vibration/shudder on acceleration (3 Viewers)

[fjraamis]

Issues as well

Hello all,

I am new to the forum as well as land cruisers. I have been driving LR Discoveries for most of my life and let me tell you, Worst rigs ever made IMHO. I LOVE my 97 Cruiser 40th edition with ONLY 80 K on the clock. The PO did not even know what diff lock was. Although i do not have front or rear lockers i love the rig nonetheless. I will post some cruiser porn later.

I am having similar issues with my rig. The PO never did any PM except change the oil 3 months or 3000 which ever came first religiously. At 80K I have put only AMSOIL products in the rig. Being a dealer helps as i get pretty good deals.

Recently, I changed my tranny fluid with AMSOIL Universal ATF following one of the threads here on MUD. Once complete, i had put over 13.5 quarts. I ran it and i could barely notice the gear shift. It was amazing.

2 weeks later I am trying to drive off the line and punch the accelerator and notice hesitation/vibration/sputtering/speed bumps occurring and only from full stop to moving. Furthermore, the issue does not occur when the rig is cold but driving stop and go in NOVA traffic the issue emerges when it gets to operating temp.

I have ordered plugs, wires, fuel filter and will change that to see if it could just be a tune up issue. I would just like some help so that I can pinpoint this issue and be done with it with your help.

I also would like to point out that when cold the AT dip stick reads WAY HIGH. Could this be an issue? Could filling up AT a high level cause this hesitation on start up? I don't know.Please Help!!

Thank you,


FJ raamis

 

[96LX450-Nick]

Old thread but Im hoping some of you have corrected yours and can comment on this. Im having the same issue. My research has led me to believe its my front O2 sensor. It is no longer working therefore not adjusting my fuel mixture properly and creating a "flooding" effect. This is supported by my ~200miles to a tank consistant MPG. Anyone else having MPG issues?

 

[Bryan E.]

Replacement of air intake tube helped my vehicle

Hi,

Just throwing this out there for something to consider. I tuned up my 94 for a trip to CO and when changing the air cleaner, the larger, rubber intake tube ripped. I've been super careful with this part in the past but old age finally got to it. When I replaced the two pieces that had torn, I was surprised to see all the tiny cracks that were hidden to me. I got my new part from Cruiser Dan, and wish I had done this a few years ago as it probably has needed it for some time and is now running smoother than has in a long time.

 

[flashT]

I have a 97 LX that does just about the same. Mine will idle and cruise just fine, but on any acceleration it stumbles and knocks. I also notice it if I am at cruising speed then let off the accelerator and get on the gas again, but it smooths right out. I am going to try plugs, wires, cap and rotor....interested to know how did yours do after you changed the plug wires?

 

[Steve7]

A couple of days ago my rig started hesitating on acceleration just as the OP describes. It happens only from a stop or very slow speed. The truck acts completely normal once it's up to speed.

At first I thought it was the transmission as I once had a similiar issue when the fluid was low. Unfortunately that was not the problem. After checking the AT fluid, I walked next to the truck as the wife accelerated and it seemed to be coming from the engine.

I came to MUD and searched for a resolution and it seems that many were able to fix the problem by swapping out the plugs, wires, rotor, and distributor cap. I replaced those items this evening and the problem persists.

I haven't checked any electrical connections, and sure that I didn't pay enough attention to vacuum lines...

Your help is greatly appreciated!

 

[fjraamis]

I drained over 2 quarts from the tranny and really the same problem was occurring. tranny was completely ruled out. I therefore decided to change the fuel filter and for over a week NO PROBLEMS. Then all of a sudden when the fuel gauge hit almost empty the issue has started to creep up again. Here is what i think could be the problem.

It may be that the tank has rust and the fuel pump sock is gummed up with rust particulates. Furthermore, once the fuel is sent to the fuel filter the remaining particulates get caught there. I think that i may need to clean the tank, change the fuel pump sock and filter again to resolve this issue. From what i have researched the initial throttle push from a stopped rig eats up a ton of fuel. Thus the starvation during acceleration from dead stop. I will let you all know.

 

[mkguyvr]

was having a hell of a time finding the problem with my 93 and it ended up being plug wires, the engine would idle really low and shudder around 70 really bad as well as accelerate like crap.The exaust smelled awful, pulled the plugs and no. 6 was black rest were fine, changed out the plugs and wires cap and rotor and it fired up and ran beautiful. When i pulled the plugs i noticed water in the no. 6 plug well, blew it out before pulling the plug. Pretty sure that the water was the problem, grounding the wire. Hope this helps.

 

[beatle_bayly]

Hello all,


I also would like to point out that when cold the AT dip stick reads WAY HIGH. Could this be an issue? Could filling up AT a high level cause this hesitation on start up? I don't know.Please Help!!

Thank you,


FJ raamis

FJ, are you checking te tranny fluid level in the correct manner? Do it in accordance with the handbook, and take a lot of readings (don't simply rely on one). Take the reading with a warm transmission.

Many vehicle manufacturrers now no longer have a dipstick for checking tranny levels as so many people do it incorrectly and overfill or underfill the transmission. Manufacturers now believe it safer to leave the level check to the mechanic at regular servicing time.

 

[fjraamis]

FJ, are you checking te tranny fluid level in the correct manner? Do it in accordance with the handbook, and take a lot of readings (don't simply rely on one). Take the reading with a warm transmission.

Many vehicle manufacturrers now no longer have a dipstick for checking tranny levels as so many people do it incorrectly and overfill or underfill the transmission. Manufacturers now believe it safer to leave the level check to the mechanic at regular servicing time.

yes sir. When filling i made sure to check the level when cold, then after fill up i drove it for a little bit and then checked again (when warm), and finally i checked the level when i drove it in stop and go traffic (hot). I dont know but i think it could be that my rig just does not like amsoil universal ATF.

