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Discussion Starter · #1 ·
Ok here is my problem at first it started out the car would not rev over 5500 rpms
so I started simple and changed the plugs didnt help at all now it will barely idle and seems as if it is running on 5 cylinders or at least that is the sound the engine is making. So a friend of mine let me borrow his coils to see if that was the problem but that also didnt help. Also this problem just came out of no where and has just gotten worst. Please help with any ideas I have had it run simialr to this when one of my injectors was unpluged could it be that one of my injectors has went out or could it be something like a bad sensor.
 

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take it to a reputable mechanic before you start throwing parts on it...it will be cheaper. No one on here will be able to diagnose it and all you will get are guesses unless you have a snapon scanner that is :)
 

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The easiest thing to check (that you can most likely check yourself) is the connection that the coilpack clips are making (even if you swap coils with your friend and they are all good, if one of the connector clips isnt making a good connection it will act this way) inside there are plastic clips that get brittle and sometimes break and fall out, check the inside of all these clips (since you say your first problem was that it would not rev over 5500, and when you went to change the plugs then it started running like this, this leads me to believe it could be one of the clips)
 

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Also, make sure you used the right plugs and gapped them right (although id look at those connector clips first and foremost) and check everything else that you touched when doing the plugs (since you say thats when the car started running like it was on 5 cyl)
 

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Discussion Starter · #6 ·
Ok all of the coils are plugged in. It didnt start running like this as soon as I put the plugs in. It ran fine for a day or two so then I wanted to see if it could rev over 5500 without boost on it, so I reved it up and then at around 5500 it started missing again and backfiring and after that it started running like this. Another thing I should mention is that before it started running like this full time it would go into spells where it would seem like it was running on 5 and then just switch back all of a sudden and run fine. Once while it was running bad I left it running and got out to look under the hood and watched it run like this for about 2 mins then I heard a click and it started running fine again any idea what the click could have been from.
 

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Discussion Starter · #7 ·
Also I just swapped out the igniter for another one from a friend and it did nothing, so it seems as if I have went through the entire ignition system and found nothing wrong with it so what else could it be only thing to check now would be the fuel system. How to I go about checking the fuel injectors.
 

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It's not your fuel system, it's you

Take it to a mechanic, there are a plethora of other things it could be. I can list them, but honestly I don't think you have the experience to rule them out 100%

If it were me, I would start with the basics, it takes 5 things to put torque on the crank of an internal combustion piston engine. Air, fuel, compression, spark and timing . Since compression should be static, we can put that to the side. Since air should also be static, we can put that to the side as well. That leaves us with fuel, spark and timing.

From that list we think back to what was the last thing we modified, touched or encountered ... viola it was the spark plugs/coil packs/ignition system. On top of that, we revved the motor up and possibly caused this condition from that, so we'll concentrate on those two things.

We know that supra's have a common problem of having coil pack connectors become brittle and break, or have the insides break, when they are removed from the coil itself, so we'd check each connector and make sure it was perfect, no missing white spacer in the middle or missing connector pieces. We'd also check the coils themselves and make sure the portion inside that clips to the spark plug hadn't dislodged itself, nor had the tip of one of the old plugs accidentially came off in a coil. Lastly we'd check are plugs, make sure one of them wasn't cracked in the ceramic (because that will definitely cause these symptoms) and we'd make sure the gap was correct and that there was no damage to the tip or electrode.

If all of that pans out, we should then check and see what timing is doing above 55xx rpms, with a scanner or monitor, maybe tech tom.

Note to yourself that toyota put a safety provision in the stock ecu, that puts an early rev limiter to the motor if you are in neutral, so that you can't blow the motor up and come in under warranty. I believe it was at 5200 or 5500 rpms. It either monitors vehicle speed or the clutch safety switch, I can't remember which. So if your's were to permanently have continuity through the switch, the vehicle would continue to think it was in neutral and would institute said motor safety provision. You might also want to try swapping ecu's with your friend.

After all of this has been double checked, then you should move onto the fuel system, starting with the pump. The chances of an injector working half ass is pretty slim, and the chance of it not wrecking your motor is even slimmer.

