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Rough Idle - No stall, No CEL
- Thread starter Ima Doit
- Start date
Previously it did. 32ish at idle, 42 when FPS vacuum disconnected. I think under load it dropped slightly. I'll need to recheck my notes.
blistovmhz
NAXJA Forum User
- Location
- Vancouver, BC
I still say valves man. You KNOW something bound up, causing that pushrod failure, and the only things that could've done that, are a seized valve or rocker, or incorrect installation in the first place.
You could do some diagnostics with a vacuum gauge which may tell you if you've got sticky intake/exhaust valves. The other obvious check, which I should've thought of earlier.... Given both your #1 rockers were loose (cause bad pushrods), that means both your intake and exhaust valves seized. A good place to start would be to do the exhaust valve check. Fire it up and stick a piece of paper over the tail pipe. The paper should only ever be pushed away. Hold it close. If it flaps and snaps cause it's getting pulled into the exhaust, you KNOW you have a bad exhaust valve. Should be some videos of this somewhere as well, but when it snaps back, it's usually pretty obvious.
You could do some diagnostics with a vacuum gauge which may tell you if you've got sticky intake/exhaust valves. The other obvious check, which I should've thought of earlier.... Given both your #1 rockers were loose (cause bad pushrods), that means both your intake and exhaust valves seized. A good place to start would be to do the exhaust valve check. Fire it up and stick a piece of paper over the tail pipe. The paper should only ever be pushed away. Hold it close. If it flaps and snaps cause it's getting pulled into the exhaust, you KNOW you have a bad exhaust valve. Should be some videos of this somewhere as well, but when it snaps back, it's usually pretty obvious.
It was actually the #2 cylinder. First rocker from the front of the vehicle. Not sure if thats intake or exhaust. The adjoining rocker had play but I assumed from the other being so out of whack. The bolts holding it were tight. Plus, when I reinstalled all pushrods everything was tight as could be. Absolutely no play.
I did the paper trick on the exhaust. Actually used a receipt. Only pushes air out.
I just rented a Fuel Pressure tester and a vacuum pump. See below pic.
Fuel pressure is at 31 psi and goes to about 40 when I pull the vacuum line. Under load rides around 38-39 psi. After about 10-15 minutes the pressure at the rail dropped to 22psi. Took two primes to bring system up to operating pressure. First rotation brought it to 10psi. Second rotation brought it to 32.
Would love to use this vacuum pump. No clue how to though. Anyone have a good write up on a test procedure for this?
Fuel pressure is at 31 psi and goes to about 40 when I pull the vacuum line. Under load rides around 38-39 psi. After about 10-15 minutes the pressure at the rail dropped to 22psi. Took two primes to bring system up to operating pressure. First rotation brought it to 10psi. Second rotation brought it to 32.
Would love to use this vacuum pump. No clue how to though. Anyone have a good write up on a test procedure for this?
Just looked at all the plugs and gap. Seem good. Had a bad connection and the connector came off cylinder 5. Replaced all plug wired new set. No change.
Disconnected 02 sensor. Nothing happened at first, but, then it sputtered and almost died. I think this is doing its job too.
I want to verify a good blue spark at each injector. This final test should rule out distributer and determine all spark is as it should be. Can I just pull the fuel pump relay and crank while looking for spark? I'll keep a trickle charge on the battery.
Disconnected 02 sensor. Nothing happened at first, but, then it sputtered and almost died. I think this is doing its job too.
I want to verify a good blue spark at each injector. This final test should rule out distributer and determine all spark is as it should be. Can I just pull the fuel pump relay and crank while looking for spark? I'll keep a trickle charge on the battery.
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blistovmhz
NAXJA Forum User
- Location
- Vancouver, BC
Spark should be checked at each plug, not the coil.
The vacuum pump, I'm not sure what to do with, but if it's also just a vacuum gauge, hook it up to intake somewhere and read through the link I sent a few posts back. It's got a whole list of tests to perform along with interpretations. Very useful.
Fuel pressure dropping after 15 minutes probably means your fuel pump is dying. The most common symptom is decreased PSI once the pump warms up. It could also be as simple as a bad internal connection in the pump assembly to the top of the tank. I ran into the same issue when doing my V8 swap as the hose would leak once things warmed up a bit. Either way, I can't think of any other reason for your FP to drop. Maybe someone else can.
