Stumped... Please help

[mr_esmit]

My car has definitely gone haywire on me!!!!!!! It's been at the shop for about a month and still no dice. When I start the car in the morning, it starts to idle really rough for about a minute then it smooths out. Scanned it and all I got was fuel trim to lean which went away after replacing the Coolant Temp Sensor. The shop has been looking at boost leaks, faulty check valves, faulty PCV, diverter etc and nothing. Anybody else have any suggestions? Thanks.

[SJorge3442]

My car has definitely gone haywire on me!!!!!!! It's been at the shop for about a month and still no dice. When I start the car in the morning, it starts to idle really rough for about a minute then it smooths out. Scanned it and all I got was fuel trim to lean which went away after replacing the Coolant Temp Sensor. The shop has been looking at boost leaks, faulty check valves, faulty PCV, diverter etc and nothing. Anybody else have any suggestions? Thanks.

Rough start and smoothing out is one sign of a bad head gasket. Coolant leaks into the cylinders as the engine cools and then when the engine heats, the gaps are sealed and it runs good.

[Seerlah]

If coolant was in the cylinders, it would make it's way into the oil as it seeps past the piston rings. Oil analysis would say for sure, but this can be tested with an oil rag that captures oil and not water. If you pour a sample of the oil onto the rag, it will absorb the oil. Water will sit on top. That is assuming it is the issue.

Real issue is the car has been in the shop for a month and the problem has yet to be resolved. Get your car back and let the the people of Audizine help you out. It'll get figured out and fixed

[diagnosticator]

You are correct about getting a coolant sample tested by an oil analysis lab like Blackstone for dissolved combustion gasses. Normally, there is zero dissolved combustion gasses in the coolant. That is the best way to diagnose a failed head gasket that has not become an emergency yet.

[mr_esmit]

Thanks guys. Will look into all of your suggestions.

Seerlah, that's what I'm hoping for.

[USAF Long]

Compression test the engine, you'll want all cylinders to be within 10% of each other.

[mr_esmit]

Compresion test done. All seems with in limits.

Unfortunately here in the Dom Rep. there are no labs for getting a coolant sample tested.

What I do have now is a rough idle (all the time) and fuel trim too lean code when I scan. Could this be a leak somewhere?

[Moncion]

MAF?

[mr_esmit]

MAF?

Replaced MAF a couple of months ago.

[PreciseD]

I bet it's a cracked in the head. Do you get a little white smoke out of the tailpipes in the mornings?

[diagnosticator]

I bet it's a cracked in the head. Do you get a little white smoke out of the tailpipes in the mornings?

I disagree. I have never seen or heard of a 1.8t cylinder head cracking that caused coolant to leak into the cylinders. OP, check the fuel pressure, it could be a bad fuel pump. Low fuel pressure will cause a lean fuel trim to a limit, and is consistent with the rough idle going from only at cold start up to all the time.

OP, After the engine temp sensor was replaced, did the fuel trim correct or still to lean? If not to lean, there must be something else not related to fuel causing the rough running and misfires. Try moving the ign coil pack and see if the misfires follow the moved coilpack/s. Do the same thing with the injectors. If the misfires follow the moved coilpack/s or injector, the moved part is faulty.

[PreciseD]

I disagree. I have never seen or heard of a 1.8t cylinder head cracking that caused coolant to leak into the cylinders.

??? I know of thousands that has happened too. Myself included.

[chad99]

When my head gasket/ warped head was bad, when I opened the coolant overflow tank and took a sniff of the coolant I could smell combustion gasses (coolant still looked very pink not dark).
My symptoms were sometimes cold start slight stumbling issues when SAI turned on, almost no white smoke out exhaust if any, and car ran fine once warmed up.
Also vagcom saw random misfires, and when looking at live data the counts were high on cylinder 2

[diagnosticator]

??? I know of thousands that has happened too. Myself included.

You know of thousands of cracked 1.8T cylinder heads that leaked coolant into one or more cylinders, including your experience, through crack/s, that were confirmed by a water tank test? I don't believe you can provide even one confirmed example of this actually happening. The configuration of the casting just doesn't crack in a way this could happen. If there was any technical factual merit to this unsupported allegation, Audi/VW would have redesigned the casting. All of the alleged cracked heads leaked from some other cause, like a failed head gasket. When the head is replaced with a new head gasket the leaks were fixed, so those who don't understand the facts involved believe the alleged cracks in the old head were confirmed by the fact the new head installation did not leak coolant into the cylinders. Duh. I am not going to debate this further, it seems to be a waste of my time.

I apologize for the terse writing style I have, I don't mean to offend you from a personal aspect.



*Terse: " brief and direct in a way that may seem rude or unfriendly"

[PreciseD]

You know of thousands of cracked 1.8T cylinder heads that leaked coolant into one or more cylinders, including your experience, through crack/s, that were confirmed by a water tank test? I don't believe you can provide even one confirmed example of this actually happening. The configuration of the casting just doesn't crack in a way this could happen. If there was any technical factual merit to this unsupported allegation, Audi/VW would have redesigned the casting. All of the alleged cracked heads leaked from some other cause, like a failed head gasket. When the head is replaced with a new head gasket the leaks were fixed, so those who don't understand the facts involved believe the alleged cracks in the old head were confirmed by the fact the new head installation did not leak coolant into the cylinders. Duh. I am not going to debate this further, it seems to be a waste of my time.

I apologize for the terse writing style I have, I don't mean to offend you from a personal aspect.



*Terse: " brief and direct in a way that may seem rude or unfriendly"

Hate to burst your bubble but there is a coolant passage between ALL of the valves as seen below. I can confirm that my head gasket was 100% in tact and had zero sign of seepage from a coolant area.

[mr_esmit]

Hate to burst your bubble but there is a coolant passage between ALL of the valves as seen below. I can confirm that my head gasket was 100% in tact and had zero sign of seepage from a coolant area.

Makes sense, but would the car be losing coolant? Cuz my coolant levels are fine.

[diagnosticator]

That cross section view does not show the areas in the head between the valve seats where thermal stress cracks occur. It shows only the cross section on the port and valve center line which is irrelevant regarding the thermal stress cracks between the valve seats.

[diagnosticator]

Hate to burst your bubble but there is a coolant passage between ALL of the valves as seen below. I can confirm that my head gasket was 100% in tact and had zero sign of seepage from a coolant area.

Again, that cross sectional view is irrelevant. It does nothing to support your claim. This cross sectional view shows no cracks that could leak coolant into the cylinder/s and does not prove anything. Show me an example of a cracked head that was tested in a test tank of water confirming the presence of cracks. The fact that there are coolant jackets in the head is also irrelevant. The cross section does not reveal the thickness of the casting or distance from any coolant jacket of the casting webs between the valve seats. The plane of section is 90 degrees from the webs between the valve seats and does not bisect any web between the valves seats.

What method did you use to conclusively confirm the head gasket was not leaking?