GM Techs....i have a grand am problem with my 3.3...slight miss

WEll i have a 1993 grand am with around 114000 miles on it. The engine
has a slight miss under load (i cant seem to tell at idle).

If i have one foot on the brake and one slowing pushing the gas i can
feel the miss.

I have replaced the intake gasket, IAC, o2 sensor, plugs (gapped
correctly), Plug wires, Coil packs and ICM, fresh tranny flush and fill
with filter replacement, Fresh oil change and various old vaccum lines
replaced as well as a new exaust cat back system.

one thing i havent done yet is a compression test.

One thing that is weird is once you hit about 7-10 mph the miss seems
to go away. It is only at a stop sign that i notice it. It is a slight
miss with hesitation.

I suppose it could be injectors as well but those all have new o rings
on them from the intake job i just finished. I havent done an ohm
reading on them yet but i suppose they could be weak. Spendy little
devils though and i dont want to replace them to find the problem still
exists. Ill get those tested asap.

I also plan to do a compression test when i get the tester.

The car seems to pull hard once you are moving and seems to drive just
fine. I just cant put my finger on it and it is driving me crazy.

I find it hard to believe that it would be a blown head gasket. That is
not very common on these engines as far as i know.

I couldnt tell you if this engine had the problem before i did all the
work on it because i just got it and when i did, it had a bad intake
gasket leak and coolant everywhere.

Any ideas or thoughts? IM pullng my hair out over here

scale wrote:
>
> WEll i have a 1993 grand am with around 114000 miles on it. The engine
> has a slight miss under load (i cant seem to tell at idle).
>
> If i have one foot on the brake and one slowing pushing the gas i can
> feel the miss.
>
> I have replaced the intake gasket, IAC, o2 sensor, plugs (gapped
> correctly), Plug wires, Coil packs and ICM, fresh tranny flush and fill
> with filter replacement, Fresh oil change and various old vaccum lines
> replaced as well as a new exaust cat back system.
>
> one thing i havent done yet is a compression test.
>
> One thing that is weird is once you hit about 7-10 mph the miss seems
> to go away. It is only at a stop sign that i notice it. It is a slight
> miss with hesitation.
>
> I suppose it could be injectors as well but those all have new o rings
> on them from the intake job i just finished. I havent done an ohm
> reading on them yet but i suppose they could be weak. Spendy little
> devils though and i dont want to replace them to find the problem still
> exists. Ill get those tested asap.
>
> I also plan to do a compression test when i get the tester.
>
> The car seems to pull hard once you are moving and seems to drive just
> fine. I just cant put my finger on it and it is driving me crazy.
>
> I find it hard to believe that it would be a blown head gasket. That is
> not very common on these engines as far as i know.
>
> I couldnt tell you if this engine had the problem before i did all the
> work on it because i just got it and when i did, it had a bad intake
> gasket leak and coolant everywhere.
>
> Any ideas or thoughts? IM pullng my hair out over here

Can you tell which cyl is the problem by removing plug wires
one at a time? Narrow it down and then swap plugs, wires, injectors, etc.
Sounds like an injector. Fortunately, injectors are easy to get to on
that engine. Check the rail pressure. Sometimes the regulator leaks.

A leaky intake gasket on this engine is very rare, indeed.
IMO, the 3.3 is probably the best v-6 GM ever made.
(Well, maybe the Gen one 3.8, also.)

do you mean head gasket is rare? Not intake

im heading out to look at my engine once again. Im going to start
pulling wires and see if i can find the problem. I am guessing an
injector as well but i cant be too sure until i find it.

I dont know if my fuel regulator would be leaking. I dont see any fuel
leaking here. would it cause an vacum leak here or a fuel leak? I have
about 16psi vaccum where my pressure reg plugs into the intake

well i pulled each plug wire and they all noticably missed harder or
more apparent then my problem which leads me to believe that i have a
bad injector or a dirty one. They all tic which i tested but i dont
know if they are spraying correctly. IM going to wait until it gets
real dark and check for a arcing problem just to be sure.

