horrible mpg and weird idle drop

[Gerbil21]

And here is the cpas before

 

[Gerbil21]

And the cpas after

 

[IllogicTC]

Your CPAS looks much happier. Carbon buildup on the pistons, but doesn't look mega-thick, but is present. Intake valve seal looks like it may be leaking. And a good example of how you can tell something used lost-foam casting - the intake area looks like metal styrofoam

 

[Gerbil21]

Your CPAS looks much happier. Carbon buildup on the pistons, but doesn't look mega-thick, but is present. Intake valve seal looks like it may be leaking. And a good example of how you can tell something used lost-foam casting - the intake area looks like metal styrofoam

lol yea it does look happy also yea its definitely not as much carbon as i had thought

i don't think its leaking since the whole intake it full of oil from the pcv

 

[gmcman]

So what kind of vacuum do you have from the large port on top of valve cover?

The intake valves surely have some crud on them, intake tract looks good but looks like some oil is concentrated at base of guides and could be from excess vacuum..or worn....Likely the reason your valves have buildup.

I'm curious how much crankcase vacuum is making it to the resonator.

I'm also curious of the previous owners oil change interval and what they used.

 

[Gerbil21]

So what kind of vacuum do you have from the large port on top of valve cover?

The intake valves surely have some crud on them, intake tract looks good but looks like some oil is concentrated at base of guides and could be from excess vacuum..or worn....Likely the reason your valves have buildup.

I'm curious how much crankcase vacuum is making it to the resonator.

I'm also curious of the previous owners oil change interval and what they used.

I actually never got the vacuum gauge, so many things have been happening and the mpg problem was put on hold unto the end of the 44k tank. I never did get to fully finish the tank since I had to take a trip upstate for family but this was a good opportunity to check mpg.

So I reset mpg and fuel used and got 18mpg before I left the city and it stood that way for a wile it then started to drop towards the high 17's going around 65mph but all uphill. The mpg stood there for the most part and went towards 17.4 -17.6mpg at a constant 75mph still going uphill after turning on ac at 75 and still going uphill it evened around 16.5

But during the drive I got P0014 again but I know why. I forgot to post yesterday but the halves of the cpas are able to move different ways so a replacement is definitely needed.

Just wondering but how do the valves look bad? Im thinking all that oil is from the pcv since its not sucking its putting it all through the intake.

idk about there oci but it looked like they used some type of additive, when we changed the oil it had a shiny color to it and was browner than dark also there was like a film on top of the oil. And the filter looked kinda old so idk but I will get a good idea when I change this current oil with 1k on it at 70% oil life but I want to use the foaming cleaner first.

One other thing is gm Tec in the can a foaming spray like the mopar? And since I could not siphon some gas for the uec spray I figured I will make a pressurized fuel injector cleaner and hook it up to the fuel rail, that is how the uec is supposed to be used and I don't have a good spray bottle but it would be a great tool to have either way.

 

[gmcman]

Getting 17 uphill, a/c on at 75 is very respectable. You can see 20/22 on a flat road at 60 if all is working correctly.

 

[gmcman]

Since you possibly have a gunked up oil system your cam phaser could have some build up and after it has been advanced, maybe it cannot fully return to it's proper position.

Just a hunch but I know some people have had good luck with KW Engine flush, available from Grainger which is where I purchased mine.

The crap shoot is how much if any crud do you have in there and could it be dislodged and clog the pickup screen.


What I would try first is to substitute 1 qtr of Marvel Mystery Oil and drive it for about 1K miles. Do this before any heavy cleaners.

 

[IllogicTC]

A P0014 should show if the cam phaser does not meet the desired position.

 

[gmcman]

A P0014 should show if the cam phaser does not meet the desired position.

That's what I'm thinking....the very tight tolerances inside the phaser could be affected if there was serious neglect with oil changes. Based on other symptoms it's a good bet.

 

[FrankR12]

So Gerbil, You go from 8-9 mpg to 17-18 mpg? That's pretty dam good....what way did you go when you left Queens.... the Taconic or the Thruway? Sounds like you were headed my way.....Catskills?

 

[Gerbil21]

So Gerbil, You go from 8-9 mpg to 17-18 mpg? That's pretty dam good....what way did you go when you left Queens.... the Taconic or the Thruway? Sounds like you were headed my way.....Catskills?

Well that's my split between city and highway mpg. I went through the thruway up to Albany

Also forgot to add I was at 9 to 9.3mpg city so it looks like the 44k helped and getting 18mpg was better than the 12mpg I got (on the way back) when I first got the car and went to jersey

 

[Sparky]

Definitely much better. Good progress for sure.

