Help! Need opinions on what could cause the stutter!

[kat]

So I have a horrible stutter, back fire and lots of black smoke at higher rpms or when you give it anymore than half throttle. I am running a KLZE with KL36 ECU, stock 1.8L throttle body & tps, as well as a 1.8l distributor.
Today we used a paper clip and put it in the TEN to GRD in the DIAG box and then revved it and it worked perfect. Was able to rev it to 7500 rpm without any issues. Once we took it out again it worked like complete crap and died as soon as you gave it gas. Adjusted the idle back up and it worked okay, still had the stutter and stuff. Put the pin back in and it works great again. Any ideas what could be causing this? Timing? TPS?

[mikeinaus]

jumping ten puts the motor in a diagnostic mode and disables all the sensors that are not necessary for the car to run. did you check for any codes when you jumped ten/ground? im not sure but your o2 sensors could be bad as they cause similar problems.

[kat]

O2 is pretty much the only thing I haven't replaced. But everything we've read/seen talks about it being and ignition and spark problem.

No codes were read any time we've done the diagnostics.

[mikeinaus]

if it was a spark problem i wouldnt think it would go away when you put the car in diagnostic mode. theres videos on youtube that can show you how to check your o2's. you basically hold the o2 over a torch and monitor the voltages being produced. they need to climb to a certain voltage and drop back to 0V within a defined amount of time.

youd probably want to take a look at your timing aswell, and changing your disty cap/rotor is never a bad idea either.

the fact it runs fine when its in diagnostic mode says its something sensor related. the ecu is getting bad readings from somewhere throwing off the air/fuel mixture or spark timing.

[kat]

I've changed the cap/rotor button about 15 times in the last 5 years...still there always.

Could it be TPS?

I've looked at videos on youtube of ze's with the same issues and it was always spark plugs/plug wires or timing related. I've had this issue for years, replaced my wires 3 times, plugs more times than i can remember...and it never helped at all. That's why we are now trying other stuff first, and looking for ideas since I'm out of them and beyond frustrated.

Do you have a link to the videos for testing the o2 sensor?

After looking into it further we found that the distributor was advanced all the way...so tomorrow we are going to check the timing, adjust the tps and change my plugs....

[mikeinaus]

http://www.youtube.com/watch?v=vdn4Dk5PSwc" onclick="window.open(this.href);return false;

sounds like youve solved the problem . theres guides on how to set the tps if you search the forum.

[kat]

Thanks we'll try it tomorrow.

Do you know how to hook up an led light to check the codes with a j-spec ecu? Or know where I can find a write up on it?

[mikeinaus]

i think its the same as the us ecu isnt it? jump ten and ground and turn the ignition on(dont start car) and your cel should flash at you. short flashes represent x1 and long flashes represent x10. ex 2 long flashes fallowed by 3 quick flashes equals 2X10 + 3X1 = 23. there will be a fairly long pause between codes something like 3-5 seconds. if your cel stays on and doesnt flash your not jumping it properly, if it goes off and doesnt flash you have no codes.

[kat]

Nope, the KL36 ecu doesn't have an CEL, need to hook up a LED light...just thinking we may be doing it wrong.

[Daninski]

jumping ten puts the motor in a diagnostic mode and disables all the sensors that are not necessary for the car to run. did you check for any codes when you jumped ten/ground? im not sure but your o2 sensors could be bad as they cause similar problems.

Suggest you unplug both of your O2 sensors and if that corrects the problem you can try connecting one at a time and isolate which one is bad. I would advise replacing both and don't buy Hosch, best ones would be Denso as they are factory originals. If you do replace the sensors be sure to clear the ECU memory then drive around for 15+ minutes for the ECU to learn the new setting.

[Ryan]

Rockauto.com can get you proper densos for ~$100 combined. just you have to solder on your old connectors again.

[kat]

Rockauto.com can get you proper densos for ~$100 combined. just you have to solder on your old connectors again.

Plus customs...I can probably get them local for that price. I remember pricing them before and it was 120....I was just always told if it was O2 I'd be throwing a code and I'm not at all. We will probably test the O2's tomorrow and just see tho. Not buying any more parts until I know for sure. Tired of throwing away hundreds of dollars guessing.

[Daninski]

That's why I suggested unplugging them to see if there was any difference. At high RPMs your engine runs in open loop anyway so the O2 sensors shouldn't matter.

[kat]

Thanks! ill give that a try tommorow when its not dark out.

I also noticed that the vris actuator #1 and #2 are both closed at idle. I thought that the passenger side one is suppose to be open (rod pushed in) at idle? Could the vris not working be another issue?

This is starting to be a big headache.

After adjusting the idle and tps with the gnd and ten in, i can actually put the gas pedal to the floor, although it still stumbles and stutters bad after 4200 rpm.

[kat]

So today we unplugged the front O2 sensor and it didn't change anything at all. Couldn't get at the second one yet.