Display Diagnostic Solved But Problem Not Fixed

[Filobedo]

But, Does the car need to be running or just the ignition on?

Problem is the car stalls & cuts off at start-up but, drove & idled fine.

That was a couple weeks ago.

Now it's shuddering under acceleration. Like the engine & Trans are gonna fall out. I did'nt have this problem until I changed plugs from AC-Delco .060 to #3 Rapidfires .045 {but that's on another post}. I have researched many Posts now and there is a LONG list of probable causes. {other than the plug change}

I would like to narrow this down with the display diagnostic before I start replacing parts. I am on disability and can not afford to just throw money at it, but I did order a new set of wires from gmpartsdirect. They have not arrived yet. The heat shields, plugs & "old" wires are installed correctly. Although after my initial inspection one of the plug wires was laying on the Oxygen Sensor & lead wire. Would that damage it? Or cause this?

PS: If it's a biggie there maybe a Reatta with GNX fender louvers and GSX emblems for sale in Gretna,Va.

[Guest wally888]

I had a similar problem( eng. rough) after changing wires and plugs. Is easy to get wires on wrong! Recheck the cylinder #'s, I had reversed going by picture in FSM.

On my 91, if the IPC has a problem, I can't enter diagnostics. Upon pressing Off and Warm, you get a flash of the IPC lights but the diagnostics doesn't work (goes back to normal display). 88/89 , of course has touch screen, 90/91 does not. May be very different?

There may be other causes of not being able to enter D. Hope others answer.

[padgett]

I always look at what was done just before the problem occurred. Suddering on accelleration (particularly light acc. from 50ish with TCC locked)and no codes says to me "secondary ignition" (coilpack, plug wires, plugs). If you just changed plugs, maybe one is bad (cracked insulator ?), not completely seated, or a wire is now shorting (run in the dark, look for sparks) at least that is where I would look.

[Filobedo]

Wires & shields not wrong... Did them one at a time. But when the new Wires arrive. I do plan to regap the #3 Rapidfires to .060 I know im not supposed to but,

At this point. I dont care... It ran better and faster with AC-Delco .060 even with the old Magnavox Coil. Next time I will buy #14's. As I feel that this gap & plug change is the cause of all of my problems. The car ran like a Champ before.

[Filobedo]

Thanks Padget, Will do tonight. Wires should arrive Monday. Thats when I will pull the plugs & recheck everything.

PS: I used to own a `70 GS 455 just like the one in your pic. No enduro bumper but, it's erie how much they look alike. Her name was

`LiL Cindy. Her & My Grand National were lost in a messy divorce

[Filobedo]

Finally got into the Display Diagnostics. Pressed "Off & Warm" for what seemed to be an eternity. This is what I got: History B446 & B552.

No ECM or CRT Codes.

I also noticed that the inverted triangle "Pointer" over 'OXY' was lit.

Does that mean that the 02 Sensor is my problem?

Also displayed '0.40 TPS ED01'.

Thanks for any and all help. Am at my wits end

[padgett]

That's not an endura bumper on my '70. Was a GMI student in Flint at the time and was able to get a bumper that had not been chromed and had it painted body color. Number of people at Buick saw the car and apparently liked the effect.

That Buick was set up for and won a lot of autocrosses including embarassing a number of Z-28s. My later Sunbird V-8 did the same to a lot of Porsches 8*).

[Filobedo]

I think moving the Spark Plug Wire away from the 02 Sensor & Wire has solved the Shuddering and Starting problem. I Hope! Thanks everybody for your help