Random misfire on acceleration

[supraGhost]

my car has been in peices for the longest time. so i know this is a shoot in the dark... it could be so many things but if someone has idea of what to look for and where to start that would be great.

basically i pulled the exhaust manifold off and helicoiled the head, i also powdercoated a bunch of parts while i was at it. anyhow

it starts up, idles good, but when i accelerating through the rpm's it goes in and out of a misfire, like it only lasts for like half a second then goes away for a second then comes back, but its completely random. its sort of like a stutter. and it seems to become more frequent the higher my rpms are.

i think i am gonna start with plugs and wires and see if that helps but anyone else have any ideas? thansk

 

[StrikeIS]

Mines kinda doing the same thing. I started with the plugs cause I though it could have been a ignition problem. I also put new isolators on the coil pack bracket and a new ground. Doing all this seemed to clear some of it up but not completely. So I tried checking the codes(which I should have done in the first place) I didnt get any thing like when you put the paper clip in it should flash repeatedly but I got nothing, so I took out the cluster and the light had been removed by the previous owner(aka asshole). So after I replaced the light I got a o2 sensor code, I went and got a new one and installed it and reset the ecu and bam no more code. I think it cleared it up but its hard to tell cause Im running open DP so theres no back persure at all it pops flames and everything if I hit boost real fast and let off the throttle, but I dont think its a good thing. So just check your codes and report back.

 

[hvyman]

did you take off the tps by chance?

 

[supraGhost]

did you take off the tps by chance?

no

 

[supraGhost]

Mines kinda doing the same thing. I started with the plugs cause I though it could have been a ignition problem. I also put new isolators on the coil pack bracket and a new ground. Doing all this seemed to clear some of it up but not completely. So I tried checking the codes(which I should have done in the first place) I didnt get any thing like when you put the paper clip in it should flash repeatedly but I got nothing, so I took out the cluster and the light had been removed by the previous owner(aka asshole). So after I replaced the light I got a o2 sensor code, I went and got a new one and installed it and reset the ecu and bam no more code. I think it cleared it up but its hard to tell cause Im running open DP so theres no back persure at all it pops flames and everything if I hit boost real fast and let off the throttle, but I dont think its a good thing. So just check your codes and report back.

so you think clearing your codes fixed it? my cel is not on but i may have a asshole previous owner as well

 

[jdub]

Check for ECU codes before you reset. Drive it and check codes again after the reset.

 

[supraGhost]

yeah that is a good place to start. are out cars obd1? i dont even know lol. i shoudl probably just buy a scanner. where would be a good place to get one for cheap? i dont need anything fancy

 

[StrikeIS]

Yes are cars are obd1, cars didnt start going obd2 until late 96. You can check your codes by using a paper clip and put one end of the paper clip in the E1 and the other end in Te1 on the dignostic plug on the driver side right behind the battery then turning the key to the on position and counting how many times it flashes. Also I got en exhaust put on my car the other day and it was still missing so I checked my coils and Im only firing on 3 of my cyl. Im not sure what would cause this but you should try checking your coils also.

 

[CajunKenny]

Here's a link on how to check for codes.

http://www.cygnusx1.net/Supra/Library/TSRM/MK3/manual.aspx?Section=FI&P=23

 

[supraGhost]

pulled a code from a problem i fixed a long time ago. i erased the codes and drove it around. came back. checked the codes again and there is nothing.

and the stutter is more of a vibrating real fast while i accelerate. i dont know how to describe it any differently. but its not a random miss here and there, it sputters for a little and then goes away and then comes back.

sorry hard to decribe. i guess i will get new plug wires.

 

[supraGhost]

i was just thinking... could this possibly be fuel related? if my fuel pump was going out or something?

 

[toyotanos]

If your fuel pump was going out, I would expect your top end to suffer, since that's when demand on the pump is greatest. I would start with new plugs and wires, but then look at the plugs and see what they look like *keep them in order so you can refer back to them later*. If one or two looks way different that the rest, you found which hole(s) are missing. Sounds like you have the right idea of where to start.

 

[supraGhost]

If your fuel pump was going out, I would expect your top end to suffer, since that's when demand on the pump is greatest. I would start with new plugs and wires, but then look at the plugs and see what they look like *keep them in order so you can refer back to them later*. If one or two looks way different that the rest, you found which hole(s) are missing. Sounds like you have the right idea of where to start.

yeah i order ngk wires and copper plugs from DM yesterday

 

[supraGhost]

pulled out the old plugs.....


cylinder 1 and 6 were covered in oil????? the tips looked good though, as did every other cylinder.

i didnt get a chance to get everything back together. i am partway through changing my oil and having trouble getting the oil filter off lol. once thats off though i will run it and hopefully see some improvement.

why was there oil on the plugs?

 

[toyotanos]

The oil could come from a lot of places, but I would guess it collected because of the cylinders not firing right.
After the plugs and wires are in, take it for a drive and see if it's better. Since #1+6 are partners, I might think the coil was going bad/getting weak. It could also have been very old wires not allowing spark energy to pass through, (which would kill both holes). Test drive results may add helpful data to the mix. Be sure to clean the plug valley of any oil that's collected in there, it can ruin new wires very quickly!

 

[supraGhost]

The oil could come from a lot of places, but I would guess it collected because of the cylinders not firing right.
After the plugs and wires are in, take it for a drive and see if it's better. Since #1+6 are partners, I might think the coil was going bad/getting weak. It could also have been very old wires not allowing spark energy to pass through, (which would kill both holes). Test drive results may add helpful data to the mix. Be sure to clean the plug valley of any oil that's collected in there, it can ruin new wires very quickly!

well the wires actually arent old. i put them on like a year ago, but something chewed on them while the car was sitting. they didnt chew through anywhere but i wasnt sure if there was any damage that i couldnt see.

 

[supraGhost]

i changed the plugs and wires, changed the oil, and flushed and changed the coolant system.

starts right up, idles smooth, temp is steady, so that is good! but it feels so slow! maybe i was just expecting it to feel faster or something but if it didnt run perfectly i would think there is something wrong with it.

 

[suprahero]

So it's not stuttering anymore?

 

[supisarethebest]

is it still stuttering?i need to know,i have the same problem

 

[RazoE]

same here, I just made a thread yesterday, might try pulling all the wires and checking the grounds on the coil packs