4bangerjp.com
General Forums => The Mess Hall => Topic started by: Eucalypta on June 26, 2010, 05:11:35 AM
-
Hello Guys,
I have the following problem which is getting worse by the mile:
My car (YJ 1994, 2.5L standard powertrain with AX5, 33" tires, had his tune up a few months ago) hiccups when driving slow and especially on a bumpy road.
It always had a "sensitive" throttle but it is getting a lot worse in the last few miles.
When I pull away or drive at pace, I look like "an old woman" as the car hiccups; launching forward and dropping back when I release the throttle, then launching forward when I push the throttle just a little bit. A bumpy road makes it even worse.
I also noticed that the gearlever is violently shaking when I accelerate from standing still and there seems lacking torque on the wheels; pulling away with screaming tires is not possible.
At my latest project the engine mount rubbers and gearbox mount, including the stabilizer have been replaced.
Someone mentioned it could be the clutch or gearbox…
Some more information:
-pulling up in the right gear (1st): car hiccups (driving like “an old woman”)
-pulling up in right gear and accelerating: Car doesn’t hiccup (noticeably) but the lever does shake violently.
-pulling away in the right gear and pushing the throttle down; the car doesn’t hiccup but the gearlever is shaking. I also notice there is not much torque at the wheels; it would be impossible to pull away with screaming tires.
-Pulling away in a higher gear: car doesn’t hiccup, or unnoticeable because of the higher gear.
-Pulling away without touching the throttle: car hiccups, but it is not aggravated by pushing the throttle accidentally by every launch forward or dent in the road.
-Driving at pace without throttle: car doesn’t hiccup
-Driving at pace in the right gear: car hiccups a lot (throttle is touched more or less by every dent in the road)
-Driving in a high gear: no hiccups or you unnoticeable because of the lack of torque to the wheels.
-Clutch pushed down: no rattling; the gearbox is reasonable quiet
-Clutch up: rattling from the gearbox (or clutch)
-When idling; the engine runs smooth. When pushing the throttle, even just lightly, there seems some delay (less than a second) before the engine picks up revs.
Could these hiccup problems (so maybe not the engine delay with the revs), be caused by problems in the gearbox or clutch?
If so, how could I fix them?
I am looking forward to your opinion!
John
-
doesn't sound like a clutch problem to me, more like one of the sensors (i'm thinking of TPS - throttle position sensor) or one or more of the injectors or having a bad connector at one of the injectors (for that someone here used zip-ties to secure the connectors to the injector body)
could also be an ignition problem as it seems to somehow be rpm related, so i would also check the distributor/rotor/wires/plugs and the Crankshaft Position Sensor (CPS)
do you have a check engine light on? if yes did you check the codes (look at the FAQ section for the procedure).
-
Mine had the same symptoms it was the connection where CPS plugs into harness.
-
Do all the basic stuff before you throw parts at it. Start with engine vacuum, see where the ignition base timing is at and if the ecm advances timing when you rev it.
Good vacuum at idle and a quick drop off when you open the throttle.
If all that is good move on to the ignition system, easiest field check is still get it barely rolling in first gear then shift to third gear and floor the Jeep, if it is just chugging and slowly accelerating without a backfire you can consider the ignition system good.
From there TPS, and check the map sensor, both of those inform the ecm about engine load, which then adjusts ignition timing and fuel delivery accordingly.
-
@sharpxmen: No faultcodes out of the ordinary (airco)
When I unplug an injector I can hear the engine react immediately; all injectors are working. I do not know if the amount they spray or the spray patern is ok (have no means to test it). They might have had a bang when I had water in the fueltank.
TPS is ok; exchanged it with the one from my GC; no improvement.
CPS: the connection has to be ok (see below). The problem does not occur while idling or revving it without driving.
@95four: The cable plug has been removed a long time ago; the wires are soldered (is this even english? :puzzled:) together. So there can be no problem with the connection. The CPS itself could be ofcourse but I do not know how to check it?