I know that the problem is very consistant in drive with the brake on
(under load) and giving it the slightest amount of gas.

It feels weaker than a full cylinder miss. THe plugs are all equal
looking as far as ignition goes.

Is there any way to check the fuel pressure? What is the proper
proceedure for this. I notice the small resivor that is circle shaped
right before my fuel rail and where the fitting is has a small pressure
release valve on it with a black cap on it. Do you hook the tester here
to check the PSI for the pump or do you pull the fitting at the rail? I
dont have a tester for this. Im just hoping that the autozone near me
will rent one out. Funny thing is the car seems fine once you start
going down the road. It is just the intial first take off from a stop
that it seems to miss or sputter or whatever is going on here.

I dont know what else to try. I can get some used injectors cheap from
the yard near me and swap one at a time until i find the bad injector
if that is the case. I just have to get another set of new orings

Any other feed back or suggestions is much appreciated as i am running
out of ideas.

scale wrote:
>
> well i pulled each plug wire and they all noticably missed harder or
> more apparent then my problem which leads me to believe that i have a
> bad injector or a dirty one. They all tic which i tested but i dont
> know if they are spraying correctly. IM going to wait until it gets
> real dark and check for a arcing problem just to be sure.
>
> I know that the problem is very consistant in drive with the brake on
> (under load) and giving it the slightest amount of gas.
>
> It feels weaker than a full cylinder miss. THe plugs are all equal
> looking as far as ignition goes.
>
> Is there any way to check the fuel pressure? What is the proper
> proceedure for this. I notice the small resivor that is circle shaped
> right before my fuel rail and where the fitting is has a small pressure
> release valve on it with a black cap on it. Do you hook the tester here
> to check the PSI for the pump or do you pull the fitting at the rail? I
> dont have a tester for this. Im just hoping that the autozone near me
> will rent one out. Funny thing is the car seems fine once you start
> going down the road. It is just the intial first take off from a stop
> that it seems to miss or sputter or whatever is going on here.
>
> I dont know what else to try. I can get some used injectors cheap from
> the yard near me and swap one at a time until i find the bad injector
> if that is the case. I just have to get another set of new orings
>
> Any other feed back or suggestions is much appreciated as i am running
> out of ideas.

On that engine,
Bad intake gaskets are very rare.
Bad head gaskets are unheard of.
I've never heard of a worn cam lobe on that engine (roller cam)
but cannot rule it out.
My guess is that the problem is probably (either/and/or) bad injector
or bad plug wire. Bad compression (i.e.: bad valve) should be noticible
under most driving conditions.
When you pulled the injectors for new 0-rings, how did they look?
Checking ohms probably won't do any good since that will not tell you
spray pattern (as you suggested) or if the pintel is opening properly.
The Shrader on the silver fuel rail can is the pressure test port.
A leaking pressure regulator would cause low fuel pressure but
show no outward signs. It should hold pressure for a long time
(hours? days?) when the engine is off.
Let us know what you find.
Paul.

"scale" > wrote in message
oups.com...
> well i pulled each plug wire and they all noticably missed harder or
> more apparent then my problem which leads me to believe that i have a
> bad injector or a dirty one. They all tic which i tested but i dont
> know if they are spraying correctly. IM going to wait until it gets
> real dark and check for a arcing problem just to be sure.

Go buy a bottle of Chevron's "Techron" fuel system cleaner. Pour it into the
tank, fill up with gas (in that order so it mixes well) and drive around for
a week.

i just was out and ran the engine in the dark and didnt see any arcing
so i have ruled that out.

I need to replace the fuel filter but have found that i cant loosen it
because it is all rusted to hell on the fitting. I might bring it to a
shop and have it done. The flat book rate would probably be better than
me breaking the fitting. The book doesnt lie.....so whatever the shop
has to do to get the fitting off and get the filter replaced should
have flat book rate price right?

Anyway.....hopefully ill have a pressure tester on the way soon (later
in the week) and also a multimeter so i can test ohms. I have a line on
some used injectors for cheap but i want to check the fuel pressure
first. Im praying it isnt my pump. It is one of those in the tank jobs
and a big pita.

