87 Gn engine mis firing when at wide open throttle

[jimmarla]

I have a 87 Buick GN, 95k original miles, all stock, cat delete, starts, runs, idles great, when under a load or at wide open throttle, it misses like crazy! Any suggestions? Thanks

 

[fitz3820]

We need more information - it does not sound like you have a scan tool or anything to monitor knock, O2, etc. Also need to know fuel pressure, boost, chip, etc.

For now, no more full throttle blasts until you know what is going on, you could be doing some MAJOR damage if your misfire is knock/detonation...

 

[jimmarla]

Ok, I dont have a scan master etc., I had it out this am just driving it before all of the heavy rain gets here. I will stop doing the wot thing. I just do it breifly trying to hope that maybe it had bad gas etc in it. I just bought this 1 a couple of days ago, just trying to figure it out. Thanks for any and all the help!!!!!!

 

[GSX-PKV]

That sounds like it most likely is the coil.

 

[Amelio]

Ok, I dont have a scan master etc., I had it out this am just driving it before all of the heavy rain gets here. I will stop doing the wot thing. I just do it breifly trying to hope that maybe it had bad gas etc in it. I just bought this 1 a couple of days ago, just trying to figure it out. Thanks for any and all the help!!!!!!

Congrats on your purchase and welcome to the board!

Start doing a lot of reading on here, there is a ton of info plenty to make your head spin! A scan master is atleast the ver basic scan tool you need to have. Doing WOT blasts where there is a problem and trying to diagnose it without a tool is a sure way to hurt something.

Until you get a scan master you can check over some basic things.......look at the plugs are they shot...if so put in new ones, plug wires too. Also look over all the vacum lines they are old even if the car is in great shape these old rubber lines get britle and can have tiny pin holes which will cause all kinds of problems. You can also verify fuel pressure if you have a fuelpressure gauge.

If you did not get any info from the previous owner regarding what has been done to the car you can do a search on here for the "spring cleaning" this is a good starting position.

Good luck!

 

[TurboDave]

Based on the info given, It sounds very likely the the coil pack/module might be on the outs.

 

[QUIP'6']

i would have to guess maf but could be coil pack. try disconnecting wastegate and see if it breaks up under wot. if it does i would say its the maf sensor. but first do a spring cleaning from www.gnttpye.org

 

[RIFF RAFF]

Spark plug gap would do this also ..

 

[jimmarla]

Thank you guys so very much for replying to my thread! I went to a local auto parts this afternoon and got a new fuel filter and a set of plugs. Got those installed, it had no bottom end at all, ran like crap! i drove back to the auto parts "Oreilly Autp Parts", and ask them again what was the gap I should put on the plugs. When I first got the plugs, they told me to gap them 060, I thought that was a bunch but I didnt question them, when I went back and told them that it ran alot worse than it did before, they said couldnt believe that it would run worse, I asked them for the 2nd time to look it up and see what the gap should be, guess what, they came back with 035!!!! Havnt had time to uninstall and re gap , my lil 3 yo baby girl had a list of things for me to do! Oh well, hope to get it right VERY soon!!! Thanks again so very much for everyones help!!!!!! Thanks again

 

[Madmustard]

I had the above problems with a ( brand new) but defective bad plug,old wires and a coil issue...Anymore to have a new set of plugs and wires and coil and module is essential on these cars if you ask me... If you do the above you just eliminated a ton of problems and gremlins down the road if your gonna be whoopin on it...just my 2 cents worth..

 

[jimmarla]

Ok, just got in from my shop, I took the plugs out and gapped them 035. Then, before I even test drove it, I took them back out and gapped them at 032. I took out, it started, ran and drove fine, It had the bottom end back into it, BUT, if you gas it hard, it still misses but not as bad! I guess next I am going to install a fuel pump and a coil. i would hope that I may be getting a lil closer to getting it figured out! I bought this car to give to my 6 week old baby girl! I have another 87 GN 'Bone Stock' that I gave to my 3 yo baby girl! Of course my wife looks at me like I have lost my mind! I'm 41, she's 28!! LOL I love the GNs and she thinks they are mullet mobiles!! Its ok, my lil girls will probably laugh at them when they get older, but thats ok also!!! My 1st car is in the garage beside the Gns. mY MOM AND DAD bought it new, its a 69 Dodge Charger RT/SE, 45k original miles, never anything done to it but 1 repaint!!! Maybe my lil girls will appreceiate their old GNs 1 day the way I apreceiate my old Charger, well, my mom's old Charger! Anyway, thanks again for all of the help!!! Happy Early Thanksgiving!!!!

 

[TurboDave]

To clerify; missing/sputtering, acting up at WOT "generally" points to a failing coi pack or ignition module. If you have similar symptoms with virtaully ANY throttle apply, IOW car just doesn't want to go, then the maf is more likely the culprit. And as you've found, widely gapped plugs can cause odd issues.

 

[jimmarla]

You are exactly right! I had an exhaust system installed on tit today. I had a 2 1/2 in with Turbo mufflers, DANG IT, I believe it runs worse!!!!!!!!!!!!!!! After i had the exhaust installed, I had to come down a long hill, I left it in Drive, not overdrive, when I got to the bottom of the hill and gassed it to continue on, it bucked and jumped like a horse!!! WTF!!!! After a couple of minutes of driving, it went back to its normal surging, also when you are in OD, 45 mph plus, when maintaining speed, it surges back and forth! It seems like it cant make its mind up, Over drive or drive, over drive or drive! That never stops!! O well!!!! GThanks again for all of the help!!!

 

[xrunner123]

...also when you are in OD, 45 mph plus, when maintaining speed, it surges back and forth! It seems like it cant make its mind up, Over drive or drive, over drive or drive! That never stops!! O well!!!! GThanks again for all of the help!!!

That sounds like the converter locking and unlocking.

 

[meanchicken]

Like previously mentioned...start here The Grand National / T-Type / Turbo Regal Buick Spring Cleaning Guide and then start trying to find any issues if it still aint running right. Invest in the scanmaster first thing before you start any upgrades and read through this website as if your life depended on it!

If you go to some of my earliest posts...you'll see I was in the same spot you are....my first issue which had the same symptoms you started the thread with was the coil pack wa shot. You can check that by measuring resistance across each coil from tower to tower (front to back) and should see 11-12Kohm.

Good luck and enjoy it...but don't break it before you get a chance....gotta stay on top of your maintenance and tune with these cars....


I also agree that the OD at 45mph is just your converter locking unlocking....prolly normal....

 

[Lateralus]

Ohm out your plug wires to see if they are all good.. I had the same problem once after I had replaced the module and found 2 plug wires to be bad. New wires solved the problem.

 

[TurboBuRick]

Sounds like a couple different problems.

1: Ignition issue.

2: Torque converter solenoid.

What brand ignition module is on the car? I'm betting it's not ac delco. These cars are real finicky on the ignition modules. Aftermarkets do not work like OE.

You can unplug the connection on the side of the trans to test the converter solenoid. Take it for a ride see if it still bucks but I would get the ignition ironed out first.

HTH

RL