RS74

well had the map checked and tweeked on the rollers yesterday ... mapper said evrything is where it should be ( ignition timing , air flow , fuel mixture etc etc) he put the boost up a little, now got 314bhp 355 lbs torque.... still cant get the figures !!!!....
mapper said does'nt understand it cause as all the settings are it should be reading more .... hmmm! i'm going to check my cam timing and also i've got a 2.5" exhaust system so wondering about a 3"... but i'm now clutching at straws ....

tjmatt

iTrader: (1)

Interesting how turning the boost up increased the torque but no net power gain. Is the turbo actually holding boost to the red line? Really you would want an AFR and boost plot to go with your torque curve to diagnose the issue better. Also note how the mapper said that airflow readings where right - assuming it still runs the MAF then this may be right but if there is a boost leak then it won't be entering the engine.

If these are ok and the mapper definately is right with saying ignition timing is ok, then that leaves you with cam-timing, boost leak, spark-blowout(would probably feel the misfire) or a mechanical problem. It may be worth checking the plugs anyway and gap to 0.65mm. Check they are not too black (over rich, possible boost leak), or worse white with deposits on. Also check they are all the same colour.

ALi-B

iTrader: (1)

That'd be next. A tooth out would be enough to make it appear to run OK but be down on power. Next step would be cylinder compressions. After that checking for weak spark blowing out (although for it do it on all four cylinders would be really exceptional, unless someones been messing with the gaps - which inccidentally can damage the platinum tips). After that I'd be checking the wastegate on the turbo to make sure its seating right (without cracks in the seat) and the actuator is working properly (no leaks), along with the impellars and shaft.

The only other thing that comes to mind is a AVCS fault although I've never heard of one fail, it has been known, so I don't what power-loss symptoms would be casued by one failing.

I presume the mapper checked the AFRs and boost pressures and has the graphs across the entire rev band. So I'd assume they are ok - but you can never go wrong in re-checking it incase he's missed something.

RS74

all this has been checked apart from cam timing and compression check ..... just ordered a belt so will change next week when i've got a hour free

Shaun

Why couldn't you of done that on the road?

RS74

sorry not put boost up just increased the initial wastegate duty to make it come on boost quicker!

jura11

iTrader: (7)

Matey you are need compression test,i've seen few cars with low dyno figure and this was cause low compression one one piston..



Jura

Jolly Green Monster

iTrader: (4)

Sorry was 366bhp from an 18g not bang on the money? No reason other than I felt it was at the power output the owner had asked for and was as expected.

The customer wanted 360 something, I told him it was 365bhp and we stopped there, he went for a dyno run and it showed 366 on clinics rr. He then happened to come to a dyno I was mapping at and mapping a friend of his car on the rr (some people dont like driving their car whilst it is mapped) and I offered to tweak a bit more out of it on the rr.
Not sure why I am having to justify myself, I never mapped OP cars etc

Simon

grahamc

iTrader: (10)

I agree... Don't like mapping my car on the road. Road conditions are terrible - potholes and doing silly speeds in 4th gear on public roads is not acceptable.

RS74

gona check this to

craigyp

iTrader: (5)

How much is a compression test?? As I'm having the same problem!! Can't get above 340 on harvy smith 18 g

dynamix

iTrader: (3)

a ghetto compression test is free craig - just unplug your crank sensor and crank it over. It should have a nice even beat to it when cranking.

If it sounds like it skips a beat when cranking it is probably down on compression on a cylinder or more.

Obviously this wont work if all 4 cylinders are down


reconnect the crank sensor and start and stop the engine 5 times to get rid of the CEL that will apear as a results of unplugging sensor afterwards.

ALi-B

iTrader: (1)

Labour-wise its just a bit longer than a spark plug change...30mins labour?

Should be done with a warm engine (although doing so will mean taking the plugs out whilst hot will be fun ).

craigyp

iTrader: (5)

Good good!! I not do it myself though...
Just getting really pissed off wi my car at the mo!!! Duncan keep a eye out for them parts though

dynamix

iTrader: (3)

Am on it for you

Shaun

Simon,
Did you get out of the wrong side of bed or something?

My question was in relation to what could be construed as being stated in your previous comment, which *could* of been interpreted as..... Dyno's are great as I achieved 20bhp more by using one over and above what I could of done on the road.

Before you know it people will start hailing from the facts according to ScoobyNet, that dyno mapping in fact means the car can achieve more power.

So hence my question and your meaningful explanation, which in fact "straightens" that interpretation out.

RS74

free for me , i run my own garage

Jolly Green Monster

iTrader: (4)

Sorry i misread your post as having attitude it obviously didnt have sorry

Shaun

In hindsight you are right. Not my intention either.

bnmotors

You have email Simon.

RS74

well i've changed timing belt , which i'm glad i did as the tensioner was leaking oil...
timing was bang on , and the compressions were :
no.1 . 120
no.2 . 120
no.3 . 125
no.4 . 125

a little low but i have installed cometic headgaskets which are much thicker than standard , so i suppose this will drop the compression

i'm just going to stop worrying about it and just drive / enjoy the car due to as mentioned before , on the road the car pulls like you would'nt belive

thanks for all the suggestions and help guys

ALi-B

iTrader: (1)

Compressions are a bit low, but not massively. For a 8.0:1 engine, I'd be expecting about 140 to 160psi. Maybe the gasket drops it to 7.5:1? The only other thing could be a catalyst or muffler breaking up and causing a partial restriction on the exhuast - that affects top end power.

Edit: workshop manual states 121psi as the lower limit for a standard engine, so its right on there.