Print

Please login or register.
1 Hour 1 Day 1 Week 1 Month Forever
Login with username, password and session length

[PhilRich]

Have you had the Exhaust Manifold heat shield off to check your manifold for cracking? The 2.2 is notorious for this with the manifold cracking dead centre between pots 2 & 3
If the crack is large enough that would cause issues with lambda metering and fuel trims

[tunnie]

Have you had the Exhaust Manifold heat shield off to check your manifold for cracking? The 2.2 is notorious for this with the manifold cracking dead centre between pots 2 & 3
If the crack is large enough that would cause issues with lambda metering and fuel trims

Really not sure what causes this, FatherT's one has cracked I think, hear it on start up, but soon goes once warmed up slightly. Think it went around 120k or so.

No sign of it on my 165k 2.2 

[x1xv45]

Have you had the Exhaust Manifold heat shield off to check your manifold for cracking? The 2.2 is notorious for this with the manifold cracking dead centre between pots 2 & 3
If the crack is large enough that would cause issues with lambda metering and fuel trims

Really not sure what causes this, FatherT's one has cracked I think, hear it on start up, but soon goes once warmed up slightly. Think it went around 120k or so.

No sign of it on my 165k 2.2 

I'll have a close look in the morning - I know about this, had a cracked manifold on a 2.0, but I thought it was more a problem for 2.0 than 2.2. I remember the distinctive fast tapping sound it made, then a growling sound as it got bigger, haven't heard that this time, but definitely worth looking. What about tiny leaks in the exhaust pipes, how do you find them besides the sound, and would that have a bearing on the starting up? Everything except the downpipe is replacement, it never sounded as nice as what came with the car, but it doesn't sound like holes to me.

[terry paget]

Have you had the Exhaust Manifold heat shield off to check your manifold for cracking? The 2.2 is notorious for this with the manifold cracking dead centre between pots 2 & 3
If the crack is large enough that would cause issues with lambda metering and fuel trims

Really not sure what causes this, FatherT's one has cracked I think, hear it on start up, but soon goes once warmed up slightly. Think it went around 120k or so.

No sign of it on my 165k 2.2 

What causes the cracking is the cycling hot/cold in a cast iron manifold. I have had it on several 2.0 Omegas. I had one welded up, but the welder said he would not guarantee it, it would go again eventually. However it did not affect the running or starting. I have one gone on a 2.5 too. I do not think a cracked manifold would cause this threads problems.

[x1xv45]

Terry: that's useful evidence. I had a local blacksmith weld up my 2.0 - he said it might be caused (in addition to what you said) by impurities in the casting, said it was rubbish material for the purpose, but couldn't be beaten for cheapness (affordability). Phil has a valid point about leaks affecting the lambda behaviour; how this is involved at startup I don't understand, I thought the lambdas had to get very hot before they kicked in.

[terry paget]

Terry: that's useful evidence. I had a local blacksmith weld up my 2.0 - he said it might be caused (in addition to what you said) by impurities in the casting, said it was rubbish material for the purpose, but couldn't be beaten for cheapness (affordability). Phil has a valid point about leaks affecting the lambda behaviour; how this is involved at startup I don't understand, I thought the lambdas had to get very hot before they kicked in.

The 2.2 has 2 lambda sensors, whereas the 2.0 had one. I have read that the upper one only controls emissions when the engine is cold, and has no effect when engine is hot. I had EML light on, took my 2.2 to a Tech2, and it read 'no. 1 O2 sensor no signal' so I changed it  Now EML stays out, fault occurs less often - in three days it did not happen.

 I still am unconvinced that a small exhaust leak at the manifold will affect the exhaust gas mixture - the gas is leaking out, not in.

[x1xv45]

Terry: that's useful evidence. I had a local blacksmith weld up my 2.0 - he said it might be caused (in addition to what you said) by impurities in the casting, said it was rubbish material for the purpose, but couldn't be beaten for cheapness (affordability). Phil has a valid point about leaks affecting the lambda behaviour; how this is involved at startup I don't understand, I thought the lambdas had to get very hot before they kicked in.

The 2.2 has 2 lambda sensors, whereas the 2.0 had one. I have read that the upper one only controls emissions when the engine is cold, and has no effect when engine is hot. I had EML light on, took my 2.2 to a Tech2, and it read 'no. 1 O2 sensor no signal' so I changed it  Now EML stays out, fault occurs less often - in three days it did not happen.

 I still am unconvinced that a small exhaust leak at the manifold will affect the exhaust gas mixture - the gas is leaking out, not in.

I checked the manifold carefully, even underneath with a mirror, and can't see any cracks. About the O2 sensor (on downpipe): are you saying you changed it but still have the rough starting issue, albeit not as bad as mine, and still get the EML, just less often?

[terry paget]

Terry: that's useful evidence. I had a local blacksmith weld up my 2.0 - he said it might be caused (in addition to what you said) by impurities in the casting, said it was rubbish material for the purpose, but couldn't be beaten for cheapness (affordability). Phil has a valid point about leaks affecting the lambda behaviour; how this is involved at startup I don't understand, I thought the lambdas had to get very hot before they kicked in.

The 2.2 has 2 lambda sensors, whereas the 2.0 had one. I have read that the upper one only controls emissions when the engine is cold, and has no effect when engine is hot. I had EML light on, took my 2.2 to a Tech2, and it read 'no. 1 O2 sensor no signal' so I changed it  Now EML stays out, fault occurs less often - in three days it did not happen.

 I still am unconvinced that a small exhaust leak at the manifold will affect the exhaust gas mixture - the gas is leaking out, not in.

I checked the manifold carefully, even underneath with a mirror, and can't see any cracks. About the O2 sensor (on downpipe): are you saying you changed it but still have the rough starting issue, albeit not as bad as mine, and still get the EML, just less often?

