TVR Griff 500 hot running issue - Rover Gauge Data
Discussion
Hi,
Posting on behalf of my mate a TVR griff owner..
1995 Griff 500, completely standard, owned for ~16years
Running map: 5
Tune: R2967
Adjustment factor: 0x6784
All temps and gauges working as expected, no fault codes showing
Symptoms:
Once running and up to temp, it can hesitate and seemingly drop to a few cylinders and barely runs.
Once the car has been left to cool for a short period of time, will run once more without issue to get you home.
Rover Gauge observations:
The MAF either direct or linear appears to stay at 5%, graphing from the log output shows there were a couple of spikes on throttle blips.
But I was expecting the MAF to be 30% to 35% at idle.. ? The filter is clean, with no obstructions/blockages.
Perhaps a drive run in the car will be better for some more accurate readings rather than just an idle test?
Going to try a run without the MAF connected, as have read this will force the ecu to use a set 30% in a for "getting" you home mode..
Just to see if the hot running issue still occurs?
Planning to clean the MAF to see if there's any difference too, its never been done.. so wont hurt to try..
The Rover Gauge log and derived xls/graphs are here on dropbox:
https://www.dropbox.com/s/zoy80r38o9mceqh/2018.06....
Rgds
Stroudy
Posting on behalf of my mate a TVR griff owner..
1995 Griff 500, completely standard, owned for ~16years
Running map: 5
Tune: R2967
Adjustment factor: 0x6784
All temps and gauges working as expected, no fault codes showing
Symptoms:
Once running and up to temp, it can hesitate and seemingly drop to a few cylinders and barely runs.
Once the car has been left to cool for a short period of time, will run once more without issue to get you home.
Rover Gauge observations:
The MAF either direct or linear appears to stay at 5%, graphing from the log output shows there were a couple of spikes on throttle blips.
But I was expecting the MAF to be 30% to 35% at idle.. ? The filter is clean, with no obstructions/blockages.
Perhaps a drive run in the car will be better for some more accurate readings rather than just an idle test?
Going to try a run without the MAF connected, as have read this will force the ecu to use a set 30% in a for "getting" you home mode..
Just to see if the hot running issue still occurs?
Planning to clean the MAF to see if there's any difference too, its never been done.. so wont hurt to try..
The Rover Gauge log and derived xls/graphs are here on dropbox:
https://www.dropbox.com/s/zoy80r38o9mceqh/2018.06....
Rgds
Stroudy
Edited by Stroudy on Monday 25th June 10:04
Edited by Stroudy on Monday 25th June 12:50
Start with the basics: fuel and spark.
Does the rev counter dip when the misfire occurs, or does it accurately track the actual engine speed? The rev counter is driven off the coil LT circuit so faults in the ignition pickup/amplifier or coil power supply will usually impact the rev counter.
Run a couple of wires from the cabin to the fuel pump and measure the voltage across the pump. If that dips when the problem occurs, suspect a failing fuel pump relay. These commonly fail in such a way that the contacts heat up and cause a poor connection when hot. The symptoms may be intermittent and get gradually worse until the engine will not run. After cooling down, they may be OK for a while. If this is the problem, check the relay socket for damage since heat from the relay often softens and oxidises the contacts.
If you can get the problem to happen with the car stopped, check whether you have a spark on all cylinders and whether the plugs are wet (implying possible ignition problem) or dry (implying possible fuel supply/injection issue).
Locate the engine coolant temp sensor at the front of the intake manifold. There will usually be a single wire sensor that drives the gauge and a twin wire sensor used by the ECU. Check the resistance across the ECU sender (loom disconnected) when the engine is hot. It is a thermister which should read about 6000 Ohms at 0c and roughly halving for every 20c above that, which corresponds to about 300 Ohms at 80c or 150 Ohms at 100c. This probably isn't the problem given the behaviour you describe, but worth checking since you have a temperature related running problem. If you're feeling keen, you can also re-measure between ECU pins 7 & 25 which should show the same reading.
Does the rev counter dip when the misfire occurs, or does it accurately track the actual engine speed? The rev counter is driven off the coil LT circuit so faults in the ignition pickup/amplifier or coil power supply will usually impact the rev counter.
Run a couple of wires from the cabin to the fuel pump and measure the voltage across the pump. If that dips when the problem occurs, suspect a failing fuel pump relay. These commonly fail in such a way that the contacts heat up and cause a poor connection when hot. The symptoms may be intermittent and get gradually worse until the engine will not run. After cooling down, they may be OK for a while. If this is the problem, check the relay socket for damage since heat from the relay often softens and oxidises the contacts.
If you can get the problem to happen with the car stopped, check whether you have a spark on all cylinders and whether the plugs are wet (implying possible ignition problem) or dry (implying possible fuel supply/injection issue).
Locate the engine coolant temp sensor at the front of the intake manifold. There will usually be a single wire sensor that drives the gauge and a twin wire sensor used by the ECU. Check the resistance across the ECU sender (loom disconnected) when the engine is hot. It is a thermister which should read about 6000 Ohms at 0c and roughly halving for every 20c above that, which corresponds to about 300 Ohms at 80c or 150 Ohms at 100c. This probably isn't the problem given the behaviour you describe, but worth checking since you have a temperature related running problem. If you're feeling keen, you can also re-measure between ECU pins 7 & 25 which should show the same reading.
update...
The MAF was removed and cleaned along with the MAF connector.. didn't look particularly dirty. But has had a positive affect..
Where before the MAF reading was pretty much flat lined..
It now has an idle %age mid 30s and peaks of over 70 during driving..
An initial run, nearly 30mins in the hot midday weather at the weekend, stop start traffic and some clear air sections.. no problems.. the car would usually have broken down way before 30 mins..
A motorway run also gave no issues.. so.. fingers crossed this continues..
Have ordered an ignition amp , will keep this as a spare for now
The MAF was removed and cleaned along with the MAF connector.. didn't look particularly dirty. But has had a positive affect..
Where before the MAF reading was pretty much flat lined..
It now has an idle %age mid 30s and peaks of over 70 during driving..
An initial run, nearly 30mins in the hot midday weather at the weekend, stop start traffic and some clear air sections.. no problems.. the car would usually have broken down way before 30 mins..
A motorway run also gave no issues.. so.. fingers crossed this continues..
Have ordered an ignition amp , will keep this as a spare for now
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