another misfire thread (poss injector related)

[sneakypete]

i have struggling with a miss ive been having. i was helping a buddy out on his supra and when we went to run to the auto parts shop, suddenly it started to happen.
i narrowed it down to cylinder 3 by pulling the spark plug wires to see if the car idles differently. plugs were dirty so i replaced those. got new wires. coilpack resistance is withing spec and i even swapped it with another good coilpack. no difference. thought it might be timing related because the timing light wasnt strobing steadily. so i reset the timing according the the tsrm. when i first fired her up, the miss seemed to gone. but shortly returned after a few minutes. next thought was the injectors, so i tested resistance on them and they were withing spec according to RC.
i checked all the wiring and no problems there. everything was properly connected , grounded and no frayed wires.
The only thing i noticed was with the new spark plug wires. normally when you connect the boot to the spark plug, it kind of clicks in place. one cylinder 1 and 3, it just kind of slid on.... no click. almost like the contact on the spark plug isnt completely touching the boot. but the weird thing is that all the other plug wires fit just right.
im out of ideas here. please let me know what else to try.
thanks in advance
-pete

 

[skipbarber]

have you stuck a screw driver in the boot and held it about an inch from ground while someone cranked it? if you see it arc to ground the loose connection is probably the culprit. otherwise check the connection at the coil with a multimeter and verify that youve got an ignition signal going to it.

 

[sneakypete]

have you stuck a screw driver in the boot and held it about an inch from ground while someone cranked it? if you see it arc to ground the loose connection is probably the culprit. otherwise check the connection at the coil with a multimeter and verify that youve got an ignition signal going to it.

i fixed that issue. i replaced the heads of the sparkplugs (that contact the spark plug wires) with new contacts. as mentioned earlier, all that has been tested and confirmed. coil pack and wiring to coil pack has the proper voltage according to the tsrm. resistances of coil and ignition wires are within spec. plugs have been checked and were even replaced with new just to see if it made a difference. injectors have been checked and are resistances are good according to rc engineering.
only other thing i can think of is that the injector is either clogged or has malfunctioned. i guess i will send them out to be inspected.
thanks
-pete

 

[7MGTEsup]

Air leaks can also cause missfires.

 

[jdub]

What make/part # plugs and at what gap?

What make plug wires?

 

[sneakypete]

What make/part # plugs and at what gap?

What make plug wires?

originally when the problem first started happening i was using NGK BCPR6E at .032 and NGK wires (dont remember the part number).
when i first started troubleshooting i had a set of bosch platinum plus part #4001 gapped at .032 in my garage (i know they arent the best, but theyre what i had), so i changed them out to eliminate plugs as an issue. i knew the wires were old and the boots were loose so i swapped them out for a new set of beck arnley part #175-5852. thats all they had in stock without having to make a special order.

 

[jdub]

Ok...that's likely not it.

Check your IC hoses for cracks...especially the ones coming off the turbo to the IC. The coupler from the 3000 pipe to the TB likes to crack too.

 

[sneakypete]

Ok...that's likely not it.

Check your IC hoses for cracks...especially the ones coming off the turbo to the IC. The coupler from the 3000 pipe to the TB likes to crack too.

i checked all that in the beginning. and last week when i installed the new turbo i removed the piping and intercooler to clean the oil residue out. when i reinstalled everything i checked all clamps and the couplers to see if they were snug and in good condition. i replace 2 of them that werent behaving, but didnt notice and cracks or tears. after the turbo went in, i had the same problem.
plus, i know that number 3 cylinder isnt firing. a boost leak shouldnt effect only one cylinder.
im beside myself here.

 

[sogi99]

did you try pulling # 3 spark plug wire while the car was running to see if there's no spark be very careful when doing this always wear a rubber glove of some sort so the spark doesn't jump to you. have you done any compression check on all 6 cylinder?

 

[sneakypete]

did you try pulling # 3 spark plug wire while the car was running to see if there's no spark be very careful when doing this always wear a rubber glove of some sort so the spark doesn't jump to you. have you done any compression check on all 6 cylinder?

i pulled the #3 wire from the coilpack and there was no reaction from the engine. there was an adequate arc jumping from the wire to the coil (very white). do you mean pull the wire from the sparkplug itself? that will be kind of difficult to do while the car is running since the coilpack sits right on top of it.
do you think it could have anything to do with the ecu?

another problem im having which i believe is related to the miss is after the car is warmed up, when i pull up to a red light, the afr drops into the mid to low 10s. and the car idles poorly and wants to die. could that be ecu related?
i tried resetting the ecu and i also reset the maftpro to eliminate those as culprits.

 

[sneakypete]

wow... it all makes sense now. i just did a compression test. it explains a lot.

#1 170
#2 180
#3 0
#4 175
#5 182
#5 180

what would the cause of this.... broken ring? how bad is to drive with a cylinder with no compression? i just need to last about 2 more weeks until i get the new motor in.

 

[7MGTEsup]

wow... it all makes sense now. i just did a compression test. it explains a lot.

#1 170
#2 180
#3 0
#4 175
#5 182
#5 180

what would the cause of this.... broken ring? how bad is to drive with a cylinder with no compression? i just need to last about 2 more weeks until i get the new motor in.

I would think to have 0 compression you must have a hole in a the piston or a valve is stuck open. even really bad rings will give you some compression.

 

[sneakypete]

I would think to have 0 compression you must have a hole in a the piston or a valve is stuck open. even really bad rings will give you some compression.

thats what i was thinking. i wish i could unstick the valve temporarily until the new motor goes in...... im guessing fuel system cleaner isnt gonna get the job done. how about racing fuel?