Thread: 2.4 PUMA - Engine Hunting at Idle, is this common?

I’m thinking it may the vacuum control valve as read of similar early symptoms with the 2•4 fuel system.
Search “VCV” in the Google box at the bottom left of the page.
To get you started ....
2.4 Puma - Possible Injector Problem

+ 1 for the Suction Control Valve (also known as a VCV). I had similar problems with no fault codes. Finally it threw a pressure relief valve (PRV) fault which can be associated with a faulty SCV but no SCV fault. ie if the SCV puts too much fuel in and triggers the PRV. Therefore Nil faults is not always a complete answer. I replaced both and all is good again. When i tried to source a SCV from a LR supplier in Sydney i was told it was not sold as an individual item, that i had to buy the fuel pump too. If you get resistance, order it from Ford (part 6C1Q9358AB - $485). It's cheaper than the LR suppliers for a genuine part and can be ordered as a single item. That SCV is found on about 30 cars including Nissans and the European makes (google the part ref, you will be surprised).

A rough idle (a rattle) is sometimes an injector. There is antidotal reports of injectors playing up around the 100k marker (mine did burning a hole in the piston). Bailey Diesel do injector testing.

Cheers for that.... What's the result when/if this fails (ie: if it failed when you're in the middle of the Desert)? Can the vehicle still be driven or is it dead in the water?

What's involved in replacing this VCV?

I believe there is also something u have to do with the ECU in regards to Re-learning?

mine was blowing lots of smoke on start up and running rough as guts. I had plenty of warning something was up. That said it still ran and once you got into the torque range of the engine it produced power (just not on full song). I doubt you will be left high and dry without warning. The SCV sits on the side of the fuel pump. Not sure how much to replace as it was part of a large service for me. You need to do a pump learn when you fit a SCV. Mechanic will do it part of the replacement SCV. GAP diagnostics tool (on both Apple and Android) has a pump learn if you want a portable diagnostic tool for fault codes and resets on the road.

As for a desert breakdown, when you are at the end of Day 2 of a crossing you have no choice but to limp along. Met a bloke in Mt Dare in a 60 Series a few weeks back. Burned out a clutch 280km from Mt Dare on the French line, cost of a skull drag back to Mt Dare $2,900. Mechanic at Mt Dare wouldn't replace the clutch. Tow driver from Coober Pedy charged $6k to tow back to Adelaide (insurance by this stage). Towy said he could fit a new clutch in Coober Pedy but wouldn't because he would loose the full value of the tow. Insurance Co wouldn't send the car to Alice because he was heading in the wrong direction to home. All a bit nuts to me.

Another vote for SCV. I have replaced mine twice in the 150,000km that I have owned the vehicle (now has 270k on the clock), hunting at idle plus occasional dead cut. First time I had a local diesel specialist do it, second time I did it myself but ended up having to limp it to him to do the pump learn! The actual replacement of the valve is a very simple job, I had read varying info about the necessity of a pump learn, thought I'd try my luck. No luck.
Both times I bought the valve from an eBay supplier, genuine Denso unit in original packaging, about $160 iirc. Add another zero if you want the oval badge on the box.

As to the Tojo owner at Mt Dare, I can't imagine going into a remote area with such a lack of mechanical competence. I could replace the clutch in my vehicle (or his) at a desert campsite with basic tools. Just a matter of getting the parts to the site.

Originally Posted by MLD

mine was blowing lots of smoke on start up and running rough as guts. I had plenty of warning something was up. That said it still ran and once you got into the torque range of the engine it produced power (just not on full song). I doubt you will be left high and dry without warning. The SCV sits on the side of the fuel pump. Not sure how much to replace as it was part of a large service for me. You need to do a pump learn when you fit a SCV. Mechanic will do it part of the replacement SCV.GAP diagnostics tool (on both Apple and Android) has a pump learn if you want a portable diagnostic tool for fault codes and resets on the road.

Curious, the GAP Diagnostics Tool how does this connect to the OBDII port? Cable or do u need to buy a BT dongle and then use BT from your phone?

Originally Posted by Robmacca

Curious, the GAP Diagnostics Tool how does this connect to the OBDII port? Cable or do u need to buy a BT dongle and then use BT from your phone?

There is an App for your iPhone and iPad (i have Apple) and you buy a BT dongle from either GAP Diagnostics in Canada or from Bell Auto Services in the UK. I did the later as i bought a tune. There is bit of stuffing around to register the licence to your VIN (follow the instructions and you will be fine). I found a YouTube tutorial which was a bit long winded and in fact sorted it before the video ended. Once set up you save your tune to the cloud (including injector codes and other info that might be useful if you replace the ECU). If you have a BAS tune you use it to upload and manage that too. You can read tested, untested and a few other codes and clear same. You can see the car configuration data and change some of it. If you had a D4/RRC/RR its money well spent as it will configure the suspension default settings (think LAMS). As mentioned earlier it also has service features like injector codes, injector learn and pump learn. And it gives you real time ECU data that can be recorded and emailed from the App. I found it a god sent on my recent trip. i shorted a wire on my throttle harness and by real time reading throttle position sensor 1 and sensor 2 i could see it was an intermittent fault at that part of the system. Poking around the harness and i found the exposed wire. Not cheap but $ comparable to the BlackBox products and more versatile. Better than Hawkeye. Lorryman did a review on Defender2, google it. That experience i mentioned, in my mind, justified the expense because at the time i was in limping through Wanarring halfway between Burke and Tibooburra (Tibooburra has no mechanic and Broken Hill was 330 kms away)

Originally Posted by Robmacca

Cheers for that.... What's the result when/if this fails (ie: if it failed when you're in the middle of the Desert)? Can the vehicle still be driven or is it dead in the water?

What's involved in replacing this VCV?

I believe there is also something u have to do with the ECU in regards to Re-learning?

*Its a very Land Rover job, so at first glance looks impossible, then hrmm maybe not too bad, then job done, easier than you thought, the same job 12 vehicles later and its simple and basic.
*If its not logging a fault yet, replace it and its done.
*If it has logged a fault, once you replace it, it will run fine but the logged fault will remain (duty cycle exceeded or not calibrated bluh bluh).

Just for info...
*Its the fuel solenoid for the feed into the high pressure pump.
*Other common rail diesels have the same solenoid (even down to the same brand and part number, i think the last one I got was in a Nissan box).
*Ford for some oddity have decided it needs to be calibrated/reset when replaced.