Real fed up...stumbling/pinging (I think)

[angrysnowplow]

When it had the manifolds, this was not a problem.(Even though it ticked like a mofo) I recently put on a set of Flowtech Afterburners. Threw in a new O2 sensor for good measure ($20.00) Read up on heated O2's, decide I need one because my O2 is in the collector ($65.00!!) but still runs like crap./forums/images/graemlins/angryfire.gif Starts and idles good, but on light throttle will chug, stumble, and make no power. It bogs down, let off the gas, it recovers. Like it did when my map sensor went. /forums/images/graemlins/thinking.gif Get on it and it will go; albeit crappily. Doesn't smoke, don't think it's rich. Plugs are new. No Check engine light. /forums/images/graemlins/1zhelp.gif
Oh yes, and after it's been driven it will shake at idle.
Ideas greatly appreciated. /forums/images/graemlins/1zhelp.gif

 

[bckinblk]

I just went through this whole ordeal I replaced all kinds of parts to find it on my 88 .It turned out to be a chaffed rotten wire grounding out on the intake manifold .I missed it several times .I would recommend looking at all your vac lines -replace them all if they are dry rotted .Then when it gets dark out pull off your air cleaner and start it up .You might be able to see an arching wire if thats the problem .. Also is your truck throwing any codes??.Also check fuel filter and fuel pump ..Good luck dude ..

 

[angrysnowplow]

I put in a new fuel pump last winter, maybe I'll pick up another filter. I don't think it is throwing any codes. The light flashes once followed by 2 short flashes; and keeps repeating this. (That's code 12, right?)
That's a good tip about the arcing wires, I gotta do that. /forums/images/graemlins/thumb.gif
I read your posts, at least I know there is someone else that knows how frustrating this is /forums/images/graemlins/angryfire.gif /forums/images/graemlins/angryfire.gif /forums/images/graemlins/angryfire.gif /forums/images/graemlins/angryfire.gif

 

[thefarside]

I needed a carb rebuild. That always seemed to cure most of my performance problems. Also, I spent the time to redo all of the vac lines. It was a pain but the truck ran a hell of a lot better. Got to love preventative maintenance.

 

[angrysnowplow]

Whoops, my bad. /forums/images/graemlins/shocked.gif I forgot to say it's a '90 TBI. Replacing vacuum lines is probably a good idea though.
BTW welcome to the site /forums/images/graemlins/thumb.gif

 

[thefarside]

[ QUOTE ]
Whoops, my bad. /forums/images/graemlins/shocked.gif I forgot to say it's a '90 TBI. Replacing vacuum lines is probably a good idea though.
BTW welcome to the site /forums/images/graemlins/thumb.gif

[/ QUOTE ]

Thanks!

 

[bckinblk]

Yes it is sending a 12 code consecutively .It means that all systems are normal Also have you changed your egr valve ? I read many posts that the egr or the egr selonoid was the culprit .And also pull out your Idle Air Control valve .Clean out the orafice and pintle with throttle body cleaner .That helped alot on mine it was full of carbon. and when you get it back together .Leave off the air cleaner and start it up .Then spray the cleaner around the base of the throttle body and see if it changes the idle.If so then you could have a bad TB gasket..

 

[dyeager535]

Scanner and the right GM manual.

 

[angrysnowplow]

[ QUOTE ]
Scanner and the right GM manual.

[/ QUOTE ]

But it just flashes code 12...or does that have nothing to do with it /forums/images/graemlins/confused.gif

 

[jmd]

[ QUOTE ]
Scanner and the right GM manual.

[/ QUOTE ]

/forums/images/graemlins/cool.gif


[ QUOTE ]
But it just flashes code 12...or does that have nothing to do with it /forums/images/graemlins/confused.gif

[/ QUOTE ]

Watching live data is important. Scanners are NOT just for reading codes; that's what the magical paperclip is for. /forums/images/graemlins/k5.gif /forums/images/graemlins/thinking.gif

 

[Thunder]

Reasons to get a scanner/manual:
Just because the computer has no codes stored doesn't mean you dont have a bad sensor or something.
For instance: Your TPS may be telling the computer it is OK. But in reality it may have a dead spot in the circut while accelerating that the ECM cant see. When you press the gas the TPS may only be telling the ECM to give only enough gas for idle. This will cause a lean condition.
If you have a scanner you will be able to see the voltage rise when you press on the gas. If the voltage stays the same or drops as you press the gas you would know the TPS is bad.( you can also do this test with a DVM)
You can also see if all the other sensors are functioning properly. The ECM only tests sensor function under certain circumstances. If the sensor meete the function test it will set no codes but it can still be bad.
A scanner wont tell you everything that is worng with your engine. But it will tell you what is working right which will save you from needlessy replacing parts.
An AutoXRay scanner is around 150.00 and will pay for its self everytime you use it. They can also be upgraded for any vehicle including OBD 2. I have one. It has sure saved me many hours of frustration dealing with all my FId cars.

 

[angrysnowplow]

Wish I didn't just spend $730 on a soft top and roll bar /forums/images/graemlins/blush.gif
I will definitely look into one of those thanks /forums/images/graemlins/thumb.gif
A "dead spot" in an ECM circuit makes sense in my mind...seems to go along with how it acts /forums/images/graemlins/thinking.gif