@AW12345: Vacuum seems ok. I have suction ad idling but more when the engines it as 2000rpm or more. It does not drop off until the revs go down (is ok?)
Ignition: need to do that including the clutch test later this week; not able to drive it at the moment. Will inform on this later on.
TPS is ok: have several spare and none take away the problem (or there are more sensors defected). Map sensor: will look into that.
My clutch might still be worn out: there is a ratling noice when the clutch is up. Whne I push it down the ratling is gone....
Probably have multiple problems; will know more after the fieldtests. :biggrin:
-
@sharpxmen: No faultcodes out of the ordinary (airco)
what is airco?
O2 can also cause some issues but from what you describe is less likely.
From your project thread i assume you checked the fuel pressure while under load so that's ruled out.
-
The rattle could very well be gear clash in the transmission that or the throwout bearing is toast (druklager). vacuum near 21" at idle or atleast above 19" needs to drop near zero when goosing the throttle (vol gas) also no fluttering of the vacuum gauge needle. Match vacuum reading with map sensor voltage on the sensor wire leading back to the ecm, should be around 1 volt at idle and near 4.5 to 5 volts at WOT.
To check injectors you need a fuel pressure gauge, which you have and a contraption to pulse the injectors, a good toolplace or auto parts store should have it.
All you do is block the return line to the tank cycle the key to build fuel pressure in the rail, then pulse the injector and note the pressure drop, do the same thing for each injector, then compare results, should be fairly close.
-
what is airco?
O2 can also cause some issues but from what you describe is less likely.
From your project thread i assume you checked the fuel pressure while under load so that's ruled out.
Airco = Air Conditioning
-
Jeffy: airconditioning indeed ::)
Have not yet had the chance doing the tests or look at the sensors. Been working all day in an hot office (need bigger AIRCO here ??? )
However I did have the time to read ALOT through this forum and found some other topics about hiccup and surging when driving slowly or on a bumpy road.
On one of them the issue seemed to be, and Jeffy you stated you seen it many times before, that a bolts turned on too tight of the springs, might give it a bucking ride.
I do not dare to jump to cunclusions but indeed the springs were bolted back on the new chassis last week. About the same time as this bucking started to aggrevate.
Could this be the problem or part of it? And how "tight" should the bolts be? First time we bolted them to FSM torque specs, this time I am unsure how tight the are. :confused:
I also think there are many ideas of what bucking, hiccuping, surging etc is.
I put hiccup in the title but maybe the word bucking or surging is better.
To describe my problem a bit better:
At idle or revving without driving, the engine runs smooth; this makes me doubt a bit that the sensors might be bad :puzzled: .
When I drive slowly and I do not touch the throttle, the car drives smoothly. At any RPM.
However when I just tough the throttle a bit the car reacts fierce; surging forward. Because of it the pedal will be pushed down a bit (my foot does not absorb the movement by the surging) and the car surges forward again. Of course I take my foot of the pedal and the car slows down, just until I want it to go a bit faster and pushes the pedal a bit again.
When driving on a bumpy road and I want to go at a steady pace; the same thing happens. On a bump the pedal is pressed a bit down making the car surge forward, etc.
Only shifting to a high gear or not touching the pedal makes it possible to drive slow or pull away in a smooth way.
I do not know what causes this problem. I hope this piece of information helps to find the problem.
The other thing with the shift stick shaking might have to do with the clutch been worn out or oil leaking on the clutch plates. The fieldtests of AW12345 might bring more light into this.
And I will of course pursue the sensor sugestions mentioned earlier.
-
I never used a torque wrench when I tighten the shackle to leaf bolts. I just make sure there is a locking nut (not lock washer) either a nyloc or a all metal one. I tighten with a socket wrench until it's snug. I make sure there is a few threads sticking out of the nut to be sure there is enough engagement to make the lock nut work. It could be as little as 40# but like I said I never measured.
