Hi, ive noticed that even at low speeds like 50k in traffic that just touching the throttle and then taking ur foot off will cause the ecu to momentarily cut the fuel - most annoying!! I know its the zero throttle switch that activates it but at such low speeds and rpm causes the car to 'bunny hop' Any workarounds, even disable the pest altogether? Its designed to save fuel when decellerating from high speed but imo the theory is flawed anyway. btw, its an auto stock turbo

Just took the NA for a drive, it seemed to have the same behaviour from cold, but when the engine/trans temp got up i couldn't feel the cutoff at all, at any speed, even with the trans in power mode??

check your vehicle speed sensor is conected mate.

id be checking if ur TPS is adjusted right first... Im sure over time the adjustments on vital items like the TPS change due to age and general wear. Especially on a VL ud be checking all the wiring loom plugs are in and not corroded.

Like the others said, check the TPS. You shouldn't be able to feel the switch on point. Dunno how the factory ecu achieves this, but i know my haltech will switch the injectors back on when revs drop below 1800rpm (if the throttle is still at 0%). I think it also retards the ignition by 5deg or so for a brief moment to smooth out the transition.

Apart from the TPS... I'm not sure about the VL's but the import nissan engines RB20/25/26 etc have an ignition retard below a water temp of 50degree's. Retarding the ignition brings the engine temp up quicker. This can sometimes cause a flat spot type feel on the tip of the accelerator when say limping around a car park. If you find yours isn't coming up to temp to quickly throw a genuine nissan thermostat in there as they are much more precise than aftermarkets. The difference being my rb30det & even the rb20det gets to 50degree's water temp within 1km of driving, its up to operating temp ~80-83degree's by 2km's. With the aftermarket thermostat it takes around 10km's to get up to operating temp. I don't idle to warm my cars up, i drive them lightly from the word go. I was told to do this by my engine builder. Driving the car stops piston slap within 2km's. Idle the car and it will be slapping away for 15minutes idling or 10minutes and a km' of driving. I suspect the aftermarkets open a little early and also open too much, my sisters VL had issues up Willunga hill using an aftermarket thermostat as the water was flowing through the radiator too quickly and not having enough time to cool, the genuine thermostat brought temps up quicker, made the car run ever so slightly warmer 3rd notch but it never went over that. In other words it made the water temp consistent, not fluctuating like the aftermarket. Well.. I rambled on a little there. lol Some original photos have not been recovered yet.

my car has the 'bunny hop' on and off throttle too. its horribly annoying and makes gearchanges very hard to get smooth. i suspect the TPS but haven't had a chance to adjust it yet. mine is a 5spd tho, im suprised you notice it with the auto.

Hey thanks for the responses here. ok, heres what I have found. After studying the GM manual on ecu diagnostics procedure, I ran the ecu in diagnostic mode and the speed sensor checked out ok [no error 14 after driving the car at more than 10kmph], but what did show up was error 34 - detonation sensor! A check of the harness revealed the wire from the sensor was pinched between the oil filter and engine block, shorting it to ground. This was easily rectified and no more error 34 after clearing the diagnostic memory and running the tests again. Final code was 44 [31 without air cond.] which is the 'all ok' code. Took the car for a drive and the bunny hop is now barely noticable, if at all. Will need to drive it some more to check it's exact behaviour, as it is now hard to tell whats happening at what speed and rpm, but hey, im a much happier camper now after having found that problem. Ignition timing would have been on the retard, maybe making bunny hop very noticable. With regard to thermostat, yep i have gen nissan part installed and engine comes up to temp very quickly. I suspect that the aftermarket ones dont seal off very well [this is very critical!] and too much water is flowing even when cold, increasing the time to normal temp. Then at the other end, when the 'pressure is on', they don't open enough causing premature excess temp rise. Not sure about the 'water flow being too fast' theory, yes its not in the radiator for as long, but then its not in the block for as long either. There's only a minium flow rate which is tied to the thermal cooefficient [thermal load]of the fluid being used

Nice find. With regards to my bodgy water flowing too fast theory, I thought that may be the case as I dropped the genuine thermostat and 2 different brand aftermarket ones in boiling water. I noticed the aftermarkets opened completely very quickly where as the genuine item opened slower and didn't open as much as the aftermarket. The Genuine was also quicker to close where as the aftermarkets would hang open for a little longer. So thrashing it up the hill, that is what I came up with.. Possibly the water is flowing to fast OR having the thermostat so wide open at 3000rpm or what ever it was was causing cavitation? :P No idea really, All i know is the genuine item opens slower, closes quicker and doesn't open as wide works better. I noticed the aftermarket items ran cooler on cruise but hotter once there was some load. Genuine item was simply more consistent with its ability to regulate the engine temperature. Also.. For those that like to play, Nismo thermostats are available that are rated at 68c instead of the 76.5c. Some original photos have not been recovered yet.

hi cubes, thats an interesting observation that doesnt add up for me. will think about that and get back to you.

Quote: my car has the 'bunny hop' on and off throttle too. its horribly annoying and makes gearchanges very hard to get smooth. Glad to hear I'm not the only one with 'bunnies in the boot' I'm doing some intensive r 'n' d on this ecu to see if I can find a way to evict the bunny. I've tried one rough hack just to prove a point or two, and it did stop the bunny making the car much better to drive, but it was a crude attack, need to refine it... oh yes, the fixing of the det sensor fault did improve it, but its still there. Some original photos have not been recovered yet.

Well after doing the rounds today I can say that the car's manners are much improved. There are two notables. The bunny, while still present, is much less severe, and the transmission up changes are much smoother also. I had noted in an earlier thread that my transmission up shift seemed a bit 'thumpy' I'm sure this would be because the timing is now running right and I dont need as much throttle to get the same power from the engine, therefore the transmission changes at a lower hydraulic pressure [higher vacuum for a given road speed] Natho, is worth noting that there is a difference in behaviour between the ecu in manuals and autos. With autos, the fuel is cut to all cylinders 0.6 sec after the zero throttle switch is closed. With NA manuals, cylinders 1,3,5 are cut after 0.3 secs then 2,4,6 after a further 0.3 secs. For turbo manuals, the timings are 0.2 secs and 0.1 secs [taken from the GM manual] Another difference is the minimum rpm that the engine must be at b4 fuel cutoff is activated. With manuals, its around 2200 rpm at normal engine temp, for autos its around 1200 rpm, which adds to the annoyance factor in autos. For a cold engine, add about 700 rpm to those numbers. Its also worth noting the differences in the throttle assembly between manual and auto. For autos, you have all three - throttle position sensor [tps], zero throttle switch and full throttle switch. For manuals there's only the zero throttle switch. Please note that all of the above only applies to the stock factory setup.