mmelton
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Idle Irregularities

Post by mmelton »

My '85 GTV6 is developing some idle/start oddities. Its formerly steady 900 rpm idle is now a stumbling, rumpy 400-500 on start-up (and if left alone to warm up will at times die). But after warming up and running down the road it will idle at around 1500. Also, the immediate burst into life at the touch of a key might now be a long spinning of the motor before firing, and might even (particularly in the evening) require the forbidden romp on the throttle.

And...I'm beginning to smell gas. Just solved that problem once--loose fuel line entering the fuel rail and loose hose clamp on an injector. No indications of leaking fuel anywhere above or below decks this time (and the air filter shouldn't be dirty--recently replaced)

Probably an air leak somewhere, and when I get an afternoon free I'll check. But I'm wondering if there's a "yeah, mine did that. Try this..." out there.

You guys have been magic is solutions so far, so I thought I'd ask.

Thanks for the help, past, present and future.
Mel Melton
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Post by GTV6GPTT »

air leaks are the major cause of the problem
also look into the rubber in the idle valve.

could be anything tho.

just going to have to try as u go.
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Post by mmelton »

Many thanks:

That was my thought: air leaks--could be anywhere or anything. We did notice a collapsing hose on the right side (passenger side on a LHD) at the rear of the motor. Hose comes from the bottom back of the plenum to a valve or regulator mounted on the valve cover. A little pancake affair with inlet and outlet type orifices. The front one has a hose that Ts into the big accordian hose from the air flow meter, and into the side of the plenum.

Don't know what this valve/regulator is called or what it does, but Spiders have them, too. Apparently a standard L-Jet fixture. When I get some time next weekend I'll replace that hose and, perhaps, try another of those valve/regulator fixtures from my Milano.

What is that device? And what and where is the idle valve?

Thanks again for the suggestion.
Mel Melton
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Post by Murray »

Mel the device you're describing is the AAV (auxiliary air valve.) It is bolted to the valve cover and provides an extra shot of air during cold startup.It is important that the hoses going to and from be in good order so that may resolve your problem.As far as smelling gas, that`s likely a seperate issue and should be dealt with NOW unless you don`t really love your car :lol:
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Post by mmelton »

Murray:

Many thanks. This looks highly probable. I'll try another vacuum hose, then the AAV from my old Milano.

I've really been looking for the source of that occasional petrol stench. Checked from the fuel tank fittings forward along fuel lines to the filter, pump, and under and over the motor. Not a sign of a leak. Until now, that oder has been easy to trace--always an obvious spray from a hose or fitting around the injectors. This time, I'm mystified. Think I'll fill the tank all the way up the filler neck again, see if that has any bearing, and if so pop the filler cap and see if relieving tank pressure might be the key.

Thanks again. Hope this AAV hose is the culprit.
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Post by Murray »

Mel last year I went down this road with my GTV6 (gas smell).Based on my experience :evil: I would recommend the following:

If you are reasonably certain that none of the external lines are leaking or weeping.....

1) Check the rubber hose inside the trunk that runs from the fuel filler to the tank.This often cracks with age-like me.

2)The outlet from the fuel tank sits over a round hole through the car body.This is where the outlet hose goes out to the fuel filter and pump.This tank outlet sits on a piece of foam which is inside the car between the body and the tank.Over time moisture collects in the foam and in my case had led to pinholes in the gastank.You're going to have to pull the tank to verify this but it's not that nasty a job.I'll gladly lead you through the process if necesssary.

3) The fuel return line from the injector rail/regulator back to the gastank is a hard plastic line which comes into the car through the firewall and then runs through the passenger compartment (those Italians like a little bit of danger in their lives :roll: ) and back to the tank.If it leaks well....
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Post by mmelton »

Murray:

Thanks for the suggestions on tracing that gas smell. It hasn't been an issue lately, but you're absolutely right: It's something to be more than a little concerned about. I do recall that when we had the tank out cleaning out the congealed gas (tar, really, after sitting for five years), I had that filler neck hose in my hand and thought: "That'll need to be replaced one of these days." I'll look at it this week. I intend to pull the dash and insulate my heater/AC outfit (thanks for asking about that last fall: I'm following the advice you got), so I'll remove the seats and pull up the carpet and check that return hose, too. I don't believe it's a pin-hole leak in the tank. We inspected that tank pretty well, and I didn't see or smell gas under it when I was checking the fuel lines, filter, etc. I'd be surprised if it had started to leak (that said, I'd better have another look).

On the irregular idle issue that started all this conversation: I pulled the AAV and hose from my Milano parts car and put it on the GTV6. Made things better, but things are still not just right. We looked and tested for air leaks again, and can't come up with anything. This week it's plugs, cam belt, and valve adjustment time. Once I've got those issues taken care of, we'll see where we're at.

Again, thanks for the help
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Post by mjr »

From my experience with various GTVs I have owned

Idling problems wise, the air flow meters always get missed. Ive had many gtv6 models, and at one time or another all have developed idling problems with age. In 90 percent of the cases it was basic cleaning required. less often was it an air leak on mine.

The air flow meter always gets over looked, even by main dealers. most modern cars have mass air flow meters and suffer from gumming up of the hot elements.

