Ok heres the story, several months ago my car developed a higher than normal idle and a noticeable miss when warmed up, at the time I didn't pay much mind to it as my drive to work was longer with very little stop and go so I blew it off.
Since i've moved back into the city my drive is shorter but with stop and go traffic it has become worse and the fuel consumption has gotten really bad, in the morning it's not noticeable at all (usually) but on my way home it's more prominant.
I'm thinking the differance in temp from early AM to late PM when the sun is out and the car gets hotter ???
In the last 2 weeks I have installed new plugs and wires which got rid of most of the miss, new PCV valve and found the Y union to be rotted behind the intake so I fixed that, removed the IAC valve and cleaned it, removed throttle body and cleaned it, cleaned the MAF (just sprayed not touched), air filter is clean and has not been touched in many months.
I have sprayed starting fluid, carb cleaner and brake clean along every nook and crevace of the intake, brake booster, air pump lines, vacuume lines, inlet piping to MAF, TB and related sensors, pretty much the entire engine and with the car running pushed and pulled on the intake TB, MAF, hoses ETC and I cannot find any leaks.
I have unplugged the MAF and IAC turned the ignition on for a few min to reset them and I still have the problem.
I am at my wit's end and getting more grey hair trying to figure out this problem, I know that higher Idle is more air coming in, but from where ??? I think I have exhausted all my options as to where to look and test.
The car is not flashing any SES, MIL etc codes and I have scanned for any pending codes and my scanner will not do real time, not that I know what to look for if it did.
can you guys point me in another direction of where / what to look for ??

Any and all help or Ideas would be greatly appreciated.
Thanks for your time
Bill

 

even though you cleaned the MAF it could be shot still, as far as the idling problem I'd start there personally. My 95 Z28 did that (yes I know you have the LS but I'm trying to relate) so I had it replaced and the problem went away even though my car wasn't throwing any codes like yours isn't. IMO replace the MAF with a new one and go from there.

 

It would really be beneficial to look at live data to help rule a few things out like MAF, possible IAC, etc. Other possibilities could be vacuum leak(internal or external), but a vac. leak should throw lean codes P0171/p0174. Do you hear any type of hissing in or around the intake?

 

im wanting to possibly lean towrd either the iacv or maf

 

Thanks for the replies everyone, I'm looking in the classifieds for a MAF and IAC (no luck yet) if I have to try one i would rather it be a cheap used one than a new one.
I hate throwing parts at a problem in the hopes of fixing it, especially since I cant get that $$ tree to grow in the back yard lol.
I also read somewhere here about the MAF and unplugging it, I have done that the idle dropped about 50 rpm then went right back to what seems to be 975 ish.
could it be the problem even tho unplugging it made almost no diff ??
any Ideas where to get live data as the car is running that wont cost an arm and leg ??

Thanks again guys, I really appreciate the Ideas.

 

U can unplug the MAF, the car will default to speed denisty. If the car still has the same problems you can prolly rule out the MAF. Being that is it more noticable hot i would do a collant pressure test you may have a slight coolant leak/head gasket leak

 

Another thing to check is your o2's. I have had plenty going out or on there way, abd I never got any code. When your o2's start to fail you get a real bad idle. Also if they were all the way gone, you would have bad surging abd horrible ride intill 3-4krpm. Also I would get a volt Metter on your tps. You need to start over, and work you way from front to back of car ruling everything out. It could be a clogged filter or pump on it's last leg. Also double check your coil harness is plugged in and getting power.I've had to put some elec grease on mine due to #7 cutting in and out.

 

I never thought of a coolant leak and I did add a little to it yesterday, wouldn't the plugs I changed out shown some signs of a leak ? all were light tan except #1 it was a little darker but I chalked that up to the plug wire broke when I pulled it off so I was thinking it wasn't making good contact ?







I'm assuming by checking the 02's you mean data logging ? I dont have the equipment to do live data, my scanner doesn't do it.
I will try a search for the TPS voltages and steps on how to check it.
harness is connected and powering and the dialectic grease is a good preventative I will do.
filter should be good since I changed it in the last 7 months and the car still does it, fuel pump will suck unless I cut a hole behind the back seats, I'll see if I can borrow a fuel pressure test kit before I start hacking the car up lol.

I should have brought that damn predator scanner when I had the chance then I could have live data, oh well....live and learn.

Thanks very much for the ideas and suggestions guys.

 

I have the cut hatch in my car for fuelpump, it's the best thing that I did, can't even tell it's there. Also you cab see if you can borrow o2s from some1. And I know doc at efi Is close to you. I don't know what he will charge to do a data log though

 

Well.....I think I have a leaking head gasket
I did a coolant pressure test and it fails miserably, I pump it to 15 psi and it instantly bleeds down to a steady 4 psi.
&^^%#$%$@^&& POS
I checked under for leaks and none, nothing in the oil, I tried to see if I could hear a hissing in the oil filler cap and nothing.
no hissing at the pump cap either so I know it has a good seal.

anyone know of any sales on headgaskets and bolts ??

 

I would also say o2's

 

Make sure it's not leaking coolant at the water pump. They all seem to leak a little there.

Also I have a spare maf, I do not think I want to sell it but I work in Gainesville at the autozone on univeristy. If you want I will bring it to work with me today. I work 12-9.

I hope it's not a headgasket. Good luck.

Steven

 

Winner!!!!!! 7 points for me.

 

well it's funny you should say that, I always let my car warm up in the morning and I was walking to my car yesterday morning and noticed a spot on the driveway, touched it but couldn't tell what it was, so I started my car and let it warm up came back out and happend to shine my flashlight under it and I be damned, it was leaking,
crazy damn thing will only leak with the nose pointed down the slope of my driveway, I pulled it in the garage yesterday after work and let it run for 25 min and no leaks, got frustrated and said screw it then parked it.
This morning same thing, leaks when pointed down the slope and now theres a little squeal from under the hood so........I will make sure Saturday morning when it's light out that it is the pump and I'll go from there.
And on another note, man thats a real nice thing to offer your MAF for me to try, I really appreciate it very much.
Things like that remind me that there still are some good people out there.

Thanks again to everyone who has replied with your Ideas and suggestions, I will update when I find more info.

 

Yea my pump only leaks, sometimes too. Has to be the right circumstances. I hope it all turns out to be the water pump gasket or the pump at worse. Let me know if you need to try the maf. I work the next 5 days straight.

Steven

 

Yep, already replaced the water pump on mine once as well. Seems to be a common thing I guess!

Derek

 

yeah Ive done a water pump on mine too. Good luck with the fix

 

Do a compression test. You will definitely know if you have a blown head gasket that way.

 

Well I picked up a new water pump Sat morning, got it all installed and no more leaks. (so far)
I could have gotten away with just replacing the gaskets since the rubber bits were really brittle and split away from the gasket frame but figured WTF I already purchased it and the old one is off.
A new WP is good preventative Maintenance anyways.
I haven't pressure tested it again yet, but i'm planning on it when I get off work tomorrow and it cools off.
Yes, a compression test would let me know if I have a problem in a cylinder with rings, valves, HG.
I've been wanting to do one anyways, I will see if my friend at work has one I can borrow.
It still has a little bit of a rough idle......I'll figure that out eventually

Thanks to everyone for their offers, suggestions, tips and ideas, I greatly appreciate it and will update how things go in the next few days etc.