Missed gear change. Now oil pressure weirdness Still looking for ideas.

[Beelzebub]

I missed a shift yesterday & bounced the engine off the limiter. Soft cut set at 7800 & the hard cut at 8000. Everything seemed fine & I only had about a mile to go before I got home. When I started the car up today the OP was noticeably higher then usual all the way from idle up to about four grand which I don't exceed until the engines warmed through. Once warm the pressure at tickover had now dropped by about 4 PSI from it's usual 29-30 psi to 25-26 psi at hot idle while the pressure whilst driving was well up from its usual max of 64-65 psi hot, 75 deg-ish to 75-76 PSI. The pressure in general seems much more variable whilst driving although stable at any given rpm

 

The engines one of DVA's Scholared 1.8 K's, mapped by the two Steve's & is running the Pace DS system with a SPA Temp/pres gauge.

 

Ideas & thoughts puleez. D.

 

 

 

Edited by - davesport on 1 Jul 2007 16:49:21

 

Edited by - davesport on 10 Jul 2007 20:50:14

[Colin Mill]

I would expect the oil pressure when cold to be sat on the pressure relief valve pressure pretty much from idle up. Is that how your engine usually behaved?

[Beelzebub]

The pump is fitted with a user adjustable relief valve which I set & haven't touched since the engine went in. The screw & locknut are still tight & dont look like they've moved. I don't know if this provides an absolute upper ceiling but the pressure when cold at idle is normally around 36 psi, to around 60 at 4000rpm. The most I've ever seen normally on the SPA gauge is in the high sixties at the highest rpm that I use of 7200 when all the shift lights are on.

 

So the answer to your question is no.

 

Usually the only thing that causes a shift in the pressure is changing the oil. This raises the pressure by a few psi over the full rpm range which I considered normal.

 

I'm stumped

 

 

 

 

[Johnty Lyons]

Ive had this with exactly the same engine and SPA guage I found that heat had partially melted the inner cores in the SPA cable causing a partiall short [intermittent] on the 5 volt line Led me a merry dance for a week or two Get an alternative guage before you do anything else and be sure it's not a SPA problem I've had SPA guages for 5 yrs now and they need very carefull looking after I've had mine back to SPA twice and they are going back again this winter To be honest they are a PITA but I still like the info they give and can't find a suitable digital alternative.

 

jj

N.I. L7C AR 🙆🏻

Membership No.3927.

 

[Beelzebub]

Thanks for that Johnty. I'll have a look at this soon. Hopefully it's a problem with the SPA gauge or sensor

[Beelzebub]

So far I've checked the SPA gauge against a new 6 bar mechanical gauge & they're reading the same. I've stripped the relief valve out of the Pace pump & it's pristine & moving freely, spring intact etc. I've changed the oil fliter & disected the old one & there no metalic fragments or bits of pump rotor in there. I have to add apart from the unusal Op there's nothing else outwardly wrong.

 

So, you might ask, "what's the problem ?" Well, around the time of the missed gear episode, something's changed. The Op's now higher whilst cold & when hot the pressure's lower at idle & higher at operating rpm's I thought that the voltage regulator could be 🙆🏻 but I'm getting a shade over 14 V at most rpm's.

 

If anyone got a theory please let me know

 

D.

 

 

 

 

 

 

 

[Tony C]

When you say you missed a gear change do you mean you rev'd the engine with the throttle while out of gear or that you let out the clutch in a gear too low for the speed and the road wheels over rev'd the engine?

 

BRG Brooklands SV 2.0L Ammo Duratec 😬 It seems that perfection is achieved not when there is nothing more to add, but when there is nothing more to take away. (Antoine de Saint-Exupery)

[Beelzebub]

The former. I hit the limiter whilst in neutral between gears.