Hi all,

My BA XR6T won't idle above 500rpm when it is hot.

I've put a new intake gasket in and cleaned the throttle body spotless.. put a new TPS in and checked for leaks.. can't find anything so I don't understand why it won't idle at 700.

as a result of this, the oil pressure at idle and in gear sometimes drops to 7psi when idling in drive. At that point the revs are 450rpm, and while the engine is still reasonably smooth.. it's got buggar all oil pressure.

Also, I had been using Blue magnatec oil (15w40) since I got it and with my old falcons.. but in this car, it gets really really thin and when I drained it out hot it was as thin as water..

So yesterday I bought 70 bucks worth of Mobil 1 synthetic oil (5W50) and put that in.. It is way better.. but it isn't perfect either. the pressure still gets low when its hot. (the temp guage is straight up and down in the middle of the gauge when it the oil is that thin so the engine is not cooking) I do not yet have a oil temp guage yet, but the oil is way too hot to touch when it is thin..

The main engine oil light never comes on though.. so the oil pressure is not low enough to actually trip the cluster to turn on the oil light.. it is possible that the aftermarket oil pressure guage is wrong.. but when cold the pressure is up above 50 and even when warm (as opposed to hot) the oil pressure doesn't go under 25.. but once the needle is straight up and down.. the oil pressure at low low idle is 7-15psi. the engine has no rattles and is smooth and clean all the way though.. no sign that it is badly worn engine or anything.

Should I look into an oil cooler ? the turbo is clearly cooking the oil pretty hard.. is that normal? (I'm a fairly aggressive driver)


Also, I am running out of reasons the idle is so low.. no leaks, TB is spotlessly clean... TPS is fine. (someone told me the oxy sensor might be to blame, but I didnt' think it was being used at idle.)

Please sirs can I have some suggestions?

much ta's


Frank

I

being turbo the oil is always going to be super heated. the low oil pressure is a part result of the low idle speed.
but you would be surprised how much difference a good size oil cooler makes to the oil..

I would check the rocker cover breather, pcv valve for blockage and the check valve on the pcv line, any restriction here can cause a lower than average idle, although the ecu should compensate if the idle is lower than specified..

the 02 sensors only work at idle and light cruise, but I doubt that is the cause of the low idle

Thankyou Troyman, once again.


OK so a big oil cooler is the go.. have not found anything on eBay yet.

where do they go in the oil line? I'd have thought the turbo oil return line to the sump would be the go?

I shall check the PCV today but I'm fairly certain I've already done it.

I'm tempted to file a tiny notch in the throttle butterfly for now.. I have a spare so once I can control the idle via tune I can put the spare in.

The oil cooler lines connect to a sandwich plate between your oil filter and block. The oil pump pumps the hot sump oil through the cooler back through the oil filer into the engine...

Have you had the fault codes checked on the ecu?

Mine does the same thing. But never quite so low sits around 20ish just a bit under. Has always worried me but it has done the exact same on 2 different motors now so just must be the way they run.

Thanks for the info Sloxr6 and troyman,

I am eyeing off a 30 row cooler with a 7inch fan on it and all an10 fittings.

Wondering if its overkill.. But I guess it has to cool 7 litres of very hot oil so perhaps not.

I would be happy if it stayed up near 20 slowxr.. I think mine gets so low for a number of reasons.., the BTR seems to apply much more resistance to engine rpm than my mates NA ba falc. My car lurches much more when I put it in drive and the idle drops more too. I wondered if it was some change for the turbo models that caused this. In any case the first T56 that shows up for a reasonable price will be going in this car... Right now I'd probably buy a ba xr6t T5 if the price was low enough, just to get rid of the BTR.

I also suspect my cheap electronic oil pressure guage accuracy at low pressures..

Then there is oil temp, I have an oil temp guage on its way so I can see how hot its getting. And the cooler should help too.

