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My low vacuum issue from a new perspective - still troubleshooting

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Gremo87

Proven Member
128
2
Mar 14, 2013
Decatur, Illinois
Been working on this issue for a couple weeks now. Car ran great when I bought it, aside from an unstable idle which I was told was a tuning issue. (has Link, and hadn't been tuned well)

*Speed density car*

Couple weeks after buying it, started to notice power loss, slower spooling (22 psi at 4500 rpm), less BOV noise. During a 2nd gear pull, experienced a 'floating' feeling where the RPM's stopped climbing and it felt sort of like losing traction, but like I said the RPM's didn't rise, nor fall - they just stopped and hovered where they were at while I was at WOT. This happened again in 2nd and then again when I shifted into 3rd, and I parked it in the driveway then until I can get it figured out.

Symptoms/Info:

- It has low vacuum at idle, and it's probably been like this since I bought it but the gauge was hooked up somewhere that didn't get vacuum at idle. Move it and gauge now reads about 15 in. HG and MAP sensor reads about 11-12.
I've done several boost leak tests and fixed every tiny leak I've found - none have made a difference. Can get to 30 psi no problem. During a BLT from the TB elbow, the drop from 25 psi to 18 psi takes just under 13 seconds, and from 18 to 11 takes an additional 24 seconds. I've blown cigar smoke into the vacuum system to the point of it coming out of the intake filter, but nowhere else. (aside from into the crank case)

- If I ground the timing pin to check timing, it has idle surge which gets progressively worse the longer the pin is grounded. If I then ground the diagnostic pin too, the car will die unless I first back the BISS screw way out - in which case it will stay running but with a horrendous idle surge. So the car can't stay running without the ECU constantly adjusting timing and air via the ISC, resulting in an idle that should be 850 but instead constantly fluctuates between 740ish and 1050ish.

- Cylinder 2 spark plug is always lighter (whitish) than the others indicating that cylinder 2 is getting more air than the others. (valve issue??) I've checked for vacuum leaks around cylinder 2 and found nothing. This has happened with 2 sets of spark plugs - one with at least a few hundred miles on them and another with less than 30.

- Hard cold starts (takes a while of cranking before it reluctantly comes to life) This has been the case since I bought it.

- Good compression (177, 165, 172.5, 172.5)

- No leakdown test yet (planning to make one very soon)

- I've checked mechanical timing at the cam gears and they're spot on. I didn't tear into everything to check the oil pump sprocket mark though.

- Base timing is at 5* but jumps just past the 1 T mark a lot (with the timing pin grounded)

- Seems to run pretty hot. Gets up to 210 (on gauge, 210-215 in Link) pretty easily after a decent amount of driving, and that's with a Mishimoto radiator, 2 aftermarket fans, ducting between FMIC and radiator, an air dam forcing air up in front of radiator...

- ISC and coolant temp sensor have been tested. ISC is a newer black model and all coils tested at 42.7-43 ohms.

- Turbo has noticeable shaft play in/out, up/down, side/side.


I think that's everything. Just wanted to get everything reframed and put together here. Thank you to everyone who has contributed to this troubleshooting process. Any ideas, I would love to hear them.

Sean

Edit to add: Here's a thread with pictures of spark plugs I pulled out with less than 40 miles on them - probably less than 30, and maybe even 20. http://www.dsmtuners.com/threads/is...gs-pictures-shiny-brown-on-insulators.495647/
 
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I'm sorry but until you know for sure about mechanical timing I think this entire post is a waste of time. There is no close enough. It's 100% right or its 100% wrong. Did you at least maybe look at the mark on the harmonic balancer?
 
Check your coolant temp sensor and like everyone keeps saying check your mechanical timing the right way.
 
Yeah pauleyman I did use the mark on the harmonic balancer. That's the point that I checked the cam gears at. I lined the balancer mark up with the mark on the lower cover, making sure piston 1 was at TDC on compression stroke, and checked cam gear marks with a ruler.

Coolant temp sensor tests good.
 
Good, the harmonic dampener has a history of shifting which is why we suggest verifying the position with finding TDC.

