Thread: 4.6 idle problems.... Ideas?

Originally Posted by daljames

Thanks heaps. I did use a non setting sealant so will re clean and apply a setting sealant when i get back from hols. I ran it this morning with the drivers side crankcase breather removed and had little change to idle speed,slight increase. I've still ordered a new tps, think ill have to get a faultmate! Any good advice on sealant? Also I removed the unichip.

You misread my post ....you need a "non-setting" sealant. Hylomar which is a solvent-based gasket that remains pliable is specified by LR. Use Light which is a liquid (available in 50ml bottle, tins and spray) on smooth true surfaces or Medium (100 g tube aerograde in Oz) which is a paste when faces are not true or a bit rough. Loctite #2 is also solvent-based and equivelent to the Hylomar Medium. These also make good gasket dressings.

Providing you removed PCV tube at plenum then with little change to idle you must have a bad air leak somewhere,.....use a aerosol of starter, carby cleaner etc to locate the sucker.

If Unichip was removed without resetting the ECU there may be a ECU fault (attached to timing / knock sensors) sitting there causing it to run retarded and rich but safe.

I have had a similar issue with my P38.
I removed the stepper motor, when i did it fell apart.
At this point i patched it up and presented it to my usual mechanic.
A new stepper motor was installed and the high idle disapeared a few weeks later on start up the idle would run at 1200-1300.
If you shut down after start up the idle returns to normal range.
I also have intermittent hot start stall problems.
Could be the stepper motor adjustment??

Go somewhere where you can access an Autologic or similar computer and find out what faults come up. Then have those faults cleared from the memory and go for a drive and recheck. That will locate the problem for you. Clearing the faults will make the car run happier too! I did that with mine and located problems I had been trying to find for months.

Willem

Hi all, back from trip o/s... Re-sealed the plenum and ram housing today. Mustve had some leaks. After about 2 mins idle went from 1800rpm gradually back to 1200rpm. Went back to 1800 on next start but gradually comes down again. No air leaks that i can tell. All new injectors have been seated properly. Cables VERY loose. I got a new stepper motor and TPS while o/s so i will try these tomorrow...

Update...

Ok so today i adjusted the fuel rail a little lower thinking that maybe the injectors where leaking air around the intake manifold holes they slide into. I also checked all high tension leads and adjusted them at the coil ends. Idle fell to about 1200 (from 1800). I put the UNICHIP back in, restarted and idle came up to 2000rpm... So back to the bridging wires. Idle back to 1200.

I gave up and lowered the idle speed with an Allen key on the adjuster above the idle speed control valve. Ill leave it like this until my Faultmate MSV 2 arrives for my birthday and reset the learned settings and start again then. At least my fuel economy remains awesome. Often better than 15l/100km and im on the hilly Northern beaches.

Oh and put in a new TPS. Although my basic OBD scanner only showed a 2% difference in position.