e320 W210 Surging issues after Head Gasket.

[kiwi_bloke]

Hi guys.

Have the following.

Car had head gasket replaced.

It now surges 300 rpm while coasting when warm (never cold).

Rough idle between 60C and 80C - ok when hot (most of the time).

Surges when coasting to a stop.

Originally had the code "MAF at lower limit". So replaced the MAF. Codes Cleared.

Now have "MAF at lower limit", MAF at upper limit", "Lambda at upper limit", "Lambda out of range".

Does this mean I now need an o2 sensor? Running got worse after the MAF, mostly in the 60 C 80C range - but tidied up when hot.

Where are the O2 sensors in this chassis?

Oh yeah, its a 1996

 

[kiwi_bloke]

Assume

Yeah,

Ive checked vaccuum hoses, etc, connections. At present I'm just assuming the head gasket change has nothing to do with it - I'm just going through the numbers.

 

[television]

Hunting is always an air leak in the inlet, either a vacuum pipe leaking or on the inlet manifold side

 

[kiwi_bloke]

Codes

Will a vaccuum leak throw codes? If so how does that logic work ? Also Can someone tell which way around the vaccuum lines go from the SOV, to the two valves on top of the exhaust?

 

[television]

Will a vaccuum leak throw codes? If so how does that logic work ?

No codes with a vacuum leak, you can check the pipes by pulling of any pipe and put your finger over the end of the tube that the pipe goes on to, or with a blanking cap.

When the engine is at idle, the vacuum is at the max, the engine sucks in air and speeds up, as the engine speeds up the vacuum goes down and the engine slows down again, and repeats the cycle

 

[kiwi_bloke]

I'll recheck all this in the next couple of days. I am going to start from the begining as I've had my mechanic do bits and peices and I've decided I'm better of doing it my self less the labour costs.

Is it possible that the MAF and O2 Sensor had both failed?

If so, is it possible for a Bad O2 sensor to trigger a MAF code or vice versa?

 

[television]

If the MAF has been replaced was this done after the head gasket, The O2 sensor will turn the engine lamp on when you move things around, why not put it all back to where it should be

 

[kiwi_bloke]

True - Head gasket was done. Approximatly 1000kms after head gasket, the MAF was replaced.

It has been returned to the mechanic once who fixed a vaccuum leak (before the MAF was replaced), that was causeing a cronic hunt at idle (2000rpm up and down). The hunt at idle is almost gone now, it is more random, and rough rather than a uniform hunt. The hunt is normally while driving. Also randomly at idle in gear when hot, the idle will drop to 200 rpm then rev back up, stabilising the revs - a minute later the same will happen. And thus the cycle continues.

Cold starts are rock solid.....and cold running is rock solid.

No check engine light, but then Im not sure if the buld is good at this stage.

Plan of attack? Put everything back, verify no vaccuum leaks?

 

[kiwi_bloke]

And this

Ive also been reading that a bad MAF can give a lambda code and vice versa... not sure how true this is, or how its possible.

Also been reading that a vaccum leak can trip a lambda code?

Truth or false?

 

[LYNALL]

I reckon an vac air leak could cause a code as to much air in exhaust gas and ecu tries to correct, arent there seperate seals on the inlet manifols on these, green o rings iirc.

I think plus gas sprayed around the manifold and any change in rpm as the gas is burnt should pinpoint the air leak.

Its the old story if it didnt do it before the hg change and did it afterwards they have done/not done something right.



Lynall

 

[television]

I reckon an vac air leak could cause a code as to much air in exhaust gas and ecu tries to correct, arent there seperate seals on the inlet manifols on these, green o rings iirc.

I think plus gas sprayed around the manifold and any change in rpm as the gas is burnt should pinpoint the air leak.

Its the old story if it didnt do it before the hg change and did it afterwards they have done/not done something right.



Lynall

I have to agree that they should have looked at their own work before changing things, I do not know how you about things now other that putting it all back to where it was, the MAF is not going to fail after changing the head gasket

 

[kiwi_bloke]

I agree, and have been trying to get this accross to the mechanic. He's wiped his hands of it.

I'm going to tackle it saturday morning so Ill report back then.

So just get some petrol and spray around the joints, etc to check for leaks.


I also disconected the MAF last night, and it runs equally bad.

 

[oigle]

I agree, and have been trying to get this accross to the mechanic. He's wiped his hands of it.

I'm going to tackle it saturday morning so Ill report back then.

