oleskool Posted December 5, 2021 Share Posted December 5, 2021 Ok. I’ve had a slightly high idle that I’ve been fighting. I replaced the IAC yesterday and it helped a little. Truck still idled at ~1100 RPM. It also randomly would idle low when the clutch was pushed coming to a stop. It wouldn’t do this everytime but would still do it. IAC didn’t really help much so today I pulled the throttle body and cleaned it. It definitely needed it. I used a soft brass brush to get the build up out with TB cleaner. Put everything back together with a new gasket and now I get an extremely rich idle that’s somewhat rough ish. Video showing start up and idle / smoke from the tail pipe. Before this it would idle high but over all ran good. It still runs great at speed and it no longer gets a low idle when hitting the clutch. I unplugged the TPS and got a high idle. Plugged it in and it went back down to what you see in the video. Any suggestions of what to test from here? TIA Link to comment Share on other sites More sharing options...
OldManComanche Posted December 5, 2021 Share Posted December 5, 2021 MAP sensor: vacuum leak or rubber connection with throttle body??? Link to comment Share on other sites More sharing options...
oleskool Posted December 6, 2021 Author Share Posted December 6, 2021 50 minutes ago, OldManComanche said: MAP sensor: vacuum leak or rubber connection with throttle body??? Haven’t checked map sensor but that what I’m thinking. As far as I can tell no vac leaks. What’s the rubber connection to the throttle body? The vac line that runs in the side? Link to comment Share on other sites More sharing options...
OldManComanche Posted December 6, 2021 Share Posted December 6, 2021 Yes on your question. If you had the throttle body off, you would have to remove the line. It has a screw to hold it in, looks like a good place for a leak. I have had the hard plastic line develop a crack in it before. It looks like the line has a piece of rubber hose in it (splice??) What about the hose connection at the MAP sensor? Link to comment Share on other sites More sharing options...
Ωhm Posted December 6, 2021 Share Posted December 6, 2021 Running RICH at IDLE, like mentioned above, it's always a good idea to check MAP/MAP vacuum. Since you did a major cleaning of the TB you may also need to check TPS voltage setting at CLOSED THROTTLE. If IDLE keeps improving with time, meaning the more you drive the vehicle the better it gets, your FUEL TRIMS are hunting and need time to settle down with this clean TB. Assuming engine enters CLOSED LOOP. Link to comment Share on other sites More sharing options...
oleskool Posted December 6, 2021 Author Share Posted December 6, 2021 53 minutes ago, OldManComanche said: Yes on your question. If you had the throttle body off, you would have to remove the line. It has a screw to hold it in, looks like a good place for a leak. I have had the hard plastic line develop a crack in it before. It looks like the line has a piece of rubber hose in it (splice??) What about the hose connection at the MAP sensor? Yeah I am digging into the vac line tomorrow. The PO spliced it. There isn’t a screw on the throttle body to hold it in. It’s just pushed in the rubber grommet. I’m planning to tap it and add a barbed fitting to make a good seal on the vac line. I will run a new line to the MAP. Link to comment Share on other sites More sharing options...
oleskool Posted December 6, 2021 Author Share Posted December 6, 2021 43 minutes ago, Ωhm said: Running RICH at IDLE, like mentioned above, it's always a good idea to check MAP/MAP vacuum. Since you did a major cleaning of the TB you may also need to check TPS voltage setting at CLOSED THROTTLE. If IDLE keeps improving with time, meaning the more you drive the vehicle the better it gets, your FUEL TRIMS are hunting and need time to settle down with this clean TB. Assuming engine enters CLOSED LOOP. I plan to dive into the TPS voltage tomorrow after I validate the MAP and vacuum to MAP. My guess is the vacuum was jacked up after removing it from the throttle body but I’ll do one at a time. Is there any way to validate the MAP with a volt meter etc? Link to comment Share on other sites More sharing options...
