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  #1  
Old 07-26-2010, 04:28 PM
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Default EGR Insufficient Flow & Running too Rich

Hello I need some assistance. I have searched and searched and just cant find where to start with this EGR insufficient Flow and now the running too rich code on my 1995 S10 Blazer LT 4x4. I have a brand new EGR valve the old one was pretty gunked up. did sea foam looked for vacuum leaks etc had 3 mechanics look at it One is stumped one says oh it has a mis could be wires/Plugs/etc then the other said I need to clean out the intake for $250.00 im sure he just wants my money cause I am a woman.
Any ideas where I can look?

Heres whats been done so far.

new EGR
New Plugs, Cap and Rotor
replaced PVC valve and boot
new Fuel Filter

reset computer i dont know how many times but the codes just come back and that Check engine light is making me nutz.

what else could cause this problem?
Any help would be appreciated.

Last edited by Chastity; 07-26-2010 at 07:52 PM.
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Old 07-26-2010, 08:47 PM
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Could be the man is right and the intake is plugged, especially if it's been running really rich. Could be a blown fuse for the EGR valve and I don't know the appropriate one(s) on a '95. If the setup is like a 2000 and there's a tube from the exhaust going to the intake to supply exhaust gas (looks kind of like a gas tube for a stove going to the front drivers side of the intake) might be that's broken or leaking (you'd hear an exhaust leak). Could also be a flaky O2 sensor that's not "seeing" the addition of exhaust gas. (once again if you were running super rich, the sensor could be plugged with carbon). If you haven't done it recently throw an air cleaner in it too, plugged one could richen it up (and it's a cheap part to throw at it).
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Old 07-27-2010, 05:21 AM
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Quote:
Originally Posted by RonJon View Post
Could be the man is right and the intake is plugged, especially if it's been running really rich. Could be a blown fuse for the EGR valve and I don't know the appropriate one(s) on a '95. If the setup is like a 2000 and there's a tube from the exhaust going to the intake to supply exhaust gas (looks kind of like a gas tube for a stove going to the front drivers side of the intake) might be that's broken or leaking (you'd hear an exhaust leak). Could also be a flaky O2 sensor that's not "seeing" the addition of exhaust gas. (once again if you were running super rich, the sensor could be plugged with carbon). If you haven't done it recently throw an air cleaner in it too, plugged one could richen it up (and it's a cheap part to throw at it).
thank you for the information. I do have a question however dont mean to sound like a typical woman but where would I find the EGR fuse? I just checked all the fuses in the fuse panel and all are good. (only did that because i pulled the dash apart and forgot to plug in the lights lol) I will look for the tube going to the exhaust today. The Air cleaner is new forgot to mention that in the original post.

how often can I seafoam the intake i really dont have the money to pull the intake and clean it and if i did do it and that didnt fix the problem i will be really upset.

thank you for the information i will start on today.
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Old 07-27-2010, 05:33 PM
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I don't know how often you can seaform it, never tried it. I've cleaned it once while I had it off to do lower intake gaskets and I used carb cleaner and a toothbrush. If all the fuses are good then they're good ( the EGR would be ECM A or ECM B or something similar). The brute test for for your EGR passages would be pull the valve off, there's two holes, one for exhaust to it, the other from it. Start the truck and exhaust should come out of the hole. The truck will barely idle. Shut it off, plug the other hole and when you start it it should idle noticeably better. If it does both those things then the passages are relatively clear.
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Old 07-28-2010, 06:44 AM
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ok update took it back to the mechanic yesterday checked it over once again put the computer on it drove it. Mechanic says there is a misfire that the seafoam might have broke lose carbon and it's on my sparkplugs to drive it for a couple of days and see if it clears up. if not then we need to replace the plugs once again. Wires are good.

The Egr fuse or ECM fuses there are 2 of them i checked those as well. I found if I pull them and put them back it resets the check engine light.

The light was off till i turned into the mechanics parking lot then it came back on but then it went off by its self. then about 30 miles down the road it went back on.

Will go to Advance Auto today and have the codes checked again to make sure it's not something else.

so i guess ill wait a couple of days and see what happens.... will update. but if you can think of anything else please let me know im at my wits end with this.

Chas
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Old 07-28-2010, 01:42 PM
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Where did you get the " EGR insufficient Flow " ?? These words and "Rich Running" don't go together.
96 and up are OBD -II which may give this code
95 and earlier models are OBD-I
Like many mfgs, GM may have split the year and later 95's may have the OBD-II system.


