Shaking at idle just won't stop!!!
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Shaking at idle just won't stop!!! - 1/10/2006 2:01:26 PM
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lovetheblazer
Posts: 91
Joined: 11/11/2005
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My car does not seem to stop wobbling, shaking and rough idling...
Changed 3 motor mounts first...still wobbled...
Measured fuel pressure...48psi...I got the fuel pump out and cleaned it, it had a lot of dirt and also cleaned the tank...checked fuel lines and one was clogged before the fuel filter...checked fuel pressure again an it is steady at 55psi...
Last week it died on me on a red light with less than 1/4 of a tank...poured around 2 gallons to check this...and the next day when it had less than 1/4 of a tank I saw that the low fuel light was lid and it died...turned back on instantly!!! Yesterday I took the fuel pump relay and it had corrosion, cleaned it an electrical cleaner and I am carefully checking this if it happens again...
Also did the following...
changed everything possible there is to my car and nothing has helped...rotor, cap, fuel filter, air filter, wires, plugs, cleaned egr, cleaned iac, cleaned throttle body, clenaned maf with electrical cleaner, etc, etc....
DO these symptoms and very rough idle and shaking have to do with a bad fuel pump?
Vacuum leaks?
I checked mine and found none...will prolly double check today and see...
Anyways I just ordered: 6 new ac delco plugs, new air temp sensor, new pcv and new vacuum tee...
Only things I can think of left to buy is:
-Throttle position sensor (rpm is steady at 550, it is not jumping up and down)
-both knock sensors
-all oxygen sensors
-map sensor
The IAC and complete throttle body got cleaned a month ago and the truck accelerates better but the jumping at idle is still there...I even cleaned the maf with electrical cleaner...the fuel pump is reading 55 psi steady...cranks neat...
I am about to sell the friggin truck...I am thinking that It may die on me on a hwy but its only rough at idle...
Also, I am getting some gas smell the past few days...
I know its long but the more info the better, I think...
I have 99 Blazer with:
-Custom y-pipe
-Flowtech Raptor Muffler
-Gutted cat
-MSD Blaster Coil
-K&N FIPK
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RE: Shaking at idle just won't stop!!! - 1/10/2006 3:09:53 PM
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swartlkk
Posts: 15282
Joined: 5/1/2005
From: Waterloo, NY
Status: online
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ok, you stated that you checked your fuel pressure, but did you do a leak down test? This is to make sure that you don't have a leak in the fuel system. It is possible that the injector spyder under the upper plenum has developed a leak and is causing the rough idle. In the earlier CPI 4.3L engine, the FPR (fuel pressure regulator) would blow its diaphram and fill the crankcase with fuel. The later CSFI engines have a tendancy to leak in the same area but generally only need an o-ring kit to fix the problem. Rarely, the entire spyder will need to be replaced.
I would do a leak down test on the fuel system. If you see a drop in pressure, you've got a leak and 10 to 1 its on the injector housing under the plenum.
Good luck. Sucks that you probably replaced all of that stuff for naught...
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Kyle-
04 Rainier
My Restoration Projects
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RE: Shaking at idle just won't stop!!! - 1/10/2006 5:11:41 PM
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ivannj
Posts: 321
Joined: 11/2/2005
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Egr valve may be faulty check it out.
_____________________________
97 Blazer LS 4wd 4.3l 2dr 71,000 miles
E-fan, Low Drag Pullies, Intake, Gibson Exhuast, B&M Deep Tranny Pan, B&M Shift Plus, Hypertech Tuner, TB Spacer
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RE: Shaking at idle just won't stop!!! - 1/10/2006 7:46:46 PM
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ShadowHawk
Posts: 72
Joined: 8/15/2005
Status: offline
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The leaky fuel pressure regulator gave my Blazer the same symtoms. Fixed it with a new spider kit/pressure regulater/nut kit. Bought from an online Chevy dealer (through Ebay) for $308 and 2 hours' labor in my driveway. Fixed it right up, and no longer shakes at idle - and I got my mileage back up to just around 20MPG.
Here's a link to his post:
http://www.blazerforum.com/m_7118/mpage_1/key_CPI/tm.htm#7118
Also take a lookat your plugs. If the plugs on the passenger side of teh Blazer are carbon fouled, and the ones on the driver's side look fine, then suspect the pressure regulator (it sits over the passenger side of the intake manifold). When the leaking fuel gets deep enough to exit through the drain holes, thaen you'll smell it occasionally.
G'Luck! & Keep us up to date on the fix!
Rex S.
_____________________________
Rex S.
'95 S-10 Blazer 2WD, 4-Dr
'82 XJ650 Maxim
'82 XJ750 Seca
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RE: Shaking at idle just won't stop!!! - 1/10/2006 8:14:38 PM
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swartlkk
Posts: 15282
Joined: 5/1/2005
From: Waterloo, NY
Status: online
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Here again, the '99 is a CSFI, not CPI. Problem still applies, but the FPR is located at the back of the upper intake plenum where it would effect cylinders 3,5, and 6 if I remember correctly from when I had my upper plenum off replacing o-rings.
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Kyle-
04 Rainier
My Restoration Projects
Please Do Not PM for Tech Help
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RE: Shaking at idle just won't stop!!! - 1/11/2006 8:32:07 AM
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lovetheblazer
Posts: 91
Joined: 11/11/2005
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I will check the fpr this weekend anyways to see if it is leaking...
Anyways I will receive by monday a new air temp. sensor, new delco plugs, new vacuum tee, new pcv...will change all this to see if it helps in any way...
All of this started after I changed the motor mounts, an abnormal vibration started...when I rechecked and rechecked if I did the job well, I took the car to two shops and said they were put well...no disconnected hose, everything OK...some have told me that the 4.3L's shake in idle, but c'mon, as if it gonna die on you at avery stop light??? please!!!
I have spent TOO much money with no clue on the solution...Probably $650 roughly adding all I've done...parts, labor, tranny fluid flush, etc...I am not including the performance parts such as MSD coil, mufflers, FIPK, etc...
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RE: Shaking at idle just won't stop!!! - 1/11/2006 9:34:08 AM
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swartlkk
Posts: 15282
Joined: 5/1/2005
From: Waterloo, NY
Status: online
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Well, it is possible for the exhaust supply tube to be coated up pretty good and if that has started to flake off, it is possible that rather large chunks could be getting to you EGR valve. I have gone as far as to get some steel pipe cleaners and really soak the crap out of the exhaust supply line then run the pipe cleaner through it to remove the gunk. Then a nice nozzled down shop vac to suck the line out and you're good to go.
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Kyle-
04 Rainier
My Restoration Projects
Please Do Not PM for Tech Help
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RE: Shaking at idle just won't stop!!! - 1/11/2006 11:28:01 AM
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swartlkk
Posts: 15282
Joined: 5/1/2005
From: Waterloo, NY
Status: online
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By "soak the exhaust supply line", I mean to spray sensor safe carb cleaner into the port where the EGR valve mounts to, then use a pipe cleaner - a metal twisted core with either copper/steel/stainless steel wires wound into it.
Other types of pipe cleaners include those used for washing dishes which have plastic wires (or whiskers - however you look at it). Another name for them would be a bottle brush or cup brush, but the one that you will need should be some kind of metal for the wires. It also should be around a half inch in diameter. They come in various lengths, but I couldn't tell you where to buy them from. I grabbed one off the maintenance shelf at work.
You could clean both the ports in this manner. The reason why I suggest this is because, as the carbon builds up inside the EGR valve, it is also building up on the inside of the supply tube. It can get a pretty decent coating on inside there and eventually it will flake off.
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Kyle-
04 Rainier
My Restoration Projects
Please Do Not PM for Tech Help
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