Lastly its my god damned low idle that I can't find any reason for... Driving me nuts. (Checked the pcv and hoses without finding any issues too)

The last one is the most frustrating issue I've ever had as it defies diagnosis.
I was wondering of that little grub screw that holds butterfly has vibrated out a bit or something as the butterfly seems to be very close to fully closed at idle.

It will be your low idle that is causing bugger all oil pressure. I bet if you Rev it up to where it should be idling your oil pressure will come up

yeah, funny you should say that.. I just did a little test not 20 minutes ago.. thrashed my car all the way to work to make sure it was good and hot.. then parked and put it in drive and tried to get it to idle at 700ish rpm with my foot on the accelerator. (idles at about 450 in drive when hot) with me holding it at around 700rpm, the oil pressure was 19... So fixing the idle and adding the cooler should see that closer to 30psi.

just wish i knew what was causing the idle issues. I have checked or replaced everything everyone has suggested and it's all been good.

This engine has clearly had some work in it's past.. (the turbotech ported and flapper modded turbo is proof of that.) I wonder if some mod that was done that once the tune was removed could be causing this? (perhaps he had an sct and took it with him) If it has non standard cams in it.. and the tune no longer accounts for them.. that could cause the issue yes? Might be time to pull the rocker cover off and take a look at the cams and springs.

Just bought this:

http://www.ebay.com.au/itm/181279076438?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649

It isn't the 30 row one, but it's thicker and the rows are much bigger and it looks like better quality.. only thing I don't really like is that it seems to require that you use a Rodeo oil filter once you install the sandwich.

I am pretty sure you can adjust your idle through the xcal. But I couldn't see why someone would set the idle so low tho.

me either.. that was why I thought maybe having cams in the engine that required the idle be raised a bit.. and then removing the custom tune and but leaving the cams in might result in a low idle.

just speculating out of frustration..... I'm going to looking over everything one more time, and then I'm gonna file a tiny notch in the butterfly to raise the idle a tiny bit. (I have a spare TB to throw on when I can change the idle via tune.) Might swap out the oxy sensor just to be sure also as it's probably due anyway.

Ok.. just to cover all bases..

Just got this:
http://cgi.ebay.com.au/ws/eBayISAPI.dll?ViewItem&item=120865457572

A new, Genuine Bosch 4 wire narrow band O2 sensor.. #0258986603

I figured since my wideband O2 is Bosch, I would stay with that rather than the VDO unit.

doubt it will help the idle, but it won't hurt it either.

Don't wreck the butterfly. Have they still got the little idle screws on them? If so just wind that in a bit and see what it does. If the motor has mods and the car has been returned to stock with the mods still on the car that could be your problem. Get the car tuned to suit the mods and it will most likely fix your idle problem if not they will definitely be able to tell you why it is doing it.

yeah, I have plans to do that, but have to get the car running well in order to get the JTG gas system installed (it's a piggy back system that will run crap if the petrol system runs crap.) I'm just speculating about the mods until I get the covers off the motor.. I'd be very happy if it has good springs and cams in there.. would answer a lot.. but don't know for certain about anything except the turbo at present.

The reason I was gonna shave the butterfly instead of moving the grub screw is that the butterfly is electronically controlled and if it is trying to close hard against a grub screw that isn't going to give, I could fry the motor.. (I mean that the TPS tells the controller how far it is open.. and thereby how much it can close.. so if I put the grub screw in further it will still try to shut the same amount, but will be blocked by the grub screw and therefore might damage the controller motor? That makes some sort of sense yes? (the grub screw is factory set and it actually tells you in the manual not to adjust it.. it's also glued in place to stop you from trying)

It's also possible that when you do a recalibrate it works out how far it can open and close and will use the grub screw setting as it's baseline.. but who knows... spose it doesn't matter as I can get anther one of those for free too.

Yeah not sure how the work. But the amount you would have to move it would be bugger all which I wouldn't think would hurt the motor to much.