You can drop by most chain part stores and they can tell you if you have OBD-I or OBD-II
[BTW, a loose gas cap will give a check engine light on OBD-II]

I assume you don't have a California vehicle, very few were built.
If your vehicle was sold in Calif it will be a "Z" engine with a TBI [Throttle Body Injection]
The Z engine looks like a 2 barrel carb with a pair of injectors visible under the air cleaner.

Otherwise you have the standard CPFI system most likely it will be a "W" engine, With CPFI, the air cleaner is by the radiator and you will see the words Vortec in red on a Lumpy Black Aluminum Intake manifold.

EGR insufficient Flow and "Rich Running" don't go together.
Too little EGR flow will Not cause rich running, conversely it causes high combustion temperatures and a Lean condition which may result in pinging or spark knock.
If you hear spark knock or full time pinging may require the timing to be slightly retarded.
Slight Pinging when pulling hills is OK [per GM Service Manual]

I see you got a new EGR, this is just FYI
The EGR will set a code[32] if the pintle is held open with carbon, this results in rough idle and sometimes surge at road speed.
You can pull the EGR and inspect it..
It's under the throttle valve held down with 10mm head bolts.
A little hard to restart the bolts with a extension, so use fingers or a 10mm swivel socket.

If you live in areas with 20% Ethanol, I "heard" this causes more carbon buildup than lower levels, dunno myself.

The EGR should be black inside but free from chunks of carbon, the intake may need gouging out, use a vacuum to remove loose bits, a stiff wire may be needed to poke it or removal to free all passages.
If the intake is totally clogged with carbon, you will have to remove the lower intake manifold half and clean it out including the holes which come from the heads.
If you do this clean it good, any chunks can get into the EGR valve causing a code 32, which is Open EGR and Too much flow.
Time consuming but cheaper than paying flat rate at repair shops. Really this is pretty easy for the novice mechanic.

You can do without the EGR valve, E-Bay sells block off kits for about $20, you can bolt the electronic egr valve on one of the intake studs with the wires attached, this will tell the computer it's hooked up.
In areas with Emissions Checks, this will not fly

More Likely,
I suspect leaking fuel lines inside the manifold.
GM has a CP Fuel Nut kit for $110 which is nothing other than plastic fuel lines.
Rockauto.com has the same unit for $55.99 + s&h [shipping is cheap at rockauto]
http://www.rockauto.com/catalog/x,ca...e,Fuel%252FAir
click on the "Fuel Injector Hose Repair Kit"

A Chevy dealer near me says this is what the parts dept sells most for these series engines.

To diagnose this rich running condition with this repair in mind, pull the top half off the manifold, it's easy and takes about 30 min if you have tools ready.
[A Deep Well 10mm socket is mandatory for several screws]
Take note where the bolts come from, a piece of cardboard with front & rear marked is nice, poke the bolts in the pattern they came from.

With the manifold top half off, look for clean areas, it should be black if no leaks. If clean areas are spotted, have someone turn the key to the ON position NOT Start, then look for spraying fuel.
The lines tend to leak mostly at the rear of the manifold, drivers side, on the bottom of the lines. Should be clean where they leak.

This is a good time to install new O-rings under the injector[ACDELCO Part # 217452 {#22514722} $0.80 ea and the injector lock clip[dealer item]. Also a good idea to use a new gasket[FEL-PRO Part # MS95818] $7.50 .

If the FPR fuel pressure regulator is leaking [passenger side] r&r it, [Fuel Pressure Regulator OE# 17113673] $37.99

Get a Toy stethoscope, remove the end, use the hose to listen for vacuum leaks and also leaks around the coil, the coil is very likely to be leaking, $20~ you can hear it easily.
Vacuum leaks cause erratic running and many hard to diagnose conditions.
They tend to get gummy or hard, the hard ones can split on the end where they go to male fittings, the gummy ones can collapse or leak in a manner hard to hear with a stethoscope.

Sorry for the long post, hope this helps
Doctorvette

Here's the link to RockAuto's listing for your 95 Engine
http://www.rockauto.com/catalog/x,ca...e,Fuel%252FAir

Last edited by Doctorvette; 07-29-2010 at 12:27 PM. Reason: to fix rockauto's link
  #7  
Old 07-29-2010, 12:42 PM
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Quote:
Get a Toy stethoscope, remove the end, use the hose to listen for vacuum leaks and also leaks around the coil, the coil is very likely to be leaking, $20~ you can hear it easily.
Vacuum leaks cause erratic running and many hard to diagnose conditions.
They tend to get gummy and also hard, the hard ones split on the end where they go to male fittings, the gummy ones can collapse or leak in a manner hard to hear with a stethoscope.

