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too many toys
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1,206 Posts
Discussion Starter · #1 ·
The car was stumbling and stuttering and the fuel pressure was all over the place.So I installed a Walbro 340,a new filter and the ground upgrade kit.Nothing changed.The car is still stumbling(feels like a lean miss)and missing.Im getting strange readings on the scanmaster-when the car stumbles,I get all sorts of crazy numbers across the screen.Also,the o2 readings are below 100.The car also has a slightly rough idle.I did the tap test on the mass air sensor while the car was running and nothing changed,but when I unplugged it the idle it smoothed out.When I plugged it back in the car stalled.I took the sensor out of the car and found a greasy,filthy mess inside.After cleaning it with electronic cleaner the car seems to run better.It still has the same stumbling problem just not nearly as often.Bad mass air maybe?I really need some ideas here.I dont have anybody to trade parts with and chasing gremlins is starting to get expensive :confused:
 

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Lotsa G-Body Parts
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1,411 Posts
I think you answered your own question I can't believe there is nobody in Staton Island with A GN or T to help you.I know there are alot of GN's in that area.If all else fails shoot me an e-mail I'll send you 1 up to test with if that's it I'll sell you 1.
You might want to post in the regional section of the board it would be faster then me shipping you a mas air.
 

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too many toys
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1,206 Posts
Discussion Starter · #3 ·
Thanks for the offer,but I already replaced the mass air meter.Didnt do a thing.Car still stumbles and misses.The o2 readings are still below 100.At certain times the with the car idling,the numbers dont move or it hangs around 085.If I floor it,the o2 shoots up to 830+.I dont get it. dunno
 

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43,735 Posts
What are the maf readings at idle?

Have you checked for vacuum leaks or exhaust leaks before the turbo?
 

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too many toys
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1,206 Posts
Discussion Starter · #5 ·
I just changed the o2 sensor as the old one was the original.Im still getting strange readings though.When the car stumbles I get about ten digits across the screen on the scanmaster.Sometimes the scanmaster goes blank during a stumble.During the last episode the scanmaster went blank and my radio shut off.During part throttle cruising the car is fine except for the low o2 readings.Is it normal to let off the gas coming off the expressway and get readings from 003-050?The stumbles have no effect on anything else in the car,just the radio and the SM.I dont know what else to change or look at. :confused:
 

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Premium Member
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Sounds like you have a loose connection...have you verified the grounds on the back of the head, etc? That will certainly cause a stumble if the wrong thing is loose.

Yeah, it's normal to go lean when you take your foot off the gas.
 

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too many toys
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1,206 Posts
Discussion Starter · #7 ·
The grounds on the back of the head are tight.I was thinking maybe something with the ignition switch?(due to the radio turning off then coming back on after the stumble)I shook every connection I could find with the engine running and nothing happens.The scanmaster shows no codes.The one piece of good news is with the new fuel pump I was able to make a full pass without any knock.Now all I got to do is fix the stumble before I lose my mind! crazy
 

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How bout the battery cable to the starter? Any sign of it being pinched when the engine moves? Is it tight? The ground to the sheet metal from the battery? The ground from the battery to the turbo support bracket?

And, what are the mafs at idle? Did you use a rebuilt maf? About a 75% change it is not calibrated properly.
 

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too many toys
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1,206 Posts
Discussion Starter · #9 ·
The MAF is a rebuilt one.The AF at idle is 03.As far as the grounds-there is no ground going to the turbo heat shield.I will install one.As for the stumbles,when the car stumbles and the radio and scanmaster shut off its like I cycled the key.The antenna starts to go down then comes back up and the SM has 2.1 with the dashes on the screen.But I dont lose radio memory and it does not affect the headlights.I will look for pinched battery wires and install a new ground and then I will pray to the GN God.Hope it works. frown
 

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The main battery ground cable normally goes to the support bracket-sometimes people put it elsewhere, but, it should go to the block somewhere.

There should be a pigtail off the the main ground cable that goes to the inner fender sheet metal as well.

Be sure the positive cable is tight at the starter and that the group of fusible links that also attach to the starter post are held tightly along with the positive cable.

Be sure the ecm connectors are pushed all the way down also.
 

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too many toys
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1,206 Posts
Discussion Starter · #11 ·
Well I looked the car over and found some things.First the ground cable goes to the block so thats okay.The positive cable is another story.The cable goes from the battery and down to the cradle,over the cradle and down to the starter.The problem is where the cable runs across the cradle is very close to the downpipe and header.The cable is burned and exposed to the pipe.When the engine torques over the pipe was touching the cable and wala-instant short!The cable appears to be routed in the factory location.My question is can I get a longer cable that I can reroute so this doesnt happen again?The car has aftermarket headers although I dont know what brand and the bigger pipes reduced the clearance. powersix
 
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