Running Rough

BADs Crew · Post by **BADs Crew** » Sat Jun 03, 2006 7:30 am

Its not my crew but the wifes Blazer. It idles very rough on start up,after it warms up it misses at low it but seams better once your cruising. I tuned it up about 3 months ago using Bosch Platinum Plugs and a good brass pined cap and rotor. It seemed to smooth it out but after a few weeks started running bad again.

I took it to the dealer and they replaced the spider injection system and gave it back as fixed but I returned it with the same problem. It had been back to them 3 time before I started on it again myself and swaped out the Bosch plugs with a new set of stock AC Delco's. This seamed to fix the problem but after a few weeks the problem returned. I'm stumped, It's not throwing a code and sometimes it runs better than others. We have changed fuels from BP to Sunoco so I know its not the gas. Fuel filter has been changed and the air filter is new. Anyone have any ideas on this one?

killian96ss · Post by **killian96ss** » Sat Jun 03, 2006 7:43 am

Have you cleaned the MAF and IAT sensors lately? Is your fuel pressure good (60-66 psi key on, engine off)? Do you have any moisture build up in the distributor cap (plugged vent screens)? Is the EGR system working properly (is it stuck open)? Is your PCV valve clean and not all gummed up? Do you have any air leaks in the intake piping? That's all I can think of right now, but if If anything else pops into my head I will let you know.

Steve

BADs Crew · Post by **BADs Crew** » Sat Jun 03, 2006 7:53 am

I did check the cap for condensation and have went over it well for vacuum leaks. I thought anything else would throw a code. What really bugs me is I'm willing to pay the $$$$ to have it repaired but the dealer has had no luck fixing it. It's raining here now but tomorrow I will give it another going over using your suggestions. Thanks.

crew cab sonoma · Post by **crew cab sonoma** » Thu Jun 08, 2006 7:24 am

i`m still thinking its ign. related. perhaps a plug wire, or coil starting to go bad?

killian96ss · Post by **killian96ss** » Thu Jun 08, 2006 8:50 am

crew cab sonoma wrote:i`m still thinking its ign. related. perhaps a plug wire, or coil starting to go bad?

It's possible the coil could be the problem, even though the 96 and up coils have a very low failure rate.

If it was a plug wire, you would almost certainly get a misfire code for the affected cylinder. Another thing worth checking is the IAC valve on the TB. If the passage becomes restricted at all the IAC will constantly try to correct the condition which can result in a rough idle.

Steve

BADs Crew · Post by **BADs Crew** » Sat Jun 10, 2006 11:59 am

Problem Solved

After closer inspection I found a few powdery white marks on the plug wires. I put on a set of Bosch wires, replaced the cap for the second time because I found that the dealer had swaped my brass tipped cap with their POS stock cap and now the Blazer purrs like a kitten.

LUVMY02CREW · Post by **LUVMY02CREW** » Sat Jun 27, 2009 10:27 am

This is gonna be long so please bear with me, I'm trying to give as many details as possible....If this should be split to a new topic no problem...I've searched bunches and came to the conclusion that this topic most closely matches my problems...

'02 Crew with 97k, only real mods are a k&n filter and some holes in airbox(not the full deal like others) along with the tb blade mod.

My problem has been getting worse over the past couple of weeks. The truck seems to idle very rough, seems like engine wants to quit at stops, and black smoke comes out exhaust when throttling kinda hard. I've been getting codes P0300 and P0131 at various times.

1 - Replaced O2 sensors a few months ago because I was getting a code(can't remember what number) for the passenger side one. After a few weeks with the new ones, I started getting code P0131(low voltage drivers side). The ebay folks (Global-Automotive) are not honoring their advertised warranty and I would never buy from again or recommend them to anyone....but anyhow....I've been clearing the code with my scangauge and it would take from 1-2 days before it would reappear.

2 - On 6-14-2009 I reset the PCM? by removing battery cables for about 30 minutes, added a bottle of fuel injector cleaner, and cleaned and reoiled the air filter.

