Spark plug change-Won't stay started

huntin5L

Member
Mar 31, 2005
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Niles, IL
So I am not sure yet what the deal is, I fixed a huge boost leak and the car began to run a lot better with NGK coppers installed, but it still had a slight miss. I decided to put in some NGK BCPR7EIX iridiums (didn't gap them) in hopes that would stop the miss and the idle bounces just a hair just above 500 rpm and the headlights, car lamps all flicker and it ran like crap. Thought maybe it was the isvc, but that seems to click when the engine turns off. I decided to unplug it to see if it made a difference and now my car is hard to start and if it does start it won't stay started unless I am on the gas. I did have oil in the spark plug galleys and decided to take everything a part and clean all the plugs and spark plug galleys, but that didn't make a difference. At a loss.

I don't know if they could be these plugs or not, nobody around here has the NGK coppers in stock, I will have to special order them.

Could this be because of these plugs? I pulled all the plug wires from the coils and they all seem to be sparking.

Link to plugs I bought, strange thing is the "Make sure it fits" section under the product says it won't fit my model year supra. I bought them anyway.

http://www.amazon.com/gp/product/B000GZGV4I/ref=ox_ya_oh_product

Any help is much appreciated.
 
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huntin5L

Member
Mar 31, 2005
657
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Niles, IL
huntin5L;1467212 said:
So I am not sure yet what the deal is, I fixed a huge boost leak and the car began to run a lot better with NGK coppers installed, but it still had a slight miss. I decided to put in some NGK BCPR7EIX iridiums (didn't gap them) in hopes that would stop the miss and the idle bounces just a hair just above 500 rpm and the headlights, car lamps all flicker and it ran like crap. Thought maybe it was the isvc, but that seems to click when the engine turns off. I decided to unplug it to see if it made a difference and now my car is hard to start and if it does start it won't stay started unless I am on the gas. I did have oil in the spark plug galleys and decided to take everything a part and clean all the plugs and spark plug galleys, but that didn't make a difference. At a loss.

I don't know if they could be these plugs or not, nobody around here has the NGK coppers in stock, I will have to special order them.

Could this be because of these plugs?

Link to plugs I bought, strange thing is the "Make sure it fits" section under the product says it won't fit my model year supra. I bought them anyway.

http://www.amazon.com/gp/product/B000GZGV4I/ref=ox_ya_oh_product

Any help is much appreciated.

Oh yeah, almost forgot, no codes showing.
 

MKIIISupraGuy

New Member
Sep 14, 2009
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Lousy-ana
Well if you car WAS throwing code(s), it would be 31, and/or 51. These 2 codes refer to the AFM, TPS, and ECU. Since you have no codes, it might be something simple, like bad gas or maybe a clogged fuel filter.
 

huntin5L

Member
Mar 31, 2005
657
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Niles, IL
MKIIISupraGuy;1467263 said:
Well if you car WAS throwing code(s), it would be 31, and/or 51. These 2 codes refer to the AFM, TPS, and ECU. Since you have no codes, it might be something simple, like bad gas or maybe a clogged fuel filter.

Interesting though you say 51, I accidentally left te1 and e1 jumpered when I started it one time and got a 51 error while the car was on, I turned it off right away and the code didn't stay logged. I will test the iscv when I get home per tsrm and see what it says.
 

Kevin

7mgte -> 7mgte swap done.
Apr 20, 2009
865
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Windsor Ontario Canada
huntin5L;1467277 said:
Interesting though you say 51, I accidentally left te1 and e1 jumpered when I started it one time and got a 51 error while the car was on, I turned it off right away and the code didn't stay logged. I will test the iscv when I get home per tsrm and see what it says.

that is because you had your foot on the gas.. code 51 is the tps. and when you have your foot on the gas or the a/c on it should throw you that code. no big deal.
 

supradjza80

Mr. Formula SAE
Apr 24, 2007
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Appleton, WI
www.uwracing.com
I doubt it has any correlation to the spark plugs and likely something was put back together incorrectly causing the bad idle. Are you sure it doesnt have a massive IC piping leak? That would cause a terrible idle.

Also since your ISCV was working with the old plugs, and since you don't mess with it when doing plugs, I would not worry about that yet. It would be coincidental if that did turn out to be the issue, but I would check EVERYTHING that you messed with to see if you can find the problem.

