john banks

I still think it is your MAF. Your throttle voltage is the same as mine, but pulse width and lambda are considerably lower, plus you are getting retarding. If you are uncertain swap MAF with another car and rerun. Whatever your opinion is on how lean you want to run I can't believe that achieving it with a duff MAF is ideal. Now 7% CO, what next and when?

WREXY

Hi John,

I certainly don't want to achieve any lean running, let alone with a duff MAF. Unforunately I'm the only one with an Impreza turbo in my town. I have to travel 170km to find the closest one to me. So I'll just order another one. Better to spend a little than to be sorry with a bigger repair bill.

I was thinking that some cars with engine failure may have had a MAF on it's way out without realising it and it slowly got worse, then pop. I certainly couldn't tell my MAF is on it's way untill we saw the graphs of the logs. As I said, I got no symptoms, that is, bad idling, or poor running, or a fault code. So maybe it is a cause of some of the engine failures we have read about.

Cheers,

Wrexy.

WREXY

I was just browsing through Jim Theo's logs we did on the weekend, when I went up to see him 700km away and saw that his throttle voltage is around 2.2 and his lambda is 0.94V. Even when he's not at WOT he is still seeing 0.92/0.93V.

How does this happen even at part throttle? He has a stock PPP set up on a MY00.

john banks

They are unbelievably massively rich these cars. So rich they eat so much they choke themselves half to death like the man in the Monty Python sketch and fall over the folds of fat from all the stuff they eat. Imagine a crisp eating couch potato and quadruple it. Fuelling seems more based on MAF and RPM, so what was the MAF reading when it was so rich?

WREXY

It was reading 4.24V. I take it the MAF reading is the Air flow sensor voltage. Correct?

Cheers,

wrexy.

john banks

yes

JIM THEO

Hi all
Here is part of my log file with George and as you can see I prefer the data than graphs:

My car is too rich, I have always a significant knock correction (coolant temp usually more than 90 Celsius degree, ambient temp more than 15) and this is probably indication of low quality fuel (98SUL + "104+" Octane Booster during test) and happens always when I floor the throttle. First test with 5th gear, second with 4th. Could you explain me if there is any problem with my car?
JIM

john banks

On a UK unmodded car running 97 RON SUL I saw at most -0.5 degrees correction. On my car running 19 PSI and claimed 99.2 RON (including NF) I had no correction at all.

Surely it is a fuel issue? I hate to think what would happen if you turned up the boost?

WREXY

The first thing I remember Jim, is that you have the aftermarket thich plastic floor mats and I think your accelarator pedal is not going to the floor. You can see this from the data cos your throttle sensor voltage is very low. It's only around the 2 Volt area and it should be around 4.2Volts when you floor it.

Your turn to travel 700km to come my way for another re test.

Cheers

Wrexy.

Scotsman

iTrader: (3)

Stupid question but on Jim's logs above which bit tells you that it's running too rich?

Thanks.
Richard.

Cosie Convert

Front O2 sensor reading .945mv = too rich.

I prefer Wrexys set up. which is the quicker car ? I bet it's the weaker running one (Wrexy)

Wrexy, I suggest you get an exhaust gas temperature gauge, this way you can keep an eye on it to ensure you are not running weak.

WREXY

The Front O2 Sensor#1 shows this. anything over 0.91Volts is considered rich. I think under 0.7Volts and it's too lean and there is a problrem. My car is around 0.875/0.88Volts and there is a problem starting to happen. I've just caught it in time thanks to the delta dash.

Cheers

Wrexy.

Scotsman

iTrader: (3)

Cheers guys

Edited to ask - is the way that you control the richness of the fuel through a custom map? Or is there a mechanical way of doing it?

Richard.

[Edited by Scotsman - 4/27/2002 11:09:26 AM]

WREXY

Cossie your right, mine is the quicker car. I haven't raced Jim's, which is a stock PPP car, but I raced another friends car who had PPP, Falkland twin downpipe, APS induction and a HKS exhaust manifold and i got him by a bit. My mixture I think, (not sure), is perfect, but only if it was mapped like that. Since it isn't and it has the stock AE802, some thing doesn't seem right. It could be the MAF. I'm ordering one on Monday and when it arrives I'll try it, to see if there is a difference. if there isn't the MAF will still be useful at some stage later when my MAF does stuff up.

Cossie, dumb question, but how will I know if the car is running weak with the exhaust gas temperature. What readings should i be looking for.

Cheers

Wrexy.

