Ruff idle-oil in intake.

I would just like to start this out as saying I have fixed many of my vehicle's problems by reading through this site. It's excellent.

Recenty my 1995 S-10 Blazer Vin #W has been idling normally when cold, then runs ruff after warm up. It has a popping/sputter sound coming from tail pipe, and a missing every now and then from the motor.
This started after I replaced the intake manifold gasket. I took it into a dealer to have the engine timed, because I could not get it just right.

While I had the intake off I cleaned the EGR valve (Third time it's been cleaned in 2 years).
When I replaced the intake gaskets I did not see any oil in the intake plenum.

After my blazer started acting up i decided to look into the intake plenum.

I saw oil in the plenum and what looked like oil in the intake ports going into the engine.
On reading other threads I had checked the PCV and valve cover for excessive blow by and it did not appear serious. I did however take the valve on the top of the plenum off and tried to start my blazer. I heard a couple of loud pops (POSSIBLE THE CYLINDER FIRING).

I fear I may have a burnt valve, but before i do anything further i would like your input.

I would also like to add that i had my blazer's computer reprogrammed. i thought the guy had deactivated that egr when he reprogrammed the computer. would the egr still work if it was turned off.

I have replaced cap, rotor, wires, coil, plugs. I replaced these prior to taking off the intake manifold the secind time.

check you fuel pressure.

Also oil is normally in the intake from the PCV valve.

I would replace the PCV valve and remove that valve on top of the plenum and smell for gas.

Also, I don't know how you timed your engine, it is completely computer controlled and you cannot set it.

Thanks for the prompt reply.

It has a new PCV valve. The intake does not smell of raw fuel, but does have a burnt type smell (Very dirty).

When i had it timed by the dealer he said it was 17 degre off when they intitialy checked it.
I believe my blazer was manufactured in the later part of 94, because alot of the parts I have to get, match that of a 1994. It has a distributor with towers on the top.
i have read other posts that reported that the egr lowers combustion temp and that would affect the knock sensor (Due to increase in combustion temp). If the egr is stuck would that cause the popping out of the intake (when i removed that valve), and the poor idle. The popping is not audible when the valve is in place, but motor is running ruff at idle.

i am trying to get ahold of the guy that reprogrammed my computerto see if he really turned off the egr. the reason i have the computer reprogrammed was because about two years ago the egr starting acting up. i had the local dealer clean it. they said it would cost about $300.00 to fix. I was told by a guy that he knew some one that could reprogram my computer so it would not moniter the egr. i had the computer reprogramed and it ran fine until the intake change.

Any thoughts about this situation w/egr reprogramming if it is possible or if it is wise to have done this.

Thanks again for your time in answering my questions.

You want the EGR working. Not having it running will lead to less performance and less fuel economy.

The carbon and such is probably coming from a leaking fuel pressure regulator. This is the leading cause for EGR plugging.

Don't patch the problem by turning off the EGR valve, that is essentially illegal and you can be charged if they find out.

Well, I guess i will replace the fuel regulator, and then the EGR.

One more question? I replaced the injecter about 1.5-2 years ago. Blazer quit for no reason, i ended up replacing the fuel pump, fuel filter, and fuel injecter. The problem ended up being the fuel pulsator. Very expensive $10.00fix.

Sorry about the rambling.

My qestion is would you recommend that i replace just the regulator or the entire injecter.

Thanks again for your advice

Check fuel pressure first.

"leaking fuel pressure regulator"

I'd probably put my money on that one...My dealership said that was a typical problem with that yr model. Seems to drive ok but idle is where it was most noticeable for me. Also should probably hook up the EGR again and make sure PCV is clean and then keep on motorin!

When you took the intake tuning valve out, you gave the motor a big hole to breath through, thank goodness the throttle plate was closed and the TPS told the computer to idle so with the open tuning valve hole, the motor started and ran super lean indicated by pops and backfires.

For the "oil in yer intake" plenum, check the intake bolt torque, you may have a coupla loose ones.

Like 'da BlazerLT sez, fix your EGR and check your fuel pressure. Fuel pressure check kits are available at most chain type auto parts stores, get one with the bleeder and you can sample the fuel going to your injectors. If you have a buddy with a '98.5 to '02 Dodge w/Cummins diesel, you can check his lift pump fuel pressure with the same gauge and possibly save him $1200 injector pump replacement. Here's the test port on your Blazer. Turn the keyswitch on to let the fuel pump run a coupla seconds, should be 52psi or better. Does the pressure hold a few minutes after the fuel pump goes off?

http://i131.photobucket.com/albums/p288/Clunk_/Image033.jpg

well I'm just waiting to save the cash to get the fuel pressure reg and EGR valve. i will post to let you know if that fixes to problem.

thank again for everyone's input

Sorry to interupt, but a quick question for Chris, on that fuel pressure test. How long should that fuel pressure remain at or above 52lbs? It will bleed off eventually but how fast is too fast? To r235, if you do not have one now, get a fuel pressure tester, can save you big if your pump fails. Not a lot of money. You can buy EGR's on ebay from time to time, used or new, cheaper than most parts stores, just be sure of what you are getting. I got lucky and bought a new GM unit for my 93 vin W for $78, new, but usually they are more. Ditto on the spider assy, you can buy the spider and nut kit (fuel lines) very reasonable on Ebay.

well I'm just waiting to save the cash to get the fuel pressure reg and EGR valve. i will post to let you know if that fixes to problem.

thank again for everyone's input

Don't wait to do the reg, you wait, your engine will die.

The fuel in your oil is destroying your main bearings.

Q. Do you have oily deposits on your throttle butterfly?

yes, there is oil deposits on the inside of the throttle plate. What does that mean?

yes, there is oil deposits on the inside of the throttle plate. What does that mean?

Nothing, all cars have that. Even my new car has that, it is just from the PCV.

Having oil coming up into the filter means you have a block in your PCV system and crankcase pressure is going up and with a blocked PCV valve or the lines running to it, the pressure has only one way to vent and that is back into the fresh air intake.

Replace your PCV valve and remove the lines running from it to the intake and clean them out.

also check your oil level, is it overfilled?

well I found the problem. changed the IAC (Idle air control). I had checked it with a multimeter and it checked out fine. Decided to change it anyway. It ran kind of ruff at first, took it off and set it at 1.10 inch and it idle's perfect, no vibration at all. Thanks again for all of your input. You guys rock!!!!!