Ωhm Posted December 6, 2021 Share Posted December 6, 2021 20 minutes ago, oleskool said: Is there any way to validate the MAP with a volt meter etc? MAP output testing.pdf Link to comment Share on other sites More sharing options...
oleskool Posted December 6, 2021 Author Share Posted December 6, 2021 10 minutes ago, Ωhm said: MAP output testing.pdf 174.86 kB · 2 downloads Thank you! Link to comment Share on other sites More sharing options...
Ωhm Posted December 6, 2021 Share Posted December 6, 2021 Check out @cruiser54 tip #31. Throttle Body to MAP sensor hose fix | cruiser54 Link to comment Share on other sites More sharing options...
oleskool Posted December 6, 2021 Author Share Posted December 6, 2021 16 minutes ago, Ωhm said: Check out @cruiser54 tip #31. Throttle Body to MAP sensor hose fix | cruiser54 That’s the plan for tomorrow. Link to comment Share on other sites More sharing options...
oleskool Posted December 6, 2021 Author Share Posted December 6, 2021 Ok so I went out this morning and reworked the MAP vac line so all is good there. No more rich idle. I would say that the sensor appears to be working correctly. Now I have a high idle ~ 1500 RPM consistent. Even with adjusting the TPS to @cruiser54 specs (4.83V A to B and .821V B to C) I get an extremely high idle ~3k +. Went back and adjusted it while running and can get it back to ~1500 RPM but as soon as I turn the engine off and start it up again I get ~3k RPM again. At this point I am going to slap a new TPS in it to make sure the circuit inside has not been compromised etc. Any other suggestions? This is the first truly high idle issue I have had and I can't say what the PO's nephew has done or not done to this thing lol. Judging by other things I found he twisted and turned alot of knobs he should not have! Thanks for any other help / advice. Link to comment Share on other sites More sharing options...
oleskool Posted December 6, 2021 Author Share Posted December 6, 2021 I guess I should add, I have been through all the grounds, vac lines etc and all are in good working condition. I need to check manifold bolts on the bottom side but I am still trying to figure out how to get to them without removing the fuel rail haha. Link to comment Share on other sites More sharing options...
OldManComanche Posted December 6, 2021 Share Posted December 6, 2021 Did you check the throttle butterfly for closing fully when you cleaned it? Has the stop screw been tampered with? Link to comment Share on other sites More sharing options...
oleskool Posted December 6, 2021 Author Share Posted December 6, 2021 22 minutes ago, OldManComanche said: Did you check the throttle butterfly for closing fully when you cleaned it? Has the stop screw been tampered with? I checked the opening when fully closed and get very close to 3 thou. I was wondering the same thing but the best I remember that is spec for the opening. I will double check to validate that though. Link to comment Share on other sites More sharing options...
OldManComanche Posted December 6, 2021 Share Posted December 6, 2021 Sounds like you are ahead of me! Link to comment Share on other sites More sharing options...
oleskool Posted December 7, 2021 Author Share Posted December 7, 2021 On 12/6/2021 at 1:49 PM, OldManComanche said: Sounds like you are ahead of me! I thought I was. Re measured and the gap was a little wide. Adjusted it back down to spec and reset the TPS. Boom idles at 750 RPM. Runs good on the street too. Now to figure out my last issue which is a random low RPM surge when I hit the clutch. Doesn’t do it all the time but it’s annoying lol. Link to comment Share on other sites More sharing options...
