Ever since I bought my jeep, it's had a high idle. I really didn't know how high it was in comparison since it's been a while since I've owned an XJ. It idles at about 1500, and it shakes the hole cabin. Letting my foot off the brake pedal in drive has me thinking we're in a mild earthquake.
From all the cars I've owned this is making me think I've got a vacuum leak. What's tripping me up is that everything vacuum related works great. Vents work, heater core valve switches, cruse control doesn't work and ABS light is on. From all the posts I've read they basically say that if the vents work you're in the clear.
Before I broke this thing down for repairs, I overheated bad. I didn't notice my temp gauge climbing until I started loosing power. And then the engine stalled as I pulled it over to the side of the road. Shortly thereafter, a nice sheriff pulls up thinking I might be on fire. It's been downhill since then and the shaking has gotten much worse.
I replaced the plugs, wires, coil, distributor cap and rotor before the overheat. I replaced the plugs again after, along with a rad flush, new thermostat and mechanical fan. I found that I was missing two bolts on my passenger side motor mount, and the last one was hanging on by a prayer. I ripped it all apart, tapped the bottom one for a helicoil and installed rustys rubber motor mounts. The shaking is only worse, and still idling around 1500 rpm. I also get pretty heavy fluctuations in engine temp, but after replacing the fan it doesn't boil over anymore. Could be unrelated.
Could this still be a vacuum leak? Could the IAC be the culprit as well? What should I throw my wallet at next, I've got about three more tries before I'm eating instant noodle for the rest of the month.
If I hook up a vacuum gauge to the manifold, would that show low vacuum with a leak?
I wanted to get some input before I go crazy with the temp and idle issues. Would you guys believe they're related?
Thank you for all your help! If there's a wizard in the PNW who would like to drop by and call me stupid, I can offer beer, steak and homemade wine.
Ever since I bought my jeep, it's had a high idle. I really didn't know how high it was in comparison since it's been a while since I've owned an XJ. It idles at about 1500, and it shakes the hole cabin. Letting my foot off the brake pedal in drive has me thinking we're in a mild earthquake.
From all the cars I've owned this is making me think I've got a vacuum leak. What's tripping me up is that everything vacuum related works great. Vents work, heater core valve switches, cruse control doesn't work and ABS light is on. From all the posts I've read they basically say that if the vent still work....
Could this still be a vacuum leak
The fact that the HVAC still works mostly means the HVAC system is probably not leaking.
I would look really hard for leaks around the tb and intake manifold. Use brake cleaner, wd 40 or something to try to find anything. If nothing else it's cheaper than throwing parts at it
With a high idle, the IAC is my first thought.
keep your wallet away: clean the IAC first. Then clean your throttle body. Check your TPS. Check for vacuum leaks.
These things are all free and should be done in the diagnostic process.
With a high idle, the IAC is my first thought.
keep your wallet away: clean the IAC first. Then clean your throttle body. Check your TPS. Check for vacuum leaks.
These things are all free and should be done in the diagnostic process.
This is a good start and may fix your issues for free as mentioned above. The sensor components can be easily tested as well during the cleaning process and old gaskets ruled out. So start there and checking for vacuum leaks. Does it idle at 1500 both in and out of gear? Cold and hot? How does it idle from cold start to warm? Easy way to check for vacuum leaks is with a propane torch. You say it shakes when letting off brakes in gear.. from the idle bogging down or what? Does it shake like that when you put a load on the engine with the steering wheel or air conditioner and how do they affect your idle if at all.. as these are PCM to IAC inputs that could give a clue.
As for your cruise control it will be disabled with an abs code.
The fact that the HVAC still works mostly means the HVAC system is probably not leaking.
I would look really hard for leaks around the tb and intake manifold. Use brake cleaner, wd 40 or something to try to find anything. If nothing else it's cheaper than throwing parts at it
I absolutely coated the engine bay with brake clean, really tried to work it into all the vacuum fittings. I didn't find any idle speed changes. I tried propane next, with the same sort of luck. Seems like it might not be a vacuum leak, at least an easy one to reach.
Quote:
Originally Posted by Roler
With a high idle, the IAC is my first thought.
keep your wallet away: clean the IAC first. Then clean your throttle body. Check your TPS. Check for vacuum leaks.
These things are all free and should be done in the diagnostic process.
Throttle body will be torn apart ASAP and cleaned. I did notice that if I disconnected the throttle positon sensor, the car would almost die, then pick right back up. Same thing connecting it. Disconnecting the IAC had no change in the idle speed. This was with the engine warm, idling at about 1200rpm.
Quote:
Originally Posted by jakeepoo3
This is a good start and may fix your issues for free as mentioned above. The sensor components can be easily tested as well during the cleaning process and old gaskets ruled out. So start there and checking for vacuum leaks. Does it idle at 1500 both in and out of gear? Cold and hot? How does it idle from cold start to warm? Easy way to check for vacuum leaks is with a propane torch. You say it shakes when letting off brakes in gear.. from the idle bogging down or what? Does it shake like that when you put a load on the engine with the steering wheel or air conditioner and how do they affect your idle if at all.. as these are PCM to IAC inputs that could give a clue.
