VL issues - please help

[hobnog]

I have a VL 88 Berlina Auto.
Recently I have this problem where the engine starts and idles fine when cold. However once it reaches normal operating temp the idle speed drops down to almost stalling. This happens when in gear sitting at lights etc. I have had to brake and accelerate a few times to keep it going. If I put it into park the revs jump back up again to around 700.

Once I put the revs up again, such as when driving along it goes fine, although it does have some fluctuations while accelerating, kind of what it feels like when you get a sudden gust of wind into the engine bay.

I know it is not overheating as the whole cooling system has been replaced.

Let me know what you think??

[VL Berlina 5speed]

AFM could be off or stuffd
CAI could be on its way out

[harry3]

look for airleaks between the airflow meter and the engine, especially the flexible rubber sections

[hobnog]

I have checked all the clamps between the AFM and the throttle body and looks all good.

The problem only seems to really get bad when the engine is at operating temp and on warm days. When cold the idle speed is good but when heats up and in gear idle speed just drops through the floor. If it is heated up and not in gear such as neutral/park it idles fine at about 700rpm.

How can I determine whether the AFM is faulty? Can I bypass it some how in order to test?

[bangers]

could be your CAS on the way out.

[Bax]

What is the 'normal' idle speed when its cold. And what does it drop too when your in gear.

Might just pay to increase it a touch anyway, because it should run at a higher rpm at idle when cold until it reaches operating temp. Maybe its low to begin with so when it does drop its going too far?

Just a thought.

[hobnog]

When I first start up cold the idle speed sits at around 1100rpm. Once the engine has reached full operating temp but not in gear the idle speed is around 6-700rpm. When I put it in gear though and just sit there like at the lights with foot on brake the idle speed drops way down to about 50rpm. Before I slightly adjusted the TPS it would stall at this point but now it just fights on going on the verge of stall.

Tried to adjust the idle which went up compared to before (when cold or not in gear) but still had the huge drop when warm and sitting there in drive.

[hobnog]

What affect could the AAC valve have on this situation do ya think??

[Bax]

Leaning towards AFM then.

[hobnog]

Ok I have done the following yesterday:
-completely dismantled and cleaned the IAA parts (AAC etc).
-checked all hoses were connected tight and secure to manifold
-disconnected the AFM plug to test (idle got really bad when off so this is ok)

After all this I took it for a run and it went really well, powerful and responsive and seemed to correct the surge problem.
However same thing when in gear and standing - the idle dropped down to nothing and chugging along painfully.

I noticed that when this was happening the idle was dropping down in chunks like it was missing on spots (not a gradually dropping idle).

This only happens when hot? Does this discount a fuel component from being the problem??

When I did some repairs to the boot a while ago I had to remove the tank (to stop me blowing myself up with the welder!!) and as part of this I noticed that all the vapour lines back near the tank are perished/gone. Would this have anything to do with this problem I am having?

[gungazza]

have you checked your air clraner and timing

[gungazza]

yer may be thoses might be the prob

[gungazza]

yer the hoses might be the prob

[hobnog]

yeah newish air filter and timing ok

[hobnog]

Ok new air filter, fuel filter and coolant temp sensor put in. Still same - runs like a dream until warmed up then idle drops.

Vacuum or fuel - dont know??

I think I can exclude AFM and CAS as this only happens when fully warmed and if it stalls it will start up straight away...

[hobnog]

One other thing I noticed was that when it is warm and this idle problem happens I tried something. I turned off the car and then started up again about 15sec later. Noticed that the idle stayed really low but after about 10sec of idling along jumped back up to 1000rpm. After I put it back in gear though it drops again.

Could this suggest anything??

[hobnog]

Just checked the AFM with my analog ohmeter. According to the forum to test you connect ohmeter to pins 1 and 6 and the resistance should be 380ish ohms (engine off and afm cabling disconnected). I set my ohmeter to 1K ohms range and it read zero ohms??

Is this the right test method (as gregories says to test you need to connect battery pos to pin 5, neg to pin 2 and then measure the voltage between pins 3 and 2 - should be about 1.5 +- .5)

[mag]

Just checked the AFM with my analog ohmeter. According to the forum to test you connect ohmeter to pins 1 and 6 and the resistance should be 380ish ohms (engine off and afm cabling disconnected). I set my ohmeter to 1K ohms range and it read zero ohms??

Is this the right test method (as gregories says to test you need to connect battery pos to pin 5, neg to pin 2 and then measure the voltage between pins 3 and 2 - should be about 1.5 +- .5)

As I said b4 leave the plug in and slide back the rubber boot!!
engine running and try that..

[mag]

could be your CAS on the way out.

Yeah still sounds like CAS, most seem too stall when hot but ok when cool..

[hobnog]

Ok went and got another multimeter just to make sure....still zero ohms between terminals 1 and 6 and adjusting the screw makes no difference hhmm

[mag]

Ok went and got another multimeter just to make sure....still zero ohms between terminals 1 and 6 and adjusting the screw makes no difference hhmm

OK try this, engine running pull the plug off the AMF and tell me what happens then..

[Milkman]

ive had this problem i believe, i went for about 2 weeks cleaning everything i could think of and was recomended eventually it just died on springy rd and wouldnt start. turns out it was the crank angle sensor and it needed 2 b replaced. best way 2 fix the prob is 2 get a reco dizzy from bursons or something, they'r lyk $220 or something, install that and time it up and it should run lyk a dream ... hopefully, best of luck!!