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Discussion Starter · #21 ·
so even tho the EGR valve is opening too early, but still working is why it doesnt show up when i had a computer hooked up?
 

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Discussion Starter · #23 ·
alright gotchya! thanks for the info! i got a little time today before work later so i think im gonna go try that out and see if thats the problem. it has been running ALOT better now that its colder out, its more when its in reverse, which im hardly giving it any throttle that it runs rough, but going forward it dont seem to surge as bad as when it was warmer out. but ill try checking the EGR valve and if i find anything out ill post on here to let you all know that have been helping with all the info and ideas
 

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Discussion Starter · #24 ·
unhooked the vacume hose to the EGR valve and plugged it off and it fixed the problem! Runs good now at low idle/slow speed. Thanks guys... gonna take it off and check for carbon build up Thursday if the weather is good and if im not too busy, might just need cleaned or replace both the EGR valve and intake to save time cleaning out all the ports and passage ways.
 

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i got the jeep thing
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dont try to clean it, just replace it, the rubber diaphram inside the valve is weak so egr comes on too soon (less vacuum to open it)

had several of these persomally and at work
im a master certified tech so if you have further questions pm me
 

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Same problem, but hard to fix.

I just found this entry and thought I would wake people up about this issue.
I have a 1993 GMC Suburban K1500 5.7L TBI which has these same set of problems.
I have changed the EGR valve, and problem remains. I swapped the EGR Vacuum Solenoid and the problem remained. If I disconnect the power connector to the EGR Vacuum Solenoid problem solved as it when I plug the vacuum hose from the solenoid to the EGR valve. I hope this isn't the ECM as that sounds expensive. I have noticed that I have a need to a new connector on the Idel air control valve, but I doubt that is the problem.

So to echo the probelm.
When the engine is cold, the problem is not there, but I also notice the idle is about 800RPM on the tach.
When the engine is hot my problem starts.
1: Runs fine at high speeds, but I can feel the engine surge a bit at 25 MPH, and at 5 MPH it is very noticable ! If I get out and disconnect the EGR Vacuum Solenoid power connector, problem gone. I need to get this fixed as the SMOG is due, which is bad timing! Anyone out there have any more ideas? I have read about the MAP sensor, but would that be a possible cause?
Any help would I would be very grateful.
 

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I just found this entry and thought I would wake people up about this issue.
I have a 1993 GMC Suburban K1500 5.7L TBI which has these same set of problems.
I have changed the EGR valve, and problem remains. I swapped the EGR Vacuum Solenoid and the problem remained. If I disconnect the power connector to the EGR Vacuum Solenoid problem solved as it when I plug the vacuum hose from the solenoid to the EGR valve. I hope this isn't the ECM as that sounds expensive. I have noticed that I have a need to a new connector on the Idel air control valve, but I doubt that is the problem.

So to echo the probelm.
When the engine is cold, the problem is not there, but I also notice the idle is about 800RPM on the tach.
When the engine is hot my problem starts.
1: Runs fine at high speeds, but I can feel the engine surge a bit at 25 MPH, and at 5 MPH it is very noticable ! If I get out and disconnect the EGR Vacuum Solenoid power connector, problem gone. I need to get this fixed as the SMOG is due, which is bad timing! Anyone out there have any more ideas? I have read about the MAP sensor, but would that be a possible cause?
Any help would I would be very grateful.
Today I had a chance to try the MAP unit, no change. Same problem. Looking more and more like an O2 sensor or the ECM. Grumble!
 

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Direct Drive FTW
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Have you checked your vacuum lines for cracks. Those pos vacuum lines like to crack right under the rubber. Twist them off carefully, shoot the internals with a air hose to clean out any oil, then blow in one end while plugging the other.

You can make your own clear plastic ones out of fish tank hose which will allow you to see how blocked they become. You just melt it to create the bends without affecting the factory flow because the fish tank hose has a larger ID. If you use a small piece of metal at the end of the plastic line going into the old "flexible 90" it lets you keep the factory shape. Red jr. dragster hose looks more professional with the same technique. But I am cheap, for $20/4 hours you can do the entire truck and easily see how blocked or if one of your lines is leaking because it will have a oil or condensation streak at the leak point.

A faster and cheaper fix is just to reset your PCM. With every sensor plugged in, clear all your codes, pull your battery out, then turn the light switch on to drain any residual, and wait overnight. Install the battery, then turn the key to the on position and wait for everything to load. Turn the truck on writing down any codes you get, and then take it for a 10 minute test drive driving the truck hard. Do this in a area where if you break down you are not very far from the house or somewhere you can get a tow back.

Write down any engine codes you have. If you have a electronic transmission check it for codes at this point also.

My guess you either have a open EGR sensor, a bad connection at the egr sensor(if it happens at random), a bad connection in the harness, a injector going bad, or a PCM that is going bad or not properly grounded. Pull your IAC and TPS shoot them with some carb cleaner then reinstall and see if anything changes I doubt this is a issue but if you notice a change these parts are cheap. You can get the gaskets for like $2 or make your own if you pull them off and shoot them every 15-20k like I did on an 88 that I had over 340k on when the transmission went out. The last 220k were mine with lots of out of state travels towing a car dolly.
 

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Thanks for jumping in on this. I have a few comments.

The vacuum lines are fine, as I have already replaced them for the same reasons you mentioned.

