Engine problem - Not sure where to turn next

[dbroughton]

Having been in the hands of two specialists in the last month I still cannot get my car running right

The specialists know something is wrong but cannot figure out what. Car is very ragged at low revs and not convincing at the top end. The car is boosting. Wastegate isnt stuck, injectors cat etc is ok. Car has a new electric charge cooler so temps are good. The specialist tells me the scan shows nothing untoward - that said I am not sure if they are using freescan or someother fault reader.

Where do I go next? Lotus themselves? Or someone else who really understands the boost issues inherant in a Stevens car. Maybe a turbo specialist might be more use!

Maybe there is nothing wrong and GT3's are just rubbish!

This is costing me thousands!

[Bibs]

Danny - A freescan log would be really useful for diagnostics.

There's a good chance I'll be close to West London tomorrow early afternoon and perhaps we can either run Freescan or I can sell you one of the LEF freescan cables so you can do it yourself?

[t70]

Can you describe what you mean by "Ragged"?

[dbroughton]

The engine bogs down, and then stumbles all the way to 3500 rpm where the boost starts to make its self felt.

No real low down torque of any shape or form, what there is seems variable. It really is a nasty drive below 40 mph. lots of riding the clutch to keep things smooth.

I know that all GT3's are not great of the line but this car is just not fun!

Bibs, I dont get the car back until monday but a freescan cable sounds like a must! If you are around in west london, I will take one of your hands! Where abouts are you?

I am a little dissapointed that the specialist didnt use or have freescan. He mentioned there were no fault codes but I dont think they really check all the parameters. It is a bit depressing that I/we will diagnose and get them to correct!

[Jonathan]

Well my GT3 drives very smooth from 1000 rpm (ok not a the moment) - there's nothing wrong with the car itself other than it's moderatly slow acceleration until turbo boost kicks in. The only difference to that and the SE I have is the SE is slightly more urgent to boost. There's nothing intrinsically wrong with the GT3 at all.

Where abouts are you located ?

Might be able to help.

Not many dealers / specialists have even heard of freescan which is CRAZY considering most have to beg steal or borrow TECH1's

I showed it to many Lotus specialist who thought it was good but wont use it for some crazy reason.

I've also spotted issues with Esprits that 'professionals' have missed by using freescan in an instant - it's totally invaluable - everyone should have it !!

I'd be looking at sparking plugs to begin with - check the condition and gap as well as the leads and their firing order.

I've taken tables from a known working Esprit (mine....well, until yesterday when the chargecooler broke and then the throttle cable snapped) - in all seriousness that was done on wednesday so you could compare the two and an instant and probably find the issues just by looking at the data.

Lemme know - got all of next week off working on the 2 cars here anyways, you're welcome to send me the log files if you get them.

Edited June 27, 2008 by Jonathan

[Vulcan Grey]

I'll 2nd or 3rd Freescan. Run a log and post it to us here, if you can.

Did the "specialist" check spark? Coils, plugs, leads?

MAP sensor values, throttle position values, air leaks in the manifold...

[t70]

The lag in 1st gear in the lotus... should be similar to trying to accellerate your gti in 4th from about 1200rpm untill about 2200rpm (it's the only way i've been able to get the Mk 5 to show much in the way of lag). The lag should be pretty significant... more like the gti mk4. But it should not stumble or misfire except around 3000rpm on initial throttle tip-in... that's just a lotus thing. Do you have access to a wideband? proper afr readings can assist in diagnosis... have you done a compression check? #3 and #4 cylinders tend to have exhaust valve issues which would cause some mis-firing etc..

[dufour]

i have knowm same problems few months ago on my SE big troubles just after 4000 T/Mn

i have change sparks and fuel filter and the problem a been solved

Philippe

[dbroughton]

getting my freescan cable this morning so that should help!

Car has just had a C service so I am assuming filter and plugs are good.

When I picked it up it was really bad. The boost gauge seemed to show boost building fairly nomally but there was nothing. Pullling onto a motorway was horrible.

2 weeks on (100 miles) and things seem to be much better but still not right. I dont think it has anything to do with the chip learning.

Car has had a sticking waste gate in the past which made it equally nasty to drive but the way to boost came in made that problem ok to diagnose. I personally think there is a problem with the wastegate setup/spring/valve.

I will get some freescan readings and post them.

[t70]

Have you checked your cam timing? And... I wouldn't be too confident about anything that is supposed to be "checked" during a "c service"... you'll find plenty of people on here that have had stuff "checked" that hasn't, in-fact, been checked. Should also check your ignition timing.... the ignition timing does not run off the intake cam like most engines... it's a seperate pulley that is attached to your chargecooler pump... and if that's out.. you would have a very un-responsive engine. When you pull the freescan... you may want to do one once the engine is warm... and then reset the ecu and do another one -- as the knock count will increase and possible tell us if something is up with timing.

[Vulcan Grey]

Yeah at this point I wouldn't hold too much faith in anything being correct just because it had a service!

I have found that work on the engine can cause problems, such as repeated pulling on and off of the spark plug leads can cause them to break and fail. Not enough spark means a rough running car with little torque.

[chats371l]

Danny,

I changed my wastegate on my GT3 and then had about a couple of months period where I couldn't get the car to boost right at all. Ended up taking it too 2 different places and they didn't seem capable of setting the car up correctly. One got it close and then I adjusted the wastegate to finish it off. It was still overboosting slightly at the top of the rev range and bizarrely when I fitted my dump valve, it sorted the problem out, that and disconnecting and reconnecting the battery to allow the car to learn its settings again. If you change wastegates, Dave Walters does a very nice alloy one which is great.

As for the way the GT3 drives generally, Mark TC pretty much has it summed up. Yours should definately starting boosting at 3000rpm and the car does feel a little bit slow for accelerating up to 3000rpm.

Also as Jonathon mentioned, the car should definately drive smoothly up to the 3000rpm point and then at that point you do get a bit of a stumble as the turbo switches in to start boosting. The GT3 is just one of those cars that you really have to 'drive' to get the best out of it.

Hope that you manage to get to the bottom of your problem soon as I remember mine when the turbo wasn't working correctly and it did make the car a displeasure to drive.

Regards

Chats

[rogerch]

Questions to answer, in order

Are you getting a good spark to all plugs? get an old plug and cur off the electrode, if the spark will jump that it's generally OK, and you should be able to hear it crack!

Check fuel pressure

Check for air leaks.

90% of problems are right there.

Roger

[t70]

Good call Roger!

[dbroughton]

Got my freescan cable!

Handed my cash over to Bibs on a layby just of the M25. Must have looked very dodgy to anyone else parked up!

Get the car back tommorrow so I will see if I can see anything obvious.