Good luck
Dave
 

MKIIISupraGuy

New Member
Sep 14, 2009
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One more thing.. check the little vaccum line under the bottom of the accordian hose, it is directly on the underside, and the outlet points toward the engine. The other end goes to the intake mani, on the front(facing the radiator). It is a idle-up vacuum.
 

huntin5L

Member
Mar 31, 2005
657
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Niles, IL
MKIIISupraGuy;1467300 said:
One more thing.. check the little vaccum line under the bottom of the accordian hose, it is directly on the underside, and the outlet points toward the engine. The other end goes to the intake mani, on the front(facing the radiator). It is a idle-up vacuum.

I will check that also.

Thanks!
 

huntin5L

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Mar 31, 2005
657
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Niles, IL
Poodles;1467379 said:
Should still run regardless of most of that (especially at idle as it's under vacuum).

Try the old plugs?

Yeah, I might try the old plugs first, I think it might be something with the iridiums. If not, a boost leak test, then on to other things.
 

huntin5L

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Mar 31, 2005
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Niles, IL
huntin5L;1467446 said:
Yeah, I might try the old plugs first, I think it might be something with the iridiums. If not, a boost leak test, then on to other things.


Well it isn't the plugs, still running like garbage. I think this is definitely electrical, here is why. When I had the car running decent, I through a timing light on the car and the timing mark was showing in two spots, hence the reason I wanted to change the plugs to see if it corrected the miss it had. I think I need to look at the NGK wires I have had in there for a few years now. I am going to look in the tsrm for the specs.
 

huntin5L

Member
Mar 31, 2005
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Niles, IL
huntin5L;1467586 said:
Well it isn't the plugs, still running like garbage. I think this is definitely electrical, here is why. When I had the car running decent, I through a timing light on the car and the timing mark was showing in two spots, hence the reason I wanted to change the plugs to see if it corrected the miss it had. I think I need to look at the NGK wires I have had in there for a few years now. I am going to look in the tsrm for the specs.

Here goes, checked a few things out.

all 6 wires seem to be within spec.

1.51 1.40 2.15 3.07 3.91 4.41 Book said anything less than 25 kohms per wire

Checked the 3 primary coils

Each primary coil came out to .6 (suppost to be .3 - .5 ohms) Assuming this is still okay, since they were all the same. (Couldn't get any voltage readings on any of the 3 primary coil connectors for some reason, the car had the ignition switch in the on position too)

ISC Valve

Checked resistance on both sets of terminals and came within spec Book says 10-30 ohms

21.6 21.9 for both

O2 heater resistance seems off, book says 3.0 - 3.6

6.5 ohms


I went to check the TPS, but couldn't get the connector off, feel like an idiot, but didn't feel like breaking something else.:biglaugh: I also cleaned some corrosion on the battery terminals, but didn't help. Lastly, I went to turn on the a/c on and the idle did not go up and I know for a fact I have always had this problem, which shouldn't be.



I know the 02 sensor won't cause what I am seeing, at a loss still.
 
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MKIIISupraGuy

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Well if all that is OK...my thoughts venture to a couple things. The TPS sensor might be bad, or you might have a clogged/dirty fuel injector, or even trash/dirt in the fuel tank and/or fuel filter. Might sound odd for me to say this, but I used some seafoam in my fuel tank to clean out mine, and my Supra runs better since, and even picked up a couple mpg. Keep us posted.
 

huntin5L

Member
Mar 31, 2005
657
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Niles, IL
MKIIISupraGuy;1467898 said:
Well if all that is OK...my thoughts venture to a couple things. The TPS sensor might be bad, or you might have a clogged/dirty fuel injector, or even trash/dirt in the fuel tank and/or fuel filter. Might sound odd for me to say this, but I used some seafoam in my fuel tank to clean out mine, and my Supra runs better since, and even picked up a couple mpg. Keep us posted.


Yeah, I still need to do a boost leak test again, which is the first thing I am going to do next. Then, I will check the TPS. Just not sure if the TPS can make it miss that poorly causing the timing mark to show in two spots at once during the timing check. Could the idle drop when AC is turned on be caused by a bad TPS? The ISC seemed to check out fine.

Thanks Bob
 

91supran/a

Offical BAMF!
Dec 10, 2007
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my car is kinda in the same boat right now but it idles high like 1200 rpms i think its my tps cause i keep getting code 51. it kinda feels like its missing if you kinda smack the gas and let off and when ur doing like 50 and give it gas and bring it up in the R's and let off it drops to like 500 rpm and then comes back up to like 1500 in OD. sry to be a thread stealer but i figured help two people in one thread. any thoughts?

edit: the car is not my 91NA in my name its a 89 turbo auto
 
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