oh, and compression checks,
#1=160
#2=160
#3=162
#4=160
#5=162
#6=175
#1=160
#2=160
#3=162
#4=160
#5=162
#6=175
Engine surge and shutter
I had an old post about this but it has been so long since i posted about it I'll start a new one. I have been chasing a problem with this thing for awhile. it will surge sometimes and run rough like it is missing , exhaust smells rich. I have checked/replaced the following trying to fix it:
EGR valve-changed
EGR solenoid -changed
plugs, wires, coil, cap and rotor- changed
ICM-changed
MAP sensor-changed
TPS sensor- checked volts
checked base timing
fuel pressure-12psi constant
vacuum (18" until it stumbles and then dips)
ECT sensor-changed
rebuilt TBI and pressure regulator
changed O2 sensor
unplugged evap canister and plugged the port
I ran it with the ESC unplugged like when setting base timing and it did not improve.
What has me convinced it is a timing or misfire issue is that the last thing i did is unplugged one spark plug wire at a time and ran the truck and there was virtually no change in how it ran. #3 cylinder may have been slightly rougher than any other but not much. Perhaps reluctor ring in distributor? No codes and everything on scanner looks "normal" only will throw a rich code every once in a while if the O2 sensor doesn't start reacting fast enough. changing the O2 sensor made that happen a lot less.
EGR valve-changed
EGR solenoid -changed
plugs, wires, coil, cap and rotor- changed
ICM-changed
MAP sensor-changed
TPS sensor- checked volts
checked base timing
fuel pressure-12psi constant
vacuum (18" until it stumbles and then dips)
ECT sensor-changed
rebuilt TBI and pressure regulator
changed O2 sensor
unplugged evap canister and plugged the port
I ran it with the ESC unplugged like when setting base timing and it did not improve.
What has me convinced it is a timing or misfire issue is that the last thing i did is unplugged one spark plug wire at a time and ran the truck and there was virtually no change in how it ran. #3 cylinder may have been slightly rougher than any other but not much. Perhaps reluctor ring in distributor? No codes and everything on scanner looks "normal" only will throw a rich code every once in a while if the O2 sensor doesn't start reacting fast enough. changing the O2 sensor made that happen a lot less.
1 - 18 of 18 Posts
how many miles? when was the distributor replaced? what is the fule pressure throughout driving?
A spry 233,000 miles. I am on that distributor. I was testing the pick up coil and found a bit of slop in the rotor shaft last night. I only have the fuel pressure reving it up. It is not really drivable the way it is running. The previous owner had the engine out at some point It’s obvious by the orange paint and wire routing. So I do t know what the actual miles on the engine may be. I have a video of the slop. I’ll see if I can post it.how many miles? when was the distributor replaced? what is the fule pressure throughout driving?
Use YouTube and post a link.A spry 233,000 miles. I am on that distributor. I was testing the pick up coil and found a bit of slop in the rotor shaft last night. I only have the fuel pressure reving it up. It is not really drivable the way it is running. The previous owner had the engine out at some point It’s obvious by the orange paint and wire routing. So I do t know what the actual miles on the engine may be. I have a video of the slop. I’ll see if I can post it.
I’m on it.
Video of distributor
youtube.com
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new distributor, not much better. still vibrates especially at ~1200 rpm. timing jumps around at RPM also. don't know if that is the stumble making the timing mark miss or there is an actual change in ignition timing that is causing that. only thing left on the ignition is the ESC on the fire wall.
EDIT: EGR valve got disconnected when putting in the new distributor I guess. fixed that and the engine has a bad vibration gets really bad from 1000-1200 smooths out a bit after that and I hear a ticking sound from around the torque converter flywheel area. I should learn a lesson about buying a problem truck and think I can fix it without knowing what the previous owner has done or experienced with it. The thing barely ran when I got it and I had to power break it at stop lights to get it the 5 blocks home. I figured this thing would be a quick fix with some cosmetic issues. can of worms, boys, can of worms!
EDIT: EGR valve got disconnected when putting in the new distributor I guess. fixed that and the engine has a bad vibration gets really bad from 1000-1200 smooths out a bit after that and I hear a ticking sound from around the torque converter flywheel area. I should learn a lesson about buying a problem truck and think I can fix it without knowing what the previous owner has done or experienced with it. The thing barely ran when I got it and I had to power break it at stop lights to get it the 5 blocks home. I figured this thing would be a quick fix with some cosmetic issues. can of worms, boys, can of worms!
Check the PVC valve to see if it's clogged or sticky....either r/r...or spray with some brake cleaner to clean, shake it around to make sure inside move freely...reinstall on vac side and test functionality with your thumb (should snap back and return smartly), then put back in valve cover. Recently was running down a similar problem on a 1994 and turned out to be a sticky PVC valve. I was on the verge of deploying the parts cannon and lucky avoided that cost. Also, cleaning the IAC is probably worth a try (remove, spray pintle and spring with carb cleaner, wipe gently, it's a stepper motor configuration so do not push,pull or twist pintle/shaft -- also make sure the IAC pintle seating area on the intake side is clean too, i.e., more carb cleaner & a Q-tip)-- should also verify proper IAC operation via scan tool.I had an old post about this but it has been so long since i posted about it I'll start a new one. I have been chasing a problem with this thing for awhile. it will surge sometimes and run rough like it is missing , exhaust smells rich. I have checked/replaced the following trying to fix it:
EGR valve-changed
EGR solenoid -changed
plugs, wires, coil, cap and rotor- changed
ICM-changed
MAP sensor-changed
TPS sensor- checked volts
checked base timing
fuel pressure-12psi constant
vacuum (18" until it stumbles and then dips)
ECT sensor-changed
rebuilt TBI and pressure regulator
changed O2 sensor
unplugged evap canister and plugged the port
I ran it with the ESC unplugged like when setting base timing and it did not improve.
