Car Forums  

Go Back   Car Forums > Technical Discussions > Repairs & Maintenance
FAQ Search Today's Posts Mark Forums Read

Reply
 
Thread Tools Search this Thread Display Modes
Old 02-04-2005, 06:26 PM   #1
Rad1
CF Newbie
 
Rad1's Avatar
 
Join Date: Jan 2005
Posts: 28
Question Spark Plug wires good method for testing out piston firing...?

Ill explain what my problem is first.

When coming to stops my car will sound like its stalling but never does. I usually put it into neutral to calm it down when sitting at the red light or wherever

When puting the car in gear after a stop it will sound like stalling again until i give it enough gas to get it movin, then it sounds fine once im going.

The only time it seems to stall is when the car has been off for a few hours then I start it and dont give it enough time to warm up and take off, as soon as I accelerate after the first or second stop it will most likely stall out.

Now I had recently just changed my spark plugs and wires. When I did that someone told me to pull out each wire(only 1 out each time) while the engine is running to listen for a difference in sound(engine reving up then down). When i did that each wire i pulled out made a noticeable difference in sound, except for the 6th piston which made no difference in sound wheather it was in or out. Also the wires were sparking fine when puting close to engine block as i was told to check that as well.

My question is. Is that a good method of testing out my pistons firing and if so is that the problem or could it also be somthing else ???

Any ideas is most appreciated, thanks.

oh car is a 91 pontiac sunbird

Last edited by Rad1 : 02-04-2005 at 06:32 PM.
Rad1 is offline   Reply With Quote
Old 02-04-2005, 11:48 PM   #2
Rad1
CF Newbie
 
Rad1's Avatar
 
Join Date: Jan 2005
Posts: 28
ya today was an interesting day.

My car now stalls every time i stop, putting in neutral doesnt even help anymore. I have to keep the engine about 1000 rpm to keep it goin when in neutral.

would a change in temperature outside have effects on an engine cause today was pretty warm 4 Celcius. Since I had the car ive been driving in temp around -2 celcius the highest ??

whatever the case im probably gona bring her in for a diagnostic and if worse comes to worse shell be a turned into a little can cause i cant afford anymore work on this car and its not even worth it.
Rad1 is offline   Reply With Quote
Old 02-05-2005, 01:25 AM   #3
BanffAutoSpa_ap
Pants The Ripper
 
BanffAutoSpa_ap's Avatar
 
Join Date: Jan 2005
Location: Southern Alberta Likes:Long walks on the beach.....after anal
Posts: 1,510
what you were doing is basically a cylinder balance test, either #6 plug is fubar or the cylinder isn't mechanically sound, rings or valves. make sure you didn't mess up the firing order when you did the wires.
BanffAutoSpa_ap is offline   Reply With Quote
Old 02-06-2005, 12:15 AM   #4
srober32
CF Addict
 
srober32's Avatar
 
Join Date: Feb 2005
Location: Detroit, Michigan
Posts: 442
Quote:
Originally Posted by BanffAutoSpa_ap
what you were doing is basically a cylinder balance test, either #6 plug is fubar or the cylinder isn't mechanically sound, rings or valves. make sure you didn't mess up the firing order when you did the wires.
If the firing order checks out, next you need to check the cylinder itsself, using a pressure tester to determine if the valves are working properly and the rings are sealing as well. If you have noticed increased oil usage or burning you might need to have the engine re-ringed. What kind of motor and junk might help determine some of the problems.

Last edited by srober32 : 02-06-2005 at 12:17 AM. Reason: miss spelled what
srober32 is offline   Reply With Quote
Old 02-06-2005, 02:40 AM   #5
Rad1
CF Newbie
 
Rad1's Avatar
 
Join Date: Jan 2005
Posts: 28
Quote:
Originally Posted by srober32
If the firing order checks out, next you need to check the cylinder itsself, using a pressure tester to determine if the valves are working properly and the rings are sealing as well. If you have noticed increased oil usage or burning you might need to have the engine re-ringed. What kind of motor and junk might help determine some of the problems.


i have noticed increased oil usage but that could be cause my block has a crack in it, so i was told by the last owner.
Rad1 is offline   Reply With Quote
Old 02-06-2005, 03:28 AM   #6
BanffAutoSpa_ap
Pants The Ripper
 
