Turbo problem?!

[Evo8.Rob]

Originally Posted by kikiturbo

boost plot at a minimum, but you really want a log from the ecu... like ecu load, WDGC, WDGC error,

basically, evo's will usually overshoot their boost target. What happens is that when you load up the car at low rpm the boost will shoot up, and the base waste gate duty cycle (WDGC) will be too high, esp with 3 port solenoid. When the boost readches the desired level the ecu will start lowering the duty cycle, but depending on the settings in the map iit will not pull it fast enough. Also, evo ecu looks at ecu load, which is measured at MAF and not boost directly (depending on model)... so ecu will sometimes be too slow to react. As a result you will overshoot the target boost. Now, in the ecu you have some load limits in the map, and if you overshoot those you will have a pretty hard limit that you will hit and will sense it, like a hard RPM limit..
if you do not hit that limit, and overshoot boost, you can have knock, and then the ecu will pull timing and add fuel. As a result you can feel the engine boost up hard, then loose power for a while....

if you look at your boost you will probably see boost go up, spike and then drop down.. that is what is sounds to me... In any way you will need a good log of it happening to see what is going on.. maybe a look in the map too..

That is all way over my head.. i've screen dumped it to my mapper. Hopefully he can shed some light on it all for me. I know the mapper put waste gate duty to 0 and it was still spiking.

With regards to seeking a log.. is there something i can plug in to read it?

[Evo-Paul]

With the wastegate duty at 0% it should effectively run Actuator Base Boost Pressure and certainly not be spiking.

This would suggest a Problem with the Actuator or Actuator Plumbing.
Is it a stock actuator?

[Evo8.Rob]

Originally Posted by Evo-Paul

With the wastegate duty at 0% it should effectively run Actuator Base Boost Pressure and certainly not be spiking.

This would suggest a Problem with the Actuator or Actuator Plumbing.
Is it a stock actuator?

it is a stock Evo 8 actuator. They pressure tested it to see that it was moving freely. Yesterday I had a mate look over the car, he noticed the vac lines off solonoid were ever so slightly pinched. A quick re route enabled them to be free and it became ever so slightly better..

[Evo-Paul]

Originally Posted by Evo8.Rob

it is a stock Evo 8 actuator. They pressure tested it to see that it was moving freely. Yesterday I had a mate look over the car, he noticed the vac lines off solonoid were ever so slightly pinched. A quick re route enabled them to be free and it became ever so slightly better..

Did they test if the Actuator would hold pressure? Not just move when pressure was applied.

I'm wondering if the Diaphragm in the Actuator is leaking, and at high load the Actuator isn't strong enough to open the wastegate fully/at all, causing boost to climb, boost would then taper off at higher RPM.

Try connecting the nipple on the turbo outlet pipe directly to the actuator with a short piece of Vac hose, and see what sort of boost pressures you get. It should boost to what ever the actuator spring is (I'm not sure on an 8 actuator).

If it works ok like that, then try a different boost solenoid.

[Evo8.Rob]

Originally Posted by Evo-Paul

Did they test if the Actuator would hold pressure? Not just move when pressure was applied.

I'm wondering if the Diaphragm in the Actuator is leaking, and at high load the Actuator isn't strong enough to open the wastegate fully/at all, causing boost to climb, boost would then taper off at higher RPM.

Try connecting the nipple on the turbo outlet pipe directly to the actuator with a short piece of Vac hose, and see what sort of boost pressures you get. It should boost to what ever the actuator spring is (I'm not sure on an 8 actuator).

If it works ok like that, then try a different boost solenoid.

I'm not sure if they tested to see if it would hold pressure.. they did test to see if it moved. The boost seemed to spike at 3.8k under heavy load, revs would then rise to around 4.5k then drop back and would accelerate normally. Was watching the boost gauge last night it would spike up to 17psi then drop to 15psi then rise gradually back to 17psi.

[Evo-Paul]

Originally Posted by Evo8.Rob

The boost seemed to spike at 3.8k under heavy load, revs would then rise to around 4.5k then drop back and would accelerate normally.

Unfortunately that is 100% classic clutch slipping under peak boost.

The only way the revs can increase and then drop without lifting off the throttle is clutch slip or wheelspin.

Your boost pressure 'spike' is perfectly acceptable too.

[Evo8.Rob]

Originally Posted by Evo-Paul

Unfortunately that is 100% classic clutch slipping under peak boost.

The only way the revs can increase and then drop without lifting off the throttle is clutch slip or wheelspin.

Your boost pressure 'spike' is perfectly acceptable too.

alot of people have said clutch slip, i've let them drive it and they have ruled it out instantly.

The engine speed increase as does my road speed. Surely if it was slipping the road speed would not increase?!

[MikeC]

Haven’t read all the posts. All I will suggest is get a second opinion from another trusted tuner!

[kikiturbo]

Originally Posted by Evo8.Rob

That is all way over my head.. i've screen dumped it to my mapper. Hopefully he can shed some light on it all for me. I know the mapper put waste gate duty to 0 and it was still spiking.

With regards to seeking a log.. is there something i can plug in to read it?

I would double check the wg solenoid install and even remove it and run the car with wg plumbed directly to boost source. Sounds like bad 3 port install really..

as for the log you need the specail cable and evoscan to log the ecu parameters..

[Lee5]

I'll give everyone a little more info.

The car was run without any wastegate duties, and still spiked, not as bad but the spike was still there.

The more boost the more it would do it.
The 3 port was then looped so it was not in the
system and it still did it.

Rom file was changed to eliminate that as well.

On looking back over the logs the engine will slur between 3800 rpm and 4100rpm, when put under load it will raise to 4100rpm then fall back/grip to 3850rpm and this can be seen in the logs.

I know how the correction works in the ecu and it's impossible for it to cause the engine to slur, it will hold the rpm, not make it go backwards, plus all the corrections where removed.

[kikiturbo]

in that case it is clutch slip... as this is more clear description now than the original post.. maybe logging engine speed/vehicle speed as a calculated channel can identify slip easier..

[Lee5]

Originally Posted by kikiturbo

in that case it is clutch slip... as this is more clear description now than the original post.. maybe logging engine speed/vehicle speed as a calculated channel can identify slip easier..

But you can't smell it, plus you can load the dyno and hold it at 1.2bar and engine won't slur.

It is as if the turbo is running mega boost as it comes on then its like it over powers the drivetrain and it's not like it's a long slip, it lasts for 0.5 second, this is why we said could it be a turbo issue as well.

The problem is people look for answers, anyone can give advice on the net and say it's clutch, it's turbo this or that, the customer goes and spends 1k on a new clutch and the car still does it, does the net care, I don't think they would as they are not face to face.

[kikiturbo]

what does the log look like.... as in ecu load-boost, etc? Do you see the overboost situation in the log?

[Evo-Paul]

Originally Posted by Lee5

But you can't smell it, plus you can load the dyno and hold it at 1.2bar and engine won't slur.

I had peak boost clutch slip on a clio 172 I turbo'ed, was fine on the dyno, but on the road did the exact same jump up a few hundred rpm and fall back that's being described. Once the initial surge was over it drove fine.

Also never had any clutch smell.

[RaeTurbo]

Try it in fifth gear from 3000rpm see if it slips when the boost comes in uphill would be good, if it doesn’t slip then by the time it’s at full boost it’s not the clutch.