So just get some petrol and spray around the joints, etc to check for leaks.


I also disconected the MAF last night, and it runs equally bad.

I'd be super careful about using petrol - very dangerous doing that around a running engine !!! Maybe something like crc or the like would be better - As you spray it on, it temporarily will stop the airleak and the revs change. Much safer.

 

[kiwi_bloke]

Leaks

Got some WD 40 and sprayed the sh*t out of every joint, screw and bolt that could possibly let in air.

No cigar, the idle didn't change at all. At this point im rulling out a vaccuum leak. This is the third time I've checked for leaks.

It's of interest my check eng light doesn't light with the key in the 2 position. Unplugged the O2 sensor and it still doesn't come on! I should have one right ?

I'm going to change the O2 sensor tonight, I've got a known good one from my fathers car, this should test this. It is of interest that when the O2 sensor was unpluged it didn't really make a whole lot of difference.

 

[oigle]

Got some WD 40 and sprayed the sh*t out of every joint, screw and bolt that could possibly let in air.

No cigar, the idle didn't change at all. At this point im rulling out a vaccuum leak. This is the third time I've checked for leaks.

It's of interest my check eng light doesn't light with the key in the 2 position. Unplugged the O2 sensor and it still doesn't come on! I should have one right ?

I'm going to change the O2 sensor tonight, I've got a known good one from my fathers car, this should test this. It is of interest that when the O2 sensor was unpluged it didn't really make a whole lot of difference.

O2 sensors are generally only of use at cruising speeds on light throttle. Disconnecting them just creates a default setting which is "middle of the road" so to speak. Should have no effect at all on idle.

 

[kiwi_bloke]

Yep. Replaced it and it made no difference. Im going to revert back to vaccum leaks, they didn't disconect any vaccum lines - they just pushed the intake manifold to the side - what possible things could they have dislodged?

Bassically now, its consistant at idle. It will drop to 300 rpm, rev up to 1000 then settle. Only in gear though. I notice its not holding in gear for the first cold change now, is there a vaccum line that affects this, could it be related?

 

[kiwi_bloke]

Would under coil connectors be worth looking at , or spark plugs ? they never replaced them during the job.

 

[kiwi_bloke]

Advice

I took the advice of putting everything back to where it was with the original MAF and O 2 sensor.

Verified no vaccuum leaks - checked 4 times in total.

No fuel from fuel press reg port.

Since driving 2000 more km - its getting worse so I might be able to track it now its persistant.

Updated symptoms -

Colds starts are fine.

Hits operating temp and 9 times out of ten when idling in gear I'll get a low idle (500 rpm) or it'll surge from 500 to 1000 always fine accelerating or at fast running.

Excessive fuel consumption - not sure how much exactly - but possibly double the normal ?

Lacking Power.

After running for several minutes cold I pulled the plugs - they were wet with fuel. After hot running plugs dont look to bad. Maybee slightly sooty.

Originally had MAF below lower limit. Turned out the MAF I got sent was a "good second hand" one, after installing got O2 below lower, above upper, out of range. So I sent the MAF back!

3 times its surged and cut out - stating "Check battery charge" on the dash. Restarts fine with no issues - doesnt sound flat.

So i popped in a known good battery I had and got the following volt tests:

12.6 ish not running and connected.
13.5 to 14 while running - idle or fast running.
All accessores on it drops to about 12.6.

When replaced the battery the symptoms dissapeared for 200 km of driving and then started again coincidence maybee. I tested the battery again and its voltage seems to have droped to about 12.4 off.

Old battery was as follows (ive charged and verified its good now) -

13.2 running
11.6 - 12.3 not running.
Sometimes at idle and in gear i was getting 11.9 - sometimes 13.

Can this all be related ?

Where to start now - Should I Order a new MAF?

Any suggestions on how to test these?

 

[kiwi_bloke]

Video





A couple of videos of what it is doing - will make it clearer.

This is at operating temp - Cold it is rock solid.

 

[kiwi_bloke]

Update

The original problem has been fixed! The rough idle and dipping at idle are now gone.

Things replaced = O2 sensor and MAF - Fault appeared to be the MAF.

The orignal MAF sent to me was faulty - got a new one and bang - it works.

On another note - When coasting in gear, at about 1200 RPM the revs pulse very quickly, only about 200 rpm up and down. Was told this is normal ?

Also Ill chuck another question in here. Cruise never used to work - had to put my spare tire on, and now it works all the time - why?