cant really figure this out

[2g_spyderturbo]

ok first off its my dd 2g gst auto,you can cheak my profile for mods.


this started to happen about aweek ago and the problem is that when i am at a stop or going at any speed and i hit the gas about 1/4 to 1/2 way the car starts to pick up speed for 1sec or even less and then it kind of feels like it stals or stops or somthing.Also if i have my window open with no music playing i here a thump kind of noise out of the exhaust almost like a backfire.

could this be...

1.a starting to fail turbo even thow there is no shaft play

2.a minor version of a fuelcut

3.trany starting to go out even thow it got rebuilt 2 years ago

also i baby the car and only open it up maby once every 2-3 mounths if that,and the car has 78k on it


thank you

John

 

[high klicks]

one thing I can clarify is it wouldn't been the tranny because tranny wouldn't cause backfiring , so far as the rest of the stuff , need more info does the turbo spool up an if it does , does it make it to what psi . Does it happen at certain rpm's ? Does it do it all the way to redline?do you have a data logger?

 

[2g_spyderturbo]

ok the turbo spools to 14psi(what i set it too),this happens at any rpm and at any speed, and i wouldnt know if it goes up to redline because ive only taken it to 5k-55k.Also this does not happen every day more like once or twice every 2-3 days,and no i dont have a datalogger yet because i been pretty much flat broke for about ayear because of all the bills i have and not getting enoughf(sp) hours at work.So a datalogger is out of the question


p.s. this only happens for about one sec then stops and dosent happen again for quit some time

 

[GTM]

...
p.s. this only happens for about one sec then stops and dosent happen again for quit some time

Hmmm this could be any of at least half dozen things. A compression check might reveal early stage of a burned valve, at the same time the spark plugs can be inspected for anything abnormal. A bad spray pattern from an injector, lean running (o2 sensor?) vacuum leak, timing advance, dirty EGR, ign coil, spark plug wires, manifold leak.

Some of these are visual, others will require more involvment. This is not the sort of thing that an absolute put your finger on the problem diagnosis can be given without having the car.

Spark plug gap too wide would be my first choice after excluding any vacuum or manifold leaks especially if you are getting good fuel economy.

Cheers,
GTM

 

[jott5555]

start by changeing your spark plugs and gap them properly

 

[Ultimatedsm]

Time for a tune up my friend, whens the last time you changed your plugs, wires, fuel filter etc.?

 

[2g_spyderturbo]

the last time i did a tune up was right before winter

 

[GTM]

the last time i did a tune up was right before winter

You need to roll up your sleeves and get involved. Be careful who you put your faith in and what they are telling you. Interesting that without seeing the car or knowing all the facts you get such convincing advice.

The bottom line is this, nobody is going to be in a position to tell you what it is until you have done some more inspections. Do the easy, fast, free, things first then look for the more obscure or time consuming problems.

You can change your driving habits and avoid the problem but this isn't always prudent.

Cheers,
GTM

 

[2g_spyderturbo]

^ thank you for the adive gtm iv done quite a few things to cheak this problem out but still nothing major

all ive found so far is the spark plugs were fouled(sp)out,but thats from my car runnimg very rich.Ive changed those out and still nothing except that when i turn the car on in the mornings and hit the gas the car almost dies.

heres a list of what ive done

1. compression cheak-all good

2. leak done test-all good

3. coail pack-all good

4. spark plug wires-all good

5. turbo-all good

6. oil leaks- all good

the only thing that i havent chealed was the spray pattern of the injectors because i dont know how to do that.Other then that im stumped about this

 

[gsx-box]

Your car running rich is the problem itself. Did you install a blow off valve venting to atmosphere with a stock MAF or a serous boost leak?

Or did you swap injectors. Why is your car running rich in the first place.

Once you fix your overfueling problem your hesitation will stop also.

 

[2g_spyderturbo]

if you had read my last post would know that ive done a leak done test and no boost leak

for the bov it is recerculated(sp) back into the intake,i do have stock injetors on the car

and for the rich problem has been going on every since i changed the dead o2 sensor from the front about 2 years ago, and i cant figure out why its running so rich for the life of me.The only way i could think of stoping this is by buying a acf and tuning it,but in order to do that i need money

p.s. the running rich problem is not the cause of this because like i stated above its been like that for a wile,and this problem just happened

 

[GTM]

if you had read my last post would know that ive done a leak done test and no boost leak

for the bov it is recerculated(sp) back into the intake,i do have stock injetors on the car

and for the rich problem has been going on every since i changed the dead o2 sensor from the front about 2 years ago, and i cant figure out why its running so rich for the life of me.The only way i could think of stoping this is by buying a acf and tuning it,but in order to do that i need money

p.s. the running rich problem is not the cause of this because like i stated above its been like that for a wile,and this problem just happened

None are so blind as those who will not see...