-
It could be as little as 40# but like I said I never measured.
Did you encounter the same problems I have?
-
Did you encounter the same problems I have?
Not really since I didn't have them to tight in the first place. If your having a harsh, stiff ride where as you did not in the past then check to see how tight those bolts are. It could be a simple cheap fix.
-
poly bushings (greased) should take care of the problem
One thing i would look at is that you need to to make sure the bolts were tightened when the Jeep was on it's wheels (leaf springs, shackle and track bar bolts).
the other thing is to make sure you have the proper pinion angle at the rear driveshaft - if is wrong it will jump up and down or vibrate when you accelerate - since you mentioned you have a t-case drop - i had this problem and i needed smaller angle shims at the leafs and once i did that it stopped doing it (somewhat similar to what you describe but i can't be sure).
-
the other thing is to make sure you have the proper pinion angle at the rear driveshaft - if is wrong it will jump up and down or vibrate when you accelerate - since you mentioned you have a t-case drop - i had this problem and i needed smaller angle shims at the leafs and once i did that it stopped doing it (somewhat similar to what you describe but i can't be sure).
The t-case is 1" drop and I have 2,5 degree shims under the axle. Don't know if it is enough or too much since I am not sure how much lift the springs are (second hand buy with 2,5" lift "on the label")
A buddy of mine says it is about the right angle and the SY is deep enough in the TC. Don't feel really vibration. Maybe a bit when I slow down.
What would a right angle be? (I am sure the answer is somewhere on this forum?)
-
The t-case is 1" drop and I have 2,5 degree shims under the axle. Don't know if it is enough or too much since I am not sure how much lift the springs are (second hand buy with 2,5" lift "on the label")
A buddy of mine says it is about the right angle and the SY is deep enough in the TC. Don't feel really vibration. Maybe a bit when I slow down.
What would a right angle be? (I am sure the answer is somewhere on this forum?)
read this article http://www.4x4wire.com/tech/pinionangle/
on the right hand side (looks like a vertical ad banner) there are a series of images, 4th one from the top is probably what you should have with the t-case lowering kit, 3rd one is a standard setup - it is all a good read, very concise and to the subject
-
pinion angles are easy to figure out. With an SYE it has to pint straight at the yoke on the transfercase, without one simply turn the driveshaft so the yoke on the pinion and the transfercase is vertical then measure yoke ear to yoke ear if it is the same at the top and the bottom the angles are correct and it should not cause vibration
-
Ok...driveline angles are not ideal but ok for now.
Saving for a SYE ;)
Because the hickuping or bucking of my car while driving slowly is still not cured I analysed it some more:
It seems the throttle is extremely sensitive.
When driving slowly on a bumpy road this triggers the bucking ride. When hitting a bump the throttle is pressed slightly by my foot and results in surging forwards. When the cars jumps forward the pressure is slightly relieved from the throttle wich makes it slow down quickly what results in pressing the throttle again a bit, surging forward etc.....
I got an MOPAR TPS and mounted this, no cure.
Then I thought to take off the 4.0L TB and place my old 2.5TB back. I noticed that there is a slight difference in angle of the valveshaft of a 2.5 and the 4.0. Has anyone noticed this or is it just a coincidence?
With the 2.5TB the bucking gets worse. Don't know if less air is the problem or that more air camouflages the problem.
What I also notice is that at idle the engine doesnt run at a constant rev. The revs go slightly up and down.
Don't know if it is caused by the same problem or if it has another cause.
The PC doesnt throw any codes out of the obvious 12 33 and 55.
So, what now? Does anyone have a suggestion?
-
Ok...driveline angles are not ideal but ok for now.
Saving for a SYE ;)
Because the hickuping or bucking of my car while driving slowly is still not cured I analysed it some more:
It seems the throttle is extremely sensitive.
