Hi guys, I am new to forums, this is my first ever post, I am writing this to discuss my car's problem and hopefully get it resolved.
A little back story,
I have a Pakistani model (PKDM) manual 1996 Civic with D15Z4 engine (resembles D16Y7) (no catalytic Conv & O2 sensors - it has IMA). The problem started a year ago, when I felt a slight random/ erratic/ irregular misfire in the engine when I used to put my hand on the tappet cover and let it idle I used to feel it through my hand. Along with this, the car used to jerk badly when I put it in 1st, 2nd or 3rd gear and let it drive itself by removing my foot from accelerator & clutch.
To solve this issue,

1- I read all the relevant threads on this forum.
2- Got the head work done (leaky valves). I was in the office so I had to trust my mechanic for it, he said it had few valves leaking (I couldn't check it myself). I started the car and it started smoothly and ran fine the *bap bap* sound from the exhaust wasn't there I got happy but next morning the misfiring and jerking came back, back to square 1.
3- I changed the Plug wires, Distributor, Injectors, FPR, Fuel Filter, MAP Sensor, got the Ignition timing checked & Mechanical timing as well. I calibrated the TPS (0.5 - 4.8). Then I cleaned the IACV checked the resistance on both sides and it seemed okay, (however it makes a weird humming/ buzzing sound which I noticed when I put the car in "engine off switch on mode" when calibrating the TPS, it goes away when I tap it with a screwdriver).
After doing all this I didn't see any difference, the car still misfired irregularly and jerking/ bucking was still there.
Then as preventive maintenance I changed the spark plugs and 80% of the jerks went away! I was able to drive it without my foot on clutch & gas paddle (in traffic/ cruising).
For the 20% jerks I cleaned the throttle body after taking it off and still the 20% jerks that remained were still there. This is where I need your help guys,

1- Car still misfires a little little littlee bit and it's irregular.
2- Cold start is perfect, when warm started there is a 1 second delay where car stumbles for JUST a second before getting up to the idle RPMs. Whereas when cold started the car starts right up and from 0 - 1500 RPM without any delay.
3- THIS IS THE BIGGEST PROBLEM MAKING THE CAR SO ANNOYING TO DRIVE: Now, when I am driving the car in traffic and I put it in 1st gear and let go oft he clutch without or barely pressing the gas paddle (under 1.5 - 2K RPM) the car would drive smoothly. As I increase the speed being in the same gear (say around 2K or 3K RPM) and then let go of the gas paddle to slow down, the car slows down a bit aggressively (feels like it's chocking) and then when it reaches 1K RPM it jerks "forward" (feels like it got free of that chocking). Then this jerk converts into a chain of 5 6 7 back & forth jerks before the car stabilizes itself or I press the clutch to avoid it altogether. This happens in 2nd & slightly in 3rd gear as well. As I let go of the gas paddle the car slows down a bit fast and then eases off at 1K RPM causing a jerk. If I press the gas paddle when the car is slowing down fast, it jerks. If I keep shifting near 1K RPM then I feel no jerks while letting go of gas paddle or pressing clutch.
Now a little help that I can give is, I noticed when I let go of accelerator and I pressed the clutch to change gears the RPM comes down from 2-3K to 1K and then rises automatically 100 or 300 (1.1 or 1.3K) and then settles to idle RPM which is 600 700 RPM. It happens every time I press the gas paddle and take my foot off it. This automatic RPM raise at 1K RPM to 1100 1300 RPM and then coming down to idle RPM is causing the jerks!! That's what I believe.
Now please help me solve this problem.

 

Anybody?

 

I am impressed by how helpful you guys are on this forum..
Anyways I was able to solve the problem on my own if anybody needs help you can contact me. The car runs smoothly, decelerates smoothly without jerks or anything.

 

I am also from Pakistan having civic 2000.
Lately I have felt that this forum has become stale. Don't know why no one replies here.
Anyway I am also having similar issue. At idle, there is a bup bup sound from exhaust and at gear 2 3 4 if I leave the accelerator there is a jerk.

I already replaced fuel filter, distributor cap, spark plugs.
Tps is already calibrated to 0.47V as recommended by members here.

 

​​​​​​AoA Hassan.
Are you talking about a single jerk that you feel when you let go of accelerator? Do you also feel it when you press it the accelerator after letting it go?
Are the injectors stock ones? Did you get the fuel pump pressure checked? Which engine is it?
1) Check if the butterfly/ throttle plate is sticking or not? I mean it should close and open smoothly without touching the throttle wall. You would be able to feel it at your feet the accelerator padel should feel smooth.
Sometimes it is minutely free when the car is not running but with car turned on, the suction causes it to stick. If it is sticking you will have to adjust it by backing it off/ tighten the throttle stop screw. (NOT THE IDLE SCREW)
2) Check your accelerator cable for cracks or its old or not operating smoothly. Also check if it's loose and has slack this can also cause a jerk when you press the accelerator. Adjust the slack.
1) If it is just a single jerk at letting go of the accelerator then it can possibly be the calibration of the TPS. 0.47V translates to around -0.69 degrees (roughly). You can try to calibrate it to 0.49 and then check with 0.5 at closed throttle. If it fixes it. Maybe the ecu gets a reading of -0.7 degrees, causing it to cut the fuel aggressively. It shouldn't really be a problem as you can be -1 to +1 % at close throttle. But there's no harm is checking it by changing the calibration. Do reset the ecu and do the idle relearn properly (it's different for EXi & VTi).
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hello sir, am having exact problem as you tps is at 0.45v but idle start jerking when i touch the accel also it idle high.