BoxerFlat4

Ok, after yesterdays showing at the Well Lane rolling road, where I hoped to be in amongst the top 10 motors, based on my previous showing of 289BHP, you can understand my disappointment to only reach 253BHP.

More worrying was Kev @ WellLane reporting pinking at 6000 RPM. The car is a MY94 STI 1, running Optimax + Millers, and previously reached at held 16 PSI, but yesterday only just reached 14 PSI. General consensus was that the pinking was causing the ECU to retard the boost.

My question is, whats causing the pinking ? Now, I know this is a 'how long is a piece of string' type question, but given the fuel I'm running, I wasn't expecting this ! My current theories are :-

1). Service - The car is due for a service, having recieved one 6 months ago, with plenty of miles added since then. Although she's running fine, she's not as 'sharp' as many cars are after a service.

2) Fuel - Normally, I had 1/2 bottle of Millers to a full tank of Optimax, but, in a moment of madness, decided to try a full bottle of Millers. I'm not blaming Millers here, but is it possible to add too much booster, especially when running with Optimax.

Basically, my question is, could any of the above be causing the pinking ? The car will be serviced shortly, and I may change booster to NF which I've used happily before.

Comments... ?

EvoRSX

What inlet temperatures were you at during the RR session?
This is the most likely cause of detting on the rollers due to a high temperature of your inlet air. Provided that you don't get detting during normal driving then you should be fine.

Andy

BoxerFlat4

Hi EvoRSX -

The inlet temps are unknown - the ambient air temperature was probably around 10 C. Ihave to confess, I was stood right by the car on the RR session, and I couldn't hear any detting, although the noise level was rather high ! During driving, I don't *think* I'm hearing detting either, but the fact that I lost nearly 40 BHP from previous, I think it's fair to say somethings wrong with the car.

TBMeech

I am sure that running a full bottle of Millers per tankful is the reccommended dosage, so if you were running 1/2 before putting a full one in will not make the car run worse....

pob on the job

I don't think it's the millers either. I use 1 bottle to a tankful and even when I put in only 3/4 of a tank I stick the whole bottle in. I remember one really well known and respected tuner who often posts on here saying he was able to run more advance with 2 bottles in a tank and that you can't really "overdose", within reason!

john banks

What sort of flow was going over your intercooler on the RR?

chuckster

It could quite simply be a bad tank of fuel. Do u have a boost guage? When mine gets bad fuel the boost backs off and I can see that on the boost guage (and feel in via the **** dyno )
Take it easy with this tank of fuel and see what it looks like when u get the next tank in there.
Chuck

BoxerFlat4

Cheers Pob ... so the Booster theory bites the Dust !

John Banks ... you'd have to speak to the 'experts' at Well Lane that day about wether the setup was ideal : basically, most of the airflow (from memory) was directed to the radiator area, with the bonnet open. No specific IC blower hoses where used.

What concerns me is that this is the same setup as my first run in October, and yet 40 BHP has disappeared....

How about the service theory ... should I throw that one out as well ?

BoxerFlat4

chuckster - yeah, this had occurred to me as well : the tank was used up on Sunday, and replaced with a new one of Optimax + booster. Given it's from the same garage, I may use this one up, then try a different supplier of Optimax for awhile....

Keep the ideas coming, guys !

Jay m A

iTrader: (2)

Do an ECU reset. If there is a problem it may give a fault code, or if it was a bad batch of fuel then you'll wipe its knock settings and the ECU will relearn to your new tank of fuel. On the old cars the ignition could have been retarded by bad fuel many tanks ago and will still be retarded irrespective of the better fuel in the tank at present.

Justin

EvoRSX

Have you compared the two runs that you have done to see where the differences occur?

Is it just at the top end of the rev range or is it all through?
Is there a difference in the revs at which max power was achieved on the two runs i.e. did they rev it right up to the max power point 2nd time around.

What made they guy say that you were getting pinking at 6,000 rpm if there was no audible sound?

I don't like the idea of not having any airflow over the intercooler either. That can't help reducing the onset of detting....

And finally,
When driving it, does it feel like it is 30bhp down from last time. You would certainly be able to tell on the loss of 30bhp. If it doesn't feel any different on the road then put it down to detonation on the rollers that isn't happening under normal driving conditions (i.e. high intake temps) and be happy.

Andy

john banks

My car took a good 10 minutes of driving to perk up to its usual after going on a rolling road with a fan of I guess about 10mph over the intercooler yet it was driving up to over 110mph road speed in 4th gear. One car with a remap was audibly detting on the same rollers but fine on the road.

If my car was pre MY99 I would reset my ECU after a rolling road run like that.

BoxerFlat4

Thanks for all the feedback, guys ....

Evo, comparing the graphs, it SEEMS that power/torque is being lost from roughly 4000 RPM onwards, which is presumably when the turbo is well into it's stride. As for wether or not there was pinking, I couldn't hear anythin untowards, but then I'm not sure I would know what I was listening for !

The first run was done to 'warm the tyres up' according to Kev : the second and third were full power runs, all the way up to 6000 RPM. As far noticing 30 BHP loss on the road, before the first run at Well Lane I thought it was running less than 250 BHP, which shows how accurate my 'seat-of-the-pants' dyno is !

John, I considered doing an ECU reset, both before and after the rr session. I didn't before, because I was curious to see how the car was coping with Optimax, and I haven't since the session because I was hoping to figure out what was causing the detting ! I may do it once I've cleared the tank of any 'suspect' fuel - if the fuel was dodgy, then I've still got nearly a full tank to burn up.

EvoRSX

Boxer,
Even if you though you were running less than 250bhp before the last RR, the fact that you had higher doesn't matter. I don't mean does it feel like it only has 250bhp I mean does the car feel significantly slower than the last time you went on the rollers?

If not, then I wouldn't have thought you had a problem.
The ECU will definitely have retarded the ignition following the detting on the RR and so a reset will cure the ignition timing retardation. If you suspect dodgy fuel then run the car below 4,000 revs until your next tank (any det is not good for the engine) and when you've filled up again, reset the ECU.

Andy

BoxerFlat4

ignore...

[Edited by BoxerFlat4 - 2/4/2002 3:50:38 PM]