Rattle at high rmp...is it detonation? is my motor pooched?

jshot

Member
Aug 8, 2018
80
10
8
37
Ontario, Canada
Owned my first grand national (87) for just about a month now, new to fuel injection and turbos.

this has happened about 5 or 6 times. this does happen time at high RMP 2'nd and 3'rd gear. first gear shift before high rpm. thinking around 5k, there is a rattle sound then i let off. No i am reading all about detonation. I hope this is not the case. Have i pooched my motor with detonation?

before i bought the car it had only a few thousand miles on in the last couple years. If it is detonation i am sure with a lot of persistence and MONEY i can figure it out i am sure it needs a fuel tune up and i have a crack in the drivers header which i have learned is normal. the question is there damage now.

i will drain the oil tonight and look for metal. there was no metal in the oil when i first changed the oil when i got the car, but it probably wasn't too old. NO SCANMASTER YET Will order ASAP
 

williambavila

William Avila (The Buick Guy)
May 11, 2010
556
80
28
40
Moore OK
Yes that's detonation. Just a matter of time before the insides are on the outside

Sent from my SM-N950U using Tapatalk
 

mikestertwo

Well-Known Member
Sep 13, 2006
5,098
157
63
118
Warren, Oregon
this has happened about 5 or 6 times. this does happen time at high RMP 2'nd and 3'rd gear. first gear shift before high rpm. thinking around 5k, there is a rattle sound then i let off. No i am reading all about detonation. I hope this is not the case. Have i pooched my motor with detonation?
Keep your foot out of it until you find out what you have. Is the car all stock? What chip is in the computer? Any mods?
 
  • Like
Reactions: mr84ss

jshot

Member
Aug 8, 2018
80
10
8
37
Ontario, Canada
Keep your foot out of it until you find out what you have. Is the car all stock? What chip is in the computer? Any mods?
as far as i know the car is stock. all i know is it has the hot wire kit. It even has the original coil pack (sticker on top). No mods that i can see. I will have to check the Chip.
 

williambavila

William Avila (The Buick Guy)
May 11, 2010
556
80
28
40
Moore OK
You can get some great info on the link posted above and this site. Just be careful of what you are told and who tells you.Have a great day and good luck
 
  • Like
Reactions: mr84ss

mikestertwo

Well-Known Member
Sep 13, 2006
5,098
157
63
118
Warren, Oregon
how can i tell if the damage is done?
If it's still running ok with no strange noises the engine is most likely ok. The stock pistons are pretty tough. If there is no erythematic noise from the bottom end your rod bearings are ok. Sounds like you were letting off of it as soon as you heard the noise. Most damage is done from prolong states of detonation. I'm sure your ok. Just stay out of it until you find out what you have and make the necessary adjustments to keep it out of detonation.
 

williambavila

William Avila (The Buick Guy)
May 11, 2010
556
80
28
40
Moore OK
who did you buy the car from maybe they can answer some questions rather than a bunch of folks that dont know what the combo is. I would start there or give us his\her name we probably know them
 

williambavila

William Avila (The Buick Guy)
May 11, 2010
556
80
28
40
Moore OK
Get rid of that stock chip and get one from Eric @ Turbo Tweak . The original chip has to much timing for todays gas and you car will run much better with a TT chip . Get that header fixed also .
what timing is the stock chip set for?
 

jshot

Member
Aug 8, 2018
80
10
8
37
Ontario, Canada
If it's still running ok with no strange noises the engine is most likely ok. The stock pistons are pretty tough. If there is no erythematic noise from the bottom end your rod bearings are ok. Sounds like you were letting off of it as soon as you heard the noise. Most damage is done from prolong states of detonation. I'm sure your ok. Just stay out of it until you find out what you have and make the necessary adjustments to keep it out of detonation.
ok i drained oil and removed the filter. i did not see anything that scares me. definitely nothing magnetic as i ran it into a magnetic pan and let it sit. Nothing. had a few shiny flecks but i could count them on one hand.

what do you mean by "erythematic noise ". i took a video for the audio of it at idle. ignore the rough idle and header leak at this time. here is a link to the video

 
Top Bottom