requires a maximum clearance between plates, which it was far beyond)
- Stock intercooler replaced with do88 intercooler, all pipework replaced at the same time
- New airbox with new 90mm MAF housing (replacing 63mm), new MAF, new air filter element etc
- New Kinugawa 20T TD04HL turbo
- New heater matrix
Since then the idle has been ~200 rpm above what it used to be (now 1,000).
What happens when the engine dies:
- Sat idling in traffic, aircon on, in neutral with handbrake on, engine simply stops
- To give an idea, I'd just driven from Castle Combe down the M4, to A4, over Vauxhall Bridge and the engine cut out at around 17.40, so traffic was very heavy
- Oil light and check engine lights illuminate as the engine dies (just as if you'd stalled it)
- Starter spins, engine doesn't catch at all
- Push car over to curb, pop bonnet, wait 10 mins
- Car fires on the first spin, performs like nothing happened
- Aircon compressor clutch shimmed so it now works for the first time in my ownership (electromagnetic clutch that requires a maximum clearance between plates, which it was far beyond)
- Stock intercooler replaced with do88 intercooler, all pipework replaced at the same time
- New airbox with new 90mm MAF housing (replacing 63mm), new MAF, new air filter element etc
- New Kinugawa 20T TD04HL turbo
- New heater matrix
Since then the idle has been ~200 rpm above what it used to be (now 1,000).
What happens when the engine dies:
- Sat idling in traffic, aircon on, in neutral with handbrake on, engine simply stops
- To give an idea, I'd just driven from Castle Combe down the M4, to A4, over Vauxhall Bridge and the engine cut out at around 17.40, so traffic was very heavy
- Oil light and check engine lights illuminate as the engine dies (just as if you'd stalled it)
- Starter spins, engine doesn't catch at all
- Push car over to curb, pop bonnet, wait 10 mins
- Car fires on the first spin, performs like nothing happened
Ok, this is my theory:
- The MAF, enlarged in order to accommodate the much higher than stock airflow is not great at low air flow any longer
- This is ok when temperatures are low to medium - when the car is in motion, basically
- In 10 miles of typical London traffic jam on a hot day the under bonnet temperatures climb significantly
- The hot, low speed air isn't within the MAF's ability to read
- It's the MAF sending "no air flow" to the ECU, which then cuts fuel, that is causing this problem
Sound plausible?
- The MAF, enlarged in order to accommodate the much higher than stock airflow is not great at low air flow any longer
- This is ok when temperatures are low to medium - when the car is in motion, basically
- In 10 miles of typical London traffic jam on a hot day the under bonnet temperatures climb significantly
- The hot, low speed air isn't within the MAF's ability to read
- It's the MAF sending "no air flow" to the ECU, which then cuts fuel, that is causing this problem
Sound plausible?
To get a plug lead off a plug with the Volvo 5 cylinder engine you need to take a boost pipe off, then remove the cover that goes between the cams - 8mm socket and a Torx T30 driver needed. It's not something I had the tools to do in traffic.
I have, however, ordered a new coil, which I'll swap in with the crank sensor.
I have, however, ordered a new coil, which I'll swap in with the crank sensor.
Changed the coil and the crank sensor today for new units.
Cleaned up the old crank sensor and dropped it in a cup of boiling water - resistance went from 294 ohms (room temp) to 360 ohms (90 degrees or so).
These sensors are meant to be ok if the reading is between 200-500 Ohms, so this one is theoretically ok.
However - the fault only occurs when the engine is HOT, how hot could this sensor expect to get?
Yes - I am still hoping that it's the cause of the issue.
Cleaned up the old crank sensor and dropped it in a cup of boiling water - resistance went from 294 ohms (room temp) to 360 ohms (90 degrees or so).
These sensors are meant to be ok if the reading is between 200-500 Ohms, so this one is theoretically ok.
However - the fault only occurs when the engine is HOT, how hot could this sensor expect to get?
Yes - I am still hoping that it's the cause of the issue.
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