Sorry for the long post, hope this helps
Doctorvette
I know there is a vacuum leak somewhere because when I run the A/C and tromp on the gas the air comes out the defrost and the floor...... however no matter what the setting is on the A/C the air still always flows on my feet when im driving.

Im being told now there is a MISFIRE. I ran seafoam thru the system and mechanic thinks theres chunks of carbon on my plugs to drive for a few days and see what happened.


where is this coil your talking about I do most of the easy stuff on my truck before I bring it to the mechanic. tho I can say that when we replaced the plugs about a month ago all of the plugs on the passenger side were burnt black ive never seen plugs look that bad.

I think i may still have them here if I do ill take a pic and post it. if necessary

Oh the code im getting are 401 EGR insufficient flow And 172 Running rich

I do really appreciate all the help ive received here
Thanks everyone

Last edited by Chastity; 07-29-2010 at 02:07 PM.
  #8  
Old 08-02-2010, 10:44 PM
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Ask em at Autozone which system you have, just for info, OBD-I or OBD-II

How many miles on this vehicle ?

I may be wrong about the EGR thing, the ECM may see limited EGR flow and increase fuel/air mix to lower combustion temps[lower oxides of nitrogen] to compensate for a non functional EGR system.

Your comment
Quote:
all of the plugs on the passenger side were burnt black
lends me to think the FPR [fuel pressure regulator] may be leaking.
Do you notice an increase of Oil Level ?
One site said leaking FPR can ruin a engine from diluted oil.

When I removed my poppet injectors I noted the lack of O-rings, so a leaking FPR [which is on the passenger side] could be the cause of your black plugs. was the engine running ok with the black plugs installed ?
Someone correct me if I'm wrong here, please.

I suggest dropping by a highly regarded GM dealer to get their opinion. You may "tag team" them by dropping by the parts dept for info, provided they're not busy before going to service.

I'm no longer a professional wrench, and have no real expertise in modern engines except with my own vehicles and what I glean from the net and service manuals. During my time as a paid wrench, and afterwards I held a lingering clientele who praised my attention to detail.

Recent Vehicles

90 Corvette L-98 Tuned Port
91 Roadmaster SW 305 TBI
91 Caprice 305 TBI
94 GMC 350 TBI
95 Pontiac Bonneville SSE 3.8
96 GMC Yukon 4x4 5.7 Vortec
94 GMC S-15 Jimmy 4x4 4.3 CPI

I investigate each vehicle's oddities and address them one by one.

As far as check codes, often times another item or an attached item will cause an incorrect code.
i.e. low fuel pressure can cause the Oxygens Sensor/ Evaporative Emissions code to show.

Hope this helps
DoctorVette
  #9  
Old 08-02-2010, 11:19 PM
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I would concentrate on finding the vacuum leak as a first step. It is surprising how much chaos can be caused by a simple vacuum leak.

Here are the diagnostic sheets for the OBD2 codes you have stated:
P0172 - Fuel Trim System Rich Bank 1
P0401 - Exhaust Gas Recirculation Flow Insufficient Detected

A leaking FPR is very easy to check for with a quick fuel pressure test (quick once you have the tester which can sometimes be rented). There are no o-rings on the 'legs of the spider' where they enter the lower intake because they would serve no real purpose. If you have a leak inside the plenum sooner or later the fuel will find its way into the cylinder and/or oil.
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Old 08-03-2010, 12:40 PM
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Thanks swartlkk for that important note.

On your AC/heater problems, I too have similar problems. A visit to a mechanic pal yesterday led me here.

Check the ends of the vacuum hoses for split ends prior to replacement.

The 4-port vacuum control is the one most likely to give out.
[If you have manual control AC/Heat]
ACDELCO Part # 1571489 {#16047875}
VALVE,HTR & A/C CONT VAC w/A/C MAN CONT(C60)
$10

The actuator is $30

These prices are RockAuto.com
Attached Images
File Type: jpg Heater control 4-port.jpg (38.7 KB, 14 views)
File Type: jpg Heater control Upper Actuator.jpg (38.2 KB, 12 views)
Old 08-03-2010, 12:40 PM
 
 
 
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95, blazer, carbon, chevy, codes, computer, egr, forum, intake, manifold, resest, rich, running, sbc, sensor, symptoms


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