As for your cruise control it will be disabled with an abs code.
At a cold start, the car will idle around 1700rpm. As it warms up, it'll drop to 1200rpm. With AC on, it idles closer to 1500rpm.
Result with a propane torch was that I probably don't have a vacuum leak. I can't hear any noise either from the engine bay.
As for being in gear, it doesn't die, but the RPM drops to around 800rpm in gear and starts shaking the car pretty hard. It almost feels like the car is jerking. Car seems to drive great when I'm giving it some pedal.
Side note, a rattling noise that I proviously thought was my K&N air intake banging around, is actually the catalytic converter. On idle and especially on startup it rattles like dried beans in a tin can. Could this be indicative of it being plugged, and if so, could it cause any of the issues I'm currently having?
Thank you for all your help!
Good to know my ABS light is why cruise control doesn't work. Another problem for another day.
I absolutely coated the engine bay with brake clean, really tried to work it into all the vacuum fittings. I didn't find any idle speed changes. I tried propane next, with the same sort of luck. Seems like it might not be a vacuum leak, at least an easy one to reach.
Throttle body will be torn apart ASAP and cleaned. I did notice that if I disconnected the throttle positon sensor, the car would almost die, then pick right back up. Same thing connecting it. Disconnecting the IAC had no change in the idle speed. This was with the engine warm, idling at about 1200rpm.
At a cold start, the car will idle around 1700rpm. As it warms up, it'll drop to 1200rpm. With AC on, it idles closer to 1500rpm.
Result with a propane torch was that I probably don't have a vacuum leak. I can't hear any noise either from the engine bay.
As for being in gear, it doesn't die, but the RPM drops to around 800rpm in gear and starts shaking the car pretty hard. It almost feels like the car is jerking. Car seems to drive great when I'm giving it some pedal.
Side note, a rattling noise that I proviously thought was my K&N air intake banging around, is actually the catalytic converter. On idle and especially on startup it rattles like dried beans in a tin can. Could this be indicative of it being plugged, and if so, could it cause any of the issues I'm currently having?
Thank you for all your help!
Good to know my ABS light is why cruise control doesn't work. Another problem for another day.
You definitely have a high idle except when you're in gear. 750-800 rpm is right on the money. Then it begins to shake/run roughly..? Just disconnecting the sensor connector on the IAC idling won't tell you anything as it's a PCM output. After cleaning to properly test you'll need a multimeter to check for 5v, good ground from engine block to firewall and proper resistance within coils. Also the IAC pintel shaft has a tendency to gum up. The tps can be easily tested also for 5v, same ground test, resistance, and voltage output signal to PCM within parameters. New gaskets and o rings when reinstalling clean throttle and sensors. After that hopefully you'll see some noticeable improvement. If still high idle IAC maybe sticking. Check for vacuum leaks again. EVAP canister hoses, PCV fresh air and vapor outlet on valve cover, map sensor, brake booster, cruise control servo, etc.. I believe this will improve things and have to be done anyways. But now that you disclose info on the trash can cork (cat) on your exhaust that is now the number one suspect that can cause all the issues you're having. Even cause problems with good components due to a confused PCM. Bad cat means not only an obstruction choking your engines breathing process but also highly inaccurate oxygen sensor readings. Major PCM inputs for optimizing air fuel ratio. This is your major problem to fix. And why your rig starts jerking but does fair under throttle. If you give her wide open throttle that will put the PCM into open loop mode and ignore the o2s. I bet it runs much better Along with the other maintenance you should have a solid ride after fixing that.
Darrells muffler on 82nd St in Portland can help you determine if you have a plugged cat converter. I've used them on a couple of cars in the past.
i took my sons beater Toyota there with what I thought was a exhaust restriction and they ruled out a plugged cat free of charge.
74Plb
Across the river from PDX
Darrells muffler on 82nd St in Portland can help you determine if you have a plugged cat converter. I've used them on a couple of cars in the past.
i took my sons beater Toyota there with what I thought was a exhaust restriction and they ruled out a plugged cat free of charge.
74Plb
Across the river from PDX
I'll keep it in mind! Thank you for the recommendation. Unfortunately it's across the river for me, and it's hard to get the jeep to move for longer than 10 minutes now
MagnaFlow Universal Catalytic Converter Standard Grade Federal/EPA Compliant 53005 - Stainless Steel 2.25in Inlet/Outlet Diameter, 13in Overall Length, No O2 Sensor - Standard Grade Replacement https://a.co/d/78GOmRe
This seem like a good standard replacement? It's so noisy I'm going to replace it regardless. I saw a high flow cat from performance curve, but I'm not really intending on power mods.