There is a small hose that runs from the top of the plenum to the fuel
pressure regulator that looks extremely old and brittle but it isnt
leaking that i can hear / see. Those regulators are not cheap. I hope
it isnt that or that perhaps i can find a used one.

Im hoping the shop will go by the book price and not overcharge me
because they cant get it off either

I need to get my hands on a compression tester as well. I dont really
want to buy one and am hoping that autozone will rent one via the tool
rental program. I know they dont have a fuel pressure tester for rent.
Compression testers should be a different story.

I dont know if they rent out those little noid testers but it probably
wouldnt hurt to test with one of those.

I am almost 100% sure this is a fuel delivery problem.

Ill let you know what i find out once i get the parts and tools i need.

"scale" > wrote in message
oups.com...
> i just was out and ran the engine in the dark and didnt see any arcing
> so i have ruled that out.

Doesn't mean a wire doesn't have an internal fault. The set of NEW Bosch
wires I had for the wifes S-Blazer had a bad end OOB.

>
> I need to replace the fuel filter but have found that i cant loosen it
> because it is all rusted to hell on the fitting. I might bring it to a
> shop and have it done. The flat book rate would probably be better
than
> me breaking the fitting. The book doesnt lie.....so whatever the shop
> has to do to get the fitting off and get the filter replaced should
> have flat book rate price right?

NOPE. Some places do not use book rates. Especially on older
vehicles.Just the hourly labor rates plus parts.
They pull it in and try removing the filter, the rusted fitting breaks
off. They now remove and replace the fuel line with the bad fitting,
OOPs it goes all the way to the tank with another fitting there. Drop
the tank, replace the line. Replace filter.


>
> Anyway.....hopefully ill have a pressure tester on the way soon (later
> in the week) and also a multimeter so i can test ohms. I have a line
on
> some used injectors for cheap but i want to check the fuel pressure
> first. Im praying it isnt my pump. It is one of those in the tank jobs
> and a big pita.

And your SURE those used injectors are better than what you have?

>
> There is a small hose that runs from the top of the plenum to the fuel
> pressure regulator that looks extremely old and brittle but it isnt
> leaking that i can hear / see. Those regulators are not cheap. I hope
> it isnt that or that perhaps i can find a used one.

So replace it, it is just vac. line. More USED parts......

>
> Im hoping the shop will go by the book price and not overcharge me
> because they cant get it off either
>
> I need to get my hands on a compression tester as well. I dont really
> want to buy one and am hoping that autozone will rent one via the tool
> rental program. I know they dont have a fuel pressure tester for rent.
> Compression testers should be a different story.
>
> I dont know if they rent out those little noid testers but it probably
> wouldnt hurt to test with one of those.
>
> I am almost 100% sure this is a fuel delivery problem.
>
> Ill let you know what i find out once i get the parts and tools i
need.
>
>



----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==----
http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups
----= East and West-Coast Server Farms - Total Privacy via Encryption =----

Let me just say that there are a lot of things on modern engines that can
give
you little pains.

I had similar to yours in a V6 Buick with the 2.8 litre engine. It turned
out that the injectors were past their prime. Injectors don't always fail
completely..they can limp around and be a pita.

In my case, a bottle of injector cleaner in the tank would help a lot, but
as soon as the treated gas was used up, the thing developed problems again.
As it was a high mileage car, I just traded it rather than keep fighting it.

The exhaust gas recirculation system on some engines can also give you some
odd symptoms, missing at certain temperature ranges or engine speeds. It is
good not to forget this part. (My son has had similar driveability problems
on
a turbocharged Mitsubishi and has replaced a ton of parts over the past year
or
so. His latest endeavors would seem to indicate the EGR system, but until
it is
fixed and run on the road for awhile, I will reserve comment.)

check the injector resistance it may be out of specs. also check your
throttle position sensor performance. contact inside the sensor may be
wornout on the spot where you start to feel the problem when pushing the
gas pedal. and also check the egr valve it may be sticking.