Weird low-range hesitation

[group3j]

Howdy,

Came across a bit of a weird miss with my Nav on the weekend and was wondering in whether anyone had experienced the same problem.

Seems that whenever I grab low range and hold part throttle (say to climb a hill), the engine gets a hesitation.....almost like it's missing. It manifests as little surges, as if you're gently bouncing on the throttle (no, I wasn't bouncing on the throttle). Symptoms are:

- Low range problem only. Switch to high range and it disappears immediately.
- It occurs on flat or climbs. Not an issue under deceleration/decent
- It only occurs under load. Trying a dry run in neutral doesn't replicate the problem
- It only occurs on part throttle. Deceleration or modest acceleration alleviates it until you go back to part throttle again
- Seems to occur throughout the rev range. That said, I didn't labour the engine or rev it hard, so maybe it goes away at the extremities of the range; I'm not sure.
- It's pretty constant. You can go from low range to high range and back again and it immediately reappears.
- No apparent "misfire" type symptoms in terms of audible queues.

Has anyone else come across a similar issue?

I thought it could be the suction control valve, the aftermarket chip and any number of other things, but the issue is that it only occurs in low range. I would expect common things like the chip to be a problem regardless of what ratio you selected in the transfer case.....

Help?

Many ta's.

 

[jjohn]

King cab?

 

[Old.Tony]

If it's a KC it's probably happening in 4th gear. Others have experienced that, and there's a rumour that it's a software glitch that Nissan not only know about, but have a fix for - but apparently not all dealers are aware of it. We were trying to get the TSB number for the fix but I don't think that made its way here.

(as an aside, if anyone DOES know the TSB for the fix, you can PM it to me and I'll release it, keeping the source quiet).

If it's not a KC then it's unusual.

 

[ourd40]

Dual cabs do it too, My Thai built does it.. 2011 ST

 

[Dave-D40]

Dual cabs do it too, My Thai built does it.. 2011 ST

If it's a KC or early 2010/11 ST it may be a Thai thing.

 

[group3j]

G'day gents,

Thanks for the replies.

No, it's an '08 Dual Cab (Spanish, manual, ST-X for whatever that's worth). And it's gear independent (happened in both 2L and 3L).

Interestingly, it's only just appeared...well in the second to last trip. On that trip, I wrote it off as it only occurred very occasionally and I thought it must have been the terrain and an over-active imagination. This trip it was constant and very obvious. :/

Software glitch, eh? Hmmm.....nothing appears on the Scan Gauge, so it's obviously not throwing an error....
Presumably folks have already tried the battery disconnect/battery reconnect trick?

I think my truck must have something going awry. The chip (Chip It) previously addressed the annoying factory flat spot, but it's now come back. It's also started blowing more smoke than previously. That doesn't make much sense and, while I don't see how it could relate to the low-range problem, I think I'll pull the chip this weekend to baseline the config of the truck and do some more testing.
I'll report back if I find anything of interest.

 

[happy john]

Check the connectors from the chip to the rail sensor and clean with the same contact cleaner you use for your maf sensor.

 

[lookskyward1]

It may be the Neutral position switch on the main gearbox?

 

[Old.Tony]

So there's a chip involved ...

There is every chance that it's a vacuum hose on your turbocharger actuator. If you can turn the hose on its connector, toss it.

 

[camo.b]

Check the connectors from the chip to the rail sensor and clean with the same contact cleaner you use for your maf sensor.

I have to do this every few months for my cheap chip.chip is fine just the connector is crap..no grommets around the wires and now its slightly corroded.i get codes thrown, black smoke,irregular idle,injector rattle and heaps more power..all this i can put down to a dirty piggy back connector..once cleaned its perfect again

 

[Old.Tony]

I have to do this every few months for my cheap chip.chip is fine just the connector is crap..no grommets around the wires and now its slightly corroded.i get codes thrown, black smoke,irregular idle,injector rattle and heaps more power..all this i can put down to a dirty piggy back connector..once cleaned its perfect again

If that's the case, can I suggest giving it a good clean, spraying it with that blue shit that auto electricians spray on batteries, then wrap it in rescue tape? Jaycar sell it for $20 a roll but you can probably get it cheaper elsewhere.

 

[camo.b]

Its on my list Tony.the way i look at it is that it gets me to lift the bonnet and make sure the engine is still there.if that connector didnt fail every few months id never lift the bonnet

 

[group3j]

Many, many thanks for your advice/suggestions gents; all are greatly appreciated and will be pursued.

I'll rip the chip off this weekend to take it (and it's wiring) out of the equation. I'll take if for a baseline run to see if the problem still exist and then climb underneath and good dig around the gearbox and transfer case. That does seem like a likely place to start, given the symptoms.
Thanks also for the heads up on the turbo pipes Tony; I hadn't thought of those. I'll definitely give them a good check.

Many thanks again and I'll report back what I find next week.