It Idles Perfectly! :d :d :d

[NNN 1]

I´ve changed the SAD and sent the AFM to a place where it was theoretically cleaned up and the sensor in the track was relocated...Now...the idling probs with warm engine have been solved. Then, when I start the engine the revs go to 1400 aprox, great; the SAD works, but between 70° and 85° the idling works like hell. I´ve cleaned injectors, changeed every filter, checked for air "loses" and nothing. Everything seems perfect exept for the "mid warm" idling. Should I check the AFM again? What can be the prob then?

Thanks, sorry for the "bad english"...

[Ahl 4]

the problem comes from the fact that the air flow is not smooth running through the AFM at idle and therefore, the flap is going haywire. Your finger will be simulating smooth air flow and not the pulsing effect you get at idle.

I disagree. The afm meter has an opposite vane built into the rear of the flap so any pulses affect both forward and backward movement of the flap equally.

 

Pugs only start to do this when they're old.

[MartinR 0]

er... so the flap doesnt move when the engine is idling?

 

compare an AFM to a car using a MAF and the idle is s*itty exactly because of that reason

 

<edit> sorry i didnt mean to sound cúnty </edit>

Edited January 27, 2004 by MartinR

[saveloy 8]

Ahl,you are kidding? The 205 idle fluctuates +/- 100 rpm at best. The other problem,is that the rev counters often over read. So,in effect,the idle is actually set too low on most cars,adding to idle problems.

[Ahl 4]

<edit> sorry i didnt mean to sound cúnty </edit>

lol! fair enough

 

The 205 idle fluctuates +/- 100 rpm at best.

Do you mean your idles fluctuates like that at best?

 

What im getting at is although I don't think the AFM is perfect by any means, I don't believe its the cause of the wandering idle.

 

My 205 idles perfectly at 1000rpm sometimes and sometimes it wanders up and down. Its more like the ecu is trying to work out what to do, rather than a direct mechanical thing. A number of people have expressed the idea that the ecu doesn't know what temp. it is, or is reading a low temp, leading to overfuelling. I'd be inclined to agree with this as my car only does it when hot.

Edited January 27, 2004 by Ahl

[MartinR 0]

valid point, but it really is the AFM. I am trying to work out how to make a MAF perform the same as an AFM, i.e. give the same signals for the same airflow, but its proving to be difficult, coz i need to make a circuit that provides a burn off signal, but i have to get this right, coz if i dont i will f*** the MAF i have atm

[Robbie G 3]

What is the physical difference between a MAF and an AFM, and what exactly does MAF stand for?

[fiji bob 0]

mass air flow i think, they have a heated wire in a hollow tube thats cooled by the intake air, i think the management works out how much air is going in by the amount of current it takes to keep the wire at a certain temperature

 

martin you could always build a megasquirt instead and get rid of the afm/maf altogether

Edited January 27, 2004 by fiji bob

[TB_205GTI 1]

What is the physical difference between a MAF and an AFM, and what exactly does MAF stand for?

AFM = Air-Flow Meter

MAF = Mass Air Flow

 

The MAF is a thin heated wire. The teperature of the wire is kept at the same level all the time. when air is passing the thin wire, it is cooled thus the current needs to be bumped in order to keep the wire the same temperature. The current applied to the wire is read by the ECU. This signal is proportional to the mass air flow.

 

 

EDIT: Beated by fiji

Edited January 27, 2004 by TB_205GTI

[Guest seb]

Megasquirt uses a manifold pressure sensor - yes?

 

What about emerald? Same kind of thing?

 

How hard to fit a megasquirt to the 205? WHat benefits?

[fiji bob 0]

the ms is a self build fuel only controller while the emerald is a proper fuel and ignition ecu both are programmable, you lose the air flow meter which may or may not be a restriction, as for fitting the megasquirt im not sure yet you can use the existing loom and just reroute some of the wires to the ms but that would be a nightmare if something went wrong and you had to go back to the standard setup, someone did make an interface pcb that lets you plug an ms directly into l jetronic loom in place of a standard ecu but i cant find the site

[Guest seb]

So the ideal solution is an Emerald? How much does it cost to buy and fit a new one?

[MartinR 0]

fiji find that site dammit!!!!!!!!!!!!!!!

 

 

also

 

i just got in from retracking my AFM. Throttle is more responsive, still doesnt idle any better than it did

 

i took loads of photos with my bros digi camera, only the silly arse didnt bring me the cable over to get the pics off of it DOH!

 

gonna take a blast over there in a sec and see how it is.

 

Incidentally, does anyone elses car almost bloody stall when you put all the services on?? or is it just mine thats being a s*it

[laser_GTI 1]

Its worked!!!!!! At last my 205 is perfect!

[Toddman 0]

Would it help to lube the track a bit with something and what sort of stuff could you use? This might stop it wearing out so fast and might improve response.

You can clean and lube the AFM with some decent electronics gunk such as AMBERLUBE.

It's just a contact cleaner and lubricant,I am lucky mine has only done 63k and the track is pretty goood but a good blow out and a dose of the spray worked wonders

 

Cheers

Luke

[MartinR 0]

bah bollox i will give it another go 2morrow

[fiji bob 0]

link there you go

[Ahl 4]

Pluck it, lets all get carbs!

[saveloy 8]

I have written an article about this sorry mess for the PSC magazine. Ultimately,if you consider that the 1.9 engine is in a fairly high state of tune,in standard trim,that there is no idle control valve & the injection system is ancient,it is no surprise idle problems exist. Fast road cams & plenum chambers do not work well together. The air pulses mean that the AFM is constantly giving the ECU a different voltage,so the ECU is constantly altering the fuelling,which has a knock on effect when it comes to the idle. A modern high speed ECU would cope I'm sure,but the poor old LE-2 has real chips on it's mother board. And,potatoes don't age well!

[MartinR 0]

which is why a MAF is so much better as it gives an average amount of air, whereas the AFM gives you real time air flow... if that makes sense

[MartinR 0]

Update...

 

My AFM was fluked, so i nicked one of another pug, rebuilt that and it idles very well but does fluctutate still, but not as bad as it was

[Ahl 4]

That sounds just like mine.

[Guest andy.robins]

problems at idle could quite well come to down to that specific part of the track being damaged.

 

The ware on these areas will be greater than over the whole track, as your car oftern sits idleing and waring that part of the track away. These worn areas will feed inccorect resistances to the ECU prob resulting in poor idleing.

 

Retracking mine sorted the idle but not the cold start. I would like to supliment the temp sensor in the AFM and see if this is the cold start problem but I know this is not possible, so another AFM may answer this Q.

 

Megasquirt is a gr8 project, my colleague was trying to get me to do this, but im just about to buy a 2nd engine to play with a garrett T3 turbo, any1 know any1 who has used a T3 before?

 

A

[Henry Yorke 269 3 Cars]

Help!! Can you please have a look at this post on the PSOOC forum and tell me where I am going wrong!

http://209.151.80.232/psc/vbb/showthread.p...3956#post143956

[Guest tangfastic]

you do realise that this post could have maybe saved me over 200 quid.....that means i might be able get my car ticking over properly and have a new clutch in the same week. crazy nuts!!! cheers guys!!