engine running rough

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L29Sub

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BTW, the EGR circuit is nulled out with low ECT. EGR valve can still be an issue, but it will not function until the engine goes into closed loop mode...and code 15 is reset and no check engine light.
 

tannerezell077

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If you mean the egr seloniod then yes! Check all the vacuum lines again. The factory elbows on the vacuum lines tend to crack. I used all silicone vac lines no more worries. Did you clean out the egr port's under the egr? How about under the throttle body? All potential trouble spots.

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i cleaned the egr valve and the spot that i bolts to. what would be the best way to clean the port that it bolts to because i'm afraid that if i scrap it and spray carb cleaner it could mess something up down there. i bought a new gasket and the solenoid should be here today. when i unplug the solenoid with the motor running it does nothing so i'm thinking it's bad and i can put my finger in the egr valve and rev it up still no movement or vacuum
 

tannerezell077

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BTW, the EGR circuit is nulled out with low ECT. EGR valve can still be an issue, but it will not function until the engine goes into closed loop mode...and code 15 is reset and no check engine light.
code 15 is gone that problem is no longer occurring but i still get code 35 even after putting a new iac valve on. i bought a new one ($50) and it didn't change anything so i took it back and cleaned the old one and watched to see if it functions while i give it gas, turn the key, etc. and it works and moves so i'm still not sure why i'm getting the code. i done the relearn process where jumping a and b ports and turning the key for 30 seconds still no luck in thinking it's a false code and the egr is the problem
 
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Do as I did and buy the repair manual from Hayes or Chilton and it'll tell you how to check all the sensors and actuators. It'll give you the readings for the correct values. That's how I discovered my issues which like you were driving me crazy!!! As a side note make sure that you have good grounds from the battery and fuse box. Sometimes it's the simplest of things that screw everything up.

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L29Sub

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Keep in mind that the Iac will try to manage any airleak. If you're have a vacuum leak, that require resolution.
Any vacuum leak may overwhelm the
IAC...egr can be temp blocked off.
Is the IAC properly adjusted?
Had the top end been removed?
Anything that adds a port to the intake system could be some of your problem
 

tannerezell077

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Keep in mind that the Iac will try to manage any airleak. If you're have a vacuum leak, that require resolution.
Any vacuum leak may overwhelm the
IAC...egr can be temp blocked off.
Is the IAC properly adjusted?
Had the top end been removed?
Anything that adds a port to the intake system could be some of your problem
how do i properly adjust the iac? and i haven't removed the top end since i've owned it the only work i done around there was the headers
 

L29Sub

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Looks like the IAC sets itself. Requires driving at road speed, which closes the IAC port? ECM learns from that condition.
Other not so obvious could be throttle body butterfly isn't closing all the way due to cable, cruise control, carbon, or attempting to adjust the idle speed. The butterfly must shut at idle. The ECM sets idle speed...or tries to do so.
If the distributor was removed, it could be out of time, fuel pump failing, fuel pressure regulator, cracked spider...?
Some fuel related issues are slow to set codes.
If the truck ran OK when the exhaust was stock, and after changing the exhaust it ran poorly, think about what was dinked with during the install...? Wrong spark plugs, firing order (at plugs and cap), dist mistimed. Then undo any changes made while trying to make it run.
Check the idle vacuum, compression check, fuel pressure check, firing order verified, check the wiring near the headers for burnt wiring. Check for bad fuel pump ground and wiring. The fuel pump wiring is close to your driver side muffler...?
Is the fuel guage working properly?
The IAC is outside its map and is indicating it cannot compensate. Has the TPS been removed or adjusted?
I'm guessing that your truck did not have a post cat 02 sensor? If it did, it'll set a code indicating the sensor is out of range, but generally doesn't change the way it runs. L and R bank 02 sensors out of range will cause problems when warmed up. They'll also set codes quickly if heater çircuit has failed.
Still, if it ran before, very likely something is not quite as it was.
The most difficult problems to diagnose are often related to someone altering something before understanding the function and interaction. This is especially true on TBI and TPi systems.
Any good GM mechanic can plug your truck up and view the dynamics and tell what is the likely cause. Forget where I bought it, but had a Windows program for an OBD1, LT4 that showed all of the data, counts, and engine and trans temps. It didn't overwrite, but gave pages of data. The only problem was understanding what is being described. A good handheld scanner will do similar.
 

tannerezell077

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Looks like the IAC sets itself. Requires driving at road speed, which closes the IAC port? ECM learns from that condition.
Other not so obvious could be throttle body butterfly isn't closing all the way due to cable, cruise control, carbon, or attempting to adjust the idle speed. The butterfly must shut at idle. The ECM sets idle speed...or tries to do so.
If the distributor was removed, it could be out of time, fuel pump failing, fuel pressure regulator, cracked spider...?
Some fuel related issues are slow to set codes.
If the truck ran OK when the exhaust was stock, and after changing the exhaust it ran poorly, think about what was dinked with during the install...? Wrong spark plugs, firing order (at plugs and cap), dist mistimed. Then undo any changes made while trying to make it run.
Check the idle vacuum, compression check, fuel pressure check, firing order verified, check the wiring near the headers for burnt wiring. Check for bad fuel pump ground and wiring. The fuel pump wiring is close to your driver side muffler...?
Is the fuel guage working properly?
The IAC is outside its map and is indicating it cannot compensate. Has the TPS been removed or adjusted?
I'm guessing that your truck did not have a post cat 02 sensor? If it did, it'll set a code indicating the sensor is out of range, but generally doesn't change the way it runs. L and R bank 02 sensors out of range will cause problems when warmed up. They'll also set codes quickly if heater çircuit has failed.
Still, if it ran before, very likely something is not quite as it was.
The most difficult problems to diagnose are often related to someone altering something before understanding the function and interaction. This is especially true on TBI and TPi systems.
Any good GM mechanic can plug your truck up and view the dynamics and tell what is the likely cause. Forget where I bought it, but had a Windows program for an OBD1, LT4 that showed all of the data, counts, and engine and trans temps. It didn't overwrite, but gave pages of data. The only problem was understanding what is being described. A good handheld scanner will do similar.
i replaces the iac and it didn't fix anything the old one still functions and works good so i took the new one back. i replaced the gasket on the egr and cleaned it out. i replaced plug wires the one o2 sensor it has is behind the collector i replaced it. i replaced the engine coolant temp sensor and thermostat. flushed out the heater core and bled the air out of all it. i replaced the egr solenoid. could it be possible that it was running really rich before and fouled some of the plugs and it needs new ones? or maybe that i ran it low on gas and it brought up junk from the bottom of the tank and clogged the fuel filter? it has had a new fuel pump and filter within the last year i know it's not the pump. i'm running out of ideas on what to replace
 

tannerezell077

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also upon installing new plug wires i noticed that the order they are put on are different than the diagram i looked up for tbi chevy 350 c/k series. could this be the cause? because the truck ran fine in the order they are in now before the exhaust install?
 

L29Sub

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My last post...promise. If you have a cold air or high flow air filter added to exhaust system, you might be confusing your 02 sensors . Create some backpressure with a couple of beer cans.
Firing order for 5.7 is...18436573... later LS engines are different...but coil packs keep them straight.
 
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