Disconnecting the O2... I'm surprised it sputtered out. Mine never have. It'll run.. less good, and your fuel economy goes to shit, and it'll run rich to err on the side of caution, but I've never actually had it stall out. Yes, it'll sputter a bit when you first disconnect it while it's working on switching to open-loop mode, but should clean up pretty quick.
As is always my recommendation, fix the stuff you KNOW is wrong first. FP dropping like that is not normal. Also, if you have to prime every time you start up, your FP regulator is toast (has a check valve internally to prevent backflow, so you should never need to prime the pump/rails unless you've had the rails or injectors disconnected and manually relieved FP). A bad check valve points to a bad FP regulator, so that's where I'd start. If you're going to swap out the FP regulator, I'd actually just rip it right out entirely and fabricate a straight connection from your fuel pump to the top of the tank, and install an external regulator/check valve/filter, cause it's a bitch to drop the tank every time you've got fuelling issues. I never did this (until I did the v8 swap and it became necessary) and wish I had, as I had a bad check valve as well, and every time I started the Jeep, I'd have to prime the fuel system 2-3x or just let it crank for 5 or 10 seconds till it started getting fuel. I ended up dropping the tank at least 6 or 7 times before I said **** it, and left it alone till I did the v8.
The vacuum pump, I'm not sure what to do with, but if it's also just a vacuum gauge, hook it up to intake somewhere and read through the link I sent a few posts back. It's got a whole list of tests to perform along with interpretations. Very useful.
Fuel pressure dropping after 15 minutes probably means your fuel pump is dying. The most common symptom is decreased PSI once the pump warms up. It could also be as simple as a bad internal connection in the pump assembly to the top of the tank. I ran into the same issue when doing my V8 swap as the hose would leak once things warmed up a bit. Either way, I can't think of any other reason for your FP to drop. Maybe someone else can.
Disconnecting the O2... I'm surprised it sputtered out. Mine never have. It'll run.. less good, and your fuel economy goes to shit, and it'll run rich to err on the side of caution, but I've never actually had it stall out. Yes, it'll sputter a bit when you first disconnect it while it's working on switching to open-loop mode, but should clean up pretty quick.
As is always my recommendation, fix the stuff you KNOW is wrong first. FP dropping like that is not normal. Also, if you have to prime every time you start up, your FP regulator is toast (has a check valve internally to prevent backflow, so you should never need to prime the pump/rails unless you've had the rails or injectors disconnected and manually relieved FP). A bad check valve points to a bad FP regulator, so that's where I'd start. If you're going to swap out the FP regulator, I'd actually just rip it right out entirely and fabricate a straight connection from your fuel pump to the top of the tank, and install an external regulator/check valve/filter, cause it's a bitch to drop the tank every time you've got fuelling issues. I never did this (until I did the v8 swap and it became necessary) and wish I had, as I had a bad check valve as well, and every time I started the Jeep, I'd have to prime the fuel system 2-3x or just let it crank for 5 or 10 seconds till it started getting fuel. I ended up dropping the tank at least 6 or 7 times before I said **** it, and left it alone till I did the v8.
I'd have to disagree with the spark comment. Checking it at the ignition coil is worth doing. If I knew the gap the spark was supposed to jump I could tell of the coil is weak. Checking at the plugs is likewise important. I've verified spark to all cylinders already.
I'll try to find a vacuum gauge somewhere. Not available to rent. What I have more checks for leaks via pressurizing the system similar to a coolant pump. I just don't know how to use. The link you posted is very useful. I will be checking those as soon as I get a vacuum tester.
I'm back leaning towards a timing issue. I think I screwed up the check last time. I couldn't find the timing mark on the crank wheel, so, I used a screwdriver to look for TDC. I didn't verify if it was compression stroke and definitely could have been off.
Tonight I pulled the distributer and decided to reset it. I found the timing Notch and marked with paint. I couldn't fit my hand into the spark plug hole. So, I had my wife do it. I turned the crank and she said it was pushing her finger out. So, I assume this is compression stroke. I lined the notch up with 0 and went to work.
I reset the oil pump to 11 o'clock and placed a punch through the holes. Dropped the distributer in with the bracket in the 1 o'clock position. Fell perfectly in the right location lined up with the bolt hole in the block. Last time I tried this I had to remove the punch and spin it slightly to line up. I'm thinking I was off a notch. When I put the rotor back on, it was pointing to #1 spot on cap. A little past it actually, but, it was pretty close.
