'04 Surging & Smoking (1 Viewer)

[Seth_O]

Its not a truck, but Im getting no help on any Nissan forums and I trust the mud audience.

I have an '04 sentra that is surging (RPM's randomly up/down), feels underpowered and smokes like an 80yo emphysmatic sailor. This was all sudden onset. I could really use help diagnosing. Im not losing any coolant or oil, so I dont think either of those are burning and my exhaust doesnt smell oily or sweet. A compression test gets me 160-170 across all 4 cylinders.

 

[BILT4ME]

Its not a truck, but Im getting no help on any Nissan forums and I trust the mud audience.

I have an '04 sentra that is surging (RPM's randomly up/down), feels underpowered and smokes like an 80yo emphysmatic sailor. This was all sudden onset. I could really use help diagnosing. Im not losing any coolant or oil, so I dont think either of those are burning and my exhaust doesnt smell oily or sweet. A compression test gets me 160-170 across all 4 cylinders.

Based on a 30 second search, I would start looking at crank sensors.

No, first I would source a correct factory FSM.

2004 Nissan Sentra Problems & Complaints | RepairPal

Explore common problems with the 2004 Nissan Sentra, including fuel pump recalls and sensor failures. Find repair options and owner complaints on RepairPal.

repairpal.com

 

[Seth_O]

Based on a 30 second search, I would start looking at crank sensors.

No, first I would source a correct factory FSM.

2004 Nissan Sentra Problems & Complaints | RepairPal

Explore common problems with the 2004 Nissan Sentra, including fuel pump recalls and sensor failures. Find repair options and owner complaints on RepairPal.

repairpal.com

FSM is a great idea. No codes on it, which is why I was not thinking any of the sensors.

 

[Seth_O]

For your entertainment:

 

[gnob]

that looks like hg symptom to me.

long shot, hows your brake fluid level ?

 

[Seth_O]

that looks like hg symptom to me.

long shot, hows your brake fluid level ?

Brake fluid is good. I thought HG as well, but im not losing coolant and my compression test came back pretty good.

 

[Seth_O]

Hunting RPM's:

 

[BILT4ME]

Brake fluid is good. I thought HG as well, but im not losing coolant and my compression test came back pretty good.

1). Head gasket
2) brake booster
3) Stuck open injector flooding the cylinder.

Does the engine oil (or smoke) smell like gasoline or maple syrup?

 

[Seth_O]

1). Head gasket
2) brake booster
3) Stuck open injector flooding the cylinder.

Does the engine oil (or smoke) smell like gasoline or maple syrup?

Smells like really pungent exhaust. A stuck injector sounds very possible. Ill do a leak-down test and see what I get, but Im leaning away from a HG because of the consistent and good compression.

 

[Seth_O]

1). Head gasket
2) brake booster
3) Stuck open injector flooding the cylinder.

Does the engine oil (or smoke) smell like gasoline or maple syrup?

Brake booster? Can you help me understand how a bad booster would lead to this?

I have a steady ~15" vacuum at idle. Im at 1000' elevation, so that seems a little low to me, but not catastrophic.

 

[BILT4ME]

Brake booster? Can you help me understand how a bad booster would lead to this?

I have a steady ~15" vacuum at idle. Im at 1000' elevation, so that seems a little low to me, but not catastrophic.

Brake booster can fail, then suck brake fluid from the plunger of the master cylinder. It's rare, but can happen.

If it's an acrid, burn your throat smell it could be brake fluid.

What type of antifreeze is in it.

That's a lot of white smoke that is almost always HG.

 

[Seth_O]

Brake booster can fail, then suck brake fluid from the plunger of the master cylinder. It's rare, but can happen.

If it's an acrid, burn your throat smell it could be brake fluid.

What type of antifreeze is in it.

That's a lot of white smoke that is almost always HG.

Exhaust is not acrid, smells like exhaust, but really strong. After driving it a bit the billowing white smoke reduced significantly.

Running regular/green glycol antifreeze. After driving around the neighborhood tonight (neighbors loved that i am sure) I finally got a code for a bad O2 sensor on bank 1 and a code for idle RPM's being too high.

 

[BILT4ME]

Exhaust is not acrid, smells like exhaust, but really strong. After driving it a bit the billowing white smoke reduced significantly.

Running regular/green glycol antifreeze. After driving around the neighborhood tonight (neighbors loved that i am sure) I finally got a code for a bad O2 sensor on bank 1 and a code for idle RPM's being too high.

The bad O2 sensor code is a result of the smoke, not a cause.

This is perplexing.....

 

[gnob]

there are only 3 smokes, maybe 4.
white=water
blue=oil
black=fuel

go rent/borrow a coolant pressure checker.

there are other things to leak besides the hg.
could be intake manifold, tb, cracked head or block.

just because you perceive no loss doesn't make it so.

do you have a scanner to monitor data?
also helpful.

 

[Seth_O]

Ran a leak-down test tonight. Im losing 35-40% in every cylinder. No bubbles in the coolant, but i can feel air coming out the TB and out the dipstick tube. The car doesnt warrant an engine rebuild unfortunately.

 

[BILT4ME]

Ran a leak-down test tonight. Im losing 35-40% in every cylinder. No bubbles in the coolant, but i can feel air coming out the TB and out the dipstick tube. The car doesnt warrant an engine rebuild unfortunately.

Run it until it doesn't.....

 

[Seth_O]

I called my local machine shop and they quoted me $450 for a complete head rebuild. That is low enough to make it worth it to do. So i went back to the car and re-did my leak-down test to make certain ($450 is too much to throw at it and have it NOT fix the issue.....)

Im getting 35-40% loss in each cylinder. With the valve cover on the air is coming out the valve cover and the oil dipstick (I mistakenly said the TB previously.) Nothing from the radiator or the exhaust. That tells me its either valves or rings.

I poured a couple of tablespoons of ATF in the cylinders and let it sit overnight. None of the cylinders leaked out, i.e. all of them still had their ATF sitting on top of the pistons in the morning. I think that means my rings are good, and its an issue with either the valves seating or the seals. Since I didn't get any air out of the exhaust or the intake, I think that means its the stem seals.

Here's the question: this whole thing kicked off because it had 2 clogged cats that I had to replace. Could the backpressure from the clogged cats have caused my stem seals to all blow? Other wise it seems like one heck of a coincidence that my stem seals across all 4 cylinders went bad at the same time.

 

[gnob]

air cant get to the stem seal with the valves closed.

 

[aztoyman]

We had an 86 4runner with a 22RE that drove fine 65 miles to town to get groceries. And did what yours is doing when we started it after getting groceries. The difference is I could smell it was coolant.

I limped it about a mile to a friends house and by then the CEL came on and it was surging. Was O2 sensor code.

Pulled the head at my friends house and found a corroded water passage near the exhaust valve finally eroded past the head gasket. All 4 cylinders had the corrosion at that particular water passage. Just the one finally broke through suddenly that day. No evidence of coolant in the oil, was too sudden.

Just something to think about.