BanffAutoSpa_ap's Avatar
 
Join Date: Jan 2005
Location: Southern Alberta Likes:Long walks on the beach.....after anal
Posts: 1,510
wtf.... cracked block and you still bought it, uh huh, junk the motor get a new one dude
BanffAutoSpa_ap is offline   Reply With Quote
Old 02-06-2005, 04:02 AM   #7
Rad1
CF Newbie
 
Rad1's Avatar
 
Join Date: Jan 2005
Posts: 28
Quote:
Originally Posted by BanffAutoSpa_ap
wtf.... cracked block and you still bought it, uh huh, junk the motor get a new one dude

didnt buy it, car was given to me,
car started acting up a year ago but still ran and last owner didnt want to wait for it to die so they bought a new car and gave me the shit box to run it into the ground.. i guess its finally dieing...but i was hoping to fix things myself and not spend much money on it to make it last a little while longer.

crack is a very small, i usually add a bit of oil to it every 500 or more km
Rad1 is offline   Reply With Quote
Old 02-06-2005, 05:11 AM   #8
Wally
I Know More Than You
 
Wally's Avatar
 
Join Date: May 2004
Location: Oz
Posts: 2,564
Quote:
Originally Posted by Rad1
Ill explain what my problem is first.

When coming to stops my car will sound like its stalling but never does. I usually put it into neutral to calm it down when sitting at the red light or wherever

When puting the car in gear after a stop it will sound like stalling again until i give it enough gas to get it movin, then it sounds fine once im going.

The only time it seems to stall is when the car has been off for a few hours then I start it and dont give it enough time to warm up and take off, as soon as I accelerate after the first or second stop it will most likely stall out.

Now I had recently just changed my spark plugs and wires. When I did that someone told me to pull out each wire(only 1 out each time) while the engine is running to listen for a difference in sound(engine reving up then down). When i did that each wire i pulled out made a noticeable difference in sound, except for the 6th piston which made no difference in sound wheather it was in or out. Also the wires were sparking fine when puting close to engine block as i was told to check that as well.

My question is. Is that a good method of testing out my pistons firing and if so is that the problem or could it also be somthing else ???

Any ideas is most appreciated, thanks.

oh car is a 91 pontiac sunbird

You performed an "equalisation of cylinder power" test. Sounds like you have a compression problem on number 6. As it's unlikely the rings would wear at a much greater rate than the others I would be doing a compression test as suggested by srober32. You may have a badly seating or burnt valve or maybe this is the cylinder with the crack in it.
__________________
"She gave me a look only a mother could give a child."
Wally is offline   Reply With Quote
Old 02-06-2005, 05:24 AM   #9
carlos
CF Addict
 
Join Date: Feb 2005
Posts: 273
Quote:
Originally Posted by Rad1
Ill explain what my problem is first.

When coming to stops my car will sound like its stalling but never does. I usually put it into neutral to calm it down when sitting at the red light or wherever

When puting the car in gear after a stop it will sound like stalling again until i give it enough gas to get it movin, then it sounds fine once im going.

The only time it seems to stall is when the car has been off for a few hours then I start it and dont give it enough time to warm up and take off, as soon as I accelerate after the first or second stop it will most likely stall out.

Now I had recently just changed my spark plugs and wires. When I did that someone told me to pull out each wire(only 1 out each time) while the engine is running to listen for a difference in sound(engine reving up then down). When i did that each wire i pulled out made a noticeable difference in sound, except for the 6th piston which made no difference in sound wheather it was in or out. Also the wires were sparking fine when puting close to engine block as i was told to check that as well.

My question is. Is that a good method of testing out my pistons firing and if so is that the problem or could it also be somthing else ???

Any ideas is most appreciated, thanks.

oh car is a 91 pontiac sunbird
personally i wouldn't test the engine with this method cars nowadays run from 50,000 to 70,000 volts through those things. did you get shocked at all? if you didn't consider yourself lucky.
carlos is offline   Reply With Quote
Old 02-06-2005, 05:36 AM   #10
forster21
CF Newbie
 
Join Date: Feb 2005
Posts: 1
ok

all it is, is a bad head gasket which in turn is making the compression go down, when you took out the wire and the noise stayed the same, and you just put in new plugs, then the compression is gone. it is not able to bur the gas well and makes your engine stall. either heve the head gasket replaced or adjust your valves
forster21 is offline   Reply With Quote
Old 02-06-2005, 12:51 PM   #11
PeteC
CF Newbie
 
Join Date: Feb 2005
Posts: 17
Check to make sure the plug is firing. This will rule out something like a bad plug or wire. Get a compression tester and see what's going to with that cylinder. Check for codes - short the two upper right pins on the connector under the dash, turn on the ignition key, and look at the Check Engine light.

