Lumina Dies randomly... weird problem

[meuhus]

Originally Posted by quattro527

Just picked up a scan tool lastnight. Scanned the car for codes, and it gave me missfire codes. Missfires in Cylinder #6, and "Random Missfires". My plugs are only a week old, but they are completely FOULED and scorched black with carbon (richness). I didn't get any other codes other than "Evap/Emissions", which could be due to it running rich and missing.

A faulty IAC or EGR would have thrown a code i suposse? I've had a few people (including yourself now) telling me it's the injectors, and I will have them tested tonight and let you guys know the results. If it IS the injectors, it could possibly be #6 (most people are complaining about that one), and that's the same cylinder giving me the missfires.

Thanks again

Jeff

i have also been told to replace all
because one going bad is a sign that all are getting
week
or what ever
i don't know for sure if you should but it would save you time
in the long run
if another one fails in the future

[the6]

if you have 3 wires on your oil sending unit short out the 2 across from each other. at the plug with a paper clip. fuel pump won't come on if the oil pressure is low.

[quattro527]

Problem was fixed.

Cause: Fuel Pressure Regulator Pulled the vacuum hose off the FPR during idle, and massive amount of fuel squirted out of the valve, indicating a torn diaphram which is keeping the fuel pressure from being lower during idle (which explains why the car idled badly and fouled plugs, but ran normally at WOT). Cost me $70 at AutoZone, and took 30min to replace.

Future Note: Check the FPR by pulling the vacuum, to check for any fuel leaks. Fuel should NOT make it's way out to the vacuum, nor should you smell any unburned fuel from the line. Any signs of fuel in the vacuum is an indication of a FPR going bad, which will throw all the "Missfire codes", which is NOT caused by bad coils, wires, or plugs, but by the combustion chamber flooding itself.

[meuhus]

Originally Posted by quattro527

Problem was fixed.

Cause: Fuel Pressure Regulator Pulled the vacuum hose off the FPR during idle, and massive amount of fuel squirted out of the valve, indicating a torn diaphram which is keeping the fuel pressure from being lower during idle (which explains why the car idled badly and fouled plugs, but ran normally at WOT). Cost me $70 at AutoZone, and took 30min to replace.

Future Note: Check the FPR by pulling the vacuum, to check for any fuel leaks. Fuel should NOT make it's way out to the vacuum, nor should you smell any unburned fuel from the line. Any signs of fuel in the vacuum is an indication of a FPR going bad, which will throw all the "Missfire codes", which is NOT caused by bad coils, wires, or plugs, but by the combustion chamber flooding itself.

good diagnossis
but don't say that the coils can't cause a miss fire code
a combination or problems can cause one code
or one problem u don't even think could cause the problem
the computer isn't smart
it only knows if some thing is wrong
so if its miss firing it will only know its missing
and not exactly way it is

i didn't have any codes telling me my injectors were bad
i didn't even have a miss fire code
but eventually i got a o2 sensor code
after running it with the super rich mix
one or more of my injectors was stuck open
i din't have any fuel in vac line to regulator
and ohm test found a few bad injectors

[quattro527]

Originally Posted by meuhus

good diagnossis
but don't say that the coils can't cause a miss fire code
a combination or problems can cause one code
or one problem u don't even think could cause the problem
the computer isn't smart
it only knows if some thing is wrong
so if its miss firing it will only know its missing
and not exactly way it is

i didn't have any codes telling me my injectors were bad
i didn't even have a miss fire code
but eventually i got a o2 sensor code
after running it with the super rich mix
one or more of my injectors was stuck open
i din't have any fuel in vac line to regulator
and ohm test found a few bad injectors

Of course we cant say it's always NOT the coils. Unfortunately these cars have a pretty prehistoric diagnostic system, in which one must use reason and proper judgement to diagnose and fix the problem. In my case, the injectors were trimming properly, and I believe the on-time was intact, only with full WOT fuel pressure which was flooding it out. Only codes I had were "Random Missfires" and "Missfire Cyl #6". For future reference, before the guy goes out and spends ~$200+ in new coils, wires, and plugs and pulling their hair out like I did, the FPR is a fairly easy check.

Thanks again for all the help guys.

