[52racer]

this car only races, doesn’t get driven on the streets

K24a2 tsx block, k20a2 head, DC 3.2 cams w/Supertech head package

Oil: Valvoline VR1 20w50

Fuel: X85

It is a fresh build and on a cold start it’ll idle around 30-40 psi (have AEM Xseries gauge) but after running it, and getting it warmed up, the pressure drops to 15-20psi when idling at 1,000rpm. When I get back on the throttle it rises back up to normal 70-80psi (ish). Any guesses? Normal? Suggestions?
Thanks and Happy Thanksgiving everyone.

 

[KBuilt]

The cold start pressure sounds a bit low. Maybe some others will put .02 in.

 

[Bjorn]

Idle pressure is on the low end, especially for a 20w50 oil. but i wouldn't be concerned about that on its own.

The real question is why is it low? Worn oil pump? Excessive bearing clearances? Inaccurate pressure Gauge?

If it's built with large bearing clearances then id just stick with the 20w50 and send it.

 

[Lotus]

sound normal(ish) to me with larger bearing clearances. What oil temperatures are we talking about?

 

[52racer]

The cold start pressure sounds a bit low. Maybe some others will put .02 in.

I misspoke, on a true cold start it will idle fine (60-70ish) and one it gets warmed up it’ll idle 30-40 psi

 

[52racer]

The cold start pressure sounds a bit low. Maybe some others will put .02 in.

I misspoke, on a true cold start it will idle fine (60-70ish) and one it gets warmed up it’ll idle 30-40 psi

 

[52racer]

Idle pressure is on the low end, especially for a 20w50 oil. but i wouldn't be concerned about that on its own.

The real question is why is it low? Worn oil pump? Excessive bearing clearances? Inaccurate pressure Gauge?

If it's built with large bearing clearances then id just stick with the 20w50 and send it.

brand new type S oil pump, brand new AEM Xseries gauge and sensor. Not sure about the bearing clearance. Going to go run it tomorrow tonight and see what happens

 

[52racer]

sound normal(ish) to me with larger bearing clearances. What oil temperatures are we talking about?

no idea, don’t run an oil temp gauge. Coolant temp stayed relatively low.180-190°F w/ mishimoto radiator and fans on continuously.

 

[texm3x]

Check the sensors behind the head or filter in the front.. might wanna get the seal in the back of the head incase it tears.. but try cleaning that one first.. if not ur gonna need to took down cam bolts better or resurface the head on the top and oil pump resurfacingat machine shop..they can repair them .. if all fails on ur build.. but I would go there because u can check rod bearings when oil pump is dropped..

 

[LotusElise]

...on a true cold start it will idle fine (60-70ish) and one it gets warmed up it’ll idle 30-40 psi

I see no issue with these values. Mine has a 5W30, cold idle = 2.5 bar, 88 °C idle = 1.3 bar, 9000 rpm and 88 °C is 3.2 bar. The engine is fine with it. No single wear indications up to know after 35 h tuning and analysis operation, which is really hard. The bearing clearances are on the higher end of the 5W30 specification. Oil flow is more important then a high oil pressure only. If you know it flows well, lower pressures are acceptable.

 

[KBuilt]

I misspoke, on a true cold start it will idle fine (60-70ish) and one it gets warmed up it’ll idle 30-40 psi

That sounds better 👍

 

[52racer]

it did it again. Same thing as before with the surge/cut off, slow Rev and no vtec. Oil pressure was good, car was properly warmed up, fresh oil change.
I’m thinking this could be a bad TPS/MAP sensor?

 

[KBuilt]

—>

1:26 mark watch that
it did it again. Same thing as before with the surge/cut off, slow Rev and no vtec. Oil pressure was good, car was properly warmed up, fresh oil change.
I’m thinking this could be a bad TPS/MAP sensor?

Is the car reading speed properly ?

 

[52racer]

Is the car reading speed properly ?

we don’t run speedometers so I can’t say for certain

 

[Lotus]

you need to data log. It will show if VTP signal drops or the ECU loses the VSS signal. Both would trigger lower rev limits.
Same for TPS or MAP issues.

 

[KBuilt]

we don’t run speedometers so I can’t say for certain

If the computer isn’t reading speed you won’t get vtec (it thinks the car is stopped ) as lotus suggested a datalog would show all sensor values and actions and tell more about what’s going on.

 

[52racer]

Oh gotcha, makes sense. Unfortunately I don’t think I was running any data logging. Still a newb to all of this and the kpro/manager

 

[52racer]

Update: recalibrated tps sensor and it’s still acting like it’s choking itself out. Idles at 900rpm and when I get in the gas it will drop the 400-500 then come up. Talked with my tuner and he thinks it is mechanical or electrical. 🤷🏼‍♂️

 

[Lotus]

IACV may need to get cleaned. They need this at least once a year.
You can also increase IACV sensitivity in Kpro.
Hook Kpro to laptop and run while logging.
Kpro v4 has integrated memory for logging, not a lot but set a 5Hz or so, it should be good for an hour or so.
VSS sensor can be deactivated in KPro.

 

[52racer]

IACV may need to get cleaned. They need this at least once a year.
You can also increase IACV sensitivity in Kpro.
Hook Kpro to laptop and run while logging.
Kpro v4 has integrated memory for logging, not a lot but set a 5Hz or so, it should be good for an hour or so.
VSS sensor can be deactivated in KPro.

I cleaned the IACV about 3 races ago
The VSS is showing 49mph in kmanager constantly
Just recalibrated the tps sensor itself with a multimeter (it started out at 0.02 and I rotated it until it showed 0.5 at closed throttle and checked for dead spots) and about to recalibrate it through Kpro again