Did I miss the DSMLink log? In addition to logging it wilt it's running at operating temp I'd like to see what the sensors are reporting when the engine is stopped and when you start it.
I've seen a few ECUs in the past that had noise problem with the ADC.
 
Nope you didn't miss it Steve; I'll have it up this evening. So grateful for all you guys taking time out of your day to help people like me. Looking forward to your thoughts on the log.
 
Ok here are 3 logs. But first - I'm having an issue with A/F Ratio (WB) staying in displayed values. It's set by default to be displayed, but it does not stay there whenever I start a new log or when I open up a log in which it was previously displayed while creating the log.

I get this error message in the Device Status log: LOG MSG: Failed to parse DisplayChain 'conv.sys.lambda(conv.sys.reallambda(conv.sys.aemanaloggauge(rawfro2voltsinput/RawAEMAnalogWB/A/F Ratiooo/data.sys.aemanalogwbgauge)))'

If you just go to displayed values when viewing the log you should be able to make it display by double clicking it as if you were adding it to the list like usual. On mine it's called A/F Ratiooo.

Edit to add:
Just noticed I have a DTC - 0021 Engine Coolant Temperature Circuit Malfunction...?? I checked the coolant temp sensor when this issue started, a couple weeks ago. Guess I'll check it again and see what else that could be referring to....

Log 1 (Idle.From.Cold) is just that - a log from cold startup. About 700 seconds in, I began making small adjustments to bring CombinedFT more centered around 0 and ISC Pos more centered around 30. I'd just done that yesterday, but they were both higher for some reason today....
I threw in a few rev's at the end of the log in case that's useful.
Ps. I didn't used to have idle surge on cold startup, but it started within the last few days and I haven't even been driving the car. Maybe has something to do with resetting Link? I don't remember it happening right when I reset it, but...I'm not sure.

Log 2 (Shutdown) is of when I turned the engine off after completing Log 1.

Log 3 (Warm.Startup) is of turning the car back on and letting it idle for a bit.


If there's anything else I can log that would be helpful just let me know
 

Attachments

  • Log.1.Idle.From.Cold.2015.07.31.elg
    410.7 KB · Views: 43
  • Log.2.Shutdown.2015.07.31.elg
    10.1 KB · Views: 40
  • Log.3.Warm.Startup.2015.07.31.elg
    29.2 KB · Views: 31
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Hmmm the downloads are working for me, anyone else?

Is there a certain way I need to upload them? I just used the 'Upload a File' button. Is there another way?

Also - just added this to my post with the logs, but in case you don't see it:

Edit to add: Just noticed I have a DTC - 0021 Engine Coolant Temperature Circuit Malfunction...?? I checked the coolant temp sensor when this issue started, a couple weeks ago. Guess I'll check it again and see what else that could be referring to....
 
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The wires going to the CTS were brittle and broken open in one tiny spot each. I fixed that. Made no difference.

I checked voltage at one wire - 22mV
Checked voltage at other wire - 4.79V

Checked resistance between the two prongs with engine at operating temp (198ish according to gauge, though Link always shows a bit higher than the gauge so maybe 203) - it was 208 ohms and when rechecking it a few times after that, it was climbing up and hit 220 ohms a minute or so after the 208 reading.

So....that's pretty close to the values stated here: http://www.dsmtuners.com/threads/how-to-diagnose-a-no-start.217951/
(which are 280-350 ohms at operating temp)

And in the service manual it states that at 176F it should be 296 ohms, and the hotter the temp the lower the value is, so....I'm not seeing anything indicating a bad sensor here.

??
 
That code appeared and was cleared once already a week or so ago.

Injectors are FIC 1100's and fuel is E85. I calculated global using a formula in the ecmtuning wiki and then adjusted global to get CombinedFT around 0. (as instructed in the 'How to tune a 1g v3 sd ecm link with no maf' pdf.
 
So far I've only had time to look at the first log and don't see any classic idle surging. The ECU never cuts off the fuel when it reaches the decel cutoff but I do see the idle drifting from the interaction of the timing advance and ISC.