Ahha, you have done your homework, thanks for identifying what has been done. Just for the record do you remember what the compression numbers were? Might even be worth adding to your profile and changing as necessary(?)

Since I'm not a DSM expert I'm only drawing upon the zillions of other experiences with similar complaints. You might consider if nothing more as a test reducing the spark plug gap to at least the minimum gap or even a couple thou under. The rational is the coil takes less time to fill, reduces the voltage necessary to fire the plug, improves acceleration, decreases fuel mileage. A spark coil that is only shorting a few windings when it gets hot would improve. A scope showing actual plug firing voltages could reveal this.

I'm reaching close to the end of known sources that I remember solved this problem.

If you have an EGR they can leak and may be part of a scheduled maintenance as they get old so going over the valve with a wire brush and some carb spray might clean a sticky dirty seat.

Temp sensor could be failing and telling the ECU it's hotter than it really is thus leaning the mix out in those throttle ranges where it occurs. Did the old o2 sensor fail or just changed because it was suspect, if you have the old part you could again swap it as a test.

The injector spray pattern is a PIA for it requires pulling the injectors rail, then energizing each to observe the actual spray. You use a paper towel or piece of newspaper and let it fire onto the paper and see if you have a good pattern. there is a distance involved. This is not a common test (or failure) but if you have 1 plug showing some strange burn mark this can be the source. A leaking injector will show a bad pattern but then you could have some hard starting overnight as the fuel pressure drained off and flooding a particular cylr.

Intake manifold gasket, cracked vacuum hose, diaphram leak. Tightening bolts and inspection, using a piece of hose as a listening tool that you probe different areas can be helpfu. Observing shop safety practices you can spray the manifold and associated parts with carb spray to see if the engine idle condition changes.

PCV valve dirty and sticking. BOV leaking. ECU starting to fail. Throttle shaft / seals but the above spraying would spot this. A propane torch can be substituted for the carb spray but not as responsive unless you get right on top of the problem.

I may have forgotten something or someone else has additional input not covered. Cam timing with too much overlap?? Too much advance on ignition timing.

Take it behind the barn and shoot it.

Keep us posted, it's fixable when you find it.

Cheers,
GTM

 

[talontsi9095]

I had the same problem with my car and it started out like your problem and got worse over time. It turned out being my manifold gasket started to break apart and was also causing my car to run really rich and it would die after i would start it. I used carb cleaner to see if my car would rev up after i sprayed it on the gasket. When i fixed it i only had half of the gasket left.

 

[talontsi9095]

Also i had another problem one time. If you dont have a plate over your plug wires to keep them from getting into your cams ive had one get cut and it would ground out causing the car to feel like it was bogging down.

 

[GTM]

...
my manifold gasket started to break apart and was also causing my car to run really rich and it would die after i would start it. I used carb cleaner to see if my car would rev up after i sprayed it on the gasket. When i fixed it i only had half of the gasket left.

I always like to learn new things, why would a leak in the gasket cause it to run rich?? No opinions, no guessing, no my buddy told me so, facts only. I can make the argument (legal sense), I just want to know if this is a qualified statement and why.

Cheers,
GTM

 

[talontsi9095]

Well when my gasket was leaking it was reading i was getting air that wasnt going to the engine causing it to run rich. Not enough air and it was still getting the same amount of fuel. My gasket leak was a major one though it got worse over time.

 

[GTM]

Well when my gasket was leaking it was reading i was getting air that wasnt going to the engine causing it to run rich. Not enough air and it was still getting the same amount of fuel. My gasket leak was a major one though it got worse over time.

Try substituting lean for unmeasured air so that doesn't fly. (it was delivering correct fuel for given air flow) thus lean with the leaking gasket. Next.

Again argument, but why?? Let's not hijack the thread and I'm interested in solving the problem rather than some urban legend.

Cheers,
GTM

 

[talontsi9095]

Well you might be right but my afc doesnt read any air flow it is just set to deliever the fuel i figured thats why it was running rich. but i dont know alot about my afc and it was running a tad on the rich side before. Oh and good luck figuring out what it is but more than likely it want be anything that we think it is you just have to study up on it and use your own knowledge to find it.

 

[GTM]

...
i dont know alot about my afc
...
Oh and good luck figuring out what it is but more than likely it want be anything that we think it is you just have to study up on it and use your own knowledge to find it.

Now you have done it. I wonder if you tell your parents and your instructors they got their head up their backsides...

Excuse me but it's BS like this that wear us Wisemen (persons) down. Not only do we have to rack our brains for the millions of possibilities we are presented with dont for don't or do not ~, or "I had _a_ problem" ~, or "want" for whatever. The original poster says _read_ the previous posts so he doesn't keep getting unqualified replies.

Make no mistake I need all the help I can get even though I've worked on 30,000 cars in my lifetime there is always something new to be learned.

