Not firing right

NTRA08

TWINKY
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I was going to a buddy's house monday and my car was starting to get on empty. When I got to his house the car sounded like it was misfiring a little bit. Well This has happened to me before. So I did what I did last time. I changed the spark plugs. Did that and it still sounds like shit. I did a little cylinder clean out with some sea-foam and didn't help. I put gas in the car obviously. And still nothing. I pulled on wire off at a time with the car running and cylinder 1 seems to be the only one that doesn't seem to change the tone of the motor. My brother said I might have a coil going out so I changed the 1/6 coil and still nothing. Then he said I might have sucked something up with my pump running it on empty but I don't think it would have lasted this long. I do have a tiny fuel leak on the return line but that was there before the problem... and another thing how do you tighten the return on the fuel rail?
 

mkiiichip

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The one with the banjo bolt either needs to be tighter, or the crush washers replaced. If it has a hose and clamps you need, an new hose and clamps.

When you pull the plug wires, are you grounding the ignition wire so the companion cyl will still get spark? this is a tricky test on waste spark. you have to disable the cyl being tested, while completing the ignition circuit for the companion cyl, to get proper results.
 

NTRA08

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The one with the banjo bolt either needs to be tighter, or the crush washers replaced. If it has a hose and clamps you need, an new hose and clamps.

When you pull the plug wires, are you grounding the ignition wire so the companion cyl will still get spark? this is a tricky test on waste spark. you have to disable the cyl being tested, while completing the ignition circuit for the companion cyl, to get proper results.
I really don't fully get what your saying
 

NTRA08

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Did you make sure the injector is functioning properly?
well I did a few tests today and all lead to cylinder 1. I pulled the plug wire. nothing changes. I pull the wire and put an old spark plug on it and ground it out. and I'm getting spark. I test the injector and its firing. but when I take the clip off the injector when the car is running nothing changes. If I do it on all the other cylinders the tone changes. Then I just took if for a ride and its almost like the car is coming in and out of running right. Its sorta sputtering. Then I noticed the needle in my boost gauge is bouncing when I accelerate. But I know I don't have any boost leaks. Whats my deal?
 

NTRA08

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Just in cylinder 1? Everything else is fine. Would you happen to have any 440's laying around
 

IJ.

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Nope don't have much in the way of 7M stuff here at all these days sorry.

I'm sure someone will have one, do you have any buddies with a GTE car?
(swap one in and see if it clears up)

Failing that pull the injectors and take them to be cleaned and flowed.
 

NTRA08

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I have one buddy that has an n/a. I can look around. I was told that lexus injectors would work on the 7m is that true. I have 8 injectors from a sc400. If not I guess I'll just have to take them out.
 

NTRA08

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Okay well I took out the injectors and cleaned them. Put them back in and nothing changes. I moved cyl.1 injector to cyl.6 and still the same. so now I know its not the injectors. I changed the coil pack again and still the same. I have spark. Air and fuel. But on turning over there is a slight hesitation. And the car wont stay running on warm up. I have to hold my foot on the pedal for about a minute and then it idles. I was talking to a mopar friend (old guy) and he said I could have a floating valve. Well I took the valve covers off and the spark plugs, and turned the car over and my valves are fine. SoOo i'm stumped.

I'm also doing a compression test tomorrow.

Wish me luck
 

IJ.

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Plug it into the injector that isn't firing and report back.
(test both sides of the circuit ie: Test light from INJ+ to ground and Test light from Power to INJ-)

But having said that if it were a wiring/power issue you'd have 2 down, might want to inspect the wiring right at the clips.
 

NTRA08

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with the ignition on and test light grounded to battery, injector pigtail is hot on both prongs......and with the ignition off and the test light on positive on battery injector pigtail is negative and still lights the test light.

---------- Post added at 12:15 AM ---------- Previous post was at 12:14 AM ----------

i tried this on #2 and its the same.
 

NTRA08

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are we checking for pulse on the injector? rang it out with a meter on ohms and it fluctuated pretty good. the car is torn apart at the moment...will take a few to get her back together...
 

IJ.

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Yes, if you have a pulse and the injector is clean but the engine note doesn't change when you unplug that injector I have NFI what's going on....

Put it back together swap some injectors around and see if the problems follow the injector or the wiring..
 

NTRA08

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Yes, if you have a pulse and the injector is clean but the engine note doesn't change when you unplug that injector I have NFI what's going on....

Put it back together swap some injectors around and see if the problems follow the injector or the wiring..
well I got it back together and did what you said. I have pulse when its running and when i unplug it the engine note doesn't change. I swapped the injectors around again and it seems to follow the wiring and not the injectors. But only cyl. 1. I also have NFI whats going on.

---------- Post added at 02:31 AM ---------- Previous post was at 02:29 AM ----------

Another thing I know for a fact that it isn't the wiring harness because it did it on my 87 harness before I switched to a 91. And all I did to fix the problem that time was change the spark plugs.... So I think there is something seriously wrong with the motor.

Would an exhaust leak cause this happen?
 

NTRA08

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My bro says maybe I could have a valve seat that is worn. Or blow-by. Not at the cyl. to cyl. wall but the adjacent walls. I hope not. I don't want to have to tear the motor down. But I will definitely do a comp and leakdown test. BTW what time is it right now in Australia? I'm thinking early morning.
 

NTRA08

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Damn I was way off.Saturday hasn't even started for me. Its 2:46am saturday in texas. But I will do a leakdown test and comp test in a few hours. I've got to get some sleep.
 

NTRA08

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Okay I did a compression test today and after that I figured I don't need to do a leakdown test.

Here are the results:

Cyl.1: 78psi.
Cyl.2: 75psi.
Cyl.3: 170psi.
Cyl.4: 159psi.
Cyl.5: 150psi.
Cyl.6: 164psi.

I gonna jump out on a very big limb and say that the seal between cylinders 1 and 2 is gone and I have loss compression on both of the cylinders because of it. So I'm gonna say BHG!!!!
 

NTRA08

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Either way I still have to take the head off. Another question. I have another motor sitting in the garage. Sorta like a backup motor. and it has the 1.2mm HKS metal head gasket on it. Is that too thin of a h/g. I know that the stock h/g is 1.38mm crushed. And what if I take the head gasket off the other motor and use it. Are they reusable after you have already crushed them?