I'll keep it in mind! Thank you for the recommendation. Unfortunately it's across the river for me, and it's hard to get the jeep to move for longer than 10 minutes now
MagnaFlow Universal Catalytic Converter Standard Grade Federal/EPA Compliant 53005 - Stainless Steel 2.25in Inlet/Outlet Diameter, 13in Overall Length, No O2 Sensor - Standard Grade Replacement https://a.co/d/78GOmRe
This seem like a good standard replacement? It's so noisy I'm going to replace it regardless. I saw a high flow cat from performance curve, but I'm not really intending on power mods.
Thank you for all your help!
I know it's the law but there's no such thing as a high performance cat 😺. A little secret why they even exist is because humans don't/don't know how to maintain their vehicles PCM inputs throwing off stoichiometric air-fuel ratio (full combustion) which creates the pollutants. C(x)H(y)+O2>H20+CO2 I gained substantial HP and torque after cutting all that trash off but I live in the Arkansas forest where we don't give a dang about that stuff. You might as well put new O2S in also. The red hot cat probably cooked them. 👽🙏
I know it's the law but there's no such thing as a high performance cat 😺. A little secret why they even exist is because humans don't/don't know how to maintain their vehicles PCM inputs throwing off stoichiometric air-fuel ratio (full combustion) which creates the pollutants. C(x)H(y)+O2>H20+CO2 I gained substantial HP and torque after cutting all that trash off but I live in the Arkansas forest where we don't give a dang about that stuff. You might as well put new O2S in also. The red hot cat probably cooked them. 👽🙏
Unfortunately, I'm far enough out to own goats but not far enough out to avoid DEQ. Gotta keep a trash can on it. I found one I can pickup today at O'Reilly. I'll check out the O2 sensor next! Thank you.
Unfortunately, I'm far enough out to own goats but not far enough out to avoid DEQ. Gotta keep a trash can on it. I found one I can pickup today at O'Reilly. I'll check out the O2 sensor next! Thank you.
Side note Arkansas is beautiful. I'm jealous.
Haha thanks for the laugh! Trash can.. yes indeed she's beautiful! I never come out of the forest and live 10 minutes away from the gigantic Ozarks national forest. I live half my life out there on endless trial with my girlfriend digger dawn. That's what I named my 4runner. It's also what I called my sister as a little kid 😆. They both dig. 👽
I ripped the catalytic converter out. It came out in a few pieces due to rust. The honeycomb seemed alright. I replaced it with one that wasnt in three parts. It no longer rattles, but there was also no change in engine condition.
On to the throttle body. The thing was dirty. I pulled it all apart, cleaned the hell out of it and for ****s and giggles pulled out the IAC. It came out in a few pieces. Throttle position sensor seemed to be okay. I replaced the IAC and bolted everything back together with a new gasket. The result was a slightly lower idle at 1100rpm. Getting there, but still rough. Might want to replace the throttle position sensor?
I threw a vacuum gauge on the manifold. It's not a steady needle, but it doesn't fluctuate more than .5Hg. It sits right around 17in Hg. Seems alright. Could my timing be off?
What I think was my evap canister behind the coolant overflow had a disconnected tube. Didn't seem to have any vacuum and the port seemed to be plugged. The tube is cracked as hell though. Makes me wonder what it is. Disconnected hose at back of engine bay.
I'm running out of ideas now. Maybe a plugged fuel filter?
I ripped the catalytic converter out. It came out in a few pieces due to rust. The honeycomb seemed alright. I replaced it with one that wasnt in three parts. It no longer rattles, but there was also no change in engine condition.
On to the throttle body. The thing was dirty. I pulled it all apart, cleaned the hell out of it and for ****s and giggles pulled out the IAC. It came out in a few pieces. Throttle position sensor seemed to be okay. I replaced the IAC and bolted everything back together with a new gasket. The result was a slightly lower idle at 1100rpm. Getting there, but still rough. Might want to replace the throttle position sensor?
I threw a vacuum gauge on the manifold. It's not a steady needle, but it doesn't fluctuate more than .5Hg. It sits right around 17in Hg. Seems alright. Could my timing be off?
What I think was my evap canister behind the coolant overflow had a disconnected tube. Didn't seem to have any vacuum and the port seemed to be plugged. The tube is cracked as hell though. Makes me wonder what it is. Disconnected hose at back of engine bay.
I'm running out of ideas now. Maybe a plugged fuel filter?
Getting close to can't run to a good rig now. I'm sure the throttle body was filthy, that's because of the plugged cat and bad O2 readings over time. The broken IAC was causing the jerking and the majority of your high idle. Now for that EVAP canister which is part of the vacuum system.. refer to the diagram we told you about. That's a vacuum leak.. I've actually had the same hose crack on me before. It's the fuel tank vapor line. The intake manifold sucks the fumes in from the canister and burns them off. Another b_ll**** government environment thing. I'm gonna delete mine but you need to follow the law. There's a tiny oriface where the hose connects a little needle poke it out clean and fix the hose and connect it all back together right. Also you still need to check your O2 sensors for sure. Give some time for the PCM to learn how to run with proper input values again or do the relearn procedure and you'll have a good time ✌️ time to hit the trail 🌎
