Well, the honeymoon period is over: its taken nearly a year of ownership but I finally have my first engine problem... If any expertZ want to get their teeth into this it'd be much appreciated!

 

Okay, the car's been at the doctors for two weeks getting a new aircon compressor and regas. When I picked it up today, the first thing I notice after getting a few minutes down the road is that the HICAS light is coming on when I corner. (It did this for a little while a few weeks ago, but stopped when I put a little TQD in the resevoir).

 

As I'm heading out of London towards the M3 I start noticing that the idle is a bit lumpy and that the revs occasionally fluctuate. Previous the idle was very stable.

 

Finally, when there's a chance to use a bit of right foot, I start getting... not sure how to describe it... 'hesitation' under acceleration. It only seems to happen when the boost starts to rise towards equal pressure. I have a stock Jap boost gauge that reads from -7 to +7; the hesitation starts to kick in at around -3. Feels almost like a cylinder may not be firing and the car momentarily loses power as it does so. It makes a sound almost like going over a set of gentle rumble strips. Is this detonation?

 

This got progressively worse towards J4 of the M3. If anyone knows the area, I barely had enough power to climb the hill after J3! Any attempt to keep the power on through this hesitation leads to the exhaust gas warning light coming on.

 

Sorry for the huge boring post, but does this sound familiar to anyone? Thanks in advance...

 

Worried, of Hampshire

aka Raz

 

CAN HELP WITH HICAS FOLLOW THE WIRE THAT COMES OUT OF THE CAP ON THE POWER STEERING TANK AND DISCONECT IT. LEAVE IT DISCONNECTED AND DRIVE IT AROUND BUT REMEMBER TO CHECK LEVEL EACH DAY IF LIGHT STAYS OFF ITS THE SENSER ON THE CAP COMMON FAULT!!! IF LIGHT COMES ON WHEN DISCONNECTED THEN ITS BIG BUCKS MATEY.HOPE THIS HELPS.

 

 

Yes..try the disconnect lead for the HICAS.

 

Have you cleaned your throttle bodies recently? These are the same symptons that mine gets after about 3000k.

 

There is a dit in the tec section...20min job...peace of cake..sorts the problem out.

add some ATF fluid I guess...for the light coming up...if you wait longer it could be your handbrake light come up as well

Thanks for the tips guys, I'll get to it over the weekend.

 

I saw in the cleaning proceedure that I'll need some 'throttle body cleaner' - is there a particular product I need to get, or is any engine cleaning stuff okay?

 

If anyone else has more ideas regarding my original post, please do post, thanks!

 

Raz

Raz mate,

 

Check out TT.net and search for hesitation etc. Been covered loