stuttering/shaking problem

Help!!! i have a mind of its own 94 olds bravada. it has 128000 on it and when its idling it kinda acts like its going to stall for a sec and then comes back and then does it again, when it stutters it shakes too. it doesn't just do this while idling though it does it when your driving especially around 50-55. the weird thing is i let it sit for like a month and a half and then started it up and it ran fine, now a week later its doing the same thing, help i just want to get it to run good so i can get rid of this piece of bad luck!!!

Is the check engine light on?

nope no check engine lights or anything, my dad thinks it might be just the fuel filter is clogged or maybe the erg or egr and whatever the heckk its called valve so he gonna check them today and then if that doesn't work i'm going to take it to a shop to have them run a diagnostics check on it and see what codes might come up....oh ya it stopped doing it again today after it sat for a day, when it acts up though it feels almost like it feels when ur running out of gas like that sputtering lurching feeling just not quite as bad...

Does the check engine light come on when you first turn the keyswitch on then go off after a coupla seconds?

yes but so do all the rest of the lights

my dad came up on friday and put in a new pvc or pcv or something and that didn't help so he tried changing the fuel filter but the bolt thing that actually screws onto the fuel pump the one with the "o" ring on it is rusted to the other piece of fuel line so hes trying to find a new one of those, so when he gets that hes gonna see if maybe that will work but idk...we'll see, any other ideas would be greatly appreciated

all the lights come on when you turn the key to start because its a test of the lamps.

a stuck EGR valve will cause a rough idle and stalling at stops and turn on the check engine light for a short duration, but would have no effect at high rpm unless maybe it was completly plugged. if you do take it off to check it replace the gasket with one that has a screen over the opening to catch any large pieces of carbon that can come loose.

the check engine light will go on and off intermintatly, usualy for smog equipment problems. even after the light goes off again the computer stores the failure code. take it the auto parts store, they will read the codes for free usualy. Chris has a list that tells what the codes means, so if you have a failure code and need to know what it is post it here.

Hey Eric, do you have a part number for that screened EGR valve gasket?
I guess it was just a matter of time until somebody incorporated a screen to the gasket. I drilled a dime sized aluminum disc with tiny holes and Jim of Phoenix found a stainless steel faucet screen worked for him...about 5 yrs. ago at the VMag Bravada site. It was a good site until an obscene poster ruined it for everybody and now it's deader'n-a-last-years-birds-nest but the archives are still open for retrieving info.

it was funny because the stuck EGR valve on mine cleared itself on the drive to the shop and i haven't had to remove it yet. we know it was the EGR from the failure codes. the service manager showed me one of the gaskets. I don't have the part number but it was a NAPA part. i suggest just ask for it, if they don't try to upsell you anyway.

is it true that the egr valve costs $200 + to fix? and if so is that just for the part or like if u were to take it to a shop? is it hard to replace on ur own?

An EGR valve is easy to work on. It's held in place with 2 bolts and has an electrical connector. If you can change a tire, this is a piece of cake.
They're actually a pretty reliable piece except after running up the miles and carbon gets in it.
What happens is a little piece of carbon holds the plug valve in the EGR open and the computer finds out (pintle position sensor) and sets a trouble code. Removing the EGR, removing the offending piece of carbon, reinstalling the EGR and resetting the trouble code fixes it quick. Installing a screened gasket Eric described is the permanent fix for carbon lodging. Another thing that occurs is the stem on the plug valve will accumilate a little coating which will stick it closed or open. Removing the EGR and simply working the plug valve in and out unsticks the thing and after it works freely, reinstall the EGR. I haven't heard of anyone needing a new EGR...oh yeah, don't spray anything other than air in one unless you want to need a new one.

is it true that the egr valve costs $200 + to fix? and if so is that just for the part or like if u were to take it to a shop? is it hard to replace on ur own?

sounds like you found my old mechanic "250 Bob". How much to fix a fuel pump, Bob? $250. How much for new brakes, Bob. $250. How much if it's running rough and i drive by real slow past your shop while you listen, Bob? $250.

250 Bob...lol!!!

soooo....so far we've replaced the fuel filter, spark plugs, pcv valve, cleaned out the egr valve(wasn't stuck so we blew some air through it to make sure there was nothing in there) and its still running like crap maybe even worse now, and..... the check engine light finally came on tonight. i have no idea what else it could be, is it possible that there is something wrong with the egr besides just that little plunger thingy? have u ever heard of a fuel pump going gradually instead of just all at once?

we changed the plugs but not the wires, my dad said the wires look crappy but do u really think that just the wires will solve all of these shitty problems?