The engine runs great if I disconnect the EGR Solenoid connection.
The EGR valve, EGR Solenoid, and MAP sensor I have replaced one at a time, and problem still is around.

What I am trying to locate now if a docuemnt that explains "When the EGR value should be open" by the ECM. I mean it sounds like this is only to be opened at higher speeds, and not when I am sitting around at near crawling speeds.

Have had several people tell me to replace the Thermal switch. Its only a $15 part so I think I will try that tonight.

Really been an interesting debug, I have an OBD2 code reader, not sure if that will work on the 1993 OBD1 system. Need to find that one out as well.

BTW: The Check Engine light only comes on while I have the EGR Solenoid disconnected and drive for a period of time on the freeway speeds.
 

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95 Indigo Tahoe
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IAC is bad. Idle Air control valve. Swap that out and that'll solve your problem. It's on the back passangers side of the throttle body
My 1995 5.7 Tahoe made a popping noise then it stopped after a few miles but it idles rough like its missing. It still has power to move well. But never had that
happen before just out of the blue. I checked the Cap and Rotor and they look like new. I took number 1 plug out, it was kinda cruddy but I've seen worse and run fine. Idle air control vale could cause this?
 

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95 Indigo Tahoe
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Did it make some popping sounds at first and loose some power? Mine did that then went away, now it idles likes its missing and blows a little more smoke out the tailpipe. It did it just out of the blue. This truck always ran top then this.
 

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I'll Direc your TV
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Did it make some popping sounds at first and loose some power? Mine did that then went away, now it idles likes its missing and blows a little more smoke out the tailpipe. It did it just out of the blue. This truck always ran top then this.
Did you just feel like reviving a 7 year old thread?
 

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Gustafson
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Okay, so this is another version of the conversation with a couple twists. My '95 Suburban k1500, 5.7L, starts up first thing in the morning and runs perfect, no check engine light or miss. I get about 5-7 miles from the house at highway speed and it starts lurching - accelerating and decelerating, check engine light comes on, and sometimes it even dies while going down the road. Sometimes it will keep lurching for about 30 seconds, and will straighten out and run fine, until you come to a stop and then it dies. Other times it will just bog down when you hit the gas to try and keep it running. Usually starts up pretty quick when it dies, and most times I can drive 20 miles all the way home with no issues, until I stop, and it dies. Here's the kicker - the next morning the check engine light is off and it runs perfect, until I get about 5-7 miles down the road and starts all over again. I've replaced MAP sensor, AIC, EGR valve, TPS, Ignition Control Module, O2 sensor, Catalytic Converter, PCV, rebuilt the TBI, new fuel pump and filter, etc., and put in a new computer. I'm out of ideas, and all the guesses I've been listening to for the past year have added up to over $1,500.00 in parts and labor. This vehicle has over 420k miles and runs and drives like a brand new one when this weird crap isn't occurring. Would appreciate any input.
 

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Okay, so this is another version of the conversation with a couple twists. My '95 Suburban k1500, 5.7L, starts up first thing in the morning and runs perfect, no check engine light or miss. I get about 5-7 miles from the house at highway speed and it starts lurching - accelerating and decelerating, check engine light comes on, and sometimes it even dies while going down the road. Sometimes it will keep lurching for about 30 seconds, and will straighten out and run fine, until you come to a stop and then it dies. Other times it will just bog down when you hit the gas to try and keep it running. Usually starts up pretty quick when it dies, and most times I can drive 20 miles all the way home with no issues, until I stop, and it dies. Here's the kicker - the next morning the check engine light is off and it runs perfect, until I get about 5-7 miles down the road and starts all over again. I've replaced MAP sensor, AIC, EGR valve, TPS, Ignition Control Module, O2 sensor, Catalytic Converter, PCV, rebuilt the TBI, new fuel pump and filter, etc., and put in a new computer. I'm out of ideas, and all the guesses I've been listening to for the past year have added up to over $1,500.00 in parts and labor. This vehicle has over 420k miles and runs and drives like a brand new one when this weird crap isn't occurring. Would appreciate a
Okay, so this is another version of the conversation with a couple twists. My '95 Suburban k1500, 5.7L, starts up first thing in the morning and runs perfect, no check engine light or miss. I get about 5-7 miles from the house at highway speed and it starts lurching - accelerating and decelerating, check engine light comes on, and sometimes it even dies while going down the road. Sometimes it will keep lurching for about 30 seconds, and will straighten out and run fine, until you come to a stop and then it dies. Other times it will just bog down when you hit the gas to try and keep it running. Usually starts up pretty quick when it dies, and most times I can drive 20 miles all the way home with no issues, until I stop, and it dies. Here's the kicker - the next morning the check engine light is off and it runs perfect, until I get about 5-7 miles down the road and starts all over again. I've replaced MAP sensor, AIC, EGR valve, TPS, Ignition Control Module, O2 sensor, Catalytic Converter, PCV, rebuilt the TBI, new fuel pump and filter, etc., and put in a new computer. I'm out of ideas, and all the guesses I've been listening to for the past year have added up to over $1,500.00 in parts and labor. This vehicle has over 420k miles and runs and drives like a brand new one when this weird crap isn't occurring. Would appreciate any input.
Same exact issue. Did you get it resolved yet?
 
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