Although the GTV6 has a vane type air flow meter , and not striclty a MAF, it suffers just like any other from gumming with age. Take the air flow meter off and give it all a good jetting out with a can of carb cleaner, this will remove all the fine build up in the butterfly valve, spring and air temperature sensor. These assemblies are very sensitive potentiometers, the various valves, linkages and springs have to be spotlessly clean and smooth in operation, otherwise you end up with wandering voltage, which results in poor idling. An air leak has the same result, since it directly affects the input to the potentiometer.

Also worth checking the air flow meter circuit board for dry solder joints. Check for excessive play and wear too.


well worth a try

MJR
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Post by mmelton »

Hey, MJR:

I apologize for failing to reply to your suggestions. I've been so busy over the spring that I haven't even had an opportunity to get back on this site until another problem forced me to it.

I've been driving and working on an '86 recently, and have only been starting up the '85 to keep it running, so I haven't taken any time with it. But it'll soon be due for some maintenance, so I'll go after that AFM with a can of carb cleaner (bought one just for that).

Where is that AFM circuit board? And what about all those watch-work lookin' gears and springs under the D-shaped black plastic cover on top? Should I give those a blast, or is it best to leave that cover sealed and refrain from even peeking in there?

Thanks for the advice.

Mel
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Post by sh0rtlife »

if you havnt found a fuel leak anywhere ..unplug the cold start injector and see if it still happens...mine was hoseing down the intake hose and leaking out at the airfilter
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Fuel Leak?

Post by mmelton »

Thanks for the idea. I'll give that a try...I can get the problem to replicate itself.

Mel
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Post by mjr »

mmelton

no problem, I know whats its like, I never seem to get all the bits I want to get done on my gtv :lol: As far as taking the cover plate off, its fine so long as you dont introduce any grit into there, just a question of sealing it properly afterward. All the electrical connectors are inside, there also the ones on the throttle angle sensor, which you should also check. Any solder joints can just be reheated, you dont need to take any off. Set the throttle plate angle, mixture/idle after you have finished. And as shortlife says, definately disconect the cold start injector once the car has warmed up, if this is leaking it will screw up the idle. No difference after disconect, then injector is fine. Have you changed over the fuel pressure regulator too? This can cause bad idling. Also check the adjustment on the throttle angle switch. You should be able to hear the micro switch click once the throttle plate is approx 1degree open. The micro switch should click on and off with a tiny amount of pressure on the throttle lever in the egine bay. Literally just a little pressure applied with your index finger. If its out of adjustemnt and the micro switch isnt closing when the throttle plate is closed, the ecu doesnt know the throttle is closed.

hopefully servicing the air flow meter will do the trick though.

:D
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Post by Romeo69 »

Hi all,

does someone have heard about a solution on mmelton's problem?

I'm experiencing the same problem as him:
Cold start okay, running bad after approx. 1 minute, and the idle is going up as it is getting warmer...especially in the city when the heat is not very well evacuated, the idle is going up to 1400rpm...

Sounds to be a frequently found problem..

I searched the forum and found another case thats nearly the same:
see => user: AussieGTV6
Post subject: GTV6 Runs Perfectly Cold, Dies After 2mins. WTF?

Could it be a faulty "additional air-intake valve"? I do not find any leak...

Thx, pat :lol:

thanks for suggestions...
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Re: Idle Irregularities

Post by Romeo69 »

Hi,

it has been pretty long time since my last post for this problem. Since then i have done a lot of work (and miles driving my gtv6) without finding the problem.
Situation is still nearly the same, the engine is running very smooth above idle, but the idle is not that what I know from my 2 former gtv6's years ago...

But at idle..:
- car starts perfectly and runs at 1200rpm like a charm
- after 3-4 min the idle drops down to 600-700rpm and the engine is shaking and rattling
- after another 5 min it starts to run very well again at idle around 1000min
- when the engine is warm, idle is around 1100 and not that good (little shattering).
- above idle it runs perfectly without vibrations and with a lot of power.
It never smells like gas...

What I've done since:
- checked for air leaks and changed all the hoses to new ones
- changed AAV (aux. air valve) to new one
- changed CSI (cold start injector) for a new one
- changed injectors to cleaned ones (not new)
- changed fuel filter and some fuel lines
- new fuel pressure regulator
- new rotor cap and used spark plug wires
- new ignition coil
- changed AFM (air flow meter) to a used one
- checked ignition settings
- new spark plugs
- checked CTS (cold start sensor), values seem to be good
- checked idle rubber donut (i changed it to a used one, not in best shape, but with no change at all when idling...)
- checked and cleaned the electrical contacts....

I start to think that I'm chasing a ghost....Next I will change the ECU (elect. unit) and the sensor for the water-temperature..but after that..I'm maybe lost in space :cry:

Does someone have a clue where I could search the idle problem?

Thanks for any help....pat
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Re: Idle Irregularities

Post by GregoryV »

Just a note on this to actually pull the rubber intake hose off and really look at it close for cracks along the base of the ribs as they can be hard to spot, and double check that your timing belt didn't slip a tooth. GV
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