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Discussion Starter #1 (Edited)
Hey everyone and especially BaliDawg :hi:

so to make a long story short I think I have a leaking VCG or the cover itself but it's worse on hot days when the engine is XhotX heat soaked.

My LTFTs vary between 0.8 and 9.4 % according to OBDFusion. On a cold start the STFT's go way negative and draw down the LT's to the 4% range. But once the day goes on and the engine is warm both the LT and ST's go up to total more than 20%! :banghead:

Based on that data, yesterday I took off the engine covers, idled the motor and sprayed starting fluid all around. I could not detect any rpm increase anywhere I sprayed. This was after a long in town run so the motor was fully hot. I was worried that the starting fluid might ignite!

However, I did notice the STFT's go more negative when I sprayed the area between the fuel rail and the valve cover. I paid particular attention to the oil filler cap and each fuel injector spraying them individually. There was no change.

Only when I sprayed all along the "V" between the rail and the valve cover did the trims go more negative suggesting that starting fluid was being sucked in (right?).

I realize that this doesn't definitively rule out the injector o-rings, the intake manifold gaskets, nor a warped valve cover. But I'm not sure how to rule them out completely.


I recently took a road trip to cool LA and the LTFTs went as low as 0.8! However, when I returned to the heat of las vegas the trims went back up.

The VCG was replaced by me at 161k miles January of 2016. Car has 193k miles. Used a Victor Reinz gasket set and it is not leaking oil.

Should I just install a new VCG and pray that's the problem? :hi:


Things I have replaced in the last 30k miles:

MAF
VCG
SAP hose
Intake manifold caps
Dip stick
Dip stick tube o ring
Disa
CCV and hoses
Intake boots
Fuel pump
Fuel filter
Probably a few more items that I can't think of right now.

Edit: new air distribution manifold o-rings
Black and white check valve behind manifold
 

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Discussion Starter #2 (Edited)

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Have you performed a smoke test or just the starter fluid? I was going to suggest injector o-rings but if you checked them all as well as the fill cap then I'm not sure what else in that area could be leaking vacuum other than the VCG.

I can't imagine ambient temperatures would make much of a difference, the engine is still getting up to operating temperature regardless of the environment. What are you reading for intake air temperatures?

EDIT: Your first log shows IAT temperatures of 81 C (176 F)... this seems high, no?
 

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Discussion Starter #4
Have you performed a smoke test or just the starter fluid? I was going to suggest injector o-rings but if you checked them all as well as the fill cap then I'm not sure what else in that area could be leaking vacuum other than the VCG.

I can't imagine ambient temperatures would make much of a difference, the engine is still getting up to operating temperature regardless of the environment. What are you reading for intake air temperatures?

EDIT: Your first log shows IAT temperatures of 81 C (176 F)... this seems high, no?
That log was the second run of the day. So the engine had warmed up some but wasn't fully hot yet.

I did a cigar diy smoke test but I wasn't able to detect any leaks.

I haven't replaced the gas tank cap yet and mine definitely has some cracks. Would that cause fuel trims to go up?
 

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Discussion Starter #6

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2004 330Ci 85k miles
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"Hi" back at ya! :hi:

I suspect the smoke test was maybe not as thorough as needed. There are some tricks to doing it well:
- start with a fully cold engine, some leaks go away with heat expansion of parts
- put the front end up on jack stands so you can get under it while looking for smoke
- remove all engine covers (top and bottom), air box, and anything else blocking good visibility all around the intake manifold (power steering reservoir, cabin microfilter tray, etc.)
- use a mechanics mirror and bright light to search for smoke
- open the oil filler cap while you pump lots of thick smoke into the intake until smoke is coming out the oil filler cap then replace it, that ensures smoke has filled the crankcase, then keep pumping while you search for smoke leaks

There are probably tips and tricks others know, so hopefully they chime in.

Edit: wrote up this smoke test thread with the above tips and more.
https://forum.e46fanatics.com/showthread.php?t=1261077
 

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Discussion Starter #8 (Edited)
Quick Update after ~50 in-town miles:

LTFTs are holding at 4.7 and 5.5. This is after I re-tightened the Valve cover bolts to 89 in lbs.

I haven’t taken it for a long drive to heat soak the engine.

STFTs still go negative at idle until the engine warms up. Then they start to creep up.

New gas cap is on its way. (Edit: I realize that won’t affect fuel trims. But I have been having gas fumes when I fill up the tank).

I will check the brake booster per Archbid’s method probably this Sunday.

Thanks for reading!


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Discussion Starter #9 (Edited)
https://www.dropbox.com/s/y4g9hovezv4vh7f/CSVLog_20190726_204829.csv?dl=0

This log says it all.

ST Trims start out slightly positive.

I pull the brake booster hose and plug it with my thumb. ST Trims go negative. All the way to -6.3.

Then I plug the hose back in and they go back to 0 or a little above.

Anyone have a link to a good diy for replacing the brake booster?


Thanks especially to Archbid for reminding me to do this simple check.

