Oil pressure puzzle - thoughts please
Discussion
Had the car on the rolling road today.
Operator noticed that the car's oil pressure was a constant indicated 30 psi up to about 4500 rpm under load.
But above that, the indicated pressure dropped away gradually to about 15 psi.
Out of gear and revved, it stayed at 30 psi.
Any thoughts as to why?
Oil was full, not fresh but not due for replacement. Good quality Shell 10w60. Engine warmed up, but only about 15 mins into the testing.
Operator noticed that the car's oil pressure was a constant indicated 30 psi up to about 4500 rpm under load.
But above that, the indicated pressure dropped away gradually to about 15 psi.
Out of gear and revved, it stayed at 30 psi.
Any thoughts as to why?
Oil was full, not fresh but not due for replacement. Good quality Shell 10w60. Engine warmed up, but only about 15 mins into the testing.
TV8 said:
My money would be on the oil pressure sender Anthony. How did you get on with the RR session with Jools.
Yep after under reading for years thats how mine failed 
still heart stopping when it suddenly happens though glad it happened on my engine before rebuild not a sight to behold Thanks both. I will get the sender replaced.
Session was fine thanks Graham. I was basically checking to see that the map was still fine and that the car was not running too rich. Jools confirmed that it was just a tad rich but consistent right across the rev range. AFR around 13.
We then discussed future options and did a power run.
Power had increased about 5% compared to two years ago, when the engine was very new. I guess it has relaxed nicely. It does feel more powerful. So it was 300 bhp and 330 torques at SRR in 2013, now 316 Bhp, 353 torques. Jools normally finds his RR gives slightly lower readings than SRR, so that's not the reason.
Session was fine thanks Graham. I was basically checking to see that the map was still fine and that the car was not running too rich. Jools confirmed that it was just a tad rich but consistent right across the rev range. AFR around 13.
We then discussed future options and did a power run.
Power had increased about 5% compared to two years ago, when the engine was very new. I guess it has relaxed nicely. It does feel more powerful. So it was 300 bhp and 330 torques at SRR in 2013, now 316 Bhp, 353 torques. Jools normally finds his RR gives slightly lower readings than SRR, so that's not the reason.
TV8 said:
Good to know that all is well! It sounds like you are planning to spend on something?
Not for now. No spare loot. Just making sure what the options and costs are, particularly so I don't spend and waste series funds by starting off down the wrong route. My only desire is to be quicker between track day corners.
Will it be quicker if I paint it yellow?
QBee said:
TV8 said:
Good to know that all is well! It sounds like you are planning to spend on something?
Not for now. No spare loot. Just making sure what the options and costs are, particularly so I don't spend and waste series funds by starting off down the wrong route. My only desire is to be quicker between track day corners.
Will it be quicker if I paint it yellow?
Nice power Anthony,, don't worry about them straights,, just throw it through the turns a bit more 
Mmmm I've had a new sender from Powers and today the gauge dropped to zero when doing 75 mph!
Is it the gauge or a wiring fault ?
It's happened a couple of times now,,, I caught it yesterday,,,
So the needle just drops off but then you can watch the needle trying to raise again.
Dodgy sender,
Bad connection at sender,,,
Wiring breaking down,
Or something wrong with wiring or gauge itself.
This is a good thread Anthony,,,,
My gauge always seems to read low,,
It's never been consistent,, 44psi cold, on average about 30 psi as Anthony's (Qbee) and often below 30psi at say 2400 revs,,
Mine always drops to around10-15 on tick over...
I'll obviously bell Dom as they also fitted the new sender only weeks ago,,,
It never dropped off completely before but similar,,, (wiring resistance issue maybe)
Again,,,, thoughts please gents,,
Alun
Mmmm I've had a new sender from Powers and today the gauge dropped to zero when doing 75 mph!
Is it the gauge or a wiring fault ?
It's happened a couple of times now,,, I caught it yesterday,,,
So the needle just drops off but then you can watch the needle trying to raise again.
Dodgy sender,
Bad connection at sender,,,
Wiring breaking down,
Or something wrong with wiring or gauge itself.
This is a good thread Anthony,,,,
My gauge always seems to read low,,
It's never been consistent,, 44psi cold, on average about 30 psi as Anthony's (Qbee) and often below 30psi at say 2400 revs,,
Mine always drops to around10-15 on tick over...