I'm comfortable in stating with 99% certainty the problem lies within the scope of what has been written while allowing you the 1% chance to show us what a college education can do. I am deliberately being caustic with the hopes that you will confine your statements to what you know. Under no circumstances are you to tell someone to get smarter until you have achieved that for your self. I can assure you I'm capable of performing a nasal, ocular, temporal, lobomoty and know that a kaitetradodecahedron will make you go to sleep while a hydrate crystal changes state.

Again, I welcome any input as long as it's useful in solving the problem including that which contridicts any mistakes I might have made. I'm just as falable as the next person but I get tired of people wasitng my time when they take liberties with someone's pronlem to satisfy some ego thing.

My apologies to 2g_spyderturbo who doesn't need to read this crap or also be told he has to get smarter.

GTM

 

[2g_spyderturbo]

ok a new list of what i recently did


1. changed the pcv valve-nothing

2. cheaked the bov- nothing as i suspected because its only two mounths old

3. changed the spark plug wires-nothing

4. used carb spray- nothing

for the egr i will go ahead and change it again,yes i said again,because when i first got the car i had a big problem with the thing and changed everything that had to do with the egr,i even changed the egr twice and finley found out it was a sensor that i didnt know was part of the dam thing 6 mounths ago.So if you really think it is part of the problem i will do it.


The temp sesor i changed out 3 weeks ago,but since i changed it ive noticed that on cold starts about 5 min after driving the car is almost completly warmed up.Is this normal or should i rechange it.

For the o2 sensor,that was shot to $hit and no i tossed that ting out right away.

Iam staring to think its either the timing or the ecu,For the timing i dont have the right tools nor the knowledge of how to do that so i would have to bring it someware for that,but thats not a prob because i had only 10k left to change the thing.For the ecu how would i be able to cheak to see if that is failing.

once more GTM thank you for all the help you have been giveing me

 

[GTM]

ok a new list of what i recently did
...

So if you really think it is part of the problem i will do it.
The temp sesor i changed out 3 weeks ago,but since i changed it ive noticed that on cold starts about 5 min after driving the car is almost completly warmed up.Is this normal or should i rechange it.
...
Iam staring to think its either the timing or the ecu,For the timing i dont have the right tools nor the knowledge of how to do that so i would have to bring it someware for that,but thats not a prob because i had only 10k left to change the thing.For the ecu how would i be able to cheak to see if that is failing.

once more GTM thank you for all the help you have been giveing me

If we don't solve this PIA soon you may stop thanking me.

My suggestions are of a singular nature which any one of them could have caused the problem. You mentioned changing the temp sensor, was this before the problem or after the problem??

I cannot endorse changing the EGR again unless you suspect it wasn't a proper install.

You have tried just about everything that normally would have solved the problem. At this point I would suggest that if you have confidence in what you have already done then timing, either ignition or cam may be a fault or the ECU is loosing it's brains. If you can borrow an ECU for a few days it may be the easiest path to try.

There should be info here on DSMtuners or Vfaq.com which will allow you to test / adjust timing. The ECU can be checked to show any fault codes if you have not done this.

Cheers,
GTM

 

[talontsi9095]

I have a ? for you is you check engine light on and gtm could his problem be caused by trash in the fuel or dirty fuel filter?

 

[2g_spyderturbo]

no the cheak engine light is not on

 

[GTM]

...
and gtm could his problem be caused by trash in the fuel or dirty fuel filter?

Probably not... however water in the fuel maybe. Fuel injector filters are designed to filter out water but if it gets full the pump can force it through the filter element and into the injectors. The problem with that idea is it would be more random and at different speeds and load conditions. His problem is repeatable on command every couple of days if he sets it at a particular speed / rpm and then goes to accelerate at a normal rate it will occasionally cause a hesitation for a second. The hesitation if I understand correctly is a backfire into the intake which almost always suggests a lean condition.

The lean condition burns hotter thus some deposits will come off as sparks, when you have cam overlap the piston which is now traveling upward will sometimes force one of these sparks into the intake manifold and ignite the fuel mixture before it can be drawn into the cylrs. With nothing to burn the deposits cool, no more sparks and it resumes proper fuel mix to accelerate.

In addition a very dirty fuel filter will plug up and prevent fuel from passing enough fuel under maximum load or prolonged high speed driving. The fact it's not every day or hard acceleration pretty much dismisses this idea.

Jumping 1 tooth advance on the intake cam might not be noticed in performance which will exaggerat the possibility of this happening. Since he's not pushing it the chances of fouling valves or pistons may not exist. It's worth while checking to make sure this has not happened.

Cheers,
GTM

 

[2g_spyderturbo]

so after geting my buddy to lend me his ecu for the past few days i relized that that was causing the problem because after i instaled the ecu the problems that i was having didnt happen again.So now im stuck finding a new ecu for my car

once again thank you for all the help that you have given me GTM,it has really been appreciated(sp)