When driving slowly on a bumpy road this triggers the bucking ride. When hitting a bump the throttle is pressed slightly by my foot and results in surging forwards. When the cars jumps forward the pressure is slightly relieved from the throttle wich makes it slow down quickly what results in pressing the throttle again a bit, surging forward etc.....
I got an MOPAR TPS and mounted this, no cure.
Then I thought to take off the 4.0L TB and place my old 2.5TB back. I noticed that there is a slight difference in angle of the valveshaft of a 2.5 and the 4.0. Has anyone noticed this or is it just a coincidence?
With the 2.5TB the bucking gets worse. Don't know if less air is the problem or that more air camouflages the problem.
What I also notice is that at idle the engine doesnt run at a constant rev. The revs go slightly up and down.
Don't know if it is caused by the same problem or if it has another cause.
The PC doesnt throw any codes out of the obvious 12 33 and 55.
So, what now? Does anyone have a suggestion?
i'm thinking the O2 sensor but could also be a ground reference or signal loss/noise related to the sensor as well
-
O2 sensor...would that not be a problem at any speed?
And would that maybe also be the reason that at WOT, it feels like I am smothering the engine?
-
O2 sensor...would that not be a problem at any speed?
And would that maybe also be the reason that at WOT, it feels like I am smothering the engine?
not at any speed (speed won't matter) it's more if you're in closed loop or open loop - at wot it doesn't use the O2 feedback. If you get an up-down revs at idle it is usually (but not necessarily) a result of too rich mixture and that's why i was thinking O2 or something related to the O2 feedback.
-
Ok.. If I remember correctly the O2 from a 4L is the same as one from a 2.5L, I can swap the sensor with the one from a friend and see if it helps.
Also will replace the fuel filter and broken FPR.
-
Ok.. If I remember correctly the O2 from a 4L is the same as one from a 2.5L, I can swap the sensor with the one from a friend and see if it helps.
Also will replace the fuel filter and broken FPR.
just be careful when you take the O2 off, i have seen them go bad sometime when removed and reinstalled.
-
just be careful when you take the O2 off, i have seen them go bad sometime when removed and reinstalled.
:thumb: ok, going to be extra carefull (cannot afford to buy 2 sensors)
-
Having the same issue on mine at the time. Replaced my fuel filter and though I could still blow through the old one it was restricted when compared to the new one. This seemed to help reduce the frequency of the surging and bucking but I am still having an episode every once in a while. This leads me to think that perhaps my fuel pump might be dying or having issues. Anyone had a similar experience with a confirmed bad fuel pump?
-
My pump is new, as is my filter, FPR, all lines and tank are clean.
New bougies, distributer cap and rotor, spark plugs and wires, K&N airfilter (helped a bit), 4.0L TB (helped a bit), new TPS, cleaned TB+IAC housing.
It is not the loose throttle cable (installed the TJ spring), no vacuum leaks, no worn out gaskets.
Thinking about the O2 sensor, maybe the coupling (it is a bit worn out, needs to be replaced within 1K-2K km)
Is the following plausible?
Maybe the IAC is not workign correctly; not shutting down as quick as it should? When driving, the engine running on idle, IAC is open to get enough throttle for the engine not stalling while driving. When I press down the throttle the IAC should close completely (or should it stay wide open all the time?) but it stays open and there is too much air flowing into the engine, thrusting the car forward.
I'm clutching straws here, it is REALLY anoying when it bucks like this.
-
You need to find a way to look at the data stream to see where the fuel trim is at
As well as looking to see how well the 02 sensor toggles. If that is all happy it's time to look at the ignition, but I am sticking with a fuel related problem, could be as simple as low voltage at the fuel pump
-
Throttle position sensor, and FYI I bought one a while back and it was bad out of the box, ended up buying a second one.
Dave
-
Throttle position sensor, and FYI I bought one a while back and it was bad out of the box, ended up buying a second one.
Dave
That was also what I thought...even bought a mopar one istead of the shitty crown.
Still no difference, have tested them with my multimeter; both checked out to be ok...
