96 Vortec stumble/miss after changing intake gasket UPDATE PROBLEM SOLVED

[MOABDADC22]

I posted this in the garage too, but figured maybe you guys/gals could help.

I just got done changing the intake gasket /forums/images/graemlins/angryfire.gif /forums/images/graemlins/angryfire.gif on my 96 Tahoe (5.7 Vortech.) Now it has a very noticible miss. The "Check Engine" light flashes on/off at a steady rate.

All hoses/wires are in the correct spot. I have sprayed the intake with carb cleaner to check for a leak with none found.

I did get the distributor 180 degrees off on the first attempt (DUH....) but pulled it and put it in the correct spot. I am pretty sure that the base timing is set right at 0 degrees. Is this correct?? I guess I could go fire it up and turn the distributor a little and see if that cures it. If it does.......how do I clear the trouble codes??

Any help would be greatly appreciated. /forums/images/graemlins/thumb.gif /forums/images/graemlins/thumb.gif

 

[MOABDADC22]

Re: 96 Vortec stumble/miss after changing intake gasket HELP

I forgot to add that the engine runs pefectly smooth for about the first 2-3 seconds after I start it, then it develops the miss.

It ran like a top before I changed the gasket.

 

[heavy4x4]

Re: 96 Vortec stumble/miss after changing intake gasket HELP

With the engine running - grab some of your spark plug wires and move them around (not disconnect them, just move them around) - see if that does anything. You may have some wires laying on eachother and the charge going through one wire get's crossed with/taken by another wire. /forums/images/graemlins/confused.gif /forums/images/graemlins/confused.gif Worth a try. Also, re-check the placement of the sparkplug wires on the cap. If two of them are mixed up, you'll get miss-fire like you described. I know you said you have them right - but just check again *trust me* /forums/images/graemlins/smirk.gif

 

[MOABDADC22]

Re: 96 Vortec stumble/miss after changing intake gasket HELP

OK, I scanned the codes with an OBDII and got P0102 (Mass Air Flow sensor Circuit Low Frequency) and P0304 (Misfire on #4 cylinder). soooooo....I am thinking that the # 4 intake gasket area did not seal/seat good enough and that is causing the MAF to detect air leaking in and then causing the #4 to misfire??

Am I way off base or what??? I will probably buy another gasket and start over. (At least now I know that I can change the gasket in under three hours) /forums/images/graemlins/thumb.gif

Thanks for the replies /forums/images/graemlins/deal.gif /forums/images/graemlins/deal.gif.......keep them coming since I will read them again in the morning. /forums/images/graemlins/thumb.gif /forums/images/graemlins/thumb.gif

 

[ntaj*ep]

Re: 96 Vortec stumble/miss after changing intake gasket HELP

I'm starting off here ignorant to your skill level so bear with me. The Vortec engines use a SPFI(sequental port fuel injection) system which is diffrent than other GM style systems in that your injectors are firing with the firing order. The other systems fire a bank of injectors at a time not just one. Anyhow your codes tell me a few things. I would start off with the basic(easiest) stuff first. Make sure your ign. wires and injector wires are all connected to the correct cylinder. I think your good here, but check it anyway. One word of advice, do not use carb cleaner on a running feedback fuel injected motor, use intake air fuel injection safe stuff. /forums/images/graemlins/thumb.gif
With the style of gasket the Vortecs use I'm not surprised you couldn't get a change, however I don't know how bad the miss is either /forums/images/graemlins/eek.gif. The torque on the intake bolts if I'm not mistaken is like 15-20 ft-lbs. Not alot to get them tight, so keep this in mind as well. When/if you remove the intake again look for hair line cracks in the plastic (just to let you know your doing a good job, and found it) /forums/images/graemlins/thumb.gif
Hope any or all of that helps you. /forums/images/graemlins/thumb.gif

 

[finnd]

Re: 96 Vortec stumble/miss after changing intake gasket HELP

verify all the fuel injectors are hooked up correctly and working. You may get a gassy smell if one is dumping. Check the plug for that cylinder as well to see if it is getting really fouled.

 

[MOABDADC22]

Re: 96 Vortec stumble/miss after changing intake gasket HELP

Ok, I was right....the intake gasket was not sealing on the #4. I think the gasket slipped down and out of alignment when I lowered the intake. All fixed now.

How do I clear the trouble codes now and get the check engine light off?

 

[90K5]

Re: 96 Vortec stumble/miss after changing intake gasket HELP

disconnect the battery

 

[89K1500Chevy]

Re: 96 Vortec stumble/miss after changing intake gasket HELP

Its an OB2 com so youll have to go hook it up to a scaner to clear the troble codes if it were OB1 then yes the battery trick could work but its different with OB2