3 - On 6-19-2009 I filled up at a new shell station in town that said no ethanol. I have been using almost exclusively bp(up to 10% ethanol) for a long time.

4 - On 6-22-2009 very rough idle on way home from work, took wifes suburban to work on 06-23-2009 and she drove truck and said almost died on her several times.

5 - On 6-24-2009 I changed plugs, wires, cap and rotor. Cap, rotor and wires looked ok for 97k. BUT...the 3 drivers side plugs were coated in black residue, passenger side 3 looked like normal wear.

I also disconnected the battery cables for about 2 hours while working on ignition stuff(yeah, I know I'm a sissy, but didn't want to risk getting the crap shocked outta me by accident). Also sprayed cleaner on the MAF.

6 - On 06-25-2009 my local mechanic consulted with a gm mechanic about truck and gm guy said rough idle, etc sounded like the plugged precat.

7 - On 06-26-2009 I did a little ole precat-ectomy, it looked like the pics that f9k9 posted of his on the plugged pre-cat thread, not plugged/blocked...oh well.

8 - On 06-27-2009 muffler shop welded a straight piece in that mysterious hole that appeared last night.

Sooooooooo... After all that, the truck still runs/idles rough, wants to quit at stops, and spews black smoke when throttle pushed hard.

I don't want to mess anything up with my 60 mile round trip commute, so I'll be taking suburban next week. That is unless ya'll can help point me in right direction......HELP PLEASE!!!

04crewvt · Post by **04crewvt** » Sat Jun 27, 2009 11:25 am

I would suspect a blown lower intake gasket if you are running Dex-cool still. Has your coolant level gone down any? If so it's almost a sure bet.

LUVMY02CREW · Post by **LUVMY02CREW** » Sat Jun 27, 2009 11:47 am

I actually remembered to check the coolant level the other day and it was aok. Swapped over to green not long after I got truck bout 2 yrs ago.

Thanks for the idea, all are welcome!!!

Post by **HenryJ** » Sat Jun 27, 2009 11:48 am

That sounds reasonable. Have the cooling system pressure tested to see if you have a leak. Spraying cleaner around the intake while running may find a vacuum leak.
You also might consider the cap, rotor and perhaps a cracked distributor housing?
Triple check them. I know you just changed them , but take a look again just for kicks.

LUVMY02CREW · Post by **LUVMY02CREW** » Sat Jun 27, 2009 12:10 pm

HenryJ wrote:Spraying cleaner around the intake while running may find a vacuum leak.

I'm gonna show a lot of ignorance here, but I'm ok with that....
Can you explain a little more about what you mean and what I need to be looking/listening for??? I've never really understood how the vacuum system works on a vehicle.

Post by **HenryJ** » Sat Jun 27, 2009 12:14 pm

When you spray cab or injector cleaner in a running engine the rpm or sound changes. Spraying around the intake gaskets there should be no way for the cleaner to enter the engine unless there is a vacuum leak.
If you spray and hear a change there is a leak sucking cleaner into the engine and you have found a problem.

Spray around the TB, heads to intake , vacuum lines, etc.
Be careful.

Check the lines behind the brake booster to make sure they are not dry rotted and leaking.

F9K9 · Post by **F9K9** » Sat Jun 27, 2009 1:12 pm

Brule is probably "right on" with his suggestions. The stumbling and almost dying out on you is in correlation to your resetting the pcm. It is having to relearn the overall motor's condition again. Clean your throttle body next time this happens. It may not look dirty but, I'll wager that it will help. You have other problems but, maybe we can clear up that minor one.

LUVMY02CREW · Post by **LUVMY02CREW** » Sat Jun 27, 2009 2:00 pm

So far, ya'll have put on my to do list: spray check for vacuum leak, check hoses around brake booster, recheck cap and rotor and dist housing, clean throttle body.

I'll try to get around to doing these later tonight when it cools down or tomorrow early. We've just got through cleaning up after yard sale here so I'm due for a shower and nap.

Post by **HenryJ** » Sat Jun 27, 2009 4:30 pm

Pressure test the cooling system. A small leak into the intake can wreak havoc. Pumping it up to 13 lbs and watching the gauge is the only real way to tell for sure.

