Crashr

Hi Folks,

I am at wits end with my 3.2L Euro conversion engine. I have tried everything I can think of to try and address a rich running idle condition and am now out of ideas.

I have an LM-2, and in checking the idle mixture the AFR is at best around 12.9-13.0. When the car is cold it runs even richer.

Some of the things I have tried to address this issue include:
- swapped out my DME with a known good DME
- I also tested my AFM using a 9V battery and got a nice clean voltage sweep through the range.
- No O2 sensor on car because it is a Euro
- AFE leaned out to the MAX (10 turns)
- DME test ok by Ingo
- ICV tested ok
- DME in fuel position 1
- Idle Position Switch tested ok
- Microswitch test ok and makes audible click when just coming out of idle
- CHT resistance in range
- Jumpering the CHT signal still leaves the car running rich
- Fuel Pressure tested: engine off pump jumpered pressure: 40psi, engine running pressure: 31psi, engine running w/ vacuum hose disconnected from pressure regulator : 40psi
- installed factory fuel line setup for a carerra and moved fuel pump to front of car. I haven't installed a 3.2L oil tank yet, although I doubt this would make the car run rich.

Where should I look now? What else could cause a rich running condition in a 3.2?

hunterpeaks

Have you installed an adjustable fuel pressure regulator?
Then you can tweak the pressure yourself to give you what you want.

What Chip do you have? Might want to consider a custom chip from Steve Wong and 911chips.com

Hunter

theiceman

How is the driveability ?)
Have you verified the calibration of your test equipment
Have you compared your results to a known good running Carrera?

I dont know too much about tbat engine in particular but in general in cases like this the dme usually is trying to change something for a reason based on some bad input data.
Ie a sensor somewhere rather than a mechanical issue.

Doesnt that car have an altitude sensor for example ?

Shannon123

I am not anywhere near the level of the others on this board....but,

1. Did you rule out vacuum leak ?
2. Did you check seal on oil cap and gas caps

Ed Hughes

That would typically result in a lean condition (vacuum and oil cap).

peanut

an old thread I know but it was left with no conclusion and still comes up with a google search.


i recently had the same problem of a rich idle mixture and like the poster tested everything without finding the fault. My 944S2 would hard start then, cold or hot the idle would hunt from 600rpm up to 1200rpm and back continuously until eventuually it died from the plugs sooting up

Here is another simple test that can be applied as a diagnostic .

At the testing station on the exhaust emmisions tester I removed the connector for the ICV (idle control valve ) and within a few seconds the 02 and HC levels dropped significantly .

With the ICV disconnected I also removed one of the vacuum pipes and the 02 immediately dropped from 10.031 down to 1.783 ! (pass is 3.500)
The HC dropped from 1239 down to 138 ! (pass 1200 )

Incredible. So clearly the ECU had registered the extra air supply and adjusted the pulse rate to the injectors to lean the mixture back to normal .

Now I've just got to figure out why the engine is getting too much fuel at idle or insufficient air or the whether the ECU is either faulty or not receiving the data from the AFM, ICV, or engine temperature sensor etc,

New pump ,strainer and filter has already been fitted and the fuel pressure is stable at 3bar .Leak down test and flow rate are fine too so I'll start with cleaning and testing the injectors as the car has been stood unused for long periods over the past few years.

Amber Gramps

Any chance a fuel injector is leaking? May be stuck open all the time causing not only the rich idle but the hard starts.

stlrj

How long ago was it not running rich or was it born that way?


Joe

peanut

yes there is a chance of a injector leaking which is why I shall be testing them tomorrow after I carry out a further leakdown test .
I have fitted a new tank strainer , filter and pump last W/E so I need a new leakdown test result to eliminate a FPV or damper leak

peanut

The car was running perfectly up until 3x weeks ago when we had a sudden cold snap in the weather.
It started instantly every time and never coughed spluttered or missed a beat from idle to WOT.

This hard start rich idle problem has happened 3x times previously following extended periods of non use and have on every occasion been when the tank was nearly empty ie 2=3 gallons . .

On the other occasions the situation suddenly resolved itself after lots of testing and fiddling and cleaning electrical contacts etc but no specific cause was ever found and no new parts fitted other than spark plugs once.

I'm beginning to think that water and crud in the bottom of the tank is blocking the injectors or making them sticky and leak and eventually they self clean and the problem clears up.

no.radar

... it could be water vapor/condensation in the near-empty tank. That the problem seems correlated to period of non-use/storage, you might consider either a full tank or fuel stabilizer depending on how long the car's going to be inactive.

rusnak

Try tapping on the injectors with a screwdriver handle.

trackstar

What do the A/F look like while driving and under load?

peanut

thats a good suggestion. On this particular occasion the car was so full of condensation that every surface was dripping droplets of water ! even under the bonnet (hood) everything was smothered in water droplets .

There are some serious leaks on the car which I'll have to track down and fix this Spring.However that said on previous occasions when this problem has occurred it was during good dry weather.

peanut

that is really inadvisable they are very delicate components and knocking them would probably either break the plastic connectors or break the seals.

The best way is to use a proprietary injector pulser or a 9v PP3 battery . I've detailed the battery method on here some years back and it works really well to get sticky injectors moving again.

http://www.ebay.com/itm/12-VOLT-HAND...sAAOSwIgNXiTFp