 

[Gerbil21]

Ok so I'm going to be leaving home soon and I was going to log as much as I can and reset mpg is there anything specific I should record.

This is how it would come out


I can record just about anything a tech ii can
(I think idk what they can see, I can see injector pw, and fuel trim cell,shift times)

 

[gmcman]

What gadget do you have for data logging, sounds intriguing.

I think the fuel trims and map values are important, you can somewhat get a ballpark idea using INST MPG on your DIC when cruising flat and at a constant speed, slight hills etc. Generally they will drop under load then climb back up 1 or 2 MPG as the O2 sensor leans things out.


Since you mentioned it, uniform pulse width on the injectors is something to check. Ignition timing should be and this is a guess, above 25 to 30 at steady cruise at hwy speeds...just something to note. How much advance you get under a moderate load from 30 to 60 mph...should drop to around 10 to 15ish but if you are seeing very low advance numbers like low single digits that could be a carbon issue.

Granted timing is affected in many ways and I don't know all the variables but basing this on what I see with my scan tool.

I'm curious as to whatever you log...very cool.

 

[IllogicTC]

Ignition timing seems mainly affected by current engine speed, possibly the gear ratio selected, and the commanded throttle. It may also be affected by whether the engine is in open or closed loop.

The big primary factor is current engine speed, with the expectation of rising or falling RPMs right behind it (load, I believe actually is what it's using). The idea is to have the force from combustion hit the piston at some precise point, and variable timing makes sure the ideal meeting point of combustion and piston occurs. Not too soon, where engine damage can occur, and not too late, where a lot of that expanding gas is wasted.

 

[gmcman]

I guess what I'm looking at is the fact he has a lot of buildup and once everything is warmed up and at a cruise, a steady pull from 30 ish to around 60 may show some odd numbers. I agree about all the variables, would be tough to see anything conclusive but hopefully something may stand out.

But, looks like he's getting much better numbers so I want to bet that carbon knock will be minimal.

 

[KNBlazer]

Not sure if this has been suggested, but do you have a Chevron in your area? It will probably help you out with all that crap that's left....

 

[IllogicTC]

Not sure if this has been suggested, but do you have a Chevron in your area? It will probably help you out with all that crap that's left....

Chevron has that nice Techron mixed right in, but if not you can buy Techron at most auto parts stores. Follow the instructions on the bottle. Texaco also mixes Techron in at the pump.

I would say any Top-Tier-Rated gas station would be a good choice for regular use.
Here's a list directly from toptiergas.com:

In the US: 76 Stations, Aloha Petroleum, ARCO, BP, Chevron, Conoco, Costco Wholesale, CountryMark, Entec Stations, Express Convenience Centers, Exxon, Hawaii Fueling Network, Holiday Stationstores, Kwik Trip / Kwik Star, MFA Oil Co., Mobil, Ohana Fuels, Phillips 66, Quik Trip, Road Ranger, Scheirl Oil, Shell, SuperAmerica, Texaco, Tri-Par Oil Co.

Canada: Chevron Canada, CO-OP, Esso, Petro-Canada, Shell Canada, Tempo

Puerto Rico: Puma Energy Caribe, LLC, Shell

 

[Gerbil21]

Not sure if this has been suggested, but do you have a Chevron in your area? It will probably help you out with all that crap that's left....

nope as far as i know there are none at all around me the best i got is sunoco

What gadget do you have for data logging, sounds intriguing.

I think the fuel trims and map values are important, you can somewhat get a ballpark idea using INST MPG on your DIC when cruising flat and at a constant speed, slight hills etc. Generally they will drop under load then climb back up 1 or 2 MPG as the O2 sensor leans things out.


Since you mentioned it, uniform pulse width on the injectors is something to check. Ignition timing should be and this is a guess, above 25 to 30 at steady cruise at hwy speeds...just something to note. How much advance you get under a moderate load from 30 to 60 mph...should drop to around 10 to 15ish but if you are seeing very low advance numbers like low single digits that could be a carbon issue.

Granted timing is affected in many ways and I don't know all the variables but basing this on what I see with my scan tool.

I'm curious as to whatever you log...very cool.

i use Car Gauge Pro its for Android and cost $6 but is worth much more i love this app. ive used it for everything even bi-directional commands on a ford it dosent seem to work on my envoy but idk may the 06 with the different pcm might work with it.

instant mpg ended in 04 idk why but i don't got it

my phone had turned off and the log didn't get saved but i do have another log from today after the highway. i definitely have to log some more again tommorow

https://www.dropbox.com/s/12mzx8ecqz9bwce/Powertrain%202014_09_14%2017_57_12.xls?dl=0

https://www.dropbox.com/s/6qy6ycm63zf2195/Powertrain%202014_09_14%2014_14_08.xls?dl=0

 

[Gerbil21]

Ok so I had to take the trip upstate again and I logged it but the file got messed up again, I did however get some logs from smaller around town trips.