That would be top of my list if you have been a Dex user for too long.

LUVMY02CREW · Post by **LUVMY02CREW** » Sun Jun 28, 2009 4:33 pm

Alrighty....Here's the low down from earlier today....
I don't have a cooling system pressure tester, that'll have to wait a while.
BUT, I have done 3 outta 4 things on the list:

1-Rechecked the cap, rotor and housing - looked aok to me nothing unusual and no cracked feeling around the housing.

2-Felt of and looked at hoses around brake booster - no signs of cracks, kinks, breaks that I saw.

3-Sprayed some cleaner into throttle body, then ran out

4-No spray check for vacuum leak - ran out of spray cleaning throttle body

HERE'S THE BIGGY THAT HAS MADE A DEFINATE IMPROVEMENT:I know it wasn't on my to do list ya'll gave me, but...Remembering in my earlier post that I was getting a code P0131 and that the 3 old spark plugs on drivers side were covered in black funk when I changed them, I thought what the h*ll, I'll see what happens if I swap 2 sensors...SO...I decided to give it a try right quick.

I swapped out the drivers side(bank 1 sensor 1) and post cat(bank 1 sensor 2) sensors. I cleaned them with engine cleaner/degreaser and a wire brush(drivers side one was coated bad and had a few holes that were almost completly closed with the same black funk from spark plugs). Then went for a test run.

I started truck, cleared codes with scangauge and put in gear. Idled a little rough at first as the SES light was flashing for a while, then didn't come back on...until, a couple of miles into a 6 mile run, the code P0137{O2 Sensor Circuit Low Voltage (Bank 1 Sensor 2)} came on....aaahaaa....code following a bad sensor!!!!!

The truck was not idling rough at stops any more and no huge cloud of black smoke coming out when accelerating hard. No code P0300 so far.

I then went to Auto Zone and picked up a few things - a can of throttle body cleaner(not the regular carb cleaner), can of Sea Foam, can of Sea Foam Deep Creep and a fuel filter.

Went to BP and filled up tank with fuel and checked mileage - yikes - little under 13 mpg. I added 2/3 can of Sea Foam to gas and will put into brake booster line later when a little darker and neighbors won't see so much smoke rolling out

and I'll wind up changing fuel filer some time soon just for good measure.

SOOOOOO, does it make sense that the bad O2 sensor was making my truck run VERY RICH on the drivers side cylinders, and that was causing the rough idle and setting of the misfire code???

Post by **HenryJ** » Sun Jun 28, 2009 5:02 pm

Watch for that sensor to foul again.

Pressure check the cooling system to see if coolant on the left bank is what may be fouling the plugs and sensor.

LUVMY02CREW · Post by **LUVMY02CREW** » Sun Jun 28, 2009 8:45 pm

Late night update...

I sprayed down the throttle body with Deep Creep and did the Sea Foam treatment tonight after dinner.

Took the crew out for bout 8 miles and everything seemed fine and dandy. I drove slow and fast, regular acceleration and foot on the floor acceleration.

No codes at all since earlier today(cleared with scangauge after fillup). The truck seems to be running fine so I should be aok for taking to work tomorrow. Wifey had a definate scowl on her face

when I stated that I might need to take her suburban again, but tonight it turned to a big grin knowing I wasn't gonna take her baby

.

Thanks for everyone's help / ideas / suggestions!!!

F9K9 · Post by **F9K9** » Sun Jun 28, 2009 9:52 pm

So, basically you tried a bunch of different things to solve a problem and you do not have a clue what actually solved your original problem?

LUVMY02CREW · Post by **LUVMY02CREW** » Mon Jun 29, 2009 6:51 pm

WOW!!... WHAT??... WRONG!!...I don't want to seem over sensitive here...and I hope I'm reading it wrong, but I think the last post was uncalled for because if you read ALL of my posts in this thread, you would realize that I TRIED VERY SPECIFIC THINGS THAT FOLKS RECOMMEDED AND THAT I DO HAVE A CLUE AS TO WHAT ACTUALLY SOLVED MY PROBLEM AND BASICALLY STATED SUCH!