 

[beatle_bayly]

Sorry to harp on about it, and excuse me if I'm telling you how to suck eggs, but are you doing the checks with the engine idling? If the engine is off the level will be incorrect.

Cheers

 

[fjraamis]

Sorry to harp on about it, and excuse me if I'm telling you how to suck eggs, but are you doing the checks with the engine idling? If the engine is off the level will be incorrect.

Cheers

yep i measure fluid when idling. no worries even sucking eggs can be difficult some times .

regards

 

[Steve7]

Gentlemen,
Just a quick update here. I'm still having this issue, and I truly think this problem is not a transmission issue. As previous posters have mentioned, it only occurs after the engine has warmed up, from a near/dead stop, and until the rig gets up to speed. Outside of that the rig runs normal.

I was really hoping that the plugs, wires and distributer cap/ rotor would solve it. Now I'm thinking that it may be and EGR issue...Lord, I hope not.

I'll be spending some time on it this weekend, but it would be great to hear from some folks who've had this issue and successfully fixed it...Keep it coming.
Thanks!!!

 

[concretejungle]

Sorry to harp on about it, and excuse me if I'm telling you how to suck eggs, but are you doing the checks with the engine idling? If the engine is off the level will be incorrect.

Cheers

i found this to be very difficult to get an accurate reading. With the fluid swirling around, i could never really tell. I know it's the proper way to check the fluid level. That's just my experience.

 

[fjraamis]

still searching for an answer

I have no clue either. If you all find anything, anything at all please post here as I am completely lost as to what it might be. Below could be some issues that may cause it. Those of you who are very familiar with LCs please chime in and provide some feedback.

Fuel Pump --> not likely as it only happens when the rig gets warm.

Fuel Filter or fuel filter sock (located in tank) --> might happen when the rig gets hot as the filter sock will collapse after a while because of the pump sucking up the debris in tank. During the initial pull off the sock could fold into itself and restrict fuel flow

Cat Converter --> maybe when it gets hot it may throw off the air fuel mixture.

Hole in the intake hose or cracks in it.

I used proscan ODBII reader on the rig and collected some info in regards to our issues. I am attaching the charts i created and would like it if some knowledgeable fourm members could look into it and provide some thoughts.


regards,


fjraamis

Gentlemen,
Just a quick update here. I'm still having this issue, and I truly think this problem is not a transmission issue. As previous posters have mentioned, it only occurs after the engine has warmed up, from a near/dead stop, and until the rig gets up to speed. Outside of that the rig runs normal.

I was really hoping that the plugs, wires and distributer cap/ rotor would solve it. Now I'm thinking that it may be and EGR issue...Lord, I hope not.

I'll be spending some time on it this weekend, but it would be great to hear from some folks who've had this issue and successfully fixed it...Keep it coming.
Thanks!!!

 

[fjraamis]

Help

all,

has anyone figured this out yet? Please post or provide any relevant links that may be helpful.


thanks much,


fjraamis

 

[concretejungle]

i have not kept up with this thread very much or read it all. In my experience with a serious shutter/shake during acceleration it was from water being in the spark plug tube. If that gets wet from washing your motor, it will cause a serious shake/shutter. Just FYI.

 

[Steve7]

I haven't checked this thread in a while, but thought I'd post an update on my rigs hesitation.

As mentioned in the original post and my initial post; my truck developed a hestitation or shudder on accelleration from a near stop or very low speed. As the truck picked up speed the symptoms went away. Going wide open throttle at speed produced a barely noticable hesistation if any.

Did I mention...there is no hestitation when the truck was cold. It would only begin once the truck was at operating temp.

I first checked the tranny fluid as that's what it felt like...no luck there. I came here next and started my search. A lot of input to go through and a number of "good starts".

Even though I had no CEL I troubleshot the EGR system next and everything checked out good.

From there, I ordered new plugs, wires, rotor, and dist cap...nothing!

Next I removed the throttle body which was very dirty. Got it all cleaned up and the truck ran great...until it warmed up and the hestitation returned.

I had read a few threads that talked about the wire loom that runs next to the EGR causing the truck to run rough. I had looked at this previously, but didn't spend a lot of time on it. Well the weather was great today, so I decided to spend a little more time on it.

I got to looking and noticed that one of the loom holders which holds the bundle away from the EGR pipe was broken and the bundle (bound w/ heat tape) was actually resting on the EGR pipe.

I removed the EGR valve and unbolted the bundle from the firewall to gain a bit more access. I removed the old heat tape and inspected the wires individually (or best I could) and paid special attention to the spot that was rubbing on the EGR pipe.

I found a WHT/BlU wire that had the insulation rubbed off. I taped the bare spot up and rewound the bundle w/ several layers of new heat tape. Reattached the bundle and replaced the broken loom holder. The bundle now no where close to touching the EGR pipe.

I put the truck back together and took it for a long test drive. Once it was up to temp I made many stop/starts and NO HESTITATION!!!

I'm quite pleased and only hope that it was a good fix and that the symptoms don't return tomorrow during my next test run.

Sorry for the long post, but wanted to be as thorough as possible. No pics either, but there are plenty to be found under "main wiring harness."

 

[concretejungle]

cool, thanks for the follow-up.

 

[fjraamis]

i will look into this... I thought of changing the EGR modulator but before i do that i will look at the wiring harness. Thanks for the post.

 

[Slowleak]

Hmmm....so did anyone find a solution to this? I think I'm having similar symptoms. Could it be a wheel bearing? If so, would it be heard all the time instead of only during acceleration?