OldManComanche Posted December 7, 2021 Share Posted December 7, 2021 Glad to hear it! Glad to be of some help! The truck I have now is a copy of yours, same year, same color, dash, engine/trans. etc. Link to comment Share on other sites More sharing options...
oleskool Posted December 7, 2021 Author Share Posted December 7, 2021 1 hour ago, OldManComanche said: Glad to hear it! Glad to be of some help! The truck I have now is a copy of yours, same year, same color, dash, engine/trans. etc. That's awesome. This is my first Comanche but I own plenty of jeeps haha. I have to say this thing is a alot of fun to drive when it runs right lol. I am slowly trying to return it to almost completely stock form besides tire size and radio. Link to comment Share on other sites More sharing options...
cruiser54 Posted December 8, 2021 Share Posted December 8, 2021 On 12/6/2021 at 8:27 AM, oleskool said: I guess I should add, I have been through all the grounds, vac lines etc and all are in good working condition. I need to check manifold bolts on the bottom side but I am still trying to figure out how to get to them without removing the fuel rail haha. Just remove the air box. Super easy. Link to comment Share on other sites More sharing options...
cruiser54 Posted December 8, 2021 Share Posted December 8, 2021 CRUISER'S MOSTLY RENIX TIPS RENIX THROTTLE BODY BUTTERFLY ADJUSTMENT OCTOBER 31, 2015 SALAD 7 COMMENTS EDIT Okay. Let’s start from scratch. First off, that’s not an idle adjustment screw. It’s a throttle butterfly stop screw. It’s purpose is to allow the butterfly to be as close to completely closed as it can be without binding or wearing into the throttle body. It was never intended to be adjusted in the field. But, Uncle Bob didn’t know that, did he? Engine off. Back off the butterfly stop screw with a 3/32″ allen wrench until the butterfly is completely closed. Now. turn the screw in until the FAINTEST movement of the butterfly opening is detected. If you have a .003″ feeler gauge, or something that thick as measured with a caliper, use that to set the clearance. We’re talking sticky note paper here. This can be done more easily with the throttle body removed. If you remove the throttle body, be sure to replace the gasket underneath it after thoroughly cleaning the old one off. Readjust your Throttle Position Sensor. Link to comment Share on other sites More sharing options...
oleskool Posted December 8, 2021 Author Share Posted December 8, 2021 2 hours ago, cruiser54 said: CRUISER'S MOSTLY RENIX TIPS RENIX THROTTLE BODY BUTTERFLY ADJUSTMENT OCTOBER 31, 2015 SALAD 7 COMMENTS EDIT Okay. Let’s start from scratch. First off, that’s not an idle adjustment screw. It’s a throttle butterfly stop screw. It’s purpose is to allow the butterfly to be as close to completely closed as it can be without binding or wearing into the throttle body. It was never intended to be adjusted in the field. But, Uncle Bob didn’t know that, did he? Engine off. Back off the butterfly stop screw with a 3/32″ allen wrench until the butterfly is completely closed. Now. turn the screw in until the FAINTEST movement of the butterfly opening is detected. If you have a .003″ feeler gauge, or something that thick as measured with a caliper, use that to set the clearance. We’re talking sticky note paper here. This can be done more easily with the throttle body removed. If you remove the throttle body, be sure to replace the gasket underneath it after thoroughly cleaning the old one off. Readjust your Throttle Position Sensor. Thank you for the reply and all the great information. I tend to call this wrong because I work mostly on carbs lol. The throttle plate butterfly was incorrectly adjusted (I am assuming because it was so gummed up it had a low idle). I corrected this and adjusted to your spec, all is good in the world! I then adjusted the TPS to the correct spec and now we have a sweet running little jeep! This cycle sent me into a stalling issue I had noticed when I hold in the clutch, moving or stopping. I posted about this in another thread. Since I am 100% sure everything on the sensor side is correct now the next logical place would be the EGR. I pulled the vac and sealed it off.... perfect idle everytime lol. Now I need to make the decision of trying to find a replacement, clean mine and see what happens or delete it. I live in SC so no inspections leads me to the delete method but I have not made that decision just yet. Thank you for all your write ups, they have made this journey much simpler than it could have possibly be! Link to comment Share on other sites More sharing options...
cruiser54 Posted December 10, 2021 Share Posted December 10, 2021 You're welcome. Thank you for your diligence!!! Link to comment Share on other sites More sharing options...
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