idling weird...

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Toejam

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so Toejam i guess i am an idiot for recomending a standard tune up for a 2001 tahoe that has a idleing problem. or maybe you just like being a jack ass and making yourself feel better at some one elses expense. most of the parts i recomended can be had from a local auto parts store and installed by himself for less than the price of taking his truck to a dealer or auto repair shop for a diagnostics to tell him he has a fouled plug in the number 5 cylinder. in my opinion for an 01... it probably time for a tune up.. safe bet. and cheaper than you taking 3 hrs at 85 per hr for labor charging 15 for shop towels 12 for a can of fuel injector cleaner and 50 bucks for a set of factory delco plugs.. im trying to help a fellow forum member with an issue that i have had in my own vehicle not come in and be **** of the walk and make some one else look bad.

1st of all, I didnt make you look bad--you did that ALL BY YOURSELF. I wasnt the one that proposed replacing all kinds of parts. Unless you think replacing the MAF, IAC and God knows what else to you constitutes a "standard tune up".

And who said it would take 3 hours to diagnose and repair this issue?
And if you think using generic auto parts store items, NO MATTER HOW CHEAP are as good as the oem parts,you are sadly mistaken.
Also note I NEVER said to take it to the dealer or any other shop. I gave him some items to look for, and more importantly what NOT to do.
Assuming his problem is limited to a plug and coil--based on scanner diagnosis--who saved him big money?? How do you know the plug is fouled? and fouled by what? Leaking injector, defective valve stem seals, oil control rings? What if he replaces plugs, wires, and 2 months later his missfire returns--then what? Notice in my 1st post I asked a series of questions that were never answered.
And no, I am not "**** of the walk"--just a wrench-turner who has made a living by fixing it right the 1st time, by saving the customer time, effort and money by repairing/replacing only what's necessary. And fixing them for tomorrow and not just today.
Every week I get cars with drivability issues where hundreds of dollars of needless parts have been installed, when the problem--or problems( there is no law stating you can have only one fault at a time) was traced to a simple single, inexpensive part. As I said, I don't take--what you call--"a safe bet"--I have to prove what's wrong before I spend the customer's money.
A maintenance s not a repair, and if by doing the maintenance the problem is corrected by sheer luck, more power to you.
Also note I didnt call you names(*******, **** of the walk, dreaded mechanic). Children do that .
"Give a man a fish, he'll eat for a day. Teach him HOW to fish, he'll eat for a lifetime"
Have a wonderful day!
 
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DaUsedMCR

DaUsedMCR

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hey now come on. both are good suggestions, and noone has to fight about it. like you said, its helping out a forum member. just replaceing all the stuff ironman said is kinda out of my budget. hell, just doing the plugs, wires, and coils is gonna drain me for a couple weeks. so whatever suggestions can save me the most money, im all for. if this semi-tune up doesnt work, im just gonna take it to a shop, because im not all that skilled in mechanic work. just a novice level person lol. and all this fighting isnt helping ME or ANYONE lol. so what can i do about that high LTFT? could that still be caused by plugs wires or coils?
 

blueflamed03

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Agree. Guys we ALL appreciate any feedback for trying to help a fellow SUV GM die hard, no need to get nasty with each other. Do that with the Ford guys.
just because one still uses the shade tree way, doesnt mean it's the wrong way. Nor does the guy NOT willing to try to fix it and prefers to take it to the dealer. neither is wrong. But opeing up, offering advise is the main reason we have forums.

No need to get hasty, it's not worth it.


"A man that slaps the hand, should expect the slap in the face."


we're all trying to help.
 

Toejam

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hey now come on. both are good suggestions, and noone has to fight about it. like you said, its helping out a forum member. just replaceing all the stuff ironman said is kinda out of my budget. hell, just doing the plugs, wires, and coils is gonna drain me for a couple weeks. so whatever suggestions can save me the most money, im all for. if this semi-tune up doesnt work, im just gonna take it to a shop, because im not all that skilled in mechanic work. just a novice level person lol. and all this fighting isnt helping ME or ANYONE lol. so what can i do about that high LTFT? could that still be caused by plugs wires or coils?

