car still having misfire problems

[89Turbo7M]

hi i have a 1988 7mgte supra the car is misfiring and the exhaust rattles some its been like this for 3 months now i have taken it to 3 differnt dealerships one says i need a head gasket, the second doesnt know whats wrong and the third said to replace the fuel pump, fuel filter and put in a afpr kit witch i did still has the same syptoms. the spark plugs, nology wires, coil pack is fine nothing wrong. tps and cps are fine. their are no vaccum leaks whatsoever, i have checked the harrness for any broken wires etc their is nothing, i have put in oem spark plugs still the same symptoms. my fuel gauge is now not working i have checked the connections and everything was put in right still nothing. i just dont know what to do now my dad is taking it to a really good mechanic he knows tomarrow and we will see what he has to say can anyone on her help me.

 

[hvyman]

Could be a clogged injector or a bhg. You can test the resistance in the injectors or take them out and get them flow tested.

Could also do a block test and compression test.

Does it smoke at all?

 

[89Turbo7M]

no their is no smoke at all when driving normal or just at idle, my dad was reving it today twice some white smoke came out not much i dont see any coolant in the oil or smell it from the exhaust.

 

[89supracrazy]

What do you mean your fuel pressure guage is not working. If the motor is starving for fuel it will misfire. Take your plugs out and see if they look white on the ends or if they have been hot.

 

[89Turbo7M]

i am talking about the gauge in the car that says how much is in the fuel tank not working now.

 

[3.0 GT]

i have the same problem on my built 7m. it started when i replaced my oil pump driveshaft(motor in the car, big pain in the ass) and i also installed an afpr at that time too. and now it misfires bad at idle and very light throttle. any load its perfect. i changed plugs, wires are fairly new, and idk what else would cause it. idle afr is right at 14.7. when i installed my afpr i did crank the pressure up to about 100psi with the engine off bedcause i was testing it out. i wonder if that hurt the injectors...

 

[metaphysico]

OP what are the conditions of the missfire, ie only at idle, only under x amount of throttle, what is the load ect.

pro flow 62mm throttle body from rabid chimp this is one thing that sticks out to me though, because it will throw tps vs airflow out of whack.

 

[89Turbo7M]

at idle it will do it and when im driving at times it will do it or when i come to a stop and waiting it will do it i have also switched back and fourth to the stock and the pro flow tb still does the same thing. the car is getting a bunch of tests tomarrow at toyota.

 

[3.0 GT]

at idle it will do it and when im driving at times it will do it or when i come to a stop and waiting it will do it i have also switched back and fourth to the stock and the pro flow tb still does the same thing. the car is getting a bunch of tests tomarrow at toyota.

does it misfire at idle if you turn on the ac compressor? mine goes away when ac is on.

 

[89Turbo7M]

it does it when the a/c is on too driving or at idle.

 

[89Turbo7M]

got it back today the crank pulley was bad the timing was messed up had to replace crank pulley and i had a spare crank pulley too, gas gauge works too now problem solved thanks guys for your input

 

[hvyman]

Thats why you pull the no.1 spark plug and stick a chop stick in to make sure the crank pulley is right. The rubber in the middle gets screwed over the years and the mark sometimes will not be where its supposed which also could lead to other things as well.