[meuhus]

Originally Posted by quattro527

Of course we cant say it's always NOT the coils. Unfortunately these cars have a pretty prehistoric diagnostic system, in which one must use reason and proper judgement to diagnose and fix the problem. In my case, the injectors were trimming properly, and I believe the on-time was intact, only with full WOT fuel pressure which was flooding it out. Only codes I had were "Random Missfires" and "Missfire Cyl #6". For future reference, before the guy goes out and spends ~$200+ in new coils, wires, and plugs and pulling their hair out like I did, the FPR is a fairly easy check.

Thanks again for all the help guys.

well it is very important to check everything before buying parts
cars are not like they use to be
all thought they are not as complicaced as some people make them out to be
they are deffinately not as easy to trouble shoot
with out access to some special tools and equpment they are all most impossible to find the exact problem

[quattro527]

Originally Posted by meuhus

well it is very important to check everything before buying parts
cars are not like they use to be
all thought they are not as complicaced as some people make them out to be
they are deffinately not as easy to trouble shoot
with out access to some special tools and equpment they are all most impossible to find the exact problem

I think I may be too spoiled by my Audi's Motronic ECU system, which can pinpoint a simple burnt headlight bulb, to a system too rich/lean code such as this one. A burnt our coil pack is also clearly distinguish between a "Internal Resistance Too Low/High" code, to a simple "Missfire" code. []

[zephram22]

Originally Posted by NeonKnight

My 91 Lumina Euro 3.1 dies randomly.. its scaring me, i have been driving my 73 Chevy Cheyenne C20 Camper special (with a 454 Big block 4:6:3 gears 12 bolt posi) and the truck is nice and all... but i would like to get more than 7 miles per gallon....

Now the lumina does not have any codes, always checked fluids, refilled when needed, all those kinds of things. timing belt was replaced at 120k miles, car now has 144k, and its not the transmission my car has the TH-125 (3 speed no overdrive) Now for what its doing.

The car randomly dies when warmed up, or at least i think only when warmed up. Once she starts dieing, she will keep doing it if you start her back up. When she dies you can feel a rpm surge sometimes and then she just dies, othertimes i dont notice it like if im in park its a nice and quiet car.

When she dies you can turn the key and start her right back up, and she runs like normal. It died on me a few times, one time i was getting on the freeway on one of those loops that go from an overpass to get to the freeway which is going another direction. she died about halfway through since there was no throttle input.

the other time i was just sitting in the parking lot at 7-11 waiting for my friend to get out of the store, and i went to shift and pressed the gas and she was dead. started right back up though.

the third time i was driving back from a few cities over, i was doing 65 MPH and 3000 RPM all of a sudden i feel a big grab, like something locked up in the tires and i look down at the Tach and wathced the needle bounce fro 3000 right down to about 700 or so and right back up to 3000 and stopped, the car kept driving like normal. so i gave her some more gas sped up to about 80ish since if shes going to be doing this i want to be home or at least closer to it. i felt her give me another one but smaller, so i was about 20 exits from my place, about 5 miles. i let off the gas a little, and the entire way back i can feel these little rpm drops and hear them too, but it was random.

now i went around and checked all the fuses, they are fine. Altenator is new within a year its fine, battery is fine, car could use some new spark plug wires and plugs but that cant cause this, its not ignition related im sure of that.

My grandfather is a GM tech, he was thinking that it could be electrical if it happened that fast. My brother tells me he think its a Vacuum leak, and my neighbor who is a GM tech said it could be a Fuel pump. But if it was a fuel pump could it still make it run fine untill it warmed up?

Im leaning towards a Vacuum line, can anyone give me any insight on this. i really want to get her fixed by this weekend.

Thanks
-Jeff

I had a lot of problems with stalling until I pull all the sensors and valves out of the throttle body and gave a a real good cleaning.

[meuhus]

Originally Posted by zephram22

I had a lot of problems with stalling until I pull all the sensors and valves out of the throttle body and gave a a real good cleaning.

i know this is the lumina forum and not pontiac grand am
forum but
has any body had problems with the trans in those cars slipping in 1
and 2 but being ok in d
the car is my sisters
i don't drive it
but she told my dad who told me
and he thinks its the tranny on its way out
and i didn't know if a trans fluid change and filter change would help
or if the tranny is shot
he says the fluid looks ok
the engine is the 2.5 four cylinder
tranny is an automatic 3spd
don't know if its th125
the car has about 140000 miles
and never had the fluid changed
so i was hoping that would help
because i don't want to take out the transaxle
but i guess if i have to i will