For example, if it flashes once, pauses, the two times, that is a Code 12. It will flash each stored code 3 times.
PeteC is offline   Reply With Quote
Old 02-06-2005, 04:22 PM   #12
Rad1
CF Newbie
 
Rad1's Avatar
 
Join Date: Jan 2005
Posts: 28
Quote:
Originally Posted by PeteC
Check to make sure the plug is firing. This will rule out something like a bad plug or wire. Get a compression tester and see what's going to with that cylinder. Check for codes - short the two upper right pins on the connector under the dash, turn on the ignition key, and look at the Check Engine light.

For example, if it flashes once, pauses, the two times, that is a Code 12. It will flash each stored code 3 times.


ya gona do some cylinder tests like others have suggested too.
I believe wires and plugs work fine.

Checking trouble codes I would but as far as i know i don't think i have to check that cause my Check Engine light never flashes when driving so as far as the computer knows i have no problems recorded.
I was told that it would only flash if a problem was stored in the computer, can anyone confirm on that...??

Anyways thank you everyone for your help and advice, its most appreciated and i will test things out through out the weeks ahead and let you know what happens for any future references.

but please keep posting if you think of anything else....


Last edited by Rad1 : 02-06-2005 at 07:56 PM.
Rad1 is offline   Reply With Quote
Old 02-08-2005, 03:54 PM   #13
Rad1
CF Newbie
 
Rad1's Avatar
 
Join Date: Jan 2005
Posts: 28
Quote:
Originally Posted by tbaxleyjr
lf the pontiac had MFI or SFI, need to put a noid light on the injector and see if it is firing. Also need to look for vacume leaks around the #6 cylinder @ the intake and injector o-rings.

If these two checks don't help, then do a compression test and hunt for a head gasket or cracked cylinder.

I managed to fix the stalling for now by buying a new IAC valve the other one was pretty dirty and think wasnt goin in and out properly.

The Car very slightly chokes now but not as much as before. The new IAC seems to have made a big difference but i still suspect the 6th piston is screwed and im still gona test it out when i get the time and money too.

What is MFI or SFI...??

Last edited by Rad1 : 02-08-2005 at 04:00 PM.
Rad1 is offline   Reply With Quote
Old 02-11-2005, 07:16 AM   #14
Blue_Frog
CF Newbie
 
Blue_Frog's Avatar
 
Join Date: Feb 2005
Posts: 86
Lightbulb

Hmmmm I'm thinking, with all that has been said you really have a faulty wire or spark plug on number six. Possibly a dirty plug that cant fire right. You'd be seeing other probs like unusual heating (or overheating), bad milage, and remarkable odors I think if you got any driving out of it at all and it were a valve or piston problem. Not to mention assuredly a backfire or two or REALLY rough engine vibration....especially when starting up or stopping.

Spend the $40 or so for new plugs/wires. Have them gap the plugs at the store for you. I've always found they are better at it than I am. See if that gets any results before you start getting into the block.


PS: After re-looking...I agree with forster21 too. If the simple fix of tuning it up (replacing the plugs n wires) doesnt fix it then dont go deeper into the block. The next logical step is to look at lost compression from a bad head gasket. Good call forster21!

Last edited by Blue_Frog : 02-11-2005 at 07:38 AM.
Blue_Frog is offline   Reply With Quote
Old 02-11-2005, 01:25 PM   #15
Wally
I Know More Than You
 
Wally's Avatar
 
Join Date: May 2004
Location: Oz
Posts: 2,564
Quote:
Originally Posted by tbaxleyjr
MFI - multiport fuel injection
SFI - sequential fuel injection

That could be a bit misleading for a newb. You are mixing the physical with the control method.

Most engines are multi point configuration these days, the choice is between batch or sequential operation.
__________________
"She gave me a look only a mother could give a child."
Wally is offline   Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Forum Jump



All times are GMT +1. The time now is 09:18 AM.

Powered by vBulletin Version 3.5.4
Copyright ©2000 - 2017, Jelsoft Enterprises Ltd.
Copyright 2002 - 2011 Car Forums. All rights reserved.