Engine stalling when DECELERATING

[gw0071]

Hello all - another instalment in Cory Commodore's woes,

It has taken to intermittently stalling when decelerating/coasting to a stop

Starts after about a 5min rest like nothing ever happened

Not relevant to fuel qty (3/4 on last occurrence), fuel pumps runs ok

Replaced fuel filter, spark plugs and leads about one week ago. Made an incredible difference to running qualities - running quite well actually, thought I had cracked the 'code'

Had a crank angle sensor relaplaced about 6mths ago

VTII 3.6 auto, 175000km, one lady owner

Been considering options for vehicle replacement. Help me to help Cory stay a little longer


Thank you

 

[Lex]

Hi
DFI & coil packs.

 

[devilly]

sounds to me like the 3 rubber hoses at back of engine(plenum) 1 would need zippy lock and other 2 ring clamps.

and under the throttle body 2 ring clamps and then follow them 1 goes to another metal place that needs a ring clamp.

and the other is a long line that goes to plastic piece BE CAREFUL when tightening a ring clamp on this one as it's a plastic tube.

mine was at the stage when you accelerated it would bunny hop,de accelerate it would nearly stall.i only found all this out as i installed a vacuum gauge in mine

you should be able to put on idles and hover your hand around and move it closer to where the air is leaking from,other ideas would be mainifold,egr gasket. hope this helps you

have you had the engine light pop up ?

 

[gw0071]

Thank you for the advice Lex and Devilly

I should have mentioned that I replaced the DFI with an eBay OEM while avoiding a crank angle sensor. Ironically this blew up a coil park but due to being about a year or so later, I consider unrelated. I refitted the original DFI regardless

I do like the vacuum plumbing suggestion - pretty simple to achieve in shed and minimal cost. Will give it a go

Have a great w/end

 

[Lex]

Hi
Have a look at plug that plugs into dfi. Check contacts & whether the plug is a tight fit or loose. If fit is loose it can cause arcing & blow dfi & coil packs.
Lex

 

[Immortality]

Clean the throttle body paying particular attention to the IAC stepper motor and passages. Don't get any cleaner into the TPS either

 

[gw0071]

OK, removed throttle body and plenum manifold cover. Both coated in what I assume is 16yrs of ignorance

Valve still relatively smooth in operation and I couldn't be bothered removing the manifold and everything attached to it, especially in view of the coked deposits around the EGR port - reducing it down to about 25% of full diameter. Removed the build up and sprayed carby cleaner through the refitted throttle body. Will evaluate further

All flexible plumbing seems ok

BTW, the tubes off the throttle body - I short, 1 long. I'm guessing that they are for vacuum and fuel purge. The short one is split at one end (occurred after being disturbed?) Is the longer one the later? It goes under the manifold and across to a solenoid valve on the opposite side

 

[Immortality]

The short hose is probably the crank case breather hose, the long hose goes to the purge solenoid.

 

[devilly]

OK, removed throttle body and plenum manifold cover. Both coated in what I assume is 16yrs of ignorance

Valve still relatively smooth in operation and I couldn't be bothered removing the manifold and everything attached to it, especially in view of the coked deposits around the EGR port - reducing it down to about 25% of full diameter. Removed the build up and sprayed carby cleaner through the refitted throttle body. Will evaluate further

All flexible plumbing seems ok

BTW, the tubes off the throttle body - I short, 1 long. I'm guessing that they are for vacuum and fuel purge. The short one is split at one end (occurred after being disturbed?) Is the longer one the later? It goes under the manifold and across to a solenoid valve on the opposite side

whoo you just found the problem with the short one replace and use ring clamps works really well .with the big long hoses if you replace it weave an S shape through the plenum then it will sit nicely and work really good be-careful on the back of the engine is a plastic tube.

 

[gw0071]

I believe the blocked EGR port was the cause of the stall in deceleration

The hose issue may explain the intermittent failure of the engine to go beyond cranking. I saw this first hand when trying to start with various other ports on the manifold open to static while trying to find an alternate point to spray the carby cleaner into apart from the throttle body

The fuel purge line truly is a poor design - three piece, two elbows and a straight tube. Ridiculous

Thank you Devilly