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egr problems (I think)


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wccaddell
New User

May 11, 2009, 1:28 PM

Post #1 of 4 (1391 views)
egr problems (I think) Sign In

i have a 93 chevy k1500 w/ a 5.7 350 the motor has 180000 miles on it. it has plenty of power when it runs right. i am getting a trouble code 32 when the service light comes on, it seems to only come on after hwy use, i have replaced the egr, and when i vacuum test it i holds a vacuum when the motor is off, but when the motor is running the clilton manual says the motor should start to idle rough when vacuum is applied but it doesnt, it wont hold a vacuum as soon as you put a vacuum on it the needle returns to zero. i have tested the egr solenoid valve and it holds a vacuum, tested all the lines i could think of and they all seem fine,tested the vapor charcoal canister and all its lines seems fine, replaced the o2 sensor, i replaced the spark plug and the spark plugs that came out of it were white and some were lightly blistered, got good spark on all the wires, about a year i had the exhaust worked on the oe was rusted out so they replaced it with a oe of of a 06 or 07 chevy pick up. they removed the cat converter and said it wouldnt effect it, the truck only has one o2 and it was before the cat. the motor idle rough some times,seems to be after long drives at hwy speeds when drive in city truck drives fine but has a noticalbe stutter every now and again. after the service soon light comes on the truck stutters when accelerating and idle and cruises rough but will return to normal after shuting off the engine for awile. any help would be appreciated im running out of idea and the dealership was no help the charged a bunch of money and found everything else wrong with the truck except what i brought it in for


Loren Champlain Sr
Veteran / Moderator
Loren Champlain Sr profile image

May 11, 2009, 3:45 PM

Post #2 of 4 (1388 views)
Re: egr problems (I think) Sign In

wccaddell; With the engine idling, and vacuum is supplied to the EGR valve, the engine should stumble and 'want' to die. If it doesn't, and assuming you have a good EGR valve, I'd suspect that the EGR passageway is plugged. But, if it is plugged, you shouldn't notice virtually anything other than, maybe, a ping under accel. So, I'd start looking for a vacuum leak. If this is TBI, check the gasket between the TBI and the intake.
btw; It is against Federal law to remove a catalytic converter.
Loren
SW Washington


wccaddell
New User

May 11, 2009, 4:42 PM

Post #3 of 4 (1381 views)
Re: egr problems (I think) Sign In

there is a slight pinging or a metalic rattle kinda sound alittle like a diesel just not as loud. the egr is new (about a month old) the was alittle confusion on the egr to use the coouple of parts store and the dealership had a couple of diffrent part numbers for it a couple had to be ordered so i bought the one they all stocked. i was reading up on egr valve and trouble shooting and they mentioned that there was two diffrent kinds a single and a double type. i was wondering if the wrong type would cause it to test wrong. when i test it it vacuums up and then returns to its rest position. the chiltons manual says to test it at idle and put a vacuum on it and the engile will start to run rough, when i put a vacuum on mine when it at a idle it will pump up to about 5 psi with one squeeze then it will lose its vacuum you can maintain the pressure at about 10 psi if you quickly pump the hand pump but the engine doesnt seem to be effected. which makes me wonder about the egr. im will check the tbi gasket tomm and see what that shows. as far as working on looking for a vacuum leak ive checked the hoses from egr to throttle bodie and the hose to the vapor canister and the other hoses off the throttle body,is there some that im missing that would cause the problems that im having? thanks for the reply ill see if your suggestions will work.


Loren Champlain Sr
Veteran / Moderator
Loren Champlain Sr profile image

May 11, 2009, 4:49 PM

Post #4 of 4 (1376 views)
Re: egr problems (I think) Sign In

wccaddell; The EGR is probably a 'backpressure' type, so will not 'hold' vacuum like the old type. If you can get your finger under the diaghragm, pull it upwards. The aftermarket EGR valves will, generally, come with different sized orifaces which you must install. The EGR valve should have come with an instruction sheet where you match the OE number to the orifice needed. Too small, it won't do it's job. Too large, will cause the problems you are describing. Using carb spray can be dangerous, as it is very flammable, but you can spray (sparingly) around the base of the TBI while idling. If the rpm raises, you've got a vacuum leak. But, take precautions in case of fire.
Don't spray around the distributor or anywhere there is heat.
Loren
SW Washington






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