Let me start by saying I apologize if my long posts drive people crazy, but from what I can tell the more information this forum has up front, the easier/quicker it is for members to diagnose and help solve problems...

The problem as stated: "The truck seems to idle very rough, seems like engine wants to quit at stops, and black smoke comes out exhaust when throttling kinda hard. I've been getting codes P0300 and P0131 at various times."

Several very much apprecited suggestions/ideas/reccomendations came next.

I responded that "ya'll have put on my to do list: spray check for vacuum leak, check hoses around brake booster, recheck cap and rotor and dist housing, clean throttle body." I left off the list to pressure test cooling system because "I don't have a cooling system pressure tester" and I knew on Saturday evening and Sunday that I wouldn't have access to one.

I then stated "I have done 3 outta 4 things on the list" and told what I did.

Then I stated "HERE'S THE BIGGY THAT HAS MADE A DEFINATE IMPROVEMENT" when I probably should have said was "HERE'S THE BIGGY THAT SEEMS TO HAVE SOLVED MY ORIGINAL PROBLEM" when I wrote about swapping the O2 sensors.

I hope this explains things a little better and answers your question.

LUVMY02CREW · Post by **LUVMY02CREW** » Mon Jun 29, 2009 6:54 pm

Oh, yeah.....update for today.....

During commutes today, the code P0137 reappeared(post cat low voltage... which is the one I swapped positions with). So that one is obviously bad.

No P0300 today and running fine.

And, no, I haven't forgotten about the pressure test, it'll happen soon hopefully.

Again, Thanks for everyone's help / ideas / suggestions!!!

04crewvt · Post by **04crewvt** » Mon Jun 29, 2009 6:58 pm

I think the big thing is swapping the sensors is not fixing a problem it's just masking the issue. Since the sensors were fouled and the source has not yet been determined you have only temporarily fixed the rough running and codes. The fouled sensors would certainly cause rough running and idle but it's not likely the root cause.

LUVMY02CREW · Post by **LUVMY02CREW** » Mon Jun 29, 2009 7:14 pm

Just thinking outloud here, but to me it seems like the root cause of the rough running and idle was the bad sensor telling the engine to pump more fuel in the driver's side. The codes are following the one sensor when swapped. Is there a way to test the sensor to see if it is actually bad???

Thats why I asked earlier "Does it make sense that the bad O2 sensor was making my truck run VERY RICH on the drivers side cylinders, and that was causing the rough idle and setting of the misfire code???" But I don't think a solid answer was given.

I understand that the sensors and plugs could get fouled with coolant, but my coolant level hasn't dropped like I stated earlier. I will get it pressure tested for leaks soon though....

I'm also trying to work on getting pictures posted of plugs soon. I didn't get a picture of the sensor before I cleaned it

04crewvt · Post by **04crewvt** » Mon Jun 29, 2009 7:22 pm

Have you set up your scan gauge to read the O2 sensor data stream? If so you can look at them when running and you should see a voltage fluctuation from 1miliamp to about 75 switching back and forth as the engine varies depending on load and speed. A working sensor will show large numbers of cross counts where the voltage with shift from the low side of the scale to the high side with 45 being about a mid point. If you set it up to show all the sensors at once you will see them bouncing back and forth. If one never moves or is either always high or low it is most likely bad.

LUVMY02CREW · Post by **LUVMY02CREW** » Mon Jun 29, 2009 7:40 pm

04crewvt...Very interesting....I'll have to dig into the manual to check that out(brain starting to hurt already just thinking about that).

I guess I was just figuring that if a low voltage code followed the sensor when swapped I could just determine that it is bad. Your way of reading those voltages seems much more accurate.

Thanks for the info!!!!!

F9K9 · Post by **F9K9** » Mon Jun 29, 2009 7:51 pm

LUVMY02CREW wrote: WOW!!... WHAT??... WRONG!!...I don't want to seem over sensitive here...and I hope I'm reading it wrong, but I think the last post was uncalled for...................