I got the same mpg 17.9 at 80mph for the most part or 70-75mph with slightly better mpg (no ac, windows down) but since I cleaned out the cpas and noticed that the casing moves separate the effects been more noticeable (slight mpg drop, sometimes slight bouncy rpm at idle)

Yesterday I got around to changing the cpas with the newest part # from Dorman (I know there rep but I couldn't wait on the shipping time and it was the best on amazon) & the gm one was on backorder, so far so good even thought. One thing I immediately noticed was lower ignition Timing.

I did not change oil and the old cpas came out dirty, I will have to change the oil when I get back and clean the cpas. Also I still need to loose the can and I'm pretty shure the hollow can that sounds like a angry ghost when accelerating isn't helping from here or the beyond [emoji1]

Mpg still seemed low even with town driving (10mpg) but I guess i will have to wait to see when I get back to nyc.

 

[Gerbil21]

here are some logs they are xls

https://www.dropbox.com/s/z7njc9ldfa7dwzl/Data%20Log.zip?dl=0

 

[Gerbil21]

Well I finally got to save some logs on the trip back


https://www.dropbox.com/s/0c50n8n8c7flcx9/Powertrain%202014_09_20%2020_24_57.xls?dl=0

https://www.dropbox.com/s/cakicjg3r7dm6my/Powertrain%202014_09_20%2021_43_29.xls?dl=0

https://www.dropbox.com/s/17z6g610hwknf05/OBD%20II%20Generic%202014_09_20%2022_46_42.xls?dl=0


Also can anybody write what rpm they have? at 70 I stay at 2000rpm and it goes up to 2500rpm when going up hills.

sometimes it revs like it going wot to get back to the set speed, yesterday while going up a hill and about 15mph under set speed of 70 I resumed cruise control and it reved to 5500rpm easy.

Mpg was at 18 at 70, I also reset it while driving and it was 23mpg but settled at 18

The whole time I drove with 4 people including me and a bit of luggage mainly cloths and two boxes of MREs lol I ended up using half a tank of gas

 

[Gerbil21]

Well I'm finally back in the city and I reset the mpg on the dic and with some easy driving I got to 10mpg. Has anyone looked at the logs yet?

 

[Gerbil21]

ok just an update mpg have been in 10-11 range while driving it nice i haven't hit much traffic yet surprisingly so idk how it really is

 

[gmcman]

I looked at some of the logs and it looks like when the engine is up to temp, the downstream settles around .7-.8 volts and that's kinda high....it's a rich condition and likely shows inefficiency of the cat. Are you getting a code for the downstream sensor or a catalytic converter code?

Not saying the engine is running rich, but the cat isn't burning off what it needs to. Based on what your engine looks like inside, it could be crud from the crankcase and/or could be a partially clogged cat.

Do you have access to an infrared temp gun? I would shoot the temp at the inlet to the cat, not on the heat shield, but on the exhaust pipe right where it begins to flare out just prior to entering the cat. Then check the temp at the same point after the cat, right where the pipe starts to get smaller. You should see at least a 100 deg increase, generally more.

Drive the car until the temp needle sits straight up, if you can see the downstream data wait until it stabilizes then drive it for a mile or so. Then get out and check the temps.

Check the temp before, at the cat if possible, then after....record the results.

 

[Gerbil21]

I dont have one of those temp guns but I guess I will be getting one I do however have a temp probe from my multimeter I might be able to use I'm not sure what range it reads to thought, what temps are normal for these trucks?

also there are no codes for anything at the moment

 

[gmcman]

I would think around 300 for the inlet and 4-450 for the exit. That's not exact, could be 250/350-400ish.

 

[Gerbil21]

OK I'm going to have to check my multimeter if I can find it lol

 

[gmcman]

Looking at the Powertrain data, I see when your load is 100% and the accel pedal angle is high, your MAP readings are maxing out at around 14 and I believe that's still kinda low. I will compare mine tomorrow and report back but I want to say mine were repeatedly near 20 or higher......not sure but I will confirm that tomorrow.

If that's the case then that could be a major contributor to your low city mileage.

 

[Gerbil21]

Looking at the Powertrain data, I see when your load is 100% and the accel pedal angle is high, your MAP readings are maxing out at around 14 and I believe that's still kinda low. I will compare mine tomorrow and report back but I want to say mine were repeatedly near 20 or higher......not sure but I will confirm that tomorrow.

