- Thread starter
- #21
Rick,
I do appreciate the offer though.
I do appreciate the offer though.
RPMs 0 - 1200 - 3000 - 1200
- Thread starter Junk
- Start date
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semlin
curmudgeon
junk, in case the consensus does not turn out to be right I have a plan b. my brother's 91 had similar problems. the rpms would randomly vary all over the place just the way you describe, including shooting to over 2000 rpm at idle for no reason and dropping down to stalling. after a while it started throwing occasional code indicating a bad ECT which led to a cure from a new thermostat and engine coolant temp sensor plus removing and cleaning the other sensors on the thermostat housing. I know it's a different motor but the sensor and its role are similar.
How about a bad fuel regulator?
Hey Junk,
Do some tests on the TPS, yes, but don't omit the O2 sensors. Did you have both reinstalled after you had your exhaust changed? They should be installed relative to where the were originally. I was having some quirks with my 80 and was going ot replace the front O2 sensor, but when I went to disconnect it I found it wasn't pushed in all the way in the first place, so I pushed the plug together tight and so far..... it has been running good. The O2 sensors control fuel. That is another thing, does this happen when the engine is cold or warm?
Yomama
Do some tests on the TPS, yes, but don't omit the O2 sensors. Did you have both reinstalled after you had your exhaust changed? They should be installed relative to where the were originally. I was having some quirks with my 80 and was going ot replace the front O2 sensor, but when I went to disconnect it I found it wasn't pushed in all the way in the first place, so I pushed the plug together tight and so far..... it has been running good. The O2 sensors control fuel. That is another thing, does this happen when the engine is cold or warm?
Yomama
- Thread starter
- #25
Yo - happens all the time. Right now the truck is basically non-driveable. They are either exactly where they were originally or at least very close.
Rick - thanks, will check that too.
Semlin, it's not throwing bad ect, but it's tossing out P0505 which indicates idle system issues.
Rick - thanks, will check that too.
Semlin, it's not throwing bad ect, but it's tossing out P0505 which indicates idle system issues.
Junk,
So MIL light is off? I would try to get the MIL on, try disconnecting the front O2 sensor and then start it up and let her run till it sets the light, then shut it off and fire it up again. See what happens? Why? The ECM from my knowlegde has built in a bypass mode, so, if the MIL is set the ECM basically stops using sensors for fuel control. If it stops running irratically you have a better direction to go, if not you still have better info as to what it is not. Someone correct me if I am wrong.
Yomama
So MIL light is off? I would try to get the MIL on, try disconnecting the front O2 sensor and then start it up and let her run till it sets the light, then shut it off and fire it up again. See what happens? Why? The ECM from my knowlegde has built in a bypass mode, so, if the MIL is set the ECM basically stops using sensors for fuel control. If it stops running irratically you have a better direction to go, if not you still have better info as to what it is not. Someone correct me if I am wrong.
Yomama
- Thread starter
- #27
check engine light is on and it's tossing out P0505 idle system blah blah blah
Engine code 
that is what I get for trying to "work" and help others at the same time!!
I still think "I" would disconnect the O2 sensor and if it isn't too much of a pain in the !@# I would pull the front O2 sensor out. Leaving the hole in the exhaust. If your new converter is plugged the hole will allow enough passage through it. Sensor disconnected would force engine to not use O2 sensor. I believe the problem is in fuel delivery, or vacuum.
Some problems are easy to isolate and others
you know...
Yomama
that is what I get for trying to "work" and help others at the same time!!I still think "I" would disconnect the O2 sensor and if it isn't too much of a pain in the !@# I would pull the front O2 sensor out. Leaving the hole in the exhaust. If your new converter is plugged the hole will allow enough passage through it. Sensor disconnected would force engine to not use O2 sensor. I believe the problem is in fuel delivery, or vacuum.
Some problems are easy to isolate and others
you know...Yomama
Are you sure you do not have a vacuum leak?
- Thread starter
- #30
cruiserdan said:
Only as sure as I CAN be, which as you know ain't much. :whoops: Have not found any other lines other than the one we discussed.
Starting to think rag in the fuel filler and zippo. .... only a joke though 
Junk said:
Jeez Junkster, calm down it ain't all that bad. Sides that it would make a hell of a mess.
