Very rich AFR - suggestions?

[Diver944]

I've attached below my Air Fuel ratio from the Weltmeister DynoDay and you can see that I am running pretty rich with an AFR of 12/1 at 3300rpm falling to 10/1 by 4500rpm and climbing only to 11/1 by 6200rpm. Am I correct in thinking that an ideal situation is around 12.5/1 during boost, with a little leaner at the start (say 14/1) to help spool up

I actually had my boost set to 16psi for the run because I knew I was a little rich at the 15psi I've been running for the past 15k miles.

Apart from a remap or MAP kit or MAF kit I'm thinking of a stopgap solution by removing my 3 bar Fuel Pressure Regulator and reinstalling the standard 2.5 bar FPR and running at maybe 14 psi which will hopefully see me get back to an AFR of around 12/1 whilst I'm on boost. This will remove any danger of bore wash by the excess fuel, save me fuel costs [] and probably give me more power, as running that rich is robbing me of horses.

Comments?

 

[uktrucks]

Paul
Whatever the problem turns out to be, I would advise against anything over 11.5:1 at the top. On a Turbo car even only running 0.8 Bar the heat at 6000 revs is immense, the fuel is reqd as added coolant for the cylinders.

At the bottom you can run up to and close to 13 :1 but not above.

These of course are just my own opinions

Regards

Allan

 

[Guest]

Same as Andrew really. The A/F on the dyno is not NOT representative of the road conditions, you will probably find the the car will boost more on the road, up to 2psi. This will correlate to an increased A/F ratio probably back to the correct amount. Data logging and setting up on the dyno is all very well but a road test should always be used too. Probably one of the reasons the guys on Rennlist have wideband meters in their cars.

 

[Diver944]

Thanks guys. I like the idea of extra boost to balance it out [] but my current setup won't hold it in those rev ranges.

In the meantime Andrew, I'll re-check for any boost leaks, then get back to you about trying those chips. I'll also double check that I am still getting 3 bar fuel pressure, I'm sure I heard somewhere that when the FPR does fail they allow the pressure to increase.

Allan, when you say over 11.5:1 do you mean richer or leaner? I've sent you an email to see if you still have my boost graph on file as I don't seem to have a copy against RPM. Thanks again.

 

[Diver944]

OOps forgot to say that my car is an '89 with no cat so it has no O2 sensor at all. I do plan to get an onboard wideband installed when I start going for more power. Originally I was happy to do without when only at 15psi, wastegate and chips (not so sure now, 10:1 seems very rich to me)

 

[944turboS]

Paul,

I'd happily swap your results for mine which starts out at just above 10.8 stays there till 3100rpm then drops to below 10.1 by 4100rpm & stays there right up to 6250rpm.

Anyone know the best place to buy shares in Shell?

 

[Diver944]

Now that I have looked at a lot of other charts on Ricks site http://www.cannell.co.uk/944%200505%20Dyno%20Data.htm it seems there are a few Turbo cars running with similar AFR to mine.

Is a ratio of 10:1 really that bad or is it only a 'little' rich, am I being overly concerned?

I hear that Andrew will be stocking the Innovate wideband tuner shortly so I may have to start saving my pennies and stick that and my boost gauge in a twin mounting pod on teh A pillar so I can keep an eye on things [8|]

 

[eastendr]

You don't really need to go richer than about 11:1 - think of the price of petrol [][]

 

[Guest]

ORIGINAL: Diver944

Now that I have looked at a lot of other charts on Ricks site http://www.cannell.co.uk/944%200505%20Dyno%20Data.htm it seems there are a few Turbo cars running with similar AFR to mine.

Is a ratio of 10:1 really that bad or is it only a 'little' rich, am I being overly concerned?

I hear that Andrew will be stocking the Innovate wideband tuner shortly so I may have to start saving my pennies and stick that and my boost gauge in a twin mounting pod on teh A pillar so I can keep an eye on things [8|]

The point is Paul its reading 10:1 on a dyno but out on the road it could be 11:1 or 12:1.

Mine sites round the 10.5:1 mark peak at about 16psi, but i tweaked the boost up to 18psi. 10:1 is starting to get a tad low for sure.

Get a wideband fitted to your car and see whats its ike on the road. There are loads out there to choose from, if i was keeping my ride then i would be fitting one of these http://www.zeitronix.com/Products/zt2/zt2.htm

I would definatly want a data logging facility that would display rpm + other parameters like exhaust gas temps and inlet temps.

Oh so many plans now out the window!!! The annoying thing is i had the cash set aside this year too!!!!!!

 

[eastendr]

Now I know why those petrol tankers were following you through the Cotswolds on Sunday [][][]

ORIGINAL: 944turboS

Paul,

I'd happily swap your results for mine which starts out at just above 10.8 stays there till 3100rpm then drops to below 10.1 by 4100rpm & stays there right up to 6250rpm.

Anyone know the best place to buy shares in Shell?

 

[944turboS]

Ha Ha Ha [:'(]

On a better note I tightened up the hose onto the bajo joint last night at work so this weekends jolly to Shelsey Walsh (100 miles round trip) might be done on just the one tank of fuel

 

[Fen]

ORIGINAL: slim_boy_fat
Get a wideband fitted to your car and see whats its ike on the road. There are loads out there to choose from, if i was keeping my ride then i would be fitting one of these http://www.zeitronix.com/Products/zt2/zt2.htm

I would definatly want a data logging facility that would display rpm + other parameters like exhaust gas temps and inlet temps.

I ordered an Innovate kit today with data logging to laptop. It doesn't have the gauge as they are like rocking horse poo but I think the logging part is more important and the gauge can come later.

 

[Diver944]

I notice on the accessories page that they sell an analogue gauge with a simple needle for only $55. Looks much better than the XD1 flashing lights, bells and whistles.

 

[Fen]

Oh, there's a page 2 (and 3) of accessories [&:]

Slim's post got me thinking some more so I have now ordered both the analogue gauge and the AuxBox so I can datalog 5 other parameters in addition to AFR such as boost, CHT, EGT, RPM, injector duty etc.

 

[John Sims]

Slim's post got me thinking some more so I have now ordered both the analogue gauge and the AuxBox so I can datalog 5 other parameters in addition to AFR such as boost, CHT, EGT, RPM, injector duty etc.

If you weren't such I nice person I could hate you. What chance does my bank account stand with Rick dangling shiny things in front of me on one side and you dangling shiny things from the other. I will resist. []

 

[Diver944]

Do what I do John,

just remind yourself that your car has an engine in it []

 

[944Turbo]

ORIGINAL: sweetea


[2] adjust the AFM spring.

One thing I noticed when working on Davids car was that his 'barn door' was much more stiffly sprung than mine. I believe from the general condition of his car it has been very well looked after and driven relatively gently.
Unfortunately I cannot think of an easy way to measure and compare two springs and there are no reference marks to indicate if his has been adjusted tighter (the top had been off the AFM previously) or is just healthier.
Tony

 

[Diver944]

I do know that the FR Wilk DME website http://frwilk.com/944dme/afm.htm mentions not to mess with the AFM calibration as it is set very precsiely at manufacture. However, I have done some testing today and my car can happily hold 17psi or even 18psi in the zone where I am rich (3500rpm to 5000rpm) so once I have double checked that the fuel pressure is still 3 bar and I have no boost leaks anywhere then I shall do another run at Weltmeister and hopefully see an AFR of 11:1 in that range.