I know it's a long post, but hopefully it helps you to either take it to a mechanic, or shows you how to be thorough when testing it yourself, and how not to just through parts and money into the wrong areas.







bigazturbo said:
Ok all of the coils are plugged in. It didnt start running like this as soon as I put the plugs in. It ran fine for a day or two so then I wanted to see if it could rev over 5500 without boost on it, so I reved it up and then at around 5500 it started missing again and backfiring and after that it started running like this. Another thing I should mention is that before it started running like this full time it would go into spells where it would seem like it was running on 5 and then just switch back all of a sudden and run fine. Once while it was running bad I left it running and got out to look under the hood and watched it run like this for about 2 mins then I heard a click and it started running fine again any idea what the click could have been from.
 

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Discussion Starter · #9 ·
Thanks for the post but if one more person tells me to check the connectors to the coils I may screem. That was one of the first things I checked and I have checked it many times since then I would love to take it to a mechanic who knew what they were looking at but they are few and far between and if I do find a good one, they may be able to look at it in a week or two. Which with this car being my only means of transportation its not really an option. I will take out the sparkplugs and recheck them. I also agree that it sounds more like an igntion problem then a fuel problem with it not being able to rev over 5500, but that probelm came out of no where one day the car would pull hard to redline the next day it would pull hard to 5500 and then start missing. So its hard to track down what might have caused it and who knows the running on 5 cylinder thing could be a seperate issue. All I know is that my car now sounds like a WRX and the last time I heard that it was because an injector had come unplugged this is the reason I am saying injector as the problem because it sounds exactly the same. I know it could sound like this also if I had a plug not firing but I just want to justify my reasoning for saying that the injector could be a possiblity.
 

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well then we'll start guessing. Take every coil off and ground it so you can see spark...repeat on every one. If one looks like it has little or no spark, there is your problem. IF not, hook up a fuel pressure gauge and make sure you are getting the correct fuel pressure. Next, hook up a scope to it and check injector wavelengths.

Do all of this after you hook a scanner to it and see if any of the parameters are not reading correct.

Here is more stuff to play around with.
http://www.supraforums.com/forum/showthread.php?t=349206

Option B is just throwing parts on it.
 

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Discussion Starter · #12 ·
Ok just got done checking some more stuff today, first I pulled out the plugs and they were all really black so that kind of blew away the idea of fuel problem. Next I checked the codes and I got a code 14. Does anybody happen to know what this could be? I am about to go and check the ecu for any wiring problems that could be going on. I have a map ecu installed and there could be the possibility that one of the wires that hooks up to it has gotten unpluged.
 

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Discussion Starter · #14 ·
Yeah I saw that and Since I already swapped out igniters and checked that the only thing I guess is left is to check out the ecm, but when I was checking the wiring I saw that the igniter wire that goes into the ecm had and an exposed wire and that the exposed wire was laying on metal do you think that, that could have been what would have caused something to short out in the ecm, or is this just something that could have happened just out of the blue.
 

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I'd repair the bad wire and cross my fingers it didn't damage the ecu. Next, I'd try to swap the ecu out with another to see if the problem is corrected. If so, you know where the problem is (ecu).
 

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Discussion Starter · #17 ·
Yeah that was my next plan was to swap out the ecm. I have checked the igniter many times I have actaully swapped it out with a friend of mine whos igniter was working perfectly so im pretty sure that its not the igniter.
 

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Mine was running like that and it was the first O2 sensor, but i had a code set about that. Take your car to autozone or someplace with a scanner that can give you a name to go with that code, not just a number like 14.
 

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Discussion Starter · #19 ·
Well its kind of hard to drive it anywhere or I would. I can barely get it up a hill. Pretty sure its not the o2 sensor. I did get code 27 but I think thats the 2nd o2 sensor so Im not worried about that one. When i checked the coils to see if they were firing I could hardly see the spark and it was very distorted. So im pretty sure its the ecu because I have checked every single thing in the igniton system and that is the only thing left that it could be so now I guess I just have to wait on the other one to get here. Which sucks to cause i still havent got to play with my T-76 that I just put on there last week.
 

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the ecu on the supras very very very rarely goes bad...infact i can only recall 1 circumstance of that happening.
 
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