I'll obviously bell Dom as they also fitted the new sender only weeks ago,,,
It never dropped off completely before but similar,,, (wiring resistance issue maybe)
Again,,,, thoughts please gents,,
Alun
Edited by ClassiChimi on Wednesday 18th November 23:31
Had this same situation with mine Heart stopping when your giving it some beans and all of a sudden you see the gauge down at zero. I wipped the sump off thinking the worse and found a bit of silicone debris in the strainer also checked a couple of shells for any damage all was ok. Fitted a new sender but had exactly the same problem,this was always above 4500 rpm the pressure would just gradually drop to 0. Fitted a mechanical gauge to check and all was perfect ,in the middle of a rebuild at the moment so never really got to the bottom of it but it's almost as if the power supply is failing as I believe the gauge only works by reading down to earth so if the voltage falls so will the reading,maybe wrong but could be could be proved by hooking up a volt meter during engine running,this is on a 2000 4.6. Funny thing is my mate has a 4.6 and his has started doing the same ?
Rich
Rich
Guys, simple question for those with gauges dropping to zero.
Do you mean zero, or well off the bottom, ie -15?
If zero, then we need to put our heads together.
If below zero, ie the needle has gone to it's bottom stop, then it's the single wire attached to the sender that is loose.
Mine did it first, two miles away from Snetterton at 5.30pm, about to head home after a track day. Luckily for me, I had been at the trackday with a certain Chimaera racer with whom I am well acquainted, and surprisingly (not, if you know him too
) he was still at the track, deep in conversation. He arrived at my A11 layby 10 minutes later and confirmed his own phone diagnosis, and I fixed it myself the next day on the drive.
I am intrigued by the number of people with a similar issue, and by the comment that the real pressure seemed ok. It does worry me, of course it does, but I am a bit reassured now and will follow it up with Mat over the winter.
No, Richard, no money so no plans, but you know how it is, your friends put new shiny bits on their cars and wave their RR graphs under your your nose, and you want to....... But yesterday was just about making sure the car was still correctly mapped and getting Joolz to review the whole picture and make any necessary adjustments. The options discussion was more about seeing why my car is relatively low powered compared to some, and how to correct that cost-effectively. Joolz confirmed that my heads were probably the restructing factor. My only real issue with the car is speed between corners on track days/sprints. The car is perfectly behaved and huge fun on the road, and faster around track day corners than its driver, so for now at least I have time to check my oil pressure on straights! And I have to say I do check my gauges on the straights, and I have never noticed low oil pressure while hacking along at 5500 rpm.
Do you mean zero, or well off the bottom, ie -15?
If zero, then we need to put our heads together.
If below zero, ie the needle has gone to it's bottom stop, then it's the single wire attached to the sender that is loose.
Mine did it first, two miles away from Snetterton at 5.30pm, about to head home after a track day. Luckily for me, I had been at the trackday with a certain Chimaera racer with whom I am well acquainted, and surprisingly (not, if you know him too
) he was still at the track, deep in conversation. He arrived at my A11 layby 10 minutes later and confirmed his own phone diagnosis, and I fixed it myself the next day on the drive. I am intrigued by the number of people with a similar issue, and by the comment that the real pressure seemed ok. It does worry me, of course it does, but I am a bit reassured now and will follow it up with Mat over the winter.
No, Richard, no money so no plans, but you know how it is, your friends put new shiny bits on their cars and wave their RR graphs under your your nose, and you want to....... But yesterday was just about making sure the car was still correctly mapped and getting Joolz to review the whole picture and make any necessary adjustments. The options discussion was more about seeing why my car is relatively low powered compared to some, and how to correct that cost-effectively. Joolz confirmed that my heads were probably the restructing factor. My only real issue with the car is speed between corners on track days/sprints. The car is perfectly behaved and huge fun on the road, and faster around track day corners than its driver, so for now at least I have time to check my oil pressure on straights! And I have to say I do check my gauges on the straights, and I have never noticed low oil pressure while hacking along at 5500 rpm.
Mine drops to well below zero,,, it does seem electrical to me?
We have similar numbers on the Dyno Anthony,, but in reality yours feels a fair bit faster than mine,,,
It's probably an illusion but as Dom said to me years ago it's not always just about two peak graph curves which does make a lot of sence to me.
When looking at Mats, Griff 5.0 curve it's very similar to mine but what is obvious is the torque is higher almost all the way up the scale and only at 4000 revs mine peaks and is actually on par,,,that subtle difference feels considerable when driving cars back to back,,,
I'd buy some string,,,,pay me to set your car up at the track, hahahahah, aggressive geo, you'll be f
king fast for sure
I'm being a tit but all this chasing power,, costs thousands,,
Geo the car to the track that's were the time will come from,,
Also if your tyres are marginally harder this is going to cause you to come off any bend slower than the guy with massive power and fk off grippy tyres,,, 
hi Peter
He's also a bit quick let's not forget??
Your cars sound I reckon,,
It's time you had a blast in my Car mate,, that will tell us both a thing or two?
Alun
We have similar numbers on the Dyno Anthony,, but in reality yours feels a fair bit faster than mine,,,
It's probably an illusion but as Dom said to me years ago it's not always just about two peak graph curves which does make a lot of sence to me.
