fouling plugs

[quadracer500]

5.3 engine cam out in 99 and they never had the poppet injectors ,have you put a fuel pressure gauge on it, check the pressure running should be in 50psi somewhere , also check the pressure after shutting off the engine and then after 10 min should not drop over 5 psi.if it does may have leaking injector repeat the test with fuel lines blocked off .

[saltus440]

QUOTE (quadracer500 @ Feb 12 2010, 02:33 AM) <{POST_SNAPBACK}>

5.3 engine cam out in 99 and they never had the poppet injectors ,have you put a fuel pressure gauge on it, check the pressure running should be in 50psi somewhere , also check the pressure after shutting off the engine and then after 10 min should not drop over 5 psi.if it does may have leaking injector repeat the test with fuel lines blocked off .

Wow i messed up I didn't notice it was a 5.3 only saw '99, so no poppets, they had a mix of the new and old motors in their truck lineup that year.

[MX Quad Dad]

well; I checked every thing I could think of and all the tips I got from here and other people. Truck started acting up before the 10,000 miles this time. I checked everything I could find test proceedures and specs for and everthing was withen spec(even went out and bought a new multimeter). on the code reader the only fault code I was getting was for the aft O2 sensors, which some will say that it will affect driveabilty, but from what I have read and then talked to a couple of people that I trust which agreed with that. I didn't want to spend $140 and have nothing better but was ready to give up and buy them.

THEN

A coworker was having problems with a car which had a few simulare throtle reactions. he showed me what he thought was the problem and said he unpluged it and it runs good for a little while then gets worse. Get this, he was unpluging the mass air flow sensor. when I got home I looked at my 05 and the sensor looked the same. so I went on line to an auto part site and looked both of them up. they had the same part number. so I switched them. and even though the truck was allready running bad it staitened right out with the sensor off my 05. bought a remanufactured one and it runs perfect even the little querky transmission shifts that happened once in a while are gone.

the sensor checked out ok with a ohm meter (which I believe is just for the air temp) and the voltage and ground were good. I even rechecked them after swaping out with the 05's sensor. the only other test was to get an air flow reading at idle which I don't have the equipment for. I have been looking into the software and hardware to do this but havent been able to swing the $800 for the one I want.

[cannondale27]

Hard to believe it never threw a code or ruined O2 sensor.My 2000 check engine light comes on within 10mi of hooking the trailer on it.Take trailer off and within 10mi light goes off.Doesnt affect gas mileage and runs fine the whole time so I am not going to worry to much about it.Has done it all year.Figured being a Chevy it was just sensitive to a little hard work

[joep1219]

QUOTE (MX Quad Dad @ Aug 30 2010, 11:25 PM) <{POST_SNAPBACK}>

well; I checked every thing I could think of and all the tips I got from here and other people. Truck started acting up before the 10,000 miles this time. I checked everything I could find test proceedures and specs for and everthing was withen spec(even went out and bought a new multimeter). on the code reader the only fault code I was getting was for the aft O2 sensors, which some will say that it will affect driveabilty, but from what I have read and then talked to a couple of people that I trust which agreed with that. I didn't want to spend $140 and have nothing better but was ready to give up and buy them.

THEN

A coworker was having problems with a car which had a few simulare throtle reactions. he showed me what he thought was the problem and said he unpluged it and it runs good for a little while then gets worse. Get this, he was unpluging the mass air flow sensor. when I got home I looked at my 05 and the sensor looked the same. so I went on line to an auto part site and looked both of them up. they had the same part number. so I switched them. and even though the truck was allready running bad it staitened right out with the sensor off my 05. bought a remanufactured one and it runs perfect even the little querky transmission shifts that happened once in a while are gone.

the sensor checked out ok with a ohm meter (which I believe is just for the air temp) and the voltage and ground were good. I even rechecked them after swaping out with the 05's sensor. the only other test was to get an air flow reading at idle which I don't have the equipment for. I have been looking into the software and hardware to do this but havent been able to swing the $800 for the one I want.

when you unplug the mass air flow meter, the pc goes to default speed-density mode. sounds like a bad sensor, probably an o2. or even the lead going to the sensor. they get ruff after all the heat.