What has me convinced it is a timing or misfire issue is that the last thing i did is unplugged one spark plug wire at a time and ran the truck and there was virtually no change in how it ran. #3 cylinder may have been slightly rougher than any other but not much. Perhaps reluctor ring in distributor? No codes and everything on scanner looks "normal" only will throw a rich code every once in a while if the O2 sensor doesn't start reacting fast enough. changing the O2 sensor made that happen a lot less.
Which one?...some have two, one for PCM (located near thermostat housing) and one on driverside engine block (for gauge). I think the PCM ECT sensor provides one of the data inputs that the PCM uses to set the IAC.ECT sensor-changed
In the intakeWhich one?...some have two, one for PCM (located near thermostat housing) and one on driverside engine block (for gauge). I think the PCM ECT sensor provides one of the data inputs that the PCM uses to set the IAC.
I cleaned the entire TBI. I’ll check that PCV before I reload the cannon!Check the PVC valve to see if it's clogged or sticky....either r/r...or spray with some brake cleaner to clean, shake it around to make sure inside move freely...reinstall on vac side and test functionality with your thumb (should snap back and return smartly), then put back in valve cover. Recently was running down a similar problem on a 1994 and turned out to be a sticky PVC valve. I was on the verge of deploying the parts cannon and lucky avoided that cost. Also, cleaning the IAC is probably worth a try (remove, spray pintle and spring with carb cleaner, wipe gently, it's a stepper motor configuration so do not push,pull or twist pintle/shaft -- also make sure the IAC pintle seating area on the intake side is clean too, i.e., more carb cleaner & a Q-tip)-- should also verify proper IAC operation via scan tool.
LOLZ 🤣before I reload the cannon!
i checked the PCV valve by pulling it and putting my finger over it and it immediately pull a strong vacuum and when i let of I didn't hear any sucking sound. I replaced my vacuum hoses also that had some tees in them. when i first started it, it surged still it got a little better as it warmed up but still seems rough. I have a new IAC valve in there but I am starting to wonder if the new one is not functioning properly. I just can't explain the surge it's there sometimes and sounds like the engine is about to die and sometimes it not as noticeable.
I changed out the PCV valve today. It was obvious there was a difference in the "shake" test. I started the truck hoping for a miracle........and she ran the same. I read the codes i got a 42 and 45, the 42 is probably stored from when I replaced the distributor and set the timing. I started up after removing the jumper and it ran okay with no surging really. Maybe the IAC got reset when I was in diagnostic mode??? and without going into the whole backpressure thing, the previous guy put a flowmaster on this rig so it is hard to diagnose anything from exhaust tones or pulses. I am not understanding the code 45 before it is even warmed up? maybe the new CTS is bad? I am back to why is this throwing a code 45 before it should even be closed loop
this post has turned into my personal sounding board but, i think the PCV has made it turn the corner. Besides the first time I ran it afterwards and it throwing a code, after the diagnostic mode it has not surged or smell of gasoline bad . I think you may have nailed a large portion of the problem. It still vibrates but I dont think that is a related issue. I need to check the dampner and motor mounts. I stopped messing with it for a while and started putting in my jungle website radio and I noticed that my dash temp gage would go up and down with the engine off. might be something else to look into.LOLZ 🤣
Outstanding.this post has turned into my personal sounding board but, i think the PCV has made it turn the corner. Besides the first time I ran it afterwards and it throwing a code, after the diagnostic mode it has not surged or smell of gasoline bad . I think you may have nailed a large portion of the problem. It still vibrates but I dont think that is a related issue. I need to check the dampner and motor mounts. I stopped messing with it for a while and started putting in my jungle website radio and I noticed that my dash temp gage would go up and down with the engine off. might be something else to look into.
HOLY CRAP! I think I have found the dang issue! I checked the harmonic balancer and the motor mounts visually and I didn't see anything obvious. So I started overthinking things again and decided to double check the heat range of the spark plugs cause i was not sure what the factory range is and was going to compare the old plugs I still have with the new ones I put in a year ago when I first started this mess. I change spark plugs like the day after I brought it home and the wire and cap and rotor. well, let me tell you, I do not know how this got past me but the O'reilly guy put in the wrong year model for my s10 and I had plugs for 1998 s10 in there not a 1989. I am blown away! the overall length is the same but the seat position is completely different. The new plugs sat in the head about 1/2" further than they should and the heat range is 2 steps higher. I am surprised I didn't have interference problems. I can't believe I missed it on install. I must have just ripped all old plugs out and then just put all the new ones in without looking at the two side by side. I will report back after I get the CORRECT ones in.
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