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Pretty weird behaviour with my 89 XJ (Stumbling etc.)
Stock XJ Cherokee Tech. All XJ Non-modified/stock questions go hereXJ (84-01)
All OEM related XJ specific tech. Examples, no start, general maintenance or anything that's stock.
Pretty weird behaviour with my 89 XJ (Stumbling etc.)
Hey guys, i bought a great XJ from 89 two weeks ago. I drove it 250km home and except from some rust it looks great. Just needs some love.
Fist thing i did on the technical side of things, was to renew the Sparkplugs (Champion) the Wires, the Cap and the Finger.
Else i did Tips 1-5 from Cruisers Homepage.
I rebuilt the Cables to and from the Batterie, Ground, Starter Motor, added two seperate grounds as per Cruiser.
Got rid of faulty cables, cleaned every connector i could get my hands on, cleaned the Ignition Coil on the inside and put some Contactgrease inside.
Now what is wrong?
At around 1-1.5k rpm and above the jeep stutters and missfires like crazy, it ran 250km back home just fine, was stumbeling slightly at around 2k on the highway, but accelerating completely worked and it was nice to drive.
Now i cant even drive since it stutters so bad that its unbearable.
Yesterday i installed a FelPro Gasket since the Valvecover was basically just attached with RTV and i swapt the "Frontpart" of the Vacuum Harness, to the Cover and such, after that i tried it again.
It starts, when i rev it to 1-1.5k it stutters and a relay (picture attached) made a spark, just once, accelerating again and again didnt cause a spark or anything, yet it still accelerates like ****.
I tried everything in P btw. didnt want to drive it like that, yet i drove back and forth a bit and you cant drive it like that...
In addition to what Saudade asked you to do: What you are describing can be a lean fuel problem, but you didn't do anything to affect the fuel system by your description. You replaced the spark plugs with Champion RC9YC plugs? Gapped to .0035? Did you by chance remove the fuel injector connectors? If so, make sure you put the connectors back on the correct injector.
In your photo 1671, I can trace the small vacuum line from the MAP sensor to the throttle body. There appears to be another vacuum line coming from the attachment point of the MAP sensor vacuum line plug on the side of the throttle body. Can you tell where that is going? Do make sure the vacuum line to the MAP is not cracked or loose at either end.
Last edited by dmoe69; 02-14-2023 at 11:09 AM.
Reason: Additional info
Make sure all the vacuum hoses are 'good' ...that could lead to low vacuum. Clean that little 'breather' grommet at the back of the valve cover if you haven't already (or just replace with a new one). Check (tighten) the front a rear nuts on the intake manifold. They work themselves loose. Ensure the spark plug wires are not touching metal. Double-check your spark plugs. Ive had faulty plugs out of the box before.
Since it's new to you, a guy would benefit from doing basic troubleshooting:
1) Temp gauge: ohm it out ...vehicle cold and vehicle warm.
2) Check vacuuum ..with a vacuum gauge. Hook it up to see what it's reading.
3) When you go to check the spark plugs, run a compression test on it (engine warm). Maybe there's a bad valve or broken ring??
4) There's that air intake temp sensor ...remove and clean
5) Engine & Body grounds ...sounds like you did them already ...but just checking.
6) All vacuum hoses - quadruple check.
7) Corroded wire connectors ...remove and inspect.
8) Fuel pressure reading ..as mentioned above.
If you don't have some of the tools, OReilly or Autozone rent them out for free pretty much.
In addition to what Saudade asked you to do: What you are describing can be a lean fuel problem, but you didn't do anything to affect the fuel system by your description. You replaced the spark plugs with Champion RC9YC plugs? Gapped to .0035? Did you by chance remove the fuel injector connectors? If so, make sure you put the connectors back on the correct injector.
In your photo 1671, I can trace the small vacuum line from the MAP sensor to the throttle body. There appears to be another vacuum line coming from the attachment point of the MAP sensor vacuum line plug on the side of the throttle body. Can you tell where that is going? Do make sure the vacuum line to the MAP is not cracked or loose at either end.
Hey,
yes i used exactly them + i checked the gap to 0.9mm at each and everyone of them, i didnt touch the injectors and i wiggled all the plugs just 5 mins ago, they are all flush and seated very well.
I attached pictures where you can see where its going, for my understanding it should just be throttle body to map sensor, yet there is a line going from tb to the vaccum harness, i attached some pictures with more connections.
