Loss of power in high revs

[toyroom 5]

Car runs fine below 3000 revs but seems less powerful than usual. In 5th gear at 70mph, full throttle and car feels like there is a banana in the tailpipe with slight vibration and nowhere near as quick to accelerate as usual. It is almost like a very gentle rev limiter. It is more noticable in 5th gear but occurs in 4th and to some extent in 3rd. It seems more noticable when the engine is hotter. It feels like the sensation when the fuel pump was losing its oomph on an old carburettor engine or how it feels when one of your cats is self destructing. I have metal cats and the exhaust pulses feel equal. No hoses appear to be loose and all the various wires are in place. Any suggestions?

[WEllison 9]

I assume there are no error codes. So much of the Espirts power is based on the turbo boost I would start there. Get a scanner and see how much boost is being generated.

[mike_sekinger 697]

I agree - start checking how much boost and then look to those associated elements. Check:

- wastegate capsules

- wastegate solenoid

- boost leaks

Cheers,

Mike S

[toyroom 5]

Update: It's a misfire. Went out on the road with Pete from PNM and he said straight away that this was a misfire. The mystery is that it is completely regular. Exactly the effect you would get if 2 of the cylinders stopped working. However, only happens on full throttle and is only there between about 3,000 and 4,000 revs in fifth and around 4,000 to 5000 revs in fourth (around 70 mph). It is just noticable at 4500 to 6000 in 3rd. But weirdest of all, only happens with the engine hot (not warm: no problem at 80 degrees indicated) Only after a bit of spirited driving does it start. ? a coil pack being misdirected by a slightly confused ECU. I intend to change the plugs at the weekend. Considering all of the above, it has to be a spark problem but why only under very specific conditions?

Edited February 16, 2012 by toyroom

[V8 FOU 0]

Long shot, but how about the fuel filter? If that is partially blocked it would give those symptoms.

[toyroom 5]

I thought fuel at first (and still may be) but the car runs perfect for the first 15 minutes and then the problem is identical to the effect of switching off one or two cylinders. Presumably fuel filter and pump issues would not depend on gear selected or position in the warmup cycle.

[V8 FOU 0]

If the filter is partially blocked, or even if the pump is faulty, it takes a time for a vacuum to build up. A fuel filter is dead cheap and easy to change - worth a try!

I did have this some years ago on a customers nearly new Capri 2.8 (sheesh a long time ago!) and it was a dirty filter.

[Dave Hopwood 1]

It sounds like one of the four coil pack drive stages in the ECU is dropping out when warm,or possibly the coil pack itself.

Due to the "wasted spark" principal one faulty drive stage will knock out two cylinders

Regards

Dave

[toyroom 5]

Well.....common things being common. I changed the plugs and it appears to have sorted it. Plug well 6 was full of water and the bakelite insulator was completely brown. the plug was rotten and well 7 wasn't much better. The middle bolt on the plug cover sheared off last time I changed the plugs so I stuck it back on with glue for cosmetic reasons. This has recently disappeared. Consequently, the wettest winter I can remember, plus a design of engine cover which channels all the water into plug well 6, has filled the well with water which has done no harm until at an indicated 95 degrees coolant temp, the water has started to boil and shorted the plug lead leading to a 6 or 7 cylinder engine.

As well as sealing the plugs, I have designed and fitted a clever alloy guttering system to keep the rain away from the point where the plug leads cross from the valley into the cam cover. You could see this piece of engineering excellence if "hosting" and all the other rigmarole involved in posting photos wasn't harder than Errol Flynn after an overdose of Viagra!

Edited February 28, 2012 by toyroom

[WEllison 9]

Interesting analysis!

[CaptainBigleux 38]

I have exactly the same symptomas on my 96 Esprit (owner since few days) + check engine light

It was really bad when I took the car last week, as it was droven very little for last 2-3 years and only in city (at the beginning the engine was even stopping when the car was stopped, took more time to start up...). It's better after few days of driving the car quite a lot, but still not as powerfull as it should be (even tough it's my first Esprit I can feel it). Especially when hot the power is not always the same, sometimes it feel like smal misfires, not reving as quickly as always, like something is limiting the car (like your banana sensation ).

 

I just put the car in garage for classic maintenance (incl fuel filter and plugs), and I hope it will be better then.

 

I'll tell you.

[CaptainBigleux 38]

Car wasn't drive enough for many years. Workshop just started the service, and he discovered plugs completely dead and rusty, especially on left side, and also the ignition wire. So it's coherent with your symptomas and solution.

 

Now full service, oil change, all filters, plugs, wire, timebelt... can't wait to have it brand new

[Bibs 11,141]

[CaptainBigleux 38]

quick update.

I changed quickly the plugs in december... the car worked fine... but only 24 hours lol.

 

The leads which were very badly looking already probably finished to die lol.

(I will put pictures of old plugs and leads later).

 

The car was waiting for big service during many weeks at my favourite friendly local ind. workshop... and finally this week the service is done.

So time belts, all filter, all fluids, check all pipes, wires... and coming back to the topic remove the plenum to change the leads !

 

Now the car is running perfectly, no more misfires, no more bumpy revving, no more engine stopping at red light, easier start up (cold & warm), goes smoothly but surely to7KRPM, apparently all the BHP back !

 

HAPPY