ianbott

Hi guys, took my car to the rolling road on Sunday to check everything is running right but unfortunately the car is way down on power.

The car is a kit car running a STi 8 motor with all standard parts including the PPP equipped ecu. So should be running around 300 at the fly but is more like 200 at the fly.

The guys at the rolling road had a good mess and believe the problem is a faulty MAF sensor or a boost leak as it isn't holding steady boost with it rapidly going up and down around the 1 bar mark.

Now I am under the impression I should be seeing around 1.2 bar of boost? but occasionally peaks at 1.5.

Does anybody have any input as to what is causing the lack in power? Boost leak would have to be quite considerable to loses 100 hp i'm guessing?

Thanks for any input, Cheers Ian.

P.S AFR's were reading around 10.2 on boost and the guy was detecting no knock using a high tech digital listening tool thing.

Infected by sti

iTrader: (6)

If you had a boost leak you would more than likely know about it as they don't tend to be quiet, everything plumbed in correctly? If boost is jumping around maybe the boost control solenoid is dicky? Or split / perished vacuums maybe?

Best advice would be get it to a knowledgable Subaru specialist or even a mapper who could plug in to it and have a look if anything looks out of place. Are you running a management light?

Plus if you get it to a mapper you would have better throttle response and more power than a standard ecu with the ppp pack what car is the engine in by the way

yippeekayay555

had a similar issue but the car spiked //over boosted the boost solenoid pipe work was dodgey on the t pieces which fell apart when i handled it, had already replaced the boosy solenoid so bought a new t piece plumbed it up and power resumed.... no loss of power or spikes throwing you throw the dash......

Pramas

couple of yr ago my hawk sti was capped no matter what at 325hp, i got Darren at Darlington to check it out and it turned out to be a folded gasket under the dump valve. Once it was fixed turbo made expected power, the leak wasnt noticeable till it was checked out

ianbott

Hi guys thanks for the advice. Here is the power graph I received, didn't bother with any other graph as I was in a mood lol.



Sorry it's sideways but it shows how the power isn't very smoothly delivered and very low.
The engine is in a VW based beach buggy.

Fonzey

iTrader: (5)

I bet that is mental.

ianbott

Infected by sti

iTrader: (6)

I thought it may have been the beetle buggy, I been following the thread you put up

Well at least you know you are not suffering from any detonation that's always a good start although your afr I thought should be around the 11's so at 10.1 your running a little richer by there which may not be helping with your figures, from what I understand you may see more torque from it if set purposely like that on the map from the cooler cylinder temps but im just wondering if you have a vacuums leak and where its seeing more un metered air then its increasing the fuelling to match



Something is adrift somewhere tho, have you gone over all the vaccumes and breathers to make sure they plumbed in correct? Is it running an external dump valve as these can cause problems?

Can you data log? If you can then post a log up for somebody to cast their eye over it may help

ianbott

Thanks for your comments where have you followed my build? Got it on a few sites that's all.
I've been in touch with a couple of mappers and I think I'm going to take it for a remap and hopefully the mapper can sort the issue I'm having.
As for dump valve it's currently blanked so runnin no dump valve at all.
Loggin would be a good idea but wouldn't know where to start, also have gone right over the inlet system and can't find anything lose or split so don't think there is a boost/vacuum leak.

Infected by sti

iTrader: (6)

I seen your thread on here, bloody cool motor that is

If you say you have been over it and there are no leaks I would tend to believe you, after all you have put this engine in to a beetle so you must know a thing or two

Strange tho if your running a stock map to be seeing low 10's on the afr I would probably be inclined to go and take a trip to a mapper I must be honest, last thing you want is over fuelling for what ever reason, it can lead to bore wash and a whole lot of other headaches as I'm sure you probably know.

Are you running the management light and have you done a check for any codes to see what may show up?

tjmatt

iTrader: (1)

Is the air inlet system fairly similar to the standard setup? Running cone filters etc can affect the air flow and requires a MAF rescale, additionally if its way out from standard you may end up with some surge which is making your boost wobble although its normally exhaust changes that cause this. If it has the VF35 turbo some people port the wastegates to help stop the surge and regulate boost better. The different and presumably free flowing exhaust is probably contributing to this.

Whilst 10.2 is rather rich its not a million miles off and can't explain being 100hp off! A remap is going to help all round but I can't see you finding the 100hp from it though.

Was it the only car run on the rolling road at the time, if not did the other cars all make expected power?

ianbott

To answer a few of the questions asked above, firstly there were several cars on the dyno that day all making as expected power so yeah it isn't a dyno issue.

The air intake has been modified quite considerably as has the exhaust thats the reasoning for taking it to the dyno, the exhaust is about 3 feet long, 2.5" diameter with a small cherry bomb style can on the end to reduce the noise a tad. The air inlet uses a cone filter and the location of the MAF has been changed slightly so I think all these are contributing to the issue.

I am looking to take the car over to graham aka enginemapper @ group B motorsport next week or the week after so hopefully he can shed some light.

As for engine light I have one wired in and it is on, have checked the codes and it shows a couple, 1 being the fuel level sensor which i'm not surprised by as i'm not using one lol.

There are 2 more both relating to the heater circuit on both Lambda sensors but that would not cause this issue, will get these cel's mapped out I believe it's a common fault and shouldn't cause any real issues apart from when cold.

The AFR's were much lower on the initial run down into the 9's, the run was cut short by the dyno guy for this reason and I cleaned the maf sensor which brought the AFR's back up the 10 region so i'm inclined to think it's a MAF issue. If I get graham to map it I will go speed density so that's that problem solved.