This car Y188NFA is my son's car. After passing MOT I changed the cam sensor, but EML came back on and he still complained of rough starting. I took it to a Tech2, which said 'No. 1 O2 sensor no signal' I changed No. 1 (upper) lambda sensor 18 July, no EML light on, I gave car back to son saying all well. 22 July he complained of bad starting. We swopped cars for three days, it seemed fine to me. We swopped back Thursday 25 July. He has not complained since. EML is still off.

Sorry to be vague, but the car seemed fine to me. I cannot ask the forum for help unless I can describe symptons. The car is fine once warm, and has had no EML light on for ten days.

[tunnie]

Have you had the Exhaust Manifold heat shield off to check your manifold for cracking? The 2.2 is notorious for this with the manifold cracking dead centre between pots 2 & 3
If the crack is large enough that would cause issues with lambda metering and fuel trims

Really not sure what causes this, FatherT's one has cracked I think, hear it on start up, but soon goes once warmed up slightly. Think it went around 120k or so.

No sign of it on my 165k 2.2 

What causes the cracking is the cycling hot/cold in a cast iron manifold. I have had it on several 2.0 Omegas. I had one welded up, but the welder said he would not guarantee it, it would go again eventually. However it did not affect the running or starting. I have one gone on a 2.5 too. I do not think a cracked manifold would cause this threads problems.

But why some more than others? FatherT's only tends to get long journey use, hardly ever used for short runs. (so quick hot cold)

[x1xv45]

Terry: that's useful evidence. I had a local blacksmith weld up my 2.0 - he said it might be caused (in addition to what you said) by impurities in the casting, said it was rubbish material for the purpose, but couldn't be beaten for cheapness (affordability). Phil has a valid point about leaks affecting the lambda behaviour; how this is involved at startup I don't understand, I thought the lambdas had to get very hot before they kicked in.

The 2.2 has 2 lambda sensors, whereas the 2.0 had one. I have read that the upper one only controls emissions when the engine is cold, and has no effect when engine is hot. I had EML light on, took my 2.2 to a Tech2, and it read 'no. 1 O2 sensor no signal' so I changed it  Now EML stays out, fault occurs less often - in three days it did not happen.

 I still am unconvinced that a small exhaust leak at the manifold will affect the exhaust gas mixture - the gas is leaking out, not in.

I checked the manifold carefully, even underneath with a mirror, and can't see any cracks. About the O2 sensor (on downpipe): are you saying you changed it but still have the rough starting issue, albeit not as bad as mine, and still get the EML, just less often?

This car Y188NFA is my son's car. After passing MOT I changed the cam sensor, but EML came back on and he still complained of rough starting. I took it to a Tech2, which said 'No. 1 O2 sensor no signal' I changed No. 1 (upper) lambda sensor 18 July, no EML light on, I gave car back to son saying all well. 22 July he complained of bad starting. We swopped cars for three days, it seemed fine to me. We swopped back Thursday 25 July. He has not complained since. EML is still off.

Sorry to be vague, but the car seemed fine to me. I cannot ask the forum for help unless I can describe symptons. The car is fine once warm, and has had no EML light on for ten days.

Thanks for the clarification, it's anything but vague. It indicates the lambda may indeed be connected to rough starting, but I suppose time will tell.

[terry paget]

Have you had the Exhaust Manifold heat shield off to check your manifold for cracking? The 2.2 is notorious for this with the manifold cracking dead centre between pots 2 & 3
If the crack is large enough that would cause issues with lambda metering and fuel trims

Really not sure what causes this, FatherT's one has cracked I think, hear it on start up, but soon goes once warmed up slightly. Think it went around 120k or so.

No sign of it on my 165k 2.2 

What causes the cracking is the cycling hot/cold in a cast iron manifold. I have had it on several 2.0 Omegas. I had one welded up, but the welder said he would not guarantee it, it would go again eventually. However it did not affect the running or starting. I have one gone on a 2.5 too. I do not think a cracked manifold would cause this threads problems.

But why some more than others? FatherT's only tends to get long journey use, hardly ever used for short runs. (so quick hot cold)

No idea, seems like chance. My 2.5 V6 , 150K miles,has RH manifold cracked, been so for 2 years, LH not cracked. My 3.2, 180K miles, no cracks yet.

[symes]

if manifold cracked--so what----just weld it up

[PhilRich]

if manifold cracked--so what----just weld it up

[/highlight]



I had my old 2.2 saloon ( I gave it to my son) manifold welded by a coded welder who commented that the casting was like cinder toffee!  When he'd done the job he said he couldn't guarantee it and it cracked on first warm up!

[x1xv45]

Tim, have you tried with MAF disconnected on initial start up

Rob, you are onto something here - I've now tested this twice in the morning, when it's completely cold, and with MAF disconnected it started normally, then reconnect the MAF (without warming up at all) and it starts normally, until it gets cold again, then with MAF connected it's back to the poor startup. I couldn't believe it the first time, thought it must be a fluke, so I didn't say anything right away. What does this mean?

[x1xv45]

Something else I tried based on a TheBoy comment: http://oldsite.omegaowners.com/forum/YaBB.pl?num=1209489601/7#7
With engine cold, MAF connected as normal, foot to the floor crank for 5 seconds to clear the injectors, then start. Result: better than usual - lumpy for a while, but not scary rough like it usually is. I'll try that again later to confirm.
This would point to leaky injectors, with too much petrol accumulating when the car sits for a long time. I think the P0170 Lean Exhaust code that comes up sometimes, but is usually "Not present" when I check it, might be reinforcing this idea - as a load of noncombusted fuel blows out after starting. But I'm also a bit confused at this point, what with O2 sensor, MAF sensor, injectors and how they are interacting.