When looking at Mats, Griff 5.0 curve it's very similar to mine but what is obvious is the torque is higher almost all the way up the scale and only at 4000 revs mine peaks and is actually on par,,,that subtle difference feels considerable when driving cars back to back,,,
I'd buy some string,,,,pay me to set your car up at the track, hahahahah, aggressive geo, you'll be f
king fast for sure I'm being a tit but all this chasing power,, costs thousands,,
Geo the car to the track that's were the time will come from,,
Also if your tyres are marginally harder this is going to cause you to come off any bend slower than the guy with massive power and f
k off grippy tyres,,, hi Peter He's also a bit quick let's not forget??
Your cars sound I reckon,,
It's time you had a blast in my Car mate,, that will tell us both a thing or two?
Alun
I have just spent £10.50 on a set of thermal socks in order to delete my plug extenders, so am a bit cash strapped just now, but my next spend, after the full service in February, will be on a new set of track tyres. I have been using up two old sets this summer, but really need more corner grip (without going to slicks) as even an MX5 was catching me in the corners at Cadwell Park in August. 
A violent yet smooth driver in a well set up Mazda will do a Tvr in bends all day long, they are a fantastic car and of that there is no question,
Alan Henderson this summer was lapping Cadwell in the 41's with ease,, what's the fastest lap time for a Chim around there,, miles away I'd say.
They run Federals so not the best grip but they are tough tyres,,,
So if you can do those times in a car with over 100hp less it's obvious the corner speeds are way faster,,,how else can that time be achieved,
1110 kgs, so very similar weight.
I am talking about the mk3 Mazda by the way!
If your on the pace of similar Tvr's then what a Mazda can do is irrelevant to my mind.
Alan Henderson this summer was lapping Cadwell in the 41's with ease,, what's the fastest lap time for a Chim around there,, miles away I'd say.
They run Federals so not the best grip but they are tough tyres,,,
So if you can do those times in a car with over 100hp less it's obvious the corner speeds are way faster,,,how else can that time be achieved,
1110 kgs, so very similar weight.
I am talking about the mk3 Mazda by the way!
If your on the pace of similar Tvr's then what a Mazda can do is irrelevant to my mind.
QBee said:
I have just spent £10.50 on a set of thermal socks in order to delete my plug extenders, so am a bit cash strapped just now, but my next spend, after the full service in February, will be on a new set of track tyres. I have been using up two old sets this summer, but really need more corner grip (without going to slicks) as even an MX5 was catching me in the corners at Cadwell Park in August.
Don't pack the socks out with extra thermal wrap as some people have done, they work best with an air gap between the hot side of the HT lead and the inner wall of the sock. The air gap will allow hot air to escape. If you pack them out the temperature gradient across the insulation will slowly equalise and then scorch the HT lead because there is nowhere for that heat to dissipate.I clipped my HT leads to the rocker cover and pulled them tight(ish) so that they are as far from the heat source as possible and the air gap is maximised on the hot side of the HT lead
ClassiChimi said:
A violent yet smooth driver in a well set up Mazda will do a Tvr in bends all day long, they are a fantastic car and of that there is no question,
Alan Henderson this summer was lapping Cadwell in the 41's with ease,, what's the fastest lap time for a Chim around there,, miles away I'd say.
They run Federals so not the best grip but they are tough tyres,,,
So if you can do those times in a car with over 100hp less it's obvious the corner speeds are way faster,,,how else can that time be achieved,
1110 kgs, so very similar weight.
I am talking about the mk3 Mazda by the way!
If your on the pace of similar Tvr's then what a Mazda can do is irrelevant to my mind.
Absolutely, that's why many instructors use MX5s!Alan Henderson this summer was lapping Cadwell in the 41's with ease,, what's the fastest lap time for a Chim around there,, miles away I'd say.
They run Federals so not the best grip but they are tough tyres,,,
So if you can do those times in a car with over 100hp less it's obvious the corner speeds are way faster,,,how else can that time be achieved,
1110 kgs, so very similar weight.
I am talking about the mk3 Mazda by the way!
If your on the pace of similar Tvr's then what a Mazda can do is irrelevant to my mind.
Is that true Peter or are you avin me on,,,, I think their great cars, easy to work on, engine can scream all day,, seemingly bullet proof,,
Anyway oil pressure wobbles,,,
I spoke with Jas at Powers today,,,
Has anyone just re routed new wiring from oil pressure sender up into cabin straight to the gauge,,
I'm suspecting a wiring issue,,
As we know the oil pressure wiring goes via the chassis rail and joins the harness that then goes via headlight up through the wing ( I think ) and then into cockpit and onto the gauge itself,,
I'm thinking of replacing the wiring and just cutting the old one back, discard it,,,
Is there anything specific you need to consider when doing such a mod ?
Cheers Alun
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