Junk - any chance a gerbil crawled into your bypass? In the installation manual, they go to great pains to make sure you put the hose clamps on the "right" way so that you're not interfering with the bypass control. Not sure if a funky bypass would cause your problems, but easy enough to take a gander.
In the installation manual, they go to great pains to make sure you put the hose clamps on the "right" way so that you're not interfering with the bypass control. Not sure if a funky bypass would cause your problems, but easy enough to take a gander.Well Junk? What is happening in the troubleshooting process? 
Yo
Yo
yomama said:Well Junk? What is happening in the troubleshooting process?
Yo
I get the feeling the troubleshooting process involves about three hundred feet of primer cord and a pound of TNT in the engine bay! Come on Junk, walk away another while and then kick this thing in the ass by diagnosing and fixing it!!! If you're half as good at fixing things as you are at breaking them, you can definitely do this!!!
- Thread starter
- #35
Here's the update.
Was going out to check out the wires again today and noticed that 2 of the 6 wires leading into the IAC connector plug were broken off. I don't think they were the last time I checked as I would have noticed it, but I think they were brittle enough that they were toast. FYI, they were the 2 red wires and broke off flush with the rubber on the end of the connector, so of course I have no idea right now which goes where, but I guess that's what manuals are for.
Anyway, called Cbizkit and he's getting me some splice repairs I'm going to splice/repair all 6 wires leading into it figuring it was hot enough to destroy 2 then the other 4 must be in bad shape.
Kind of hoping this fixes it. This must be from the 15 minute drive I took with NO exhaust. The heat coming out the manifold was hot enough that it baked the rubber tube that goes to the bottom of the EGR modulator (not fixed with fuel line that was in the truck spare box).
Will keep ya'll posted. Thanks for all the help. .... and for good measure
Was going out to check out the wires again today and noticed that 2 of the 6 wires leading into the IAC connector plug were broken off. I don't think they were the last time I checked as I would have noticed it, but I think they were brittle enough that they were toast. FYI, they were the 2 red wires and broke off flush with the rubber on the end of the connector, so of course I have no idea right now which goes where, but I guess that's what manuals are for.
Anyway, called Cbizkit and he's getting me some splice repairs
I'm going to splice/repair all 6 wires leading into it figuring it was hot enough to destroy 2 then the other 4 must be in bad shape.Kind of hoping this fixes it. This must be from the 15 minute drive I took with NO exhaust. The heat coming out the manifold was hot enough that it baked the rubber tube that goes to the bottom of the EGR modulator (not fixed with fuel line that was in the truck spare box).
Will keep ya'll posted. Thanks for all the help. .... and
for good measure
look closely at those wires as they are color coded. The reds are either striped black or green. You might need your glasses.
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- Thread starter
- #37
Landtank, I can see they are striped. Two probs; hurt my back real bad yesterday so can not currently climb into engine bay, and second, they are broke off flush where they enter, so there is no color coded insulation on what is left on the plug end.
Thanks for the glasses thought though, I guess you think of that every time you head to the john eh?
Thanks for the glasses thought though, I guess you think of that every time you head to the john eh?
If you need it I can post the plug configuration and where the wires connect to.
Now to pee, where's those damn tweezers
Now to pee, where's those damn tweezers
- Thread starter
- #39
landtank,
I should be able to figure it out, but if you happen to know the config it would be a help. You know how well I have bonded with my electrical manual :whoops: If it helps, it's connector #11144.
Make sure you get plastic tweezers
I should be able to figure it out, but if you happen to know the config it would be a help. You know how well I have bonded with my electrical manual :whoops: If it helps, it's connector #11144.
Make sure you get plastic tweezers
pin 1 R-B Red - Black Stripe
pin 2 Y-R Yellow - Red stripe
pin 3 Y-L Yellow - Blue stripe
pin 4 R-G Red - Green stripe
pin 5 Y-R Yellow - Red stripe
From what is still attached you should be able to figure out the orientation. This is the plug at the IAC
pin 2 Y-R Yellow - Red stripe
pin 3 Y-L Yellow - Blue stripe
pin 4 R-G Red - Green stripe
pin 5 Y-R Yellow - Red stripe
From what is still attached you should be able to figure out the orientation. This is the plug at the IAC
