5.3 misfire????

02cadiHOE · Oct 27, 2007

ok my 02 tahoe has the 5.3l flex fuel. ive had it for about 6 months no problems. but just the other day it started to feel like it was losing just a little bit of power not much but noticable and it would shake at idle. finally it through a code and it said misfire cylinder 4. had my mechanic look at it briefly and he said i should change the plugs. did that and didnt help then i bought an ignition coil for that cylinder and that didnt help then wires and that didnt do anything. i even tried moving a coil from a different cylinder thinkin that the new one was bad but you guessed it, nothing. so my question is wtf is the deal with this 4th cylinder!!!??? i dont know what else to replace..... HELP!!!

johnebgoode · Oct 27, 2007

Find a mechanic with a Tech II or similar type scanner. Let him plug in to your computer and find out exactly what's wrong. Might be an injector, who knows. Guessing is useless with computers cars today.

JKmotorsports · Oct 27, 2007

Check the connector and wiring that plugs into the ignition module to make sure you have a good connection and that the coil is firing.

02cadiHOE · Oct 28, 2007

im pretty sure that the coil isnt getting the signal or voltage it needs...connection at the coil looks good. where exactly is the ignition module?

johnebgoode · Oct 28, 2007

The ignition module or ECM as it is sometimes called is located on the L/F wheelhse panel. It is an aluminum finned case with 3 plugs going to it.
Looks similar to these:
http://www.vectormotorsports.com/

Rumplemenz · Oct 28, 2007

02cadiHOE said:
ok my 02 tahoe

think you will get better answers in the older model forum... this is 07+

anyway.. wish i could be of help.. dont have the answer

wedtwuk · Nov 2, 2007

Where did you get an 02 with a 5.3 Flex Fuel engine? Flex Fuel wasn't available on the 02 models.

02cadiHOE · Nov 2, 2007

i got it used from joe ball pontiac gmc... 2002 chevy tahoe 5.3l v8 vin code Z flex fuel (E85)... easily the first of its kind.

also my misfiring problem was due to a faulty fuel injector not dumping enough fuel... found an aftermarket one for $107 and it only took about 15 minutes to install!:thumbsup:

JKmotorsports · Nov 2, 2007

Cool. Glad you fixed the problem:thumbsup:

02TAHOELT · Nov 3, 2007

wedtwuk said:
Where did you get an 02 with a 5.3 Flex Fuel engine? Flex Fuel wasn't available on the 02 models.

I also have a 02 with the Flex fuel motor

Nappers · Nov 3, 2007

I have an '00 Yukon, with Flex fuel............flexing upward gas prices

Glad you got her fixed.

Aaron

JKmotorsports · Nov 3, 2007

wedtwuk said:
Where did you get an 02 with a 5.3 Flex Fuel engine? Flex Fuel wasn't available on the 02 models.

Flexfuel was available on later 02 models with the "Z" vin. I found this out not too long ago myself. I originally thought it was only available in 03-up models, but I had one come into the shop a few weeks ago with a "Z" vin and I cross referenced it. Sure enough, later 02 models were Flex Fuel friendly.

raiderrick · Nov 4, 2007

SELL IT!

brdnboy · Dec 13, 2007

would an aftermarket granatelli maf cause the same issues? The maf sensor is clean, and i only have the issue when the engine is cold and hasn't been run for a while. It didn't do this when i first installed the maf but that was earlier in the year when it was warm outside. Since its been cold the hoe has rough idle and almost dies. It drops to 300 rpm and the computer recognizes its dying and revs it back up to 1000 ish. The engine shakes at idle until at operating temperature. My first thought was plugs or injectors but what do you guys think? Could it be the MAF? i don't have a CEL or SES. Would there be a code to check even if these lights wern't lit. I dont think any engine mounts are broken so could it be a misfire causing the shake. If so why doesn't it shake once it warm? Any help is appreciated.

brodg · Dec 13, 2007

you need intake gaskets there is a new design out to solve this problem. you get a vacum leak until the gaskets expand when at operating temp.

brdnboy · Dec 14, 2007

brodg said:
you need intake gaskets there is a new design out to solve this problem. you get a vacum leak until the gaskets expand when at operating temp.

Is this somthing i could do in a few hours or should i let the dealer do it? I can get the gasket for about $70. Are there any special tools required? Because i believe i am capable of a gasket swap if nothing special is involved. Thanks

brodg · Dec 14, 2007

its pretty easy the hardest part is disconnecting all the wiring and pulling it up out of the way once you do this its 8 bolts and a couple hoses at the throttle body.

5.3 misfire????

02cadiHOE

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