I am going to do some more analysis before throwing more parts at it.
-
That was also what I thought...even bought a mopar one istead of the shitty crown.
Still no difference, have tested them with my multimeter; both checked out to be ok...
I am going to do some more analysis before throwing more parts at it.
The Mopar part will be the exact same as Crown.
-
The Mopar part will be the exact same as Crown.
Ya under the skin Im sure they are.
The mopar was of different color than the crown though.
Well they both checked out to be ok on the multimeter...
So, throwing parts at it, doesn't solve the problem.
Would worn out spark plugs or spark plugs with a too big gap be responsible for this kind of behaviour?
-
Would worn out spark plugs or spark plugs with a too big gap be responsible for this kind of behaviour?
it can cause misfires so yes, but that depends on how much worn we are talking about - if in doubt replace the plugs with new ones, they are $10/set so really you should have them replaced.
-
What's your gap at? .035" is stock. I wouldn't really recommend going less then that. You might consider checking each plug & wire to see if you get a arc. If the engine is shaking then you're down a cylinder for sure. The engine will really feel gutless too. Idling it would sound almost OK though. Check your rotor and cap while you're at it. Although it could possible be a fuel issue as well. Maybe one of the injectors is going bad? But then again, it should throw a Code 27 and light up the CEL.
-
No codes and although it feels a bit gutless I do not feel the engine is shaking. Idling is ok.
There seems a small lag between opening the throttle and picking up refs but thats only a 1/2 second or so.
At WOT on the highway it seems to be dragging and slowing down, while when I release the throttle it feels like the car accellerates a bit.
Injectorcleaner didn't help.
Fuel pressure is ok though (31psi-39psi), fuelfilter has been replaced with the fuelpump a half year ago.
So:
-check/replace spark plugs/wires/rotary cap
-swap injectors with other stock injectors (I can use a set from a friend, which are ok)
-I can hook up the OTC monitor when I get it here and see if it tells me something
What's your gap at? .035" is stock. I wouldn't really recommend going less then that. You might consider checking each plug & wire to see if you get a arc. If the engine is shaking then you're down a cylinder for sure. The engine will really feel gutless too. Idling it would sound almost OK though. Check your rotor and cap while you're at it. Although it could possible be a fuel issue as well. Maybe one of the injectors is going bad? But then again, it should throw a Code 27 and light up the CEL.
-
At WOT it's probably running lean which is why you lose some power.
If you were dropping a cylinder, you'd know it. Running on 3 is like running on 1. It barely has enough power to move the Jeep.
Is this an intermittent issue?
-
At WOT it's probably running lean which is why you lose some power.
If you were dropping a cylinder, you'd know it. Running on 3 is like running on 1. It barely has enough power to move the Jeep.
Is this an intermittent issue?
It is always there: the slugisness at WOT, the 1/2 second lag when opening the throttle valve and the hickupping due tot he sensitve throttle.
It has enough power to run the car and the engine seems to runs smooth.
You see how I am puzzled?
-
:hitit: I hit it...at least part of it....I think... ???
The transfer case mount has a stabilizer. I did replace it together with the transfer case mount. I must have made a mistake because the stabilizer bolt was not securely tightened.
I tightened the 2 bolts (top and bottom) and it looks like the car doesnt really hickup that bad anymore. Seems it picks up the throttle bit better to make the car move forward. Also, the stickshift isn't moving sideways as much as before.
Still the stabilizer doesn't seem to be mounted properly:
It looks like I am missing some parts on it.
I can tighten it to the skidplate but I cannot tighten the rubbers on top of it to the transfer case bracket.
Parts I have on the stabilizer from top down:
Nut
Washer
Rubber (with narrow part down)
[transfercase bracket]
Rubber (with narrow part up)
Washer
[Nut of the stabilizer]
Washer
[Skid Plate]
Washer
Nut
Can anyone tell me if there should be something else on the stabilizer? Maybe an extra nut so I can tighten the stabilizer with the rubbers tightly to the bracket or something to push the rubber upwards to the bracket?
