NENO

I finally got round to fitting the STI 5 intercooler I bought off TBMeech (cheers )

Took the car out for a run last night and I noticed, for the first time, that on WOT it was running lean below 4,000. My Dawes AFR I had a green rather than blue light.

I'm sure it didn't do this before with the standard i/c, so why now? And what the hell should I do about it?

Background: UK my97, Dawes 1.05 bar, ITG panel, Decat, Walbro fuel pump.

rapac

Maybe less pressure drop with Sti IC??
Is boost higher now??

NENO

Hard to say exactly about the boost, being as I didn't test them back to back, but it's fairly similar.

The Dawes was set up for summer weather on the old i/c just below the fuel cut i.e. 1.05 bar as I didn't hit the fuel cut the boost has got to be very similar.

RICH WILD

If your inlet charge is cooler, it will be denser, if denser it will tend to make the car run leaner as there is a higher concentration of oxygen per given volume.

Wouldn't have thought it would have made THAT much difference though, especially given that you have an uprated pump. Problem may lie elsewhere. Have you ever used injector cleaner? That might be an idea, though I doubt it is the cause of the problem.

Rich

NENO

Cheers Rich, I used some a couple of months ago but it's worth another try.

How can I increase the fueling?

I was planning on increasing the boost to 1.2 once my knocklink arrives but at this rate I'm going to be in trouble. Will an adjustable fuel pressure reg. help?

Leslie

It may be flowing a bit more air than before so the AFR will be a bit weaker.

Les

AndrewC

If more air is flowing then the ECU should compensate as fueling is mostly based on MAF readings, you're not using an induction kit so there shouldn't be anything to upset the MAF value. However the ECU cannot compensate for the better combustion produced by the cooler charge the new IC is giving you. If you have an adjustable FPR then a bit more fuel pressure may well help.

Andrew...

NENO

Thanks Andrew, I think I follow what you are saying, so let me check.

The lean AFR is caused by the discrepancy in air density between the MAF and the manifold. Correct? On that basis am I likely to have more trouble in the winter or the same.

I suppose that the MAF could be on the way out, again

How do I check the Injector Duty Cycle?

Thanks for your answers by the way

Edited to make sense!



[Edited by NENO - 7/21/2003 5:12:47 PM]

greasemonkey

With one of Andrew's monitors

Leslie

What I meant was that if the charge is cooler, then the charge density is higher and the engine will be flowing more air. In this case,would this be detected by the MAF which is before the intercooler. I'd be interested to know whether the increased charge density eventually arriving after the intercooler would register on the MAF.

Les

*Sonic*

I noticed today (since fitted my STi5 Intercooler on my MY00) that I was running one led less on my Autometer AFR Gauge, still well in the safety green zone

I did notice that my boost was higher now with the Dawes, it was peaking at 17.5 PSI, and held 16.5 PSI

I put that down to today being a much cooler day today, oh and my car felt as fast as f00k today