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Cutting out in idle and gear jump at 60 troubleshooting

Posted: 02 Aug 2017, 06:04
by 1996LARGO2.4
Hello all,

Brand new to this forum and looking for some help or direction if possible.

I own a 1996 petrol 2.4 Highway Star and asides from a coolant hose going, I've had no trouble with the vehicle until now. Three weeks ago, I pulled up on the A27 with an overheating issue. It turned out a coolant hose had come off of the IAC Valve and bled the van dry. The AA man that came to my aid, identified the unit (sat atop the exhaust manifold) as the IAC unit and decided to bypass coolant away from it altogether, rather than reattach the hose to it. Subsequently, for the two weeks that followed, I was driving around with no coolant going through my IAC valve.

All of a sudden after a 2 hour motorway drive, the van started idling terribly in traffic and the last few miles of my journey ( in Bristol traffic ) were a constant struggle to get he van going ( had to keep the revs up in neutral every time I stopped). This subsequently lead to another AA callout and this time, the guy decided to unplug the electric hookup to the IAC valve. Suffice to say I got about half a mile down the road and the vehicle clapped out completely. It did not like being unplugged so I plugged it back in and engine started again but with the same shaking and clapping out, when in neutral.

In the last couple of days, I've additionally noticed the van taking longer to start and revs lowering when electrically loadbearing (full beams, etc). Also, the engine starts with a short but noticeable whining sound ( think fairground Wurlitzer but quieter).

Existing problems with the van included a slightly loose alternator pivot bolt ( now fixed) and a slight rattle in the engine timing chain. Serpentine and alternator belt tension and alignment seem fine. No engine or battery lights have come on at any point.

I can't help but think that given the timing of all this, the problem is down to a faulty IAC valve. Also worth mentioning I have cleaned the valve and reconnected it properly with the the coolant, electric etc. Problem is certainly more noticeable when the van reaches optimum heat. Perhaps the valve got broken or damaged during the time it was without coolant.

Final thing to mention ( though I'm not sure if this was pre existing ) as I accelerate, the van tends to jolt (or maybe the gears do) when hitting around 60mph, as if a surge of energy has just hit it.

Any advice I would be very grateful,

Chris
Southampton