The sluginess at WOT still is there; that problem I still have to tackle...
-
Sounds about right. The rubber bushings pass through the transfer case bracket and don't clamp tight against it.
If you want to firm it up then get some poly motor mounts. That will really firm it up. You'll end up with vibrations throughout the Jeep though. You'll feel it mostly when idle, everything will shake. Some things might not like the vibrations though, like the exhaust.
As for your WOT problem, did you ever say at what speed and at what RPM you're at right before? Also, what gearing you have?
-
Nah, don't like the polyurethane mounts; too stiff.
I tightened the rubber TC mounts on the stabilizer by adding some rings under it and the stick shift is not moving so much anymore, also the ride seems better.
Don't know if my stabilizer or skid plate likes it though....
I haven't really noted at what speed/rpm's it occurs.
I have 4.11 gears and 33" tires; I think get about 2500 rpm and would go 115 km/h (72 mph) on satnav in 5th gear.
Most of the times I do not go over 100 km/h (62 mph) but I notice it when I overtake a truck driving in front of me; when pushing the throttle, the car seems to slow dawn, when releasing the throttle a bit,the car seems to speed up.
-
That last bit means it does not get enough fuel, not enough fuel volume under full load.
-
That last bit means it does not get enough fuel, not enough fuel volume under full load.
x2
-
I had a similar problem with my Jeep. Turned out to be the MAP sensor. I had to bend the bracket down so there wasn't as much tension on the wires and replaced my MAP sensor. Never had the problem again. I changed my distributor, cap, wires, fuel pump, cleaned out fuel tank, checked exhaust.... everything. Friggin MAP sensor was all it was.
-
i had a similar problem in my yj, and it took me forever to figure out what it was. it turned out to be my distributor. the upper support bearing in the distributor was shot so there was a wiggle in the shaft and when there was a hard load on the motor it would get sluggish, hesitate, and buck back and forth. so the air gap on the cam sensor in the ditributor was loosing signal, easiest way to check it is to pull the distributor cab and rotor off and grab the shaft and see if it has a side-to-side wiggle, if it moves at all replace it and you should be good
-
That last bit means it does not get enough fuel, not enough fuel volume under full load.
Presure is checked: OK
How much should the pump deliver? And should this be before injectorrail and presure regulator (no presure on pumpcurve) or after the injectorrail and presure regulator? The volume could collapse when the pump has to deliver under pressure.
If the injectors have passed some water/fuel mixture; would that damage them in a way they would deliver less fuel/pulse ??
MAP should be ok...the OTC doesnt throw a code. Anyone know what voltage should be comming out of the MAP under what condition (pressure)?
In the danger of sounding stupid...what does the MAP do? Does it advance the ignition (like the vacuum timing advance of a carburetor)?
Will check on the distributer tomorrow; it's dark and cold outside now...
-
You would want to see what the fuel pressure is when it acts up, to test the pumps volume test pressure at top speed in top gear preferably going up hill which is a bit hard for you in flat waterland, you could ride the brakes a bit to lug the engine some more. Map voltage is roughly 1 volt at idle and around 4-4.5 at wide open throttle. You can drive it at top speed and see what the fuel trim does with the scanner have somebody ride with you to check the readings, if it adds a lot of fuel well then you know what to do
-
Been wheeling it a lot since my last reply.
I did check the fuel pressure, also the 2 second pinching of returnline and it all seems to be working within specs, the MAP sensor also seems to be fine according to my OTCscanner. (Thnx Torch_Ind)
Maybe I finally learned to drive or the problem has miraclely gone.
It is frustrating not to know what the problem was or if it could re-occur but for now I am happy with how the car handles.
Thanks for all your help!
On to the next projects:
-overhauling the clutch and AX5 gearbox
-mounting a tirecarrier
-buying and mounting a winch (not a Witch)