Make sure all the vacuum hoses are 'good' ...that could lead to low vacuum. Clean that little 'breather' grommet at the back of the valve cover if you haven't already (or just replace with a new one). Check (tighten) the front a rear nuts on the intake manifold. They work themselves loose. Ensure the spark plug wires are not touching metal. Double-check your spark plugs. Ive had faulty plugs out of the box before.
Since it's new to you, a guy would benefit from doing basic troubleshooting:
1) Temp gauge: ohm it out ...vehicle cold and vehicle warm.
2) Check vacuuum ..with a vacuum gauge. Hook it up to see what it's reading.
3) When you go to check the spark plugs, run a compression test on it (engine warm). Maybe there's a bad valve or broken ring??
4) There's that air intake temp sensor ...remove and clean
5) Engine & Body grounds ...sounds like you did them already ...but just checking.
6) All vacuum hoses - quadruple check.
7) Corroded wire connectors ...remove and inspect.
8) Fuel pressure reading ..as mentioned above.
If you don't have some of the tools, OReilly or Autozone rent them out for free pretty much.
I replaced the front harness (vac) since the L Plug in the front of the valve cover was broken, not the back one though, since i dont understand some of the connections that got spliced off from the po, like the one going to the TB wich imo should not be there.
I checked the connections so far and they look good!
The plugs are good, the spark plug wires are not touching metal (youre talking the shielding of the wires or the wiretip itself?)
1) do you have something where i can look into it?
2) Im going to try to figure that out
3) I can, but actually i dont think so, it ran fine like 2 weeks ago, i basically just stripped the whole inside to get rid of some slight rust and didnt drive it, two weeks later it runs like ****
4) Thats the one in the TB isnt it? Can i just remove and clean it?
5) I did them all, sanded them down, put contact grease on them, even installed a new batt + fender, engine (tb) to firewall one (all 1awg with copper tips)
6) I will
7) I removed everything i could get my hands one, sprayed them out with contact spray and compressed air, even the ignition coil, put them back together, nothing obviously in bad shape
8) I will, i ordered a manometer, sadly the adapters wouldnt work, have to order another one, amazon is my only sorce for stuff like that, because, germany.
The fuel pressure readings will be useful, so get a gauge if you can.
Can you show a picture and point to where you think the spark came from?
When you did Cruiser's tip number 5 what did you get for an Ohm value when you did the resistance check. Did you shake the wiring harness in several areas while observing the Ohms reading?
I'm fixated on the hose coming off of the top of the MAP sensor vacuum plug on the side of your throttle body (photo 1731). I don't think it has anything to do with your problem, unless it is somehow a vacuum leak, but it is essentially plugged into nothing. It is plugged into the friction fitting that holds the whole plug to the side of the throttle body.
The fuel pressure readings will be useful, so get a gauge if you can.
Can you show a picture and point to where you think the spark came from?
When you did Cruiser's tip number 5 what did you get for an Ohm value when you did the resistance check. Did you shake the wiring harness in several areas while observing the Ohms reading?
I'm fixated on the hose coming off of the top of the MAP sensor vacuum plug on the side of your throttle body (photo 1731). I don't think it has anything to do with your problem, unless it is somehow a vacuum leak, but it is essentially plugged into nothing. It is plugged into the friction fitting that holds the whole plug to the side of the throttle body.
In my google drive link you can see the relays, id say it was the right one or the second one from the right side, but it was so quick, it is really just guessing!
I will wiggle it completely all over tomorrow when i check the vac lines and do the preassure reading and setting the tps and i will post the results.
Im going to get the TPS set tomorrow aswell.
I literally have no clue why anyone would plug a line in there then, especially since its connected to the harness...
I meassured the grounds, pretty steady 0.8-9 overall regardless of how much i wiggle, 0.4 at the DipStick.
I tried to set my TPS, i cant get a hint of a voltage, i plug my multimeter in, put it in the b (ground) a (positive) and i get readings around 0.30.0 mv wich in my opinion should be wrong...
To check if my multi is broken i tried it at a AA battery and i get 1.6v out of it so i guess its working correctly, is it possible that the TPS is broken or should i still get some value out of it since its plugged in the harness?
I checked the VacLines, for now they look good, still need a Vac Tester, Fuel preassure i will do later, yet i found that if i accelerate FAST like i step on the throttle up to 3/4k i dont have any hesitation or stutter, if i slowly increase then the stutter is imminent at around 1-1.5k...
Theres a video -> https://drive.google.com/drive/folde...xq?usp=sharing
There is also a scratching noise all throught the video but especially when im at the dip stick area, is that normal? the ignition?
UPDATE2:
I Testet the Fuel Pressure.
If i just let it Pump on KeyOn it goes up to around 34 psi
If i start the engine it goes to a perfect 31, if i unplug the Vaccum hose from the Fuel Pressure Reg it goes up to 39
If i rev the engine, it stays at 39, like it doesnt move up a bit just 39 and i get stumble and missfire again...
.30 mv is low for the at idle output, if accurate. Does the voltage increase as you roll the throttle open? It should increase up to (or near) the reference voltage of 4.82ish. If it doesn't, I'd be suspect you are getting a true reading.
When you wiggled the harness, you were grabbing it below the MAP sensor where the looms come together and shaking it from there while measuring resistance as described in Cruiser's tip 5? If so, your resistance is pretty good.
I've tried for about a half hour to let your video download so I can open it, but it is no going to open - maybe because it is quite large. There should be no scratching noise. I would like to hear that. Maybe you could try downloading another video. In the meantime, take a look inside the distributer cap and see if there is any evidence of what that sound might be.
.30 mv is low for the at idle output, if accurate. Does the voltage increase as you roll the throttle open? It should increase up to (or near) the reference voltage of 4.82ish. If it doesn't, I'd be suspect you are getting a true reading.
When you wiggled the harness, you were grabbing it below the MAP sensor where the looms come together and shaking it from there while measuring resistance as described in Cruiser's tip 5? If so, your resistance is pretty good.
I've tried for about a half hour to let your video download so I can open it, but it is no going to open - maybe because it is quite large. There should be no scratching noise. I would like to hear that. Maybe you could try downloading another video. In the meantime, take a look inside the distributer cap and see if there is any evidence of what that sound might be.
Your fuel pressure readings are solid.
I doubt my readings too, but i dont know what i did wrong and no it didnt raise to 4.something it stayed in that general area!
Below the MAP Sensor and along the Valve cover yes!
The sound "sounds" fairly harmless, like the belt or one of its pulleys, maybe the water pump.
The computer uses fewer inputs at wide open throttle (WOT) than it does at idle and partial throttle. If, when you were rev'ing it faster, you were going to WOT, that could be an indication of a sensor issue. Next time the engine is cold, see if it will Rev normally past 1500 RPM in the first 30 seconds of operation. In those first few seconds the computer also relies on fewer sensor inputs. Be cautious not to over Rev your cold engine.
As far as back probing the TPS...Put the black probe into the B connector and check ground to the negative on the battery. Try pushing the probe in from different entry points around the conductor wire until you get a resistance reading. Once you have validated the B probe is in contact, switch your meter to voltage, turn on the key and work the red probe into the back of the A connector. Eventually you should see a reading around 4.8 volts.
Once all this is behind you, you will have learned a lot - and an XJ in good mechanical condition is actually quite reliable, so you don't have to dread this happening over and over again.
Last edited by dmoe69; 02-16-2023 at 10:28 AM.
Reason: Fixing bad info
The sound "sounds" fairly harmless, like the belt or one of its pulleys, maybe the water pump.
The computer uses fewer inputs at wide open throttle (WOT) than it does at idle and partial throttle. If, when you were rev'ing it faster, you were going to WOT, that could be an indication of a sensor issue. Next time the engine is cold, see if it will Rev normally past 1500 RPM in the first 30 seconds of operation. In those first few seconds the computer also relies on fewer sensor inputs. Be cautious not to over Rev your cold engine.
As far as back probing the TPS...Put the black probe into the B connector and check ground to the negative on the battery. Try pushing the probe in from different entry points around the conductor wire until you get a resistance reading. Once you have validated the B probe is in contact, switch your meter to voltage, turn on the key and work the red probe into the back of the A connector. Eventually you should see a reading around .8 volts.
Once all this is behind you, you will have learned a lot - and an XJ in good mechanical condition is actually quite reliable, so you don't have to dread this happening over and over again.
I cleaned the IAT since it was pretty dirty, used residue free contact cleaner and put some contact grease on the plug.
That video is a few Seconds after starting,
It started kind of wacky, then it turned out like this, yet you can see after the first thirty seconds when i go out it starts to stutter / missfire, if im back in it does it once and then runs smooth again...
Im going to check the TPS later, and use some Throttle Body spray to clean the TB, i dont have a gasket so i cant fully remove it yet.
02-14-2023, 01:54 AM
Pretty weird behaviour with my 89 XJ (Stumbling etc.)
