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Discussion Starter · #1 ·
I'm after some help and advice to solve a knock problem I (think I have) on my R32 GTR.

Purchased it about 3 weeks ago as a fresh import. The engine is standard. It was fine at first (made 4.5 on the boost gauge) but after a week it developed hesitation through the mid range, and the boost dropped a little.

After a week of trying to trouble shoot my ignition and fuelling I finally got around to reading the fault codes using the procedure posted by MS33 (thread title "Reading ecu fault codes"). Thanks to this info I've now diagnosed a knock issue that presents in the following way:

I've read the fault code (34) and cleared it a about 15 times now using the above mentioned procedure. No other codes present.

Once it's warm (after 15 mins of slow driving) if I clear the codes they don't come back (regardless how I drive it), and the car drives like a dream. But when I restart it the next day and drive it, the fault code is back with associated running problems!

The pattern I'm seeing is therefore:
1, Car always detects knock & goes into safe mode while driving off boost & <3k RPM during first 15 mins warm up phase.
2, car doesn't detect knock once fully warm, even while accelerating from 3 to 7k RPM at full boost.

I've been running Tesco 99 and Shell V power. It's done it on both fuels. I know the standard cars are mapped to run on 100 RON but I supposed a std car would be OK on premium UK fuel as nobody I spoke to so far mentioned any different (I did buy from a reputable importer).

I'm aware it could be faulty sensor or wiring but with the pattern I'm seeing it just doesn't feel like it. and I'm loath to start stripping the inlet off to get to the sensors until I've solved this particular conundrum.

So my questions to the knowledgeable:

Are standard cars normally OK on UK premium fuel, or should the base timing have been retarded to compensate?

How long would it take for the car to go into closed loop mode? Could this coincide with the cars ability to drive without detecting knock?

Does anybody local to me (Warwickshire / west mid's) have any det. cans they would be willing to assist with?

Any Help advice or assistance will be gratefully received!

Cheers,

Andy "Raw" Skelton
 

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Discussion Starter · #2 ·
made some good progress this evening.

Here's what (I think) I've learned:

Knock sensor #1 reading (approx) 13 ohms at ECU plug
Knock sensor #2 reading (approx) 550 ohms at ECU plug
Knock sensor #1 is the one at front of engine
Knock sensor #1 on it's own reads (approx) 550 ohms
Knock sensor #1 wire when left open at sensor plug doesn't short to ground (no continuity at all)

So still a puzzle, as I'd expected to find Knock #1 wire shorting to ground until the very last test. Back on it in the morning.
 

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Discussion Starter · #3 ·
Think I've solved it: Found a break in the loom where Knock sensor #1 lead breaks out of the spur. The wire is shielded so it was shorting to ground through the shield.

Still doesn't fully explain the behaviour but (touch wood) it's OK after 2 test drives.

Best thing now is that I can stop talking to myself on here!
 

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Do check or try a different boost solenoid, the factory one from memory caused a similar issue on a friends car, it would just suddenly go into limp cutting boost from 0.7 to 0.5.
He did eventually fit an ebc and that came with its own solenoid so problem solved.

I remember he had someone check the car for dett as you say and they could hear nothing clean as a whistle but the factory solenoid caused the issue. I may have one lying around will have to check if you want to try it although I am in Bucks so quite a trek!

Hopefully you have sorted it yourself .
 
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