Anyways, reassembled everything now it won't start. I must be 180 out? Cranks strong though. Seems to be stronger and smother than previous. Unless my wife is crazy, a possibility, I think I had it at TDC on the compression stroke. Not sure what happened.
I verified the crank position sensor was re-connected and double checked firing order. Not sure what happened here. Maybe I disconnected something prior to testing this weekend. Really don't think so though. I should have verified it started before doing the test. Hell, maybe it's out of gas.
I'll try to find a vacuum gauge somewhere. Not available to rent. What I have more checks for leaks via pressurizing the system similar to a coolant pump. I just don't know how to use. The link you posted is very useful. I will be checking those as soon as I get a vacuum tester.
I'm back leaning towards a timing issue. I think I screwed up the check last time. I couldn't find the timing mark on the crank wheel, so, I used a screwdriver to look for TDC. I didn't verify if it was compression stroke and definitely could have been off.
Tonight I pulled the distributer and decided to reset it. I found the timing Notch and marked with paint. I couldn't fit my hand into the spark plug hole. So, I had my wife do it. I turned the crank and she said it was pushing her finger out. So, I assume this is compression stroke. I lined the notch up with 0 and went to work.
I reset the oil pump to 11 o'clock and placed a punch through the holes. Dropped the distributer in with the bracket in the 1 o'clock position. Fell perfectly in the right location lined up with the bolt hole in the block. Last time I tried this I had to remove the punch and spin it slightly to line up. I'm thinking I was off a notch. When I put the rotor back on, it was pointing to #1 spot on cap. A little past it actually, but, it was pretty close.
Anyways, reassembled everything now it won't start. I must be 180 out? Cranks strong though. Seems to be stronger and smother than previous. Unless my wife is crazy, a possibility, I think I had it at TDC on the compression stroke. Not sure what happened.
I verified the crank position sensor was re-connected and double checked firing order. Not sure what happened here. Maybe I disconnected something prior to testing this weekend. Really don't think so though. I should have verified it started before doing the test. Hell, maybe it's out of gas.
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- Location
- Southern Maryland
that spark looks orange, should be blue/white
[ps--oil pump drive everybody says 11 o'clock, but it is really 5 o'clock (#1 post), just easier to see 11 and it doesn't really matter]
[ps--oil pump drive everybody says 11 o'clock, but it is really 5 o'clock (#1 post), just easier to see 11 and it doesn't really matter]
It's actually blue/white. I don't know why the video looks like that. The strength of the spark is suspect to me though. I thought I had another ignition coil to test. Turns out I was wrong. The one I have is damaged and missing the connector. Only other thing i know to do is measure the spark jump.
My god. I reset the timing three times, installed a new fuel pump (used known working) replaced strainer (original was trash). I swapped another throttle body on complete with sensors. When I swapped the throttle body, the idle was very high around 1500 RPMs and moving. Figured it was a bad IAC on this unit, so, I put in the old. Idled normal rpm range. Went to restart and it idled high again. Wasn't doing this prior to swapping throttle body.
The new fuel pump also shakes between 30-32 psi very fast. Needle bounces. Unplug the vacuum line on the FPR and it is steady at 40psi. No shaking needle.
Either way, nothing I did changed the rough idle and power loss. Ugh.
The new fuel pump also shakes between 30-32 psi very fast. Needle bounces. Unplug the vacuum line on the FPR and it is steady at 40psi. No shaking needle.
Either way, nothing I did changed the rough idle and power loss. Ugh.
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RedHeep
NAXJA #1499
- Location
- Landenberg, PA
I'm going out on a limb here and guessing you've never been introduced to a troubleshooting flowchart.
You're all over the place. You're checking fuel system stuff, you're checking ignition stuff, then you completely change the game and put a different component on with its own set of sensors.
Pick a system and troubleshoot it. Shot gunning parts will only make you frustrated. You don't know what problems are symptoms and what symptoms you've introduced with used and junk parts.
You're all over the place. You're checking fuel system stuff, you're checking ignition stuff, then you completely change the game and put a different component on with its own set of sensors.
Pick a system and troubleshoot it. Shot gunning parts will only make you frustrated. You don't know what problems are symptoms and what symptoms you've introduced with used and junk parts.