I had a bad one on the '92 and it didn't even look crappy.
I put together a set of Accel spiral core wires to last me to the other side of Social Security.

I would just take it to a shop, dish out 40 bucks and have them find out what is wrong, then you do the work yourself.

after all the work you've done, changing the plug wires is cheap and easy. even if it doesn't fix the problem you have one less thing to worry about down the road.

yes a fuel pump can go slowley bad, getting weaker as time goes on, or just getting weaker as it warms up sometimes. chris mentiond in one of his earlier post that there is a test point for fuel pressure. did you change the fuel filter yet? if you can't get it off just take it to the quick lube and tell them to change it along with your oil change, and ask to see the old one when their done. then it's their problem. they do it for a low flat rate.

the only other thing i can think of is a vaccum leak. did you check all your vaccum hoses for cracks or disconects?

yea the fuel filter is changed still no difference

can a shop check for vaccuum leaks?

If you were having a rough idle the first thing you should have gone after would have been the plugs wires cap and rotor. Always start with the cheapest and most obvious places. I did have a fuel pump going slowly but it equaled a no start every now and then and slowly got worse but had nothing to do with a rough idle. I bet the wires will solve you rproblem. I had a rough idle only after the truck was running for about ten minutes turns out one of my wires was against the manifold and when the engine warmed up it was causing the rubber to expand and was grounding a wire to the manifold.

I would just take it to a shop, dish out 40 bucks and have them find out what is wrong, then you do the work yourself.

There's so much truth in that. If only you could be certain that they're that certain what the problem is.
I don't give myself good warranties either :grinno:

I am having this same problem on my 94 Olds Bravada. I am just wondering if the plugs and the wires fixed the problem. My car runs a little low on the idle and then for the first 50 ft of driving it runs crappy but once it shifts to 2nd gear it runs better until about 50-55 miles per hour and then i get the stuttering and shaking problem. So we are in the same battle and i am dying to know if the plugs and wires actually fixed it. Thanks

Does your Bravada have a Check Engine light on?
I think the '94 is OBDII so it'll have to be scanned if the Check Engine light is on.

Me too! At start up, blows carbon. Past experiences indicates ERG. Found code 45 is set but I haven't had a chance to look it up yet. I also had a problem with injector. I turned the screw in the center of the pressure regulator all the way in then back out 2 full turns. It wasn't wise for me to mess with it in the first place but I was frustrater with stalling problem.

AnybodY know how to correct the fuel pressure regulator setting? I have gotten quick at removing the mainifold. I am thinking of turning the screw in at 1/8 increments and test driving.

Code 45 turned out to be "reading rich". Oh well, back to the fuel pressure regulator

Code 45 turned out to be "reading rich". Oh well, back to the fuel pressure regulator

my 92 set a code 45 when trying to drive thru a cold start misfire. the engine was running rough cold and i hoped it would clear up as it warmed up because i needed to get to work. raw fuel being pumped thru by a misfiring cylinder caused it. i suspected an ignition problem right away and after going thru the plugs and wires it turned out to be a shot distributor but didn't find it until after being ripped off by the shop i took it to who ignored my description and chased a fuel system problem based on the code instead.

read these two threads for more information:
http://www.automotiveforums.com/vbulletin/showthread.php?t=514233
http://www.automotiveforums.com/vbulletin/showthread.php?t=518453

Code 45 turned out to be "reading rich". Oh well, back to the fuel pressure regulator

My wires did solve the problem sorry if this is a late response I am now driving a jeep and have not been to the board in a while!!

Code 45 turned out to be "reading rich". Oh well, back to the fuel pressure regulator

Since you have the intake plenum open, what does the area next to the regulator side of the CPI look like? Do you see any areas in the plenum clean and wet with gasoline? That is evidence that the diaphram of the regulator has a hole in it and could end up damaging the engine.

My wires did solve the problem sorry if this is a late response I am now driving a jeep and have not been to the board in a while!!

Thanks for the update Derhells!!!

hey Chris thanks again. The plenums fairly clean since I have been workinc on it more then driving. There is some fluid in the bottom around th bolts. I'm going to replace the regulator only. thanks to the link to the Help part number

Help! Part # 55162 (the reugulator) Includes the needed Torx security bit for retainer removal. (About $40.00 at Autozone, Pepboys, or Advance autoparts)

Check for vacuum leaks.

Change O2 sensor(s).

check the codes with a code reader.

Cat. convertor may have had a melt down.

Water it the fuel?

Intake manifold leaking.

I go for a vacuum leaks first.

You may have just started to trouble shoot. Remeber replacing parts
is a bad way to trouble shoot. You may spend a lot of dollars only to find
a 3 dollar part was the problem.