15th Sep 2006, 05:45
Spot on, same as the 2.5 Duratec, the IMRC (inlet manifold runner control) is a motorised unit that opens up at around the 3500 rpm to open the other 6 valves.That's why its pretty good on fuel as can totter around on 18 valves until you accelerate harder.
16th Feb 2008, 06:23
I think some people are a bit confused by the comments on the "valves". All of the inlet valves work all the time. The valves the IMRC controls are the throttle valves. I think there are 2 per cylinder. Below 3,500 RPM only one is open per cylinder; as the engine reaches 3500 rpm the IMRC starts to open the other 6 inlet throttle valves, thus feeding more fuel and air to the engine.
31st Aug 2008, 09:16
Jeez! it's a 24 v, where the control unit keeps 12 shut then on 3500 opens the other 12 that will result in 24v working together.
How can a car be 24 v where its only two valves per cylinder???
3rd Dec 2008, 14:57
Right, lets get this sorted.
All 24 valves (4 inlet and 4 exhaust per cylinder) work all the time together.
The IMRC is the inlet manifold runner control unit.
This lets the inlet manifold work as a normal inlet manifold would below 3500 rpm thus helping the torque values of the engine and helping fuel economy, then above 3500 the IMRC unit rotates a secondary part of the inlet manifold changing the air flow pattern inside, thus producing the induction noise and increasing the full potential of the engine.
It works in exactly the same way as the ST170 Focus.
9th Dec 2008, 07:35
I have a 2.5 V6 2000 Cougar with a drop of performance in acceleration, the rev's seem to stick whilst changing gears. I've had the engine checked with 1518 code being identified, which is the IMRC bank 2??
Is it easy to change the IMRC?
Is this definitely the fault?
Is this a garage job or can a novice do it?
Any help is appreciated.
27th Feb 2009, 10:13
On the Duratech 24v V6 engine there are 2 inlets and 2 exhaust valves per cylinder - (that's (2+2) x6=24. Forget the exhaust valves, these are not important. Concentrate on the 12 inlet valves. All 12 of them are operated by the camshafts - 2 in each cylinder opening at the very same moment each time the cyclinder is on its inlet stroke. The biggest valve is fed via the manifold, but there is a secondary route for more air to enter the cylinder via the secondary throttle valves operated by the IMRC above 3.5K revs OR on rapid depression of the throttle.
Hope it sorts you lot out - even if it's a year late.
7th Mar 2009, 21:34
Guys you are all wrong. Only the 2.5 V6 has IMRC and primary and secondary intakes. The 3.0 V6 doesn't bother with such nonsense and has a single fixed inlet.
The cam profile is tuned for a kick at around 3750rpm though, and you certainly feel and hear this on the 3.0 V6.
29th Jun 2009, 12:37
Actually the second to last poster was only slightly wrong, the 2.5 V6 Mondeo engine does have an imrc controller that 'seals' shut 6 of the inlet valves until around 3.5k rpm.
This is sort of a vtec system as it restricts airflow to all 6 cylinders until the specified rpm so as to increase economy and smooth running.
I should know; I've stripped and rebuilt 5 of these engines in road and race trim.
8th Jul 2009, 09:07
This is a review of the ST220, which has the 3.0 V6, which has a fixed intake, no IMRC and all intake valves are fed via the same intake route at all rpm.
The 3.0V6 does not suffer from any of the 2.5V6 intake issues.
11th Aug 2012, 13:34
I have the same problem with my 98 Cougar. It will not rev past 5000 RPM, and when I drive it and let off the gas, the RPM sticks at 3000 RPM. This is after I had the intake manifold cleaned. When you take the throttle body off, there is a grove to the right. It was blocked, but my car says no fault, and my car was doing the same thing yours is or was. Did you get it fixed? This is a cry for help.
p.s. How many catalytic converters are on the 98 Cougar?