These are high impedance injectors, right? Is the injector resistor removed and the connector bypassed to power them directly?

It was running well before and it just started acting up?
 
Well, the idle was about the same when I bought it. (maybe a month ago) It now goes up and down for a while until it warms up a bit which it didn't do when I got it, but other than that, idle is the same. You're right though it's not the typical repetitive surging. However - it DOES do that when the timing pin, or the timing and the diagnostic pins, are grounded. Doesn't do it if only the diagnostic pin is grounded.

It spooled a little slower than it should when I got it (maybe due to worn turbo) but then it started spooling even slower along with the very noticeable power loss...and much quieter turbo and bov sound - though it still reaches 22+ psi and holds it.

I was trying to remember exactly when I started to notice the power loss and such - and I think it was one day when I'd set Link to notify by CEL of 1 degree of knock, and then I did a pull in 2nd and maybe around 4k or a lil above, the CEL came on and it stuttered and bucked until I let off the throttle. It had never done anything like that, and I can't be sure but I think things went downhill from there. It's now very noticeably slower and had that weird floating issue the last couple times I went WOT.

It's likely that it's had low vacuum all along though. When I got it the boost gauge was hooked up to a source that didn't see vacuum at idle - just while driving. Once I changed that I noticed the low vacuum.

The base timing thing could have been there all along too, for all I know. Didn't check it till I started having issues.

As for the injectors, I'll check the paperwork I have from FIC given to me by the PO and find out what the resistor is and check that out.

Edit to add: It seems to me that all of these issues are connected and the seller got rid of the car before things really started going downhill - which I'm now getting to experience. Could be wrong though.
 
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Injector resistor is removed.

I'm tempted to take the TB off and rule out the FIAV, but if the FIAV was malfunctioning, could that even cause base timing to be so unsteady and have such a wide range? Looks to be about a 7-8 degree range.

What kinds of things can cause that? I know very little about all this but I would think base timing would stay the same even with a vacuum leak from the FIAV. Ignition parts? (something I've never delved in to...) ECU?
I could be wrong, but I think I may have unplugged the ECU once without disconnecting the battery first (and plugged it back in, if so)....that could be bad right? I didn't see any visible signs of damage on the board when I took it out last time but I've read they can be very small...
 
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Just noticed that when I ground the diagnostic pin, Link still shows the ISC making adjustments as usual. But it definitely does something, because if the timing pin is already grounded, the car dies when I ground the diagnostic pin unless I back the BISS way out, away from ISC pos 30.

But if I only ground the diagnostic pin, nothing seems to change at all.


And, I just remembered something really stupid I did one day. I'd topped off the coolant and forgot to put the cap back on...drove it...and it got up to 250*F (gauge max) really fast, before I noticed. I pulled over and shut the car off and there was steam billowing out from under the hood. (couldn't tell while driving) And there was coolant all over the engine bay. What sensors would be vulnerable to something like that? I've read that the CAS is....and am now wondering if that could be part of my issue.

I know...terrible mistake, and even worse to let it get to 250+ degrees. :/
 
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Have you checked the valve timing lately?

I'm sorry but until you know for sure about mechanical timing I think this entire post is a waste of time. There is no close enough. It's 100% right or its 100% wrong. Did you at least maybe look at the mark on the harmonic balancer?

Alright guys, mechanical timing is dead on. Marks on crank and oil pump sprockets and cam gears all line up perfectly.

But I have new information. First off you may want to see what my spark plugs looked like last time I pulled them: http://www.dsmtuners.com/threads/is...gs-pictures-shiny-brown-on-insulators.495647/
I assumed that was caused by oil, but luv2rallye and a couple other people didn't think so. But I've now confirmed excessive oil in the combustion chamber - explanation below.

I don't think the car has been driven since those pictures were taken - if it has, it's less than 10 miles. It has been ran at idle a decent amount since then though, while I investigated for vacuum leaks, messed with the BISS, Link, etc. Well today I pulled the lower timing cover and checked the timing. I used an extension in #1 spark plug hole to watch the piston's travel. I lined up the marks once, and then to be absolutely sure, I cranked it over 6 rotations at least 2 more times, checking with a ruler each time - with the extension in the plug hole the whole time. When I took it out, it had a bunch of oil on the end that was touching the piston. I used a flashlight to see the top of the piston, and there was a lot of dark buildup and wet oil. The plug itself was a lot dirtier and darker than the last time I had it out, too.