I've been trying to do that. I've been careful about only doing one thing at a time. I'm having to jump around a little. Partly because I have stop and look for a test procedure and partly because I may not have what I need to test. So, I'll test something else until I can get what I need. Besides, I think of ruled out spark completely unless this jeep just doesn't like my plugs. I know people say champion coppers are the way to go, but, I just can't see this thing not running on just about anything.
I was going to just replace the IACV and the TPS independently, but, the new throttle body seemed to be in better shape. So, figured why not. I've since changed back to the originally IACV as I thought the other had an issue.
I'm not sure what you mean by junk parts. If I have 4 IACV, why would I go buy a new one? I'm sure 1 out of 4 works. They all probably do. Outside of the throttle body with sensors today, I've replaced or tested everything one at a time to avoid creating more issues or compounding them.
If you'll recall, I'm pretty sure my first post said that I did NOT want to shotgun parts at this thing. I want to test and verify the problem prior to purchasing new parts. So, I'm really not sure what you're talking about. Do you have a suggestion of what to check next? I'm out of ideas outside of starting to replace parts.
I was going to just replace the IACV and the TPS independently, but, the new throttle body seemed to be in better shape. So, figured why not. I've since changed back to the originally IACV as I thought the other had an issue.
I'm not sure what you mean by junk parts. If I have 4 IACV, why would I go buy a new one? I'm sure 1 out of 4 works. They all probably do. Outside of the throttle body with sensors today, I've replaced or tested everything one at a time to avoid creating more issues or compounding them.
If you'll recall, I'm pretty sure my first post said that I did NOT want to shotgun parts at this thing. I want to test and verify the problem prior to purchasing new parts. So, I'm really not sure what you're talking about. Do you have a suggestion of what to check next? I'm out of ideas outside of starting to replace parts.
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blistovmhz
NAXJA Forum User
- Location
- Vancouver, BC
Still valves. Seriously, do the vacuum tests. Problem sounds like a valve issue, you KNOW you had a valve issue (pushrods), and you've ruled almost everything else out. Silly to not throw a $20 vacuum gauge on there are this point .
Okay. I will. Just have to find a place that has one or order from Amazon. Should be here Wednesday if I order today.
Would the leak down do the same thing? It should tell me I have a leak in intake or exhaust valves plus give a percentage....if I rent the guage.
Or is there still benefit to the vacuum?
Would the leak down do the same thing? It should tell me I have a leak in intake or exhaust valves plus give a percentage....if I rent the guage.
Or is there still benefit to the vacuum?
blistovmhz
NAXJA Forum User
- Location
- Vancouver, BC
Leakdown only tells you if you have a leak. Vacuum tells you if you have a leak, if so, where it is, will give you an idea of the condition of your cam/lifters/pushrods/valves, etc. Check the link I posted again. There are LOADS of things you can check in about 5 minutes with a vacuum gauge, that otherwise would require a complete teardown of the motor to inspect.
I consider a vacuum gauge as important as a multimeter when it comes to engine diagnostics. When I have a motor problem that isn't throwing a code, vacuum is the first thing I check because it takes <5 minutes to rule out a large number of mechanical problems.
Again, given you are already absolutely positive that you had an issue in your head, and that it was almost certainly caused by a valve, I wouldn't have bothered moving forward with the troubleshooting until the condition of the head/valves/cam/lifters/rockers/pushrods were all verified. A rough idle persisting after finding a bend pushrod... first suspect for me would be valves. I could absolutely be wrong but it's a 5 minute/$20 test.
I consider a vacuum gauge as important as a multimeter when it comes to engine diagnostics. When I have a motor problem that isn't throwing a code, vacuum is the first thing I check because it takes <5 minutes to rule out a large number of mechanical problems.
Again, given you are already absolutely positive that you had an issue in your head, and that it was almost certainly caused by a valve, I wouldn't have bothered moving forward with the troubleshooting until the condition of the head/valves/cam/lifters/rockers/pushrods were all verified. A rough idle persisting after finding a bend pushrod... first suspect for me would be valves. I could absolutely be wrong but it's a 5 minute/$20 test.
blistovmhz
NAXJA Forum User
- Location
- Vancouver, BC
Any source of vacuum that isn't necessary for correct engine operation. ie: anything that goes back to the dash, or your cruise control.
If you take some video of the gauge while you do each of the tests, myself or someone else here can probably help interpret them.
If you take some video of the gauge while you do each of the tests, myself or someone else here can probably help interpret them.
