pings on high boost? dyno graph included.

[EVOSTi]

i just had my car dyno tuned today, was expecting to produce around the 200RWKW mark but instead ran into some problems. the car in question is my 4agte sprinter.

i made 150KW at 14psi and the power curve was fine, but when the boost was upped to 18psi the engine started to ping and so only made 170KW.

the reason for the tune was, when i first installed my turbo setup and got it tuned, i had problems with the wastegate actuator so when we tuned it the boost was all over the place but it still made 174KW with peak boost falling as rpm went up, i also have the printout for this if needed. the car was tuned to run extra rich to compensate for the problems, i installed the new actuator and fixed the problem but didnt get around to tuning it again till a year and a half later (today).

so the only differences to the car are: blitz dual sbc boost controller, 3in exhaust changed from under the diff to now over the diff, different idle motor. i had a look at the cat when the exhaust was off (two weeks ago) and it was sweet. plugs were changed today, running 98ron fuel from BP, last tune was running 95!

any suggestions?

heres the graph:

[Hurricane]

dam hay just run it on AVGAS nar maybe look at your timeing? might be a bit to advanced?

[EVOSTi]

im running a CAS fixed to the block (not adjustable without bending the bracket) which picks up a signal from a wheel mounted to the crank pulley so it hasnt been touched since last tune, and i can only assume the tuner would know to check/modify the timing to suite?

[Lambolica]

Probably a stupid sugestion, however I don't know the spec on your car.

Could be the injectors maxing out?

[jonra23]

As above fuel leaning out or too much spark advance most likely candidates, both of which you woul hope tuner would have been on top of as there isnt much else to a tune.

regards
jon

[EVOSTi]

yes you would think they would be the obvious points of consideration.
i can say however than the turbo setup i am running i actually purchased from said tuner, including turbo, manifolds, injectors and intercooler setup and he is very experienced with 4a's.
with the setup i bought from him he made 209RWKW on a standard engine, mine is also standard but with a lower compression HKS metal head gasket and TRD valve springs. the injectors are 7MGTE injectors, 440's i believe.

[jonra23]

Did he happen to mention injector duty cycle % when it started to ping?

regards
jon

[EVOSTi]

no.
from memory (years ago now) when the setup was on his car he made is 200KW on 18psi the injectors were somewhere around the 90% duty cycle mark. but i could be wrong about this.

[jonra23]

How old is your fuel pump and filter?

90% is pretty up there if you are lookin for same numbers.

regards
jon

[EVOSTi]

fuel filters were recently changed, pump, well i have two VL pumps run in parallel, only one in use at a time. i put two in a while back when i was having fuel pump problems so i could switch between the pumps when one overheated and died, but that problem has since been sorted.

you would think if it was a fuel supply issue he would be able to identify that? same with timing. i guess ill take the cat out tomorrow and double check it, then i might get the injectors serviced (were done 2 years ago) for good measure. i just dont know how im acutally going to identify the problem before i take it back for a tune, i mean the pinging isnt even noticable except for on the graph, so how will i know if i have found the problem?

i love cars

[jonra23]

Think it is unlikely to be a blocked cat as you have no trouble making the required boost.

Run it again on dyno and log/watch duty cycle to see if fuel system is maxing out somewhere.

To check the base tune and see if problem has been solved disconnect the knock sensor and tune/run on dyno listening very closely, the ECU will not let you hear detonation as it will pull timing before it is audible.

regards
jon

[1JZ-Rolla]

Forget the duty cycle, what was the air fuel ratio showing when it was on the dyno with the wideband mixture meter in the tailpipe? I'm sure adam was watching this while tuning, and would identify if lack of fuel was the issue.

440cc injectors should be sufficient for your 200kw target, as should the VL bosch pump.

Knock sensor? Is there really one in the system with the aftermarket ECU? What ECU is it by the way?

Cheers

[1JZ-Rolla]

Just had a thought, what are your plug gaps? You mentioned that plugs were changed today, I assume before the tune? Don't underestimate the ability of dying spark to completely fark up your day Sometimes its felt as a light miss, or generally lathargic power delivery, and will get worse with more boost (higher combustion pressures, harder to jump the electrode gap)

Don't be afraid to go down to 0.7mm to test this theory... Also look for causes for weak spark, like bad leads, coils, 12V power supply to coils etc.

Best of luck finding it! The dyno graph looks pretty typical of an ignition issue with the higher boost, but hey, i'm not a professional tuner

Phil

[SL666]

Running a big intercooler? same as the car that made over 200rwkw on it?

what reason did your tuner give for it pinging/not making as much as hoped?

[The Witzl]

Just had a thought, what are your plug gaps? You mentioned that plugs were changed today, I assume before the tune? Don't underestimate the ability of dying spark to completely fark up your day Sometimes its felt as a light miss, or generally lathargic power delivery, and will get worse with more boost (higher combustion pressures, harder to jump the electrode gap)

Don't be afraid to go down to 0.7mm to test this theory... Also look for causes for weak spark, like bad leads, coils, 12V power supply to coils etc.

Best of luck finding it! The dyno graph looks pretty typical of an ignition issue with the higher boost, but hey, i'm not a professional tuner

Phil

me = echoing Phil.
The way that the power is plateued doesnt look like knocking, it's just like the engine has hit a wall and refuses to go further....