If that's the case then that could be a major contributor to your low city mileage.

which logs are you looking at here are some new ones i took today i noticed when load is 100% the map was in the high 20's to low 30's

https://www.dropbox.com/s/6jy6suf2aocwoji/OBD%20II%20Generic%202014_09_24%2016_16_52.xls?dl=0

https://www.dropbox.com/s/g1vr3swh2zvcdo3/OBD%20II%20Generic%202014_09_24%2016_29_05.xls?dl=0

https://www.dropbox.com/s/je2czhycdq6euap/OBD%20II%20Generic%202014_09_24%2016_53_17.xls?dl=0

https://www.dropbox.com/s/eabpsn0natp1hqy/OBD%20II%20Generic%202014_09_24%2017_20_06.xls?dl=0 -this one is long

one thing ive notice is the the fuel trims seem off

 

[gmcman]

I was looking at the ones in post #182, the ones you just posted appear to be from revving in Park and idling? Is this correct?

A good log would be RPM, accel pedal,TPS, MAP, OS1, OS2, STFT, LTFT while driving when hot.

MAP readings will be different when not under a driving load.

 

[Gerbil21]

I was looking at the ones in post #182, the ones you just posted appear to be from revving in Park and idling? Is this correct?

A good log would be RPM, accel pedal,TPS, MAP, OS1, OS2, STFT, LTFT while driving when hot.

MAP readings will be different when not under a driving load.

no they are all driving all that "idling" is wating at red lights that take forever.

also here is a old one but it shows the post cat o2 and the fuel/air ratio when f/a goes to 13 the o2 goes to .40-50mv

https://www.dropbox.com/s/6qy6ycm63zf2195/Powertrain%202014_09_14%2014_14_08.xls?dl=0

 

[Gerbil21]

Here are some logs from today

https://www.dropbox.com/s/n8coehn7eh0yt16/OBD%20II%20Generic%202014_09_25%2011_06_47.xls?dl=0

https://www.dropbox.com/s/t9xtqz8p3bufp0k/OBD%20II%20Generic%202014_09_25%2011_20_55.xls?dl=0

https://www.dropbox.com/s/hst600dhrr1cz8x/Powertrain%202014_09_25%2011_26_10.xls?dl=0

https://www.dropbox.com/s/7tv57c5g0p5k3q9/Powertrain%202014_09_25%2015_09_06.xls?dl=0

https://www.dropbox.com/s/w4k681t4fz3xb91/Powertrain%202014_09_25%2015_13_40.xls?dl=0

The first one I was holding revs at 2k since I was giving my brother's car a boost

 

[gmcman]

I haven't looked at them yet but I watched the live data on mine this am.

My MAP at idle is around 10, accelerating lightly is around 18 to 22, steady cruise is still around 10 and heavy acceleration is at 29.

What does your air filter look like?

 

[Gerbil21]

Its 1k miles old but I will take another look at it

 

[Gerbil21]

I could of sware I posted that the air filter was still brand new a few days ago idk what's wrong with taptalk

 

[Gerbil21]

ok well i know there hasn't been much updates but so far mpg seem higher i ve been on the same tank for a while now but i will see at the next refill also according to the dic i am getting 10mpg plus or minus 1 mpg with idling or with light cruising traffic but with real light cruising around 35-45mph i saw 12mpg so its definitely is higher

also i just put in a order for a new cat
http://shop.advanceautoparts.com/p/magnaflow-universal-catalytic-converter-99006hm/22315793-P?searchTerm=catalytic+converters

and a shift kit from ctpowertrain to take care of the 1-2 and help it live longer
http://www.ctpowertrain.com/servlet/the-719/4L60E-4L65E-1996-dsh-2006-1870/Detail

 

[Gerbil21]

ok one update, the parts will be in Tuesday also i did another upstate trip and reset mpg before leaving and with full tank and writing down miles i got a total of 17.4mpg which is exactly spot on with the dic so that's good there's no optimism from gm trying to satisfy customers also i used 10.7 gallons going 186 miles

one other thing i am about 20 - 25mph under set cruise control speed and put it to resume what happens? when i do it the things basically floors it, it will jump to 5k or redline trying to resume speed even if im not on a hill and it sounds crazy at that high rpm but at least it dose rev just fine and dosent bog down

 

[Gerbil21]

This is a video of a tapping/knocking noise I only hear it when its cold I'm not shure what it is any ideas?

https://www.dropbox.com/s/suhihikwl9ownlj/VIDEO0043.mp4?dl=0