Please accept my apology. I was out of line and couldn't follow your line of reasoning.

I am glad things seem to have come together and the issue is possibly resolved.

LUVMY02CREW · Post by **LUVMY02CREW** » Mon Jun 29, 2009 8:14 pm

Apology graciously offered and wholehertedly accepted!

Like I've seen so many times before, what we think and type don't necessarily match up on the internet. I think that was the case with your post and my posts. I was trying to not leave anything out that could possibly be important. I guess I went for information overload.

Like I said before, the truck ran great today, so fingers crossed.

Still gonna get the system pressure tested and try to read up about what 04crewvt said about the scangauge readings.

Thanks for all the help you give to folks here and (I'm sure) other forums/places.

F9K9 · Post by **F9K9** » Mon Jun 29, 2009 8:44 pm

LUVMY02CREW wrote:...............Thanks for all the help you give to folks here and (I'm sure) other forums/places.

Actually, I am probably more of a burden on other forums than I am able to help out here and elsewhere.

You need to understand my relationship with ducks.

This is how my day went yesterday The user "DoctorD" in the post actually is requested to help write "MASTER" ASE tech tests. It is truly hard to reign him in but, I was somewhat successful in prepping him if, I had toasted my PDC

BTW, I had linked my problem to Brule via PM and he was hours ahead of any answers found on a heep forum and had already solved my problem.

Why you never should own a heep!

All is good!

roadrunner · Post by **roadrunner** » Tue Jun 30, 2009 2:21 pm

Been following this thread since it's beginning. IMO you are on the right track with the O2 sensor. My .02 worth.

LUVMY02CREW · Post by **LUVMY02CREW** » Sat Jul 11, 2009 8:20 pm

A little update....truck running fine and dandy. MPG back to normal since swapping drivers side and post cat O2 sensors

Still need to get cooling system pressure tested, spray around intake, set up scangauge to read voltages, and go ahead and get a replacement O2 sensor....

....I haven't forgotten, just too many things on honey-do list for me to make time for my crew

But, wifey and I did get a few pictures up on forum of the original plugs that I changed out...the drivers side looked really fouled up when changed...

http://www.s-10crewcab.com/coppermine/d ... =234&pos=0
http://www.s-10crewcab.com/coppermine/d ... =234&pos=1

They looked like the pictures of a carbon fouled spark plug I found on the web-- Carbon fouled plug mixture too rich

Again, thanks for everyone's ideas and suggestions!

Horsehammerr · Post by **Horsehammerr** » Sat Nov 14, 2009 4:54 am

Exellant read !! I think Luvmycrew is a master of explaining the problems and solves the best I've come across. This whole post tells it just like what my '02 is doing now. So I'm going to start at the top and do it all.

Horsehammerr · Post by **Horsehammerr** » Mon Jan 11, 2010 6:47 am

Well since we can converse again, here I go, I'll try to shorten it. I have now put a NEW aluminum based distributor in, came complete. Cap black with brass machined pins, Rotor matches. New Taylor 8.2 Thunder-Volt plug wires. Autolite XP605 plugs and no improvement in MPG. Ran nice and smooth, Started right up, but then the evil SES light came on. P0101: Mass Air Flow ( MAF ) sensor error.

Bought a new MAF, I thought 5 cleanings were enough. But NO, SES on again, same P0101 plus P0171 and P0174:Bank 1 system too lean and Bank 2 system too lean

So I gently RIPPED the new MAF off of there and got out the cotton Q-tips and rubbing alcohol and did a micro cleanup on the original and gently CRAMMED it back in. While I had both MAF parts side by side my micro eye noticed a slight difference. The screened inlet sides did not match. The new $ 85.00 , 8 days to ship via ups part was 3/8" smaller in Inside Diameter than the original ? I don"t know if that was or is the problem,but so far so good. Oh ! I forgot to tell about the slight rough running and stalling when coming to a stop that is also gone now. I hope I can get my money back for the problem MAF and I don't need one anyway. We'll see.

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