WREXY

Richard,

Custom map is the answer.

Cheers,

Wrexy.

Scotsman

iTrader: (3)

Cheers Wrexy

WREXY

Actually the additon of cold air kits and exhaust manifolds and downpipes will lean it out a bit.

Cheers,

Wrexy.

john banks

Trouble is you can end up losing torque low down with a lean spot with induction kits on MY99/00.

If the MAF is dodgy and giving you a nice 7% CO now the trouble is you don't know what it will do over time unless you continuously watch it. If it is failing it could give you 3% CO tomorrow. I would have thought the best way to get it running well is to make it run to spec as standard first of all.

WREXY

I think it is the MAF cos on my second graph that Ozzy posted for me on page 2 of this thread, (thanks Aussie), you can see that I had lowered the boost to stock specs and the FCD is not cutting in, yet the mixture was still running 0.86 Volts. I've been to the Sube dealer an hour ago and ordered a new MAF so we'll see what happens when it arrives and I change it. I don't drive my car much. My next drive of it will be after I change the MAF. I couldn't be bothered taking everything apart, back to stock. There's quite a bit of work involved.

Cheers,

Wrexy.

WREXY

Actually you can't see it on the graph but in the data table it didn't go over 13.9 psi. It held it between 13.5 and 13.9 psi. Whereas on my first and third run where the FCD cuts in, the data table shows boost at 14.2 held all the way through, even though it was around 17 psi from my boost controller.

Cheers,

wrexy.

JIM THEO

Before some days a friend told me that the petrol station where usually fill my tank has bad fuel cause in his car (tuned Peugeot 106 Rallye) He saw det when fitted a knock sensor and this happens only when He fill his tank there. Hope this is the reason for the increased knock correction in my car, I don't understand what else could be!!!
Do you Guys have other opinions about it?
JIM

Cosie Convert

Wrexy

I can only quote my own EGT's. I need to get down to around 820mv which is approx 4% CO before I get my EGT's starting to rise.
My EGT at 850mv is only about 30 degrees higher than at 920mv but I have 25 more bhp at the weaker mixture

My probe is in the turbo inlet casing. Different positions will give different results. On cruise I get 620 C. Full boost max revs I see 750 - 800 C. I believe anything above 900C is getting risky.

john banks

I need an EGT Cossie to tell me where to stop - your readings are without WI? It will probably encourage me to go further than I want! Are you on the standard clutch?

WREXY

Cossie thanks for that info mate. Much appreciated. I have a guideline now.

Cheers,

Wrexy.

Cosie Convert

Yes, the full power temp was with water inj on. Not sure exactly how much the w/i drops the EGT as I have been changing that much on the car lately and trying different dilutions with Methanol.

My clutch is also standard but must be a good one as it held 349lbs-ft today on Star rolling road Mind you, that was only after I reduced the boost by 4 psi as it was starting to slip last night whilst out testing my new a/w cooler

john banks

Cosie you are certifiable, but I love your car!

MattRus

You may already know this but the recommended max. exhaust gas temp for the Mitsubishi TD range of turbo's is 900C. You're getting near!

Cosie Convert

Mmmmm

Recommend 900C I must try harder

A soon as I see 800, I change something to bring it back down.

WREXY

Last night I was doing some searching on here, the hard way, day by day. I went back 100 days.

It seems to me that there are three different ways in which a dying MAF lets you know it's going on you.

The first one is uneven idle and it's a good way of letting you know cause you can catch it. The second is when the select monitor or engine light picks it up and the car goes in limp mode,(another good one). And the third way is the worst way. There are no symptoms, the car idles nicely, drives well you plug in the select monitor and it shows no fault yet really , the MAF sensor is on it's way, with the mixtures getting leaner and leaner till your engine pops. This is the way my MAF is going on me, but I was lucky I bought Delta Dash and saw my mixtures starting to lean out and have caught the MAF in time before I do further damage.

An example of this case is here, where it is rumoured that the MAF was faulty, causing the engine to run lean, which in turn caused detonation, thus causing the engine to blow. There have been more examples of engines blowing due to failed MAFs over here and at least one I know of in Germany. You can see my slightly lean mixtures on the graph on page 2 and 3 of this thread.

http://www.scoobynet.co.uk/bbs/threa...ThreadID=72098

Cheers,

Wrexy.



[Edited by WREXY - 4/30/2002 10:43:17 AM]

Floyd

iTrader: (9)

Wrexy

I guess that if you had one of John's AFR's then this would have shown you as well?

F