Hesitation When on Boost?

[S15_SAM]

It really sounds like that 02 sensor or MAF. I know the feeling your describing, and your ecu is holding back the fueling and timing because it is seeing one of the sensors is not right.

The other issue may be the VVT solenoid.

 

[pegliobaglio]

You can eliminate the o2 sensor easy enough though just unplug it,its fine to drive withough I did for a couple of months

 

[dave_t]

Right, here's where im up to-


i couldnt find any boost leaks. i then spoke to craig and he suggested doing the 'paper clip trick'. (self diagnosis)


I carried this out, and it through up a code 34 - knock sensor. now that i had replaced the spark plugs and got rid of the misfire, i reset the ecu, to eradicate the fault from the memory.


I reconnected the battery, and it showed 55 - no fault. i started the car, turned it off, checked again and it showed 34 - knock sensor


so it was a recurring fault.


i decided the next step would be to replace the possibly duff o2 sensor


Today i did just that, with a brand new bosch unit. reset the ecu, showed a 55 - no fault. started the car and test drove.


it still had a definite lack of power, like i was towing another car behind me. at 5,000rpm there is a jump in power, and it picks up.


Checked again, and it showed a 34 - knock sensor. same fault


so is something triggering the sensor, or is the knock sensor itself faulty


mooching about on the internet, it seems like the knock sensor is a pretty common fault on the SR's.


It's located underneath the inlet manifold and will be an absolute B***H to change, + My local motorfactor quoted me £155 for it! so i dont want to change it if it's actually working


not sure which direction to go in now

 

[dave_t]

​well i managed to get a new knock sensor for a decent price, so today i went at changing it.

in order to get to it, i remove the oil filter (excuse to do an oil change too) and also the alternator

after a lot of swearing i got it off, and pulled the loom up to the top of the engine to swap to the new sensor

refitted - tested - still throwing a code 34...........what to do!

 

[craig8585]

I'd leave it where it's supposed to be mate as it'll be a very sensitive item and designed to be where Nissan fitted it.

Very interested to see if this cures your problems. Thank you for the photos and looking forward to the next update

 

[LuPix_S15]

Hopefully this will sort it mate... at least the more you work on the SR the more you understand and can diagnose faults in future! :thumbs:

 

[dave_t]

Well i never updated this thread with the eventual 'cure'. so here it is, for anyone searching for info on the same fault.

So i replaced the Knock Sensor itself, and it was still throwing a code 34 - knock sensor, so after looking at the possible causes, and eliminating a few, including changing the knock sensor itself, i changed the coilpacks.

OEM items were coming up pretty pricey, and wherever possible i like to upgrade instead of simply replace, so i went for those blue tops :thumbs:

Splitfire DIS-007's

After a week wait, and a hefty £50 import fee, they were here. I hastily got to fitting them and to my disappointment it didn't cure the fault :down:

Having a rare free day i could spend on her, i decided to crack on. I traced the knock sensor loom back, which turned out to be only 8-9 inches long! removed it for inspection.

This is what i found!

Looks like the loom was the problem all along


I managed to find a replacement knock sensor loom.

I stripped it apart to inspect it, as that's how i found the split in the old one. all good, so was time to fit.

Being as you have to remove the knock sensor to swap over the loom, it was such a frustrating job, as its positioned right under the inlet manifold, only accessible from underneath.
Alternator off, oil filter off - and its still only at 'finger tip' reach. a lot of swearing later and it was fitted.

Replaced the oil filter, re-fitted the alternator, re-connected the battery, turned the engine over - did the paperclip trick - code 55 - no fault.

I took it for a test drive and to my delight, IT WAS FIXED!

Finally she drove how it should, and it fets amazing. Power all the way through the rev range, for the first time since it rolled onto English soil.