Engine fault....HELP !!

[toyroom]

No sooner do I get the gearbox fixed that the engine stops working properly. The engine revs freely and normall to the red line in neutral but will only get to about 4 and a half thousand revs when driving along the road in first, second or third. The point it revs to is a bit lower in each gear, 5 thousand in second, 4 and a half in third, and so on. Below this point, the engine feels a bit less powerful than usual.
The other change is that the boost guage hardly moves at all in any gear whilst this usually goes to .2 in second and third, .3 in fourth and .4 to .5 in fifth.
What could this be ?
When the rev counter stops climbing, it kind of hovers around almost like the sensation you get with a faulty fuel pump but nothing like the rev limiter. This wasn't like this last week as I managed to get the rev limiter to cut in on one occasion.
The car idles and starts the same as it ever did and the secondary fuel pump relay looks OK inside. The secondary fuel pump fuse is intact. Please help! I need an answer soon, or I'll be sleeping in the car tonight !! Thanks !!

[teigan]

sometimes a vacuum leak won't manifest itself when the engine is not under load. hope it's something that simple.

[toyroom]

Any advance on vacuum leak ? I got my money on failed secondary fuel pump, Jon from St Helens reckons the turbo actuator lines.

[lotusse89]

Check the line to the MAP sensor for leaks or being disconnected.
If not check spark and fuel pressure.

Look at all the grounds too.

Anything that might have been knocked loose around the time the transmission was re-fitted.

[green_meanie]

My money is on a failing coil pack.

My car had similar symptoms, would start and idle OK and under heavy load would stumble and have no power, after a couple of days it got worse and then under any load would have no power at all. Replaced the coil pack and solved it.

[toyroom]

I had a Merc which did this twice. First time it was the engine ECM ( took 2 weeks for MB to find !!) second time it was a coil pack. Do they have to be replaced in total (all4 4) or can they be replaced individually ?
PNM think it might be a cat blockage or a sensor. Strange that the MIL doesn't come on though.
I have checked the wastegaetes and they feel normal and the vac pipes look OK on the turbos.

[sanj]

Definitely look into cat blockage, though usually the symptoms are worse. Take it off and shake it, if little shiny particles come out, it's a goner, even if it appears intact.

[toyroom]

A new development! There is a 'machinery' type noise that sounds like a noisy gearbox or a can full of nuts and bolts being shaken somewhere in the vicinity of the left side turbo. The noise is subtle and quieter than the engine noise and it is only there if the engine is under load. ie, it's not there when the engine is revved at a standstill, but present at 3,000 revs and third gear going up hill. Does this help ??

[oilchange]

may well be a cat rattling its innerds about.

[teigan]

toyroom said:

.... a can full of nuts and bolts being shaken.... ??

is that not the signature music of a genuine lotus engine?

you might want to check your exhaust chain for cracked welds or loose joints. that'll cause a subtle mechanical sound too. the turbo would make a louder complaint noise, so i guess the bearing is healthy.

[toyroom]

Noise seems to eminate from viscinity of left turbo, not the cat. However, it's hard to tell as the noise is almost absent at standstill compared to driving along the road.

[oilchange]

Sherlock would say something like 'if you eliminate the obvious, whatever is left, however improbable, is the solution.
Look at the turbo more closely, you might have a turbine missing causing an imbalance or something.

[GKP]

I've not heard of the turbos self destructing on the V8s, however it's not impossible.
I have heard of lots of cats failing giving the symptoms described. I'd be poking around the catalytic converter first.

[toyroom]

The sensation is identical to the effect of a failing fuel pump which just can't supply enough fuel to make the engine go any faster. I would have thought that blocking the exhaust partially would have exactly the same effect. Would this still happen with a V8 as the other side is presumably OK ?

[Combover]

Jeeez JW just get a car that won't break...like a nice V8 Jag...

[oilchange]

get under the car and give the cats a thump with your hand to see if they rattle at all. My old Laguna had a knackered cat that made noise and reduced power as it partially blocked the exhaust gasses. I thumped it and it identified it.

[toyroom]

The problem with the Jag is that I get the blame for that as well ! As in: "I would have been quite happy with a four cylinder C class,...It was you that wanted one with a stupid great big V8 engine!" If you don't know what's special about a V8 engine (and she doesn't) then you probably never will.....And you also probably have no soul!

[toyroom]

Aha !! Got under the car with a rubber mallet and gave both cats a belt with it. Left one went thunk, right one went clatter, clatter. Wish I'd thought to do this last week! Could it still be the cat even though it doesn't rattle during tickover ? And...could it still limit engine speed even though there is nothing wrong with at least half of the exhaust system? Finally, would this fault not cause a yellow light on the dash (MIL)? Thanks for all the help, by the way.

[peter_england99]

With the engine check/MIL light on the ECU/ECM may be running the car in "limp back" mode. Hence the reduced performance.

Regards,
Peter.

[Combover]

JW, has Jon Sorted his Esprit yet?