This led me to remove the other plugs. #2, which was totally white before, now has some color on it, and 3 and 4 are both worse as well. Piston #2 is the only one that is clean enough to read the part number on top of the piston. No major buildup at all really, just dark coloring. The others all have buildup and #1 and #4 are the worst, both with a very noticeable amount of oil.

Pictures of plugs:

Spark Plug #1

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Spark Plug #2

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Spark Plug #3

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Spark Plug #4

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All together (4, 3, 2, 1):

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So that seems like a pretty solid confirmation of excessive oil in the combustion chamber, right?

Compression numbers were:

Cylinder 1: 172.5
2: 165
3: 172.5
4: 177

I'd thought that meant something was wrong with #2, but now I see that #2 was in better shape than the others and the higher numbers were due to inadvertently doing a wet test because oil ends up on the pistons just from cranking the engine over.

Is there any specific thing that would result in oil on top of the pistons just from cranking it over? Is it more likely something in the head than the rings?
 
Ok so the front of the engine's still apart from checking timing so I just did a leakdown test on cylinder 1 cold. Is that helpful at all? Or does it absolutely have to be warm? I only did cylinder 1 because it's the worst of the 4 (going off of the spark plugs) and it's rainy outside - I can always put it all back together and do it warm on each cylinder.

Regardless, there was no noticeable leakage (using stethoscope) from the intake or exhaust, no bubbles in thermostat housing, but a lot of air coming from the valve cover and the dipstick tube. Enough to feel it coming out of the oil fill with my hand, and it was very audible both from there and the dipstick tube.

Is that conclusive enough or is a lot of air leaking past the rings when cold normal? I know some will, but I'm not experienced enough to know whether this is conclusive or not. Could be far from it, I know.
 
Nope I was just getting back with that - I started with 95psi. When I hooked it up it went to 77psi and then slowly dropped to 60 - at that point my compressor turned on again because it'd dropped down to 75 psi, and the tester rose up to 61 and hung there while it ran. The compressor could only maintain 75psi at the compressor gauge, and I'm wondering if it had more reserve capacity if the tester would have kept going higher (it's a 2 gallon)...either way:

From 95 to 77 is about 19% loss.
From 95 to 61 is 35.8% loss.

Edit to add: In case I hadn't mentioned it here I was told the engine was rebuilt less than 3000 miles ago. New pistons. (confirmed with flashlight through spark plug hole - Probe Industries 14481 - 0.50 - 0.020" overbore)

Also just learned that the standard length for a tester's 1mm orifice is 1/4" and mine is at least 1/2" long...

And seeing quite a few people on forums saying that cold tests are fine and that good engines should still have less than 5-10% leakage cold...
 
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New numbers for all 4 cylinders:

#1
Began with 95psi at tester, dropped to 79 when connected, then slowly crept down to 65 and hung there, then down to 60. I think the creeping down after the initial reading is just because my compressor is so small and can't hold the charge needed to keep it at 84...that sound right?
17% initial loss

#2 (driest cylinder)
95 to 50. Then crept down to 44 and hung there, then down to 38 and stayed there.
47% initial loss

#3
95 to 84. Then crept down to 66, and up to 67 as my compressor kicked back on and stayed there.
12% initial loss

#4
95 to 82. Then crept down to 65, and up to 66 a compressor kicked back on and stayed there.
14% initial loss


Just a reminder that the 3 cylinders with less leakage all have visible oil on top of the pistons so those numbers are probably closer to being wet test results than dry. #2 has a little bit, but just a small area. The top surfaces of the other pistons are fully wet.

But I've never seen any smoke out of it....
 
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So if it's blowing out of the oil fill hole and dipstick tube, that's got to be rings right? That's the only cause I can find in my reading. I just don't understand how they would fail so soon after a rebuild...
 
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