[MX Quad Dad]

QUOTE (joep1219 @ Aug 31 2010, 01:05 AM) <{POST_SNAPBACK}>

when you unplug the mass air flow meter, the pc goes to default speed-density mode. sounds like a bad sensor, probably an o2. or even the lead going to the sensor. they get ruff after all the heat.

I never ran mine with the sensor unpluged. It was that he (the coworker) had made comment on how his was running. one of which was that it seemed to run all right when fired up in the morning but, after that when you refired up (say to leave work) it ran like fuel filter was pluged when you accellerated off idle until somewhere around 1500rpm. at first it would just do it on first attemped to accellerate but would get worse on mine if I didn't change the plugs.

I think its been close to four weeks and it runs perfect and thats with the same plugs.

I am pretty sure my aft o2 sensors are bad but I'm not spending the money on them unless someone can convince me it will help in milage or reliabilty. performance is right on now and with the load I carry I can't complain about mileage

I am looking into the software and hardware to tune the GM trucks. I would like one capable of "real time" but would also like to access the BCM and ABS codes. and from what I can understand I will be able to disable the aft sensors.

I am surely surpriised that none of the dyno guroo's here have ever looked into these.

[cannondale27]

Aft is the rear sensors right?Why disable them?For towing?I hate the fronts.Get a little rust under them and they are dangerous when A.B. kicks in at 2 or 3 mph.Solution is simple.Disconnect one or both and put a piece of electrical tape over the annoying light on dash that will appear or do it right way and remove them to clean the rust off.Hard to believe Toyota got slammed and never hear a peep about Chevy's doing that.Is a very common issue at least around here.Dangerous issue.

If I had a Vette or something similar would for sure be into tuning.But for me trucks and cars are just a means to get to riding as comfortably and cheaply as possible.

[MX Quad Dad]

steve, the truck came with a "I LOVE HOOTERS" sticker over that light.

the main thing I want correct is the weird feeling that when accelerating from a dead stop you are faster gradually pressing down the throttle verses dropping it to the floor. I had read on a truck fourm about someone who was behind a delivery truck and was going to use the right lane to pass, you know the ones that end shortly after a traffic lite. he said he matted it when the lite changed and he almost thought the delivery truck was going to beat him. he said he bought one of these tuners and used it in a stock run simular to his last incounter and found that the timming was extremly retarded until the engine reached a certain rpm

My 2000 GMC had a glich or somthing in the computer that if I backed off the throttle a certain amount then hammered it, it would smoke the tires, but even on wet pavement it would hardly turn the tires if you hammered it from a dead stop.

the other thing is, my son has to have his truck lifted and over size tires on it and over size tires seem to really take the snot out of these trucks. besides needing more hp to turn the tires it seems to confuse the ECU. the neat thing about these tuners is they are alot like the optimum setup we use on the dales. they are a bit pricey but you can add multpul vehicals (some even have a open licens you can buy so it would be like dealer cal) so I'm hopping to have a partner to go in half with me.

one more thing. with one of these units I could have found my problem earlier since the Mass air flow reading would be available.

[cannondale27]

I hear you.There are alot of little things in there that would be nice to access.Now all the trucks are going to come with if your foot is on brake throttle does nothing.How do you do a powerstand with that?For basic code reading and your MAF sensor reading Autozone does it free.Of course they are trying to sell you parts but you are free to look at all the readings and codes.Just dont count on them to make a accurate diagnosis.They tried selling my sister a O2 sensor AND the $150 wiring harness going to it based off a open in O2 circuit!

[MX Quad Dad]

I didn't know autozone could give me a reading from the MAF. I bought the sensor there and was asking a bunch of questions and they never offered anything other than a code reading. and I know the code readers help but, I think they a very missleading. when my son bought this truck it was giving a random missfire (i believe # 6). there was a list of possible causes. I can't remember them all but one for sure was that coil which was simple to elemanate buy just switching coils with another cylinder. anyway I had a 2000 GMC with the 5.3 and we elimnated every thing on the list. a call to a good friend we got the right info which wasn't even on the list from autozone.