Alfa Romeo Forum banner

1 - 3 of 3 Posts

·
Registered
Joined
·
70 Posts
Discussion Starter #1
Hi Alfaholics,

After some advice, my engine is hunting at low revs on tick-over, any ideas? Also whilst I am on, how do you get heat and wind from the damn heater, fan works OK and changed the thermostat, any other thoughts.

Will:eek:
 

·
Registered
Joined
·
1,665 Posts
For the idle problem,I would start by checking the black tube connecting the air intake on the filter side to the inlet manifold on the other side of the engine.
It is designed to flex and stretch as the engine moves, it has concertina folds at one end to allow this. It often perishes and splits and that leads to air leaks. Hunting is a classic symptom.

Check it by:
- with engine running, squeeze it and flex it by hand. You will soon know if it is bad!
- take it off and look at it. It is secured by clips at both ends and just slides off.

I replaced one recently with this part and it cured the problem:

FL035 AIR HOSE - FUEL INJECTION SPIDER 1988-93 - Classic Alfa

For the lack of heat, the valve for the heater matrix, controlled by the "hot cold lever" can go bad and stop the flow of water through it. I've not had the problem (yet!) but get the impression it is a PITA to get to. Can you take the inlet and outlet hoses for the heater matrix off at source and see if you can flush water through with the valve open?
I replaced the thermostat on one recently and it took a good blast of driving for a few miles at high revs in 4th before the system self bled and I started getting hot air. It shouldn't need this, apparently, but mine did.
 

·
Registered
Joined
·
3,875 Posts
As for the hunting:

1. Check the big air hose over the engine has no small cracks in it. The ONLY way to properly check this is to take it off completely (easy) and especially check the areas around and under the Jubilee clips. Any leak here and it will run like a pig! (part available, but not cheap)

2. Check the 4 x intake "plenum-to inlet manifold" rubbers are not cracked - if they are you need to replace them. If you suspect a leak let it tick over and spray them with carb cleaner spray, if the engine note gets better suddenly, you have a leak there. Replace. (parts readily available, not expensive, but the job will take a good hour or two, or three or....!)

3. Remove the Bosch Idle Air meter (see photo, top left) very simple 5 minute job to remove (once you have removed the electric connector which is held on with a spring clip!), and spray it in both orifices with brake cleaner spray and make sure the rubber grommet it slides into on the plenum makes a nice seal when you put it back, if it is hard spray it with some silicone spray - the cleaning of this unit sometimes clears up the junk inside it and allows the car to idle smoothly - you cannot adjust idle on the S4, the ECU does all that, but requires all units to work smoothly.
Note: when putting it back, do not over tighten the bracket mounting bolt, as it tends to round out the soft aluminium grooves, then the whole intake plenum needs to come off to fit a helicoil! pita! (Part available, shared with a lot of cars, not too expensive, not too cheap)

4. Another thing affecting idling is the OVS, the Oil vapour Seperator (photo top right), situated right beside the coil - take it off the car (2 big hoses and smaller hose below, 2 bolts) and again fill it up with brake cleaner spray and shake the hell out of it and knock it about with a rubber mallet....you will be amazed at the junk that falls out...they rot completely out from the inside and cause all sorts of rough running issues. Once the brake fluid starts to come out clean, you know you are there (I do this once a year, and every year it is filthy!) (Part unobtainium, but in the US they do a copy in stainless steel, expensive)

5. VVT (Variable Valve Timing unit) on the front of the cam cover on the inlet camshaft side: check that the little pin inside (you can look through the inspection hole and see it with a torch) is not stuck......spray it with WD whilst idling and try to see if it moves with a small screwdriver, sometimes you can get away with this to free it up. To test correct operation of the VVT, remove the rubber boot and two wire connectors. Run two wires from the battery (or easier is a wire from the electrical connector box on the left wing, the one with the big red wires going into it......this is live and then any wire from a good earth) and put these onto the VVT contacts (doesn't matter which wire goes where) and you should hear a distinct click. A click means it is working and you will see the pin in the inspection hole jump like a solenoid.
If the VVT is stuck on, the car idles like a pig! See photo bottom left (part unobtanium)

6. Purge solenoid: can cause idle trouble and is always overlooked. This is mounted on the same bracket as the OVS, and is a small square thing with 2 wires and 2 vacuum hoses - make sure the connections here are clean and the 2 small vac. hoses are attached...follow the vacuum hoses to make sure the one is attached to the crankcase and the other goes along the wing inside the bulkhead on the passenger side (it eventually goes into a charcoal filter cannister, but this is hidden under the wing behind a panel, passenger side). See photo lower right for position of solenoid. (part unobtanium)

well, there are other things, but that will get you started! Good luck and report back!:)
 
1 - 3 of 3 Posts
Top