Sorry, I was not getting nasty--I just called it based on 40 years of doing this professionally. Needless parts replacement helps no one except the parts store. Again, I asked questions and did not get one answer as to who pays for these parts, what to replace next if the problem still is present, etc.
And I understand your situation with both money and experience, but you
did manage to get Freeze Frame Data.
If you DID replace all that was suggested, and the problem was repaired, how could you know exactly what the main culprit was? if the problem reoccurred would you replace then all over again? Diagnosis is the key here, and it isnt rocket science.
As for your high LFT, allow me to explain: 02 sensors do not read until heated up to 600 degrees F, and your ECT shows 76%, which should have been in degrees either C or F. Your SFT's both read zero, which tells me that the 02's hadnt heated up enough to give you a reading. Your missfire event was recorded when the engine was cold. So here is where we go next:
Write down code and Freeze Frame Data, then clear the code.This will reset the Freeze Frame Data. Run the engine til it's at normal operating temperature, then using thje scanner, monitor DATASTREAM. This is live data as it's actually being gathered. As soon as the 02s start sending data to the engine control unit, your SFT's will begin showing numbers, + or - in %.
If there is a lean condition on the SFT will rise to a predetermined point, then revert to 0% and the LFT which was at 0% will rise. I noticed that your high LFT was on one bank. Possible causes include: vacuum leak, partially clogged fuel injector, manifold gasket leaking etc. And there are simple diagnostic procedures to determine where the problem lies.
You mentioned using NGK Iridium plugs, and whatever coil your auto parts store carries. Why would you not use the oem plugs and Delco coil? These are available at most auto parts stores. Ive repaired countless vehicles where the aftermarket replacement part caused more problems than the part it replaced. When you are diagnosing, a non-stock item introduces a variable which can have you chasing your tail. Remember--new just means new, not necessarily good. And Ive had defective oem parts too, but MUCH less frequently than aftermarket.
Last week I had a '95 4-cylinder car come to me with poor acceleration and severe hesitation. The owner himself replaced: spark plug wires, distributor cap and rotor, distributor(which is the cam angle sensor--times both injection and ignition), the Mass Airflow sensor and..the engine control unit. Roughly $1500 in parts.
I ran a compression test, was a little low on the center 2 cylinders but would not have caused this symptom. I check cam timing, was right on the money. I pulled the distributor and found it had been installed 2 teeth off, reset and installed it--wouldnt run! The rotor had been installed in the wrong one of 3 positions, corrected it and it was smooth as silk. But the hesitation remained. New wires ohmed out good, fuel trims were normal, and adding an additional fuel source--propane into the intake air duct only made matters worse--it was not a fuel delivery problem. I pulled out the spark plugs--oem NGKs with some miles on them, but not worn out, and replaced them with a new set out of stock. PROBLEM RESOLVED! Thew old plugs would not fire under load. Had I not checked everything in a diagnostic sequence, I might have missed the distributor timing. And here is the bottom line---the original problem was the spark plugs--but the owner botched the distributor installation and rotor position which compounded his problem. $1500 in parts when a $15 set of NGKs--at our dealership price--would have fixed it.
Happens all the time.
 

Ironman1979

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i nver said replace the maf sensor and the iac.. i said check.. as in clean with maf sensor cleaner and the iac. also while changing the plugs (normal maintenance) there would possibly be noticable soot oil or plain old burned material or even a complete failure of the electrode. either way diagnosing teh issure.. so far less than 20 bucks in parts.. next as he is inspecting the plugs.. the wires can be inspected for cracks wear and tear, burned through spots and possibly replaced for around 30 - 50 bucks depending on the preferred brand of wires. if the wires are good then no need to replace them still diagnosing the issue. if the misfire still happens on that cylinder.. change the plug wires around.. some faults can not bee seen with the naked eye. if it still happens next change the coils around to see if the problem duplicates on a different cylinder. if it does then it is the coil. if it dosent and stayes there.. then most likley it is on to inspecting the compression ratio on each cylinder. and also an easy check is also the egr valve for proper opperation. so far all easy checks and minimal expense. no where near 1500 bucks.
 

Toejam

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no, it is in the ignition wiring.. if your alternator or bat was having a problem your volt meter would drop low and your headlights would start flashing before completely dying.. also check your throttle position sensor as it could be faulty.. but most likely you have come to a point that you need a tune up. plugs wires cap rotor o2 sensors air filter pvc valve and clean your maf sensor and probably go ahead and replace the tps sensor and iac motor. easy mostly cheep stuff before going to see the dreaded mechanic

Ironman, In your original post I do not see where you say to check the plugs, wires, cap, rotor, air filter, pcv valve or 02 sensors. Cleaning a MAF doesnt always repair it, and you said to probably replace the TPS sensor and iac motor. How do you propose he check all that without replacing them?
You also said to check the TPS, but most TPS glitches can only be seen on a labscope or scanner with scoping capabilities--an ohmeter usually misses the dropout. Then too, most TPS problems will register a diagnostic trouble code for that sensor not one for missfire as he stated he had. Likewise a MAF or 02 will set their own codes.
And after all that, you started the post with.."No, it's in your ignition wiring." Which contradicts the rest of your post. Why check and replace all that if the problem is in the ignition wiring? And which wiring--primary or secondary?
My point here is that replacing isnt the same as checking. There are, however specific circumstances when, in the words of most shop manuals after all other diagnostic steps are taken.."Replace with known good unit and retest operation." Problem here is that I can go to my parts department and do just that. The average consumer does not have that option available to them, so somebody has to pay for these non-returnable parts.

As for the $1500 mentioned in my post, that was that specific vehicle and what that specific owner needlessly
paid when a $15 spark plug set was all he needed in the 1st place. There's a lesson there.
You also realize that when an owner does replace a lot of items, then brings it to a tech when the problem isnt fixed the tech isnt just going to pick up where the owner left off. He will check everything that the owner did, everything the owner replaced, and diagnose from that point.
Engine mechanical, ignition, then fuel system checkouts in that order so as to not only repair the customer's stated complaint, but to uncover other problems that could be present, or caused the original failure. This is a two-way street, as this also prevents a comeback on the tech and an unhappy customer.
I applaud those individuals that can do their own maintenance and repairs. But I am more in tune with those that can diagnose as well. And less so with those that needlessly replace parts or perform unnecessary procedures at either their own or a customer's expense.
Please explain the term "Dreaded Mechanic"
 
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DaUsedMCR

DaUsedMCR

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so i discovered that one of the wires (cylinder 5) had been rubbing on the steering column, and it shorted it out. i replaced all the plugs and wires (NGK iridium IX and AC delco wires) and i erased the codes. now, its still idling the same and driving jerkily, but its not throwing ANY codes!!!! WTF!!!! i just disconnected the battery to reset the computer to see if itll clear it up or throw a code. if not, im gonna take it in to a shop cuz i have a lot going on right now, and i just want this thing fixed.
 

Toejam

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so i discovered that one of the wires (cylinder 5) had been rubbing on the steering column, and it shorted it out. i replaced all the plugs and wires (NGK iridium IX and AC delco wires) and i erased the codes. now, its still idling the same and driving jerkily, but its not throwing ANY codes!!!! WTF!!!! i just disconnected the battery to reset the computer to see if itll clear it up or throw a code. if not, im gonna take it in to a shop cuz i have a lot going on right now, and i just want this thing fixed.

Understood. As in one of my earlier posts, use your scanner and see if you can read Datastream. Look at your SFTs while the engine is jerking.
Also, at idle, feel your EGR valve and if it is red hot,it is flowing at idle which will cause your exact symptom. Engines cannot tolerate EGR flow at idle. The valve can be removed and cleaned, many are replaced, but check it for flow at idle before you buy one. This is a very common failure. Many times an EGR flow malfunction will exhibit a P0400, 401, or 402 code, sometimes not. An open EGR can also cause a high SFT or LFT %, so that might be it.
And again--you may have had more than one thing happening at the same time, the ignition wire shorting against your steering shaft being one of them.
 
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indohoe

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too me it sounds like carbon build up . Clean the intake . the butterfly valve. all sghould be good .
 
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DaUsedMCR

DaUsedMCR

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too me it sounds like carbon build up . Clean the intake . the butterfly valve. all sghould be good .

i tried that already. i also cleaned the MAF. a i reset the computer, and it was the same, jerky and shaky. im gonna take it into the shop tomorrow and hopefully get it back early next week.
 

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