Edit: found the 50sKid video.


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Brake booster is definitely affected by temperature.

It is a bitch to replace, but be patient. Remove everything around it that you can.
 

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Discussion Starter #11 (Edited)
Brake booster is definitely affected by temperature.



It is a bitch to replace, but be patient. Remove everything around it that you can.


Do you recommend replacing the master cylinder as well? I have changed the fluid several times usually every 2-3 years. The last few times I have used the Motiv pressure bleeder to do it.

Or no need? Thanks.

Edit: would it be ok to re-use the fluid reservoir and cap?
 

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Do you recommend replacing the master cylinder as well? I have changed the fluid several times usually every 2-3 years. The last few times I have used the Motiv pressure bleeder to do it.

Or no need? Thanks.

Edit: would it be ok to re-use the fluid reservoir and cap?
You can reuse the fluid reservoir and cap. I only suggest replacing the mc if you have play in the pedal with the car off. Replacing mine made a big difference in pedal feel
 

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Discussion Starter #13
You can reuse the fluid reservoir and cap. I only suggest replacing the mc if you have play in the pedal with the car off. Replacing mine made a big difference in pedal feel


Yes there’s play in the pedal. Maybe an inch or so with ignition off. Even once I have pressed it a few times and the residual vacuum is gone.

I have ordered a new MC and booster from
FCP.

Trims today started off as low as 3.9 and intake air temp at 45. But after about 30 minutes of driving and IAT at 60+ the LT trims were at 6.3 and STs were more than 10.
 

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Discussion Starter #14
New gas cap. Trims down to 1.6 LT.

After 10 miles or so they crept up to 3.9 LT. Gas cap seems to have made a difference. But it was cooler today (<100) since it rained.

STFTs usually negative or slightly positive. The brake booster may have a vacuum leak. I’ll check it when the temps warm up again.

For now:

https://www.dropbox.com/s/w57m4y9y66wwg54/CSVLog_20190731_232359.csv?dl=0




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Discussion Starter #15
After 100+ temps and 42 miles with the new gas cap LT trims are back up to 7.0%.

So it’s definitely heat related. New brake booster still on the boat from NJ.


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Discussion Starter #16 (Edited)
WTH?

I live in Las Vegas. The shipment was in town on Saturday then went to Rialto, CA??? I’m taking crazy pills.

Sunday , 8/04/2019
1:47 am
RIALTO, CA
In transit

Saturday , 8/03/2019
10:00 am
LAS VEGAS, NV
In transit

Friday , 8/02/2019
10:59 pm
EAGLE, CO
In transit

11:52 am
MINDEN, IA
In transit

12:50 am
CLYDE, OH
In transit

Thursday , 8/01/2019
12:42 pm
MIDDLETOWN, CT
Departed FedEx location
5:11 am
MIDDLETOWN, CT
Arrived at FedEx location
Wednesday , 7/31/2019
11:50 pm
STRATFORD, CT
Left FedEx origin facility
10:18 pm
STRATFORD, CT
Arrived at FedEx location
7:25 pm
STRATFORD, CT
Picked up


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WTH?

I live in Las Vegas. The shipment was in town on Saturday then went to Rialto, CA??? I***8217;m taking crazy pills.

Sunday , 8/04/2019
1:47 am
RIALTO, CA
In transit

Saturday , 8/03/2019
10:00 am
LAS VEGAS, NV
In transit

Friday , 8/02/2019
10:59 pm
EAGLE, CO
In transit

11:52 am
MINDEN, IA
In transit

12:50 am
CLYDE, OH
In transit

Thursday , 8/01/2019
12:42 pm
MIDDLETOWN, CT
Departed FedEx location
5:11 am
MIDDLETOWN, CT
Arrived at FedEx location
Wednesday , 7/31/2019
11:50 pm
STRATFORD, CT
Left FedEx origin facility
10:18 pm
STRATFORD, CT
Arrived at FedEx location
7:25 pm
STRATFORD, CT
Picked up
What the ever-loving hell is going on with that package?
Is Rialto the new Vega$??? Uh.....nope!
 

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What the ever-loving hell is going on with that package?
Is Rialto the new Vega$??? Uh.....nope!
Some forgot to take it off the truck maybe in Vegas? FedEx apparently has their own way of doing things.

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Discussion Starter #19 (Edited)
Package arrived on schedule the second time it came through las Vegas! Lol.

Anyway, now that I’ve been reading about ethanol causing high LTFTs I’m not in such a hurry to replace it.

I’m going to try a tank or two of non-ethanol gas and see if there’s a difference before I R&R the booster/MC.

I will keep you updated.

Edit: I’ll wait for cooler temps before I replace them.




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Discussion Starter #20
Quick update:

I have put in 2 half tanks of ethanol free gas.

The highest LTFTs I have seen are 4.7 on either bank.

Last night while driving I was at 0.8 left and 3.1 right banks. I’m still on the second half tank so there’s still a little ethanol in there.

But so far the ethanol free seems to be working to lower the LT fuel trims.




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