My problem is getting worse every month and is starting to really affect my driving. I almost ran into someones bumper.

Whenever I'm driving, say in 4th gear, and I let off the gas to decelerate, the car buckles forward and feels like it's loose. So once I'm decelerating and slow down to around 25-20 mph and stopping, the car then feels like it's holding on then suddenly it will buckle forward and backward like it's not holding on to the power no more. It just waves back and fourth, almost in a bouncing motion. So when I come do a stop and then start to move, I can gently press the gas or gun it and the car will bang forward. It's no smooth transaction from slow to fast or from stop to go. I can be doing 30, 45, 55, etc. and it does the same thing, It lurches forward when I hit the gas and buckles back when I let off the gas. Even If I let off the gas slightly or just drop it, the car will buckle back harshly.

So the other day when I'm following close to a car and they keep slowing down and gassing it, I'm trying to hit the gas as slightly as possible, but the car will lunge forward and I have to hit the brakes fast cause the I would almost hit the guys bumper. It almost has a little hop to it when it does it.

I've tryed revving it up in my driveway, in neutral with my ebrake on the car does not buckle at all or the engine doesn't buckle at all either. It's smooth when I let off the gas and smooth when I hit the gas like it should be. But when I jacked it up in the drive way, letting both front wells dangle, I started it, put it in 1st and let it run. Then I hit the gas or let off of it and the car does the same thing of the clunking as I described. So considering the problems, it has to be something when the car is moving cause it didn't do this while sitting on all fours in my driveway.

We've just replaced the front and back mounts with energy suspension inserts cause you would you think the mounts would be doing it, but that didn't fix it. We've replaced the dist. cap, rotor, pcv valve, adjusted the clutch, adjusted the throttle cable and even adjusted the dashpot and still not luck.

What other possiblitys could it be? Someone over on AF said something the 02 sensor but could it be it?

 

Man, just take it to the dealership.

 

I'd like to solve the problem before dealing with the dealership. It might be something simple that I'm missing and don't want to fork out $100's for something I overlooked. What else could it be?

 

It sounds like partial throttle bucking or something of the sort? Check your TPS votlage and switch out your ECUs with another working one and see if that helps any... Try resetting your current ECU and check both your cam timming and ignition timming. My car used to jerk when decelerating (still does) ign. timming is off and I dont think that the TPS is set right... This is a tuff problem, but its always something small, and if it isnt, its prolly really apparent... Good luck!

Blaze

 

Thanks Blaze45. I'll check the tps and see if it's good or not. And I do know that the original owner said that he had advanced the timing more than what it should be cause of the pinging the engine was producing. I tryed timing it right, but the pinging is to great, so I put it back to where he had made the red marks on the dizzy.

 

Checked the tps and it's at 5v so it's good.

Did check the timing and it was off, so we advanced the dizzy toward the firewall and almost got the red mark lined up but couldn't cause the dizzy wouldn't advance anymore. Is this a problem? And could the possibility of either the cam timing being off of the timing belt skipping a tooth do this?

And one more question. How much does the o2 sensor screw up the car when it's going really bad? My CEL is on and code 1 is blinking so it's the 02 sensor but could that lead to all this jerkiness?

 

It sounds like your timing belt did infact skip a tooth as I am having the same problem with advancing the distributor and still not getting it just on. If you hit it with a timing light and you only missed one tooth, your timing should be at ~ 10 degrees with the distributor all the way to the firewall. For each tooth skipped your timing will be off ~ 8 degrees or so.

 

OK I had the same Problem. Have you done any suspension work latley? If so you have 2 stabalizer bars in the front. These stop your control arm from going back and forth. Make sure the 2 nuts are completley tightened. You will find these on your crossmember right behind the core support. You can also check it easy. Turn your wheels slighlty left or right and with your foot or hands push or pull the front wheel. YOu will see it jerk back and forth if they arent tight you will notice something isnt right.
When I would get on and off the gas the car would lurch forward and back off real bad.


Modified by Crakadic at 7:14 PM 12/4/2004

 

Jacked it up and tried both wheels pointing opposite directions for both and they are pretty darn solid. No movement what so ever.

 

I wouldnt have jacked it up to do that test. I would still double check all of your suspension and make sure everything is tight. Especially the front stabalizers

 

But I do want to mention something though.

Today, I drove around our mall to get from one side to the other and the speed is 5mph. So I'm going 5 mph, holding my foot on the pedal steady, no foot movements what so ever and when going steady, the car will wobble back and forth. It's like the car can't hold on to the power steady and just wobbles back and forth. And this all happens when my foot is steady on the accelerator. But when I rev it higher going about 10 mph, it stops and is steady going with no wobbling. It's almost like a dead spot where I can play around making the car go back (by just tapping the gas) or lurch forward(by letting off the gas) but holding it, it just wobbles back and forth on it's self. Also noticed it does it when I'm under 2k rpms too if that helps. This seems like the core of the problem to me. Any help, cause the guys over at Automotiveforums are clueless?

 

Well, since my car is an std model, It doesn't have stabilizer bars in the front at all. The dx's did as far I know.

 

Did you ever check my advice on the timing?<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by dr_latino999 &raquo;</TD></TR><TR><TD CLASS="quote">It sounds like your timing belt did infact skip a tooth as I am having the same problem with advancing the distributor and still not getting it just on. If you hit it with a timing light and you only missed one tooth, your timing should be at ~ 10 degrees with the distributor all the way to the firewall. For each tooth skipped your timing will be off ~ 8 degrees or so.</TD></TR></TABLE>

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by dr_latino999 &raquo;</TD></TR><TR><TD CLASS="quote">Did you ever check my advice on the timing?</TD></TR></TABLE>

I was about to post about that. If I did infact skip a tooth on the timing, how can see it and fix it. If I take off the timing cover, what should I look for exactly? Or should I just get a new timing belt put on it since it's going on to be 15 years old? I'll do anything to fix this problem.

 

You said you found 5v at the tps, but did you check the range to make sure there's no dead spots or spikes or something? Slowing move the throttle and check that the voltage slowly increases with no wierdness.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by drdisco69 &raquo;</TD></TR><TR><TD CLASS="quote">You said you found 5v at the tps, but did you check the range to make sure there's no dead spots or spikes or something? Slowing move the throttle and check that the voltage slowly increases with no wierdness.</TD></TR></TABLE>

Is that with the engine running or with just the ignition on? I also read that it should be 4.5v at full throttle, right?

 

You just need the ignition on, power going to the ecu. You're right, it's 4.5v, not 5v. The idea though is to make sure it's a smooth transition.

 

have you checked your plugs and wires? do you know someone with a dist. you could test out?. do you smell gas when it's doing this? sounds like a timing or firing issue.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by drdisco69 &raquo;</TD></TR><TR><TD CLASS="quote">You just need the ignition on, power going to the ecu. You're right, it's 4.5v, not 5v. The idea though is to make sure it's a smooth transition.</TD></TR></TABLE>

I check it out here in a little bit. Last time though I was dumb and checked from the plug, not the terminals on the TPS so this time I'll tell for sure.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by mr. carpenter &raquo;</TD></TR><TR><TD CLASS="quote">have you checked your plugs and wires? do you know someone with a dist. you could test out?. do you smell gas when it's doing this? sounds like a timing or firing issue.</TD></TR></TABLE>

There is a huge amount of sulfur smell but that could be cause of my catlytic convertor being bad and my o2 sensor, which is starting to go bad. But if the tps reads out fine, the timing belt and cam timing will surely be next on my list.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by drdisco69 &raquo;</TD></TR><TR><TD CLASS="quote">You just need the ignition on, power going to the ecu. You're right, it's 4.5v, not 5v. The idea though is to make sure it's a smooth transition.</TD></TR></TABLE>

And one more question. Do you check the voltage on the two terminals on the sensor itself or on two of the three wires on the plug connected to the harness? I just wasn't quite sure.

 

Bump, need some info

 

Alright, got a good voltmeter today and tired it out and the readings are a little bad. Closed throttle is at .63v while full throttle is at 4.34v.

So what are we looking at here, replacing or adjusting? Since I'm tite on money, I really don't want to got searching for a tps now, but is it alright to adjust it? I'm not going to mess anything up right? And all you have to do is imprint the flat head of the screw, unscrew slighty, move it till readings are right, tighten it and see if that fixes it, or should I just leave it alone and find another?

Now where getting somewhere

 

Bumpty, bump, bump, bump. Come on guys, need help big time on this.

 

Well, I went out today, measured it again and got the readings .56v and 4.33v. And as I moved the throttle plate myself, I noticed that when I let it lay down at idle by itself, the readings were .61v. So I pushed the plate up, relieving it more and the reading of voltage went down to .47v. So I bent the tab on the throttle plate and got it to where the readings are .51v. So I take it for a test spin and it doesn't solve it. But the WOT is still at 4.33v though.

What else would cause the bogging like sensation that it does?
- map sensor
- 02 sensor
- EACV sensor
- Clogged cat

Or is it me and it's the crappiness of the DPFI throttle body since it's just a supped up carburator? Is this normal?

 

EACV could cause bogging, unplug the EACV and drive it like that for a bit (at N.O.T.)

You'll burn a little fuel because it'll run rich but if your problem clears up maybe it's the EACV.

NOTE: Unplugging the EACV on a properly working DPFI Mani shouldn't have a severe affect in performance. It will bogg slightly, but generally you'll just run rich.