Idle hiccup

[Skym]

Remove catback exhaust, look inside cat with a torch. If want good amount of hp, use a sports cat (less restrictive, can take higher exhaust temps).

[krystalized_jdm]

Looked inside of it before putting my cat-back on. Only seen a black filtery looking thing. The filter part could be plugged, if I replace fuel filter and still have issues I'll look into it.

[Skym]

If cat is fully clogged, exhaust temps should rise and cat light on dash light's up (over 800 degrees C).

From what I can remember, the holes in filtering material are smaller and there's more of them inside stock cats (small holes are easier to clog) and in performance cats the holes are bigger, less of them.

[krystalized_jdm]

No dashlights are on.

I think my TPS has something to do with this, idle voltage should be .48 and mine is .66. Seen this in the "fix your hesitation" forum.

I'll check this out today as well.

[ToroGTS]

If you are having a 'rev limiting' type symptom where you give it full boost and it wont go over 3 or 4 k rpm, its MAF signal related.

If the car runs normally at light throttle but at full throttle revs out audibly smooth all the way to red line while making almost no power, this is a lack of fuel, knock sensor retarding timing all the way back to fight crazy lean mixture.

If your car runs fairly normal out of boost, but once higher boost is reached engine rapidly misfires through rpm range and makes less power than expected, likely ignition problem, failed ignitor or high resistance in oem coils.

High or bouncing rpm at idle, possible issues with improper advance under boost would look like a TPS issue. .66 volts is way out of whack... take that bad boy to 0.46 or so, I've found even 0.48 to be slightly to high on older TPS (voltage measured at the ecu harness).

[krystalized_jdm]

^ this is helpful, thank you toro.

[Skym]

TPS should be around 0.44v when on idle contact. If have access to Nissan's Consult (hand held diagnostic computer) or Nistune tuning software a idle contact light light's up in software when TPS touches idle contact, so is really easy to set properly.

Via multimeter it's a guess unless you know where idle contact roughly is. But be aware that idle contact (and WOT / Wide Open Throttle or basically foot to floor contact) can bend over time, so might not be where it was when new (might be slighty lower than 0.44v).

If pull TPS apart, there's a circuit board with a curved track on it (0-5V) and on one end of curved track there's a thin piece of metal (idle contact) and on the opposite end of curved track is another thin piece of metal (WOT contact). The track on circuit board can wearout and the idle, WOT contact's bend.

On later model TPS (I think late R33, R34 RB25DET engines) they removed the idle, WOT contact's and used preset voltage value on ECU to activate idle, WOT contact's (alot harder to set without Consult). From what I can remember, this TPS looks different with shape when compared to R32 TPS, so should be easy to spot.

If TPS is not touching idle contact, engine can stall (even at idle), rev higher than normal. Also ECU doesn't switch to idle stabilisation (adjust's ignition timing to keep engine idling) tables or kickdown tables (that kicks rpm up and prevents engine from stalling when suddenly back off throttle), etc.

This is the correct TPS voltages from Consult printout (new TPS and WOT / depressed voltage is 0.02V too high, should be 4.00V, released is idle contact voltage) -

DEPRESSED : 4.02V
RELEASED : 0.44V
RANGE : 3.58V
SPEC : MORE3.0V

I think you need Conzult (with idle contact feature), Nissan's Consult or someone local with Nistune tuning software to help you set TPS properly.

[krystalized_jdm]

So I should go about this monitoring voltage via consult reader rather then multimeter?

I have access to a program that shows me tps voltage, i have a screenshot in one of my earlier posts.

Above post is also very helpful, thanks sky.

[Skym]

Consult is better for setting idle rpm (can see it accurately on screen), setting TPS idle contact. But need to make sure software has the idle contact button / light feature (there's some free Consult software that has the idle contact feature, need to search web, try them). I think software named OBD SCANTECH (PC edition) has all the buttons, features, even for accessing auto transmission, ABS, etc error codes on later model Nissan's.

It usually has a button looking thing in software labeled "Idle Contact" and light's up red (or whatever colour they have programmed it to use) when on idle contact.

[krystalized_jdm]

I believe I have obdscantech.

The seller I got the consult reader from gave me a crapton of freeware links so I have basically every freeware program for consult.

I'll look into this

[ToroGTS]

I'd give it a shot at 0.44v first and see if it changes or eliviates the issue. Its a simple simple procedure, hardest part is just inserting the safety pin or what ever and getting a reading on multi meter.

[krystalized_jdm]

Changed tps to .46 volts while reading in the program consult2. Replaced fuel filter, my high end hesitation is gone. I almost creamed at how awesome she pulled compared to before. Idle hiccup is there but I'm not to worries for the time being


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