Windstar Swap Now Burnt Valve and Other Issues?

ScarletStang

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Aug 16, 2019
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Hi folks, so I did a windstar swap on my '00 'Stang and now I'm experiencing issues. When the car is up to temp it has a rough idle and an intermittent popping sound(like decel burble) from the exhaust. I noticed it started sucking from the exhaust pipe like a burnt or stuck valve. I did the paper towel trick where you hold out a paper towel to the exhaust tip and it'll suck it in on certain exhaust pulses. It only does this when it's warm, not cold and wasn't present before the windstar swap. (Next is not as important as the aforementioned)The iac isn't working right either. On a cold start it'll fire up like it's warm, jumps to ~1300rpm and drops immediately to idle. When the ac compressor kicks in, the car almost dies, and in between shifts the rpms drop like a rock. I used 3/8in inside diameter hose to relocate it. Is that not big enough?
Please help, and thank you if actually read all this,
-Wesley "The Scarlet 'Stang"
633437
 
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Since you're asking Windstar Engine questions, I'd tend to think the Windstar forum (if there's such a thing) would know more about that motor than we would on Stangnet. :shrug:

We don't deal with too many (any) Windstar motor swaps (until now) that I'm aware of. :scratch:

I wonder how they are supercharged :shrug:
 
Since you're asking Windstar Engine questions, I'd tend to think the Windstar forum (if there's such a thing) would know more about that motor than we would on Stangnet. :shrug:

We don't deal with too many (any) Windstar motor swaps (until now) that I'm aware of. :scratch:

I wonder how they are supercharged :shrug:

Well technically it is a windstar engine, since it's the same 3.8 as the mustangs, but no. It's the stock mustang engine with the windstar upper intake. The windstars had 200hp and the mustangs has 190hp, only difference is the upper intake.
 
Question: Do you have an Air/Fuel ratio meter installed?

Can and have you pulled codes? You got any for a lean condition?

Nope, I don't have any air to fuel ratio meters. Just the stock oxygen sensors. No codes or mil either, I've driven it nearly 300 miles since the swap, and about 250ish since the new tune for the intake.
 
Well technically it is a windstar engine, since it's the same 3.8 as the mustangs, but no. It's the stock mustang engine with the windstar upper intake. The windstars had 200hp and the mustangs has 190hp, only difference is the upper intake.


Ahhh... I see.

Was this intake installed without a tune or any reference to the Air Fuel Ratio?

Did anything else change besides the intake such as... The throttle body or mass air meter?

Pretty sure you're running lean.
 
Ahhh... I see.

Was this intake installed without a tune or any reference to the Air Fuel Ratio?

Did anything else change besides the intake such as... The throttle body or mass air meter?

Pretty sure you're running lean.

Well yes, it was installed without a tune, but as soon as I finished I sent off for a revision for the intake. I only drove about 50 miles without a tune, it took them 4 days to get back. The only other thing to change is the throttle body, a 65mm throttle body from a 4.6
 
I only drove about 50 miles without a tune


You have to understand that it doesn't take even this long to kill a motor if it's running lean.


I'm pretty certain you know what needs to be done next: Compression and leak-down test. No point in going forward if the motor is sucking and farting unmetered air.
 
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You have to understand that it doesn't take even this long to kill a motor if it's running lean.


I'm pretty certain you know what needs to be done next: Compression and leak-down test. No point in going forward if the motor is sucking and farting unmetered air.

Thank you for your replies. Actually I did do a compression check today. The results were all within 8psi of each other, 192-200psi across the board. I don't have the proper tools to do a leak down test, but as much it sucks through the exhaust (it'll pull my palm against the exhaust tip if I put it close), you would think a "burnt valve" of that nature would be present in just a compression test?

Tons of the windstar intake swap write ups on the forums say a tune isn't necessary for the swap, since the maf meters the extra air and compensates for it. I figured it'd be fine. Is there anyway to tell if it's running lean on these cars, short of an air/fuel meter?
 

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A valve that is burnt will leak. You should be able find that on your compression test. You could also pull the heads.

Anything beyond that, you would need somebody better acquainted with that engine.
 
A valve that is burnt will leak. You should be able find that on your compression test. You could also pull the heads.

Anything beyond that, you would need somebody better acquainted with that engine.

It should show on a compression test, a cylinder with a burnt valve isn't gonna have nearly 200psi of compression. But I'm not pulling the heads until I'm 100% sure that's what it is. What confuses me is a burnt valve doesn't come and go, it doesn't suck back through the exhaust when it's cold, and I recently discovered it doesn't do it when the ac is on and it actually idles right not trying to die.

It is a v6 mustang, I figured there'd be someone with some insight here on the 3.8
 
but as much it sucks through the exhaust (it'll pull my palm against the exhaust tip if I put it close), you would think a "burnt valve" of that nature would be present in just a compression test?
There are other things that could cause this symptom besides a burnt valve. After a new engine build I would also consider the possibility of incorrect cam and crank timing. If the timing is off by a mark or two this could create a situation where the exhaust value is open during part of an intake stroke. Further it's likely the compression test would be normal.

Should I also assume that the intake manifold runners (IMRC) have been deleted or held fully open?

A note regarding idle and how the IAC works. The Mustang maintains two IAC idle trim settings. AC on and AC off. The PCM needs time to learn new idle trim settings in each operating mode. If the AC is short cycling then the PCM will be unable to learn. In the same vein, one can't expect the motor to idle correctly unless the IAC is actually working.

I also have to agree that the compression numbers actually seem high. Is it possible there is carbon build up inside the combustion chamber?

Do you have an ODB2 scanner? If you did look at the long term fuel trims (LTFT) as this would give an indication IF the motor is running lean or not. An ODB2 scanner might also provide other information that might make short work of your problem.

ForScan ODB2 scanner w ELM327 USB

Troubleshoot IAC idle problems 1996-2004
 
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There are other things that could cause this symptom besides a burnt valve. After a new engine build I would also consider the possibility of incorrect cam and crank timing. If the timing is off by a mark or two this could create a situation where the exhaust value is open during part of an intake stroke. Further it's likely the compression test would be normal.
That's something I would defiantly consider if I had actually opened up the engine. I've never had the timing cover off of this car.
Should I also assume that the intake manifold runners (IMRC) have been deleted or held fully open?
Well no, this car is a 2000 and is not equipped with IMRCs.
I also have to agree that the compression numbers actually seem high. Is it possible there is carbon build up inside the combustion chamber?
Then you'll think they're extremely high when I tell you the mileage on the car 270k(original engine). Sure, there could be some carbon build up, but before the windstar upper intake swap, it idled just fine. And it cruises perfectly, plenty of low end torque at 2k rpms going 65-75mph. I average about 30mpg on the highway.
Do you have an ODB2 scanner? If you did look at the long term fuel trims (LTFT) as this would give an indication IF the motor is running lean or not. An ODB2 scanner might also provide other information that might make short work of your problem.
Yes I do, also my bama tuner. What is good range in the fuel trim for these cars? Thank you.
 
I looked at the fuel trims today, and bank 1 keeps pulling fuel at idle. LTFT1 is around -20 to -25; STFT1 is around -5 to -10. While cruising the LTFT & STFT fluctuate around 0 +/- 5. Now bank 2 was fattening up real good after cold start, STFT2 was around 25 but LTFT2 was at 0. After it warmed up, was still rich. About 5ish STFT & LTFT. While cruising STFT would fluctuate the most from -5 to +10; but stayed on the rich side most of the time. LTFT2 cruising stayed around 0 +/- 2.