GNX runs really rough on startup

[rkreigh]

Helping a good friend with his low mile GNX just reconnected with him after working with him a long while back. anyway, he has a nice 700 mile GNX. car runs really rough until it warms up a bit. car mostly sits. no codes. looking for some ideas on tearing into it and trouble shooting it. I have a factory service manual somewhere around but honestly I haven't had to work on my car (for sale) for many years as it runs great (full boogie regal type T, on ebay now)

some of the things I thought to check

stuck EGR valve
injectors gummed up
bad wires, plugs

don't want to just throw parts at it, and my neighbor is a much better mechanic than I am

let me know how you all would best tackle the trouble shooting thanks!

boostamuv!

 

[deezdad]

Sounds like a real piece of crap, I'll take it off his hands for 5 grand and save you the headache ..

 

[notacarlo]

New gas i would assume....or there's some work to be done.

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[GNRick]

Does the idle go up and down, and sometimes just die out? But then after driving around the block, it idles fine? If so, replace the original chip.

 

[chopped39]

Does the idle go up and down, and sometimes just die out? But then after driving around the block, it idles fine? If so, replace the original chip.

When I first bought my car I received a recall notice for the same problem and the dealer replaced the chip for Idle quality.

 

[John Larkin]

Ohm plug wires, should not be more than 1K each.
Ohm coil pack towers, each pair should be between 11K & 13K
Pull plugs and if dirty, replace them (easily can make a car run like crap), stockers were CR44TS gapped to .032" I think?
Remove IAC valve, clean with carb cleaner and resintall.
Check vacuum lines, rub between fingers, if black comes off, they are dry rotted and need replaced - take various sizes to store and get some replacement line.
As mentioned, flush all gas out of the car and replace with fresh - you'll need 6 feet of 3/8" clear hose from home store and a hose clamp + a schrader valve tool for the end of the fuel rail. I presume you know how to pump the gas out using the electric connector behind the a/c compressor. Measure the end of the rail to be sure on that size - working from memory.

That should keep you busy for an afternoon.

 

[rkreigh]

thanks John, this sounds like the right approach and I appreciate the feeback.

I don't think the car is for sale, and certainly not for 5k, but like I said, it's not my car.

 

[TURBOPOWERED68]

Why are you running the engine? Aren't GNX's supposed to just sit in garages for ever?
My car does the same crap every once in a while no matter what chip is in it, Good luck with the fix.

 

[notacarlo]

I have a GNX HI-FLO chip. I think its a pre-90's chip. Can't remember why I have it.

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[rkreigh]

guys, again, it's NOT my car :> wish it was. I offered to trade him my 133k mile T for it straight up :>

he might be interested in the chip. let me know if you can find it and what you need for it

are the stock GNX chips with the code fix still available. he's kinda anal and wants to keep it bone stock

GNX or not I would hot rod that B in a blink and have another 9 sec buick

 

[TRICKSIXPA]

Tell him to get in his car and take it for a spin I'm sure it will clear up the idle. Is his battery dead when he goes to turn it on? It might be taking sometime for the computer to learn and adjust. When was the last time 02 sensor was replaced.


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[X Ray]

Replace fuel filter (not as easy in a GNX)....new gas...drive it....

 

[John Larkin]

X Ray, when did you work at ASC? Was it in Southgate, MI?

 

[X Ray]

X Ray, when did you work at ASC? Was it in Southgate, MI?

82-2000....yes Southgate.

 

[notacarlo]

All I know is that it is an updated chip. Not sure if the "hi-flo" is actually a GNX chip. I've had it for 20 years. You can have it. Pm me an address and I'll send it. That way if it doesn't work, neither of us are out anything

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[whitehot1]

Maybe if he drove the car a little more it would clean itself up and run better.

700 miles in 26 years what's that, about 3 tanks of gas with in town driving.

 

[John Larkin]

82-2000....yes Southgate.

I dated a girl that was a secretary there in 1992 - 1993. Slim, Mexican heritage. She had a purple Thunderbird. And that's not a clever allusion. Her name was Jacquie.

 

[usetaboost]

could just be a gummed up iac

 

[Phoff]

Check the plugs. If he starts it up every couple weeks without driving it, the plugs could be fouled.

Like xray said...new gas and drive it. get on the highway and open it up a couple times. Only after new gas of course.

Pete

 

[TurboBob]

Gnx hiflow chip is a race chip, aftermarket, do not run it. If the.car is rarely driven then the wastegate hoses should be checked before making full throttle tests. Clean the injectors, New plugs wires and coil, look for vacuum leaks,

Bob

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