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Misfire/stutter At Idle/low Revs (neo Rb25det).. Have Searched

revolt

By revolt,
in Engines & Forced Induction

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revolt Contributor

revolt

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yeah its wierd that when the engine is running it doesnt go anywhere near the normal values

that would make the car run like ass as the ECU has mapping and fuel enrichment etc based on TPS (and AFM, but TPS is also used)

so whilst your floor it, the ECU doesn't detect you are flooring it and thinks the engine is only under some minor levels of load even though AFM is probably showing normal full voltage

I had to take it out for a 10 min drive just then and something occured to me -- the aftermarket cruise control is not turning on now (was working 2 days ago). Do they connect in with the TPS? I will have a look tomorrow.

revolt Contributor

revolt

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I had to take it out for a 10 min drive just then and something occured to me -- the aftermarket cruise control is not turning on now (was working 2 days ago). Do they connect in with the TPS? I will have a look tomorrow.

What TPS will fit? It has 6 wires coming out of it, going into 2x 3-pin connectors. After some research, I need another auto one.. What about an auto rb30e?

Edited by revolt
revolt Contributor

revolt

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What TPS will fit? It has 6 wires coming out of it, going into 2x 3-pin connectors. After some research, I need another auto one.. What about an auto rb30e?

Sigh, the saga continues. The TPS, when on WOT does momentarily register over 3v. However, the other figures are accurate >> 6k RPM was 1.2v..... 3k RPM was about 0.7v. Idle is 0.4v.

6k rpm at idle only requires slight throttle, so that is why it's only showing 1.2v. I think this is working properly. Also, if the 0.40v at idle is correct, it should idle properly if the TPS was the problem shouldn't it?

I am gonna look up what readings the CTS is supposed to give and test that.. because when I was testing just then, the car was up to temperature, but revved did not drop. Stayed at 1500rpm. argh.

EDIT: CTS is definitely working when hot.. measuring 300 OHMs, exactly what it is supposed to be. ;)

ARGH, Pages 47-52 on the R34 workshop manual here-- http://www.importworkshop.com/nissanskyline.html -- all of my sensors are registering perfectly. Time to grab a boost gauge I guess and see if vacuum is weird. Wouldn't a vacuum leak cause idle problems straight away though? Not just when warm?

Edited by revolt
Calvz86 Enthusiast

Calvz86

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Hey mate, I just went through a very similar problem to urs. Thought of everything and did everything and couldn't find out where the problem is coming from. Chucked in on the dyno, everything was fine, took it to a performance shop and got computer diagnosis and it returned as normal, anyway, found out it was the air filter box, worn. Changed that and only $300 later and my car runs like a dream. Perhaps ur experiencing the same problem. Check the condition of ur box and look for loose wires etc.. So anyway, Mine was doing it at 2600rpm.. Sounds v similar to ur prob though.. Hope it helps

revolt Contributor

revolt

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Do you mean the Air Flow Meter in the airbox?

Cleaned that and checked the voltages. All perfect according to the workshop manual. :blink:

Put some Injector cleaner + 98 octane through it today and took it for a 20 min drive. It now stutters badly from 2-4k ish rpm, then all of a sudden comes good from 4 til it changes.

Hopefully borrowing a Consult cable from Chuckie (and maybe try another AFM/TPS), so hopefully that sorts it out.

Hey mate, I just went through a very similar problem to urs. Thought of everything and did everything and couldn't find out where the problem is coming from. Chucked in on the dyno, everything was fine, took it to a performance shop and got computer diagnosis and it returned as normal, anyway, found out it was the air filter box, worn. Changed that and only $300 later and my car runs like a dream. Perhaps ur experiencing the same problem. Check the condition of ur box and look for loose wires etc.. So anyway, Mine was doing it at 2600rpm.. Sounds v similar to ur prob though.. Hope it helps
revolt Contributor

revolt

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Problem possibly solved. :D

Today I pulled off all of the intake hoses.. couldn't see any cracks or brittle sections. Replaced 2 small vacuum hoses that were starting to get old, but I doubt they were leaking, I untaped the coil pack harness and looked at the wiring.. looked all good.

I then put my OLD COIL PACKS in (which were causing the ECU to give a coil error, but worked fine).... car is idling perfect after 20 mins running. I will drive it around today with the oil packs in, then swap the almost brand new coil packs in and see if the problem comes back.

:) Won't be happy with the $500 coil packs already have problems after ~5000km.

revolt Contributor

revolt

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Yeah.. Super Sparks.. Yellow Jackets weren't available for the NEO when I was looking. :rofl:

Super Sparks right? Havnt heard great things about them.

Yellow Jackets seem to be the go for the non-Japanese coil packs.

  • 4 months later...
V28VX37 Veteran

V28VX37

Posted
Posted
A few weeks ago my S2 Stag developed a very slight misfire at idle. Previous to this, it has always been super smooth (have to look at tacho to see it's running).

Sounds like I may have a similar issue with my R34 GTT, more details here.

I am getting code 34 though (knock sensor) so will need to look into that first. If that doesn't help I'll follow your list to see if anything there would resolve it.

Did you get this sorted completely since the January update?

  • 1 year later...
Stephen Thorpe Proficient

Stephen Thorpe

Posted
Posted

Problem possibly solved. :D

Today I pulled off all of the intake hoses.. couldn't see any cracks or brittle sections. Replaced 2 small vacuum hoses that were starting to get old, but I doubt they were leaking, I untaped the coil pack harness and looked at the wiring.. looked all good.

I then put my OLD COIL PACKS in (which were causing the ECU to give a coil error, but worked fine).... car is idling perfect after 20 mins running. I will drive it around today with the oil packs in, then swap the almost brand new coil packs in and see if the problem comes back.

:) Won't be happy with the $500 coil packs already have problems after ~5000km.

mine lasted a bit longer... bought about 25mths ago, probably installed about 50ks ago. All of a sudden after a boot full on a cold morning at least one of them gave up.

Super Sparks right? Havnt heard great things about them.

Yellow Jackets seem to be the go for the non-Japanese coil packs.

thought they were ok!

Yeah.. Super Sparks.. Yellow Jackets weren't available for the NEO when I was looking. :rofl:

put my stock ones back in, that'll do for the moment

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