[Jack_155Q4]

Hi all,

The other morning my dad started his 164 and it had a very lumpy idle. We suspected the plugs were bad and they were, so all 6 have been changed. Have checked for any hint of an air leak in the inlet plenumn, again nothing. Also have tested the lambda - it appears to fluctuate between 0.2 and 0.6 volts, which I think is sort of ok, I used this as a guide: Just Lambda, Suppliers of Bosch and NTK lambda sensors including zirconia and titania sensors by post

Not sure what to check now - is there a way to test the AFM? We disconnected it and the engine cut out, but the second time we tried this it stayed running. Have taken it off for a look and the flap moves freely, not much else to see, its all clean etc.

Where is the idle control valve?

This is only an idle problem as the car actually drives perfectly well. The other day on a long drive to Birmingham we did notice once that the injector light was on for a few seconds when we were on over run - did not affect the running, and it still goes better than our 166 3.0 V6!

Any ideas?

Thanks
Jack

 

[Alfisto Steve]

Cam timing jumped a tooth or two maybe.

 

[Jack_155Q4]

Possible, I hear the 24v engines can do that but I do not think it is that serious as I do not think it would not drive perfectly if that was the case.

 

[g84]

[


The idler control sits at the back of the inlet not far from the AFM. Have you checked all the vacum hoses. Another thing is the temp sensor on the termostat housing. Don't sound like a belt jump. If so you would feel less power under 3000rpm and it would vibrate when idling.

 

[twoliterlover]

Ah, yes, another 24 valve idling problem

My friend. You have an ignition aplifier going bad. This is the third of of these I have heard of, one of which was mine. There is another thread going on this. I have mailed off my only remaining spare. Contact Jungle Justice who is active on the BB. He probably can find you another. See the photos. Symptoms exactly, problem only on idle, seems like a tooth skip (if it were a 12 valve), runs well at regular speed. Specific problem that only a 24 valve has when the trigger from ICU unit must be amplified to make the spark hot enough. Best way is to switch the leads to the two boxes just under the air intake. If a different cylinder on the other bank starts missing, then you know one of the amplifiers is bad. Photos show the installation taken out of a wrecked LS upside down. Use your spacial abilities and turn it over in your mind to see where the two leads fit. The other end of the lead goes to the spark packs on top of the head. JAY

 

[john.harrill]

Do you get a strong sulfur smell?
Any codes stored in the ECU?

 

[Jack_155Q4]

Thank for all the suggestions. He will have a better look today and will let you know!

@John, no noticeable sulphur smell but the plugs do look like it was running rich. We have not checked for codes, do you know the procedure?

 

[john.harrill]

The strong sulfur smell is a symptom of slipped timing, a concept I'm very familiar with. It is most commonly the rear exhaust camshaft. If you don't notice it, that's a good sign. It means that your problem is probably induction or ignition related.

To read the ECU codes, turn the key to the "run" position, but don't start it. Press the accelerator 5 times and watch the check engine light. It will flash once, for about a second. Then the light will produce a series of flashes that represent the 4-digit status codes stored in the ECU. For example:

One second flash + pause +
4 flashes in succession +
4 flashes in succession +
4 flashes in succession +
4 flashes in succession = 4444

This means no errors are stored in the ECU.

After the last series of flashes, the light will come on and stay lit. If you miss the light's sequences (everyone does) let things run their course, turn off the ignition and try again.

The code descriptions can be found on the CarDisc, or on the 164 Digest website.

 

[Jack_155Q4]

Thanks John, I will do that test.

But I think twoliterlover is on to something, my dad swapped the plugs on the amplifier and the problem seems have moved to the front bank. Will try and get a spare part and fit it this week

 

[john.harrill]

Thanks John, I will do that test.

But I think twoliterlover is on to something, my dad swapped the plugs on the amplifier and the problem seems have moved to the front bank. Will try and get a spare part and fit it this week

That's good news. Much easier than re-timing the cams!

 

[Jack_155Q4]

The amplifiers have been fitted but unfortunately the problem remains.

Will now check the idle control valve.

Jack

 

[Alfisto Steve]

Pulling codes on 24v 164

Euro spec car may not work this way but here is how to do code check: Alfa 164 Motronic M1.7 Self-Diagnosis

 

[Jack_155Q4]

ICV is clean but we cleaned it again anyway,

Also, tonight we tried all combinations of old and newer amps and it was the same bad idle.

But we did discover a clicking noise, at first thought it was a loud injector, but on closer inspection after taking the front bank coil pack cover off, we could see some sparks from Cyl1 coil pack. We removed it and sprayed with electrical cleaner and put back, it is no longer sparking, the idle is slightly better but not 100% - I think once this is replaced it might be fixed!

 

[richardbradford]

ICV is clean but we cleaned it again anyway,

Also, tonight we tried all combinations of old and newer amps and it was the same bad idle.

But we did discover a clicking noise, at first thought it was a loud injector, but on closer inspection after taking the front bank coil pack cover off, we could see some sparks from Cyl1 coil pack. We removed it and sprayed with electrical cleaner and put back, it is no longer sparking, the idle is slightly better but not 100% - I think once this is replaced it might be fixed!

I have had a similar problem with my 1995 24v UK spec 164. The general conclusion is that is it probably the coil packs on the rea bank arcing - the rear gets much hotter than the front. Due to work/weather issues have yet to swap them over but if your idle is worse when the engine is warm than when cold then you probably have this problem too.

 

[Jack_155Q4]

but if your idle is worse when the engine is warm than when cold then you probably have this problem too.

Yes that is the case, thanks for your input!

 

[Jack_155Q4]

Problem solved at last - the timing had jumped as many of you suggested and we have now fixed it and is running as it normally should

Thanks
Jack