156 2.0Ts Shuddering On Idle

[leongsoon 8]

Car has been behaving itself for the best part of 2 weeks. Yesterday, I parked the car after a nearly hour long drive. On starting it up again about 15 minutes later, the car idles at abouy 800 - 900 rpm, normally it idles at roughly 980 -1020 rpm.

 

When I restarted it this morning, the idling was nice again but I performed an ECU reset anyway. All through the reset it was idling nicely with no problems at all. After the reset, I took the car out, the throttle response and power was great, I can definitely feel an improvement and was rather happy. However, a few minutes later the low idling came back and the car shudders again. Power has decreased, revs go up slower and the car sounds like it's missing a cylinder. I hooked up FES and no errors came up, there weren't even any warning lights on the dashboard.

 

Does anybody know what might be causing this? Many thanks for your help

[jhc 28]

If you hadn't talked about ecu resets etc I'd say clutch, engine mounts or flywheel as the cause of judder...

 

But if it changes with ecu stuff it's not that.

 

Is it a derv? If not, it's idling way too high at 900 or the other one..

 

either way, check air intake hoses for leaks. Thats a good start... Then look at electrical stuff like ht leads, coil packs, plugs etc... The judder is probably uneven firing of some kind.

[leongsoon 8]

Thanks Munky! I removed the engine cover and found that a small hose branching from the main intake hose after the MAF has came loose. When I used my finger to cover the hole the shuddering engine smoothed out again, so I just reclipped that hose. Sure enough the car behaved well and the power is all back.

 

After driving for about 10 more minutes, the idling started to lower again and the shuddering restarts. This time though the power doesn't drop; it just seems to have a huge lag. Once I get to 2000rpm and above the car just seems to surge, anything below that and the car feels like it will stall any moment.

 

I'm not too sure but it also seems that every time the temperature rises to about 80 celcius, the shuddering starts. Any ideas?

Edited July 21, 2012 by leongsoon

[K9d 108]

It may be worth doing another reset, if you've cured a problem it could have screwed up the first reset.

[Smaky 73]

oil in plugs, split air duct, faulty MAF, dodgy coolant temp sensor, CF2 - ICV, blocked air filter, poor engine earth, bad plugs/coil pack/lead. some places to start before thinking of the sinister things....

[leongsoon 8]

Thanks K9D, I thought so too, but since it's erratic now I figured something else still might be amiss.

 

Smaky! I checked the air duct first and it should be fine. I last checked the air filter a few weeks back and it's very clean.

 

1. Poor engine earth or bad plugs, coil pack, leads. How should I check these?

2. My engine's from a 1999 156 2.0 TS. I think it's a CF1. How do I check the ICV as well as the coolant temp sensor?

 

In the mean time I'll try to have a look at the plugs. The MAF was the first thing I wanted to check but I don't have the proper tools to remove it.

[Smaky 73]

I can guarentee it's NOT a CF1, they aere only fitted to the 145/146,155, 164 and ph1 GTV/Spider. Take a pic and I'll tell you which you have.

 

Check resistance between the blk and body, it should be 0 Ohms.

 

Unplug each coil pack in turn and see if there is a change in the engine note whilst running, if there is none then you found the culprit.

 

ICV and CTS require software to test/reset, if the ICV (cable operated throttle only) is shot then it'll need replacing and calibrating.

[leongsoon 8]

Sorry, I just assumed away that since it's the earliest type of 156 it's gotta be CF1

 

Here's how the engine looks like:

 

 

I guess these are the coils; can't say how horrified I am to be greeted by this sight:

 

The five left most spark plug shafts are filled with water, some plugs are totally submerged. It quite a while to soak up all the water with newspaper and cotton.

 

These are how the spark plugs look like upon removal, I guess they don't look too bad. I measured the gap for the spark plugs and they are consistent.

 

Cleaned the coils and applied plenty of contact cleaner.

 

Unfortunately, as I was retightening the very last spark plug, the rightmost small one, it snapped clear and left it's threads screwed within the shaft. My dad managed to extract the snapped part without much ordeal. I cranked the engine with all plugs off and nothing came out, so that's a relief. Gonna get some new plugs tomorrow.

[Smaky 73]

They are the coils, That is a CF3 engine and you don't need to worry about the ICV (you don't have one), those plugs and that nasty mess will be the problem as I expected and a simple clean and new plugs (sit down for the price) will sort it out.

[Smaky 73]

Again it's a shame your not nearer, I have loads of used leftovers for just such an occasion to help folk out of the fix your in.

[xyy81t 0]

phew you were lucky with those spark plugs, i would have warned you not to put them back in if i'd have seen this thread earlier. One of the little ones in my old QV snapped off on the way out requiring a head-off job and helicoil insert aaaah good times :/

 

here's the thread if you're intersted

 

http://forum.alfa145.com/index.php?showtopic=17670

[leongsoon 8]

Haha thanks Smaky! It's a shame really I'm not nearer; my car wouldn't have had half as much downtime as it has accumulated now hehe! Turns out like every other part for this car, it's NOT available here and I've had to order a set of PMR7A plugs. RM180 or 37GBP for the lot of em, the figure is a bit astronomical but I wish I could say I was shocked hehe. Anyway I'll be getting them tomorrow and hopefully that will sort the idling out.

 

xyy81t I got off very easy compared to you; I would have broken down and cried if I that happened to my engine Good job sorting the engine out!

[Smaky 73]

Haha thanks Smaky! It's a shame really I'm not nearer; my car wouldn't have had half as much downtime as it has accumulated now hehe! Turns out like every other part for this car, it's NOT available here and I've had to order a set of PMR7A plugs. RM180 or 37GBP for the lot of em, the figure is a bit astronomical but I wish I could say I was shocked hehe. Anyway I'll be getting them tomorrow and hopefully that will sort the idling out.

 

xyy81t I got off very easy compared to you; I would have broken down and cried if I that happened to my engine Good job sorting the engine out!

 

37 quid for 4 NGK plugs is cheap, places here are flogging them for 15 sheets EACH now.

[leongsoon 8]

Whoah! What does it cost for all 8 plugs then? That's really surprising as I've been sourcing a lot of my parts from UK because they're considerably cheaper.

 

Anyway, I've installed the new plugs in the car last night and went on an hour-long drive; slow, mostly fast, just letting the car idle doing nothing and it has been great! I think the engine is smoother now than it has ever been and I can't be sure but it probably sounds nicer too! I haven't been able to get the temperature up to even 80c to see if the rough idling will return, so I'll be holding my breath a bit until then!

[Smaky 73]

Sounds like the thermostats gone too then as it should be running at 90, especially after an hour drive.

[leongsoon 8]

Really? It's normally operating at 70+ and sometimes 80 on a really hot afternoon. It rained last evening so the needle was hovering below the 70 mark. The only 2 times I've seen it at 90 or higher was when the radiator fan isn't running with the air conditioning turned off. That really freaked me out but it was all good again soon after I switched the AC on. Haven't quite figured out why the ac needs to be on to make the fan run, tried swapping the red relays in front of the battery around but doesn't seem to be any difference I wanted to change the black 50A relay, but that one has to be ordered.

[xyy81t 0]

The fan comes on with the air con to irrespective of the engine temp, I believe the Ecu switches the fan on when the coolant temperature reaches 93 degrees, well on the cf2 it does shouldn't think it's much different on the cf3

[leongsoon 8]

That's what freaked me out; I was expecting it the fan to cut in anytime around the 90 mark but it didn't. Maybe I freaked out and switched the air con on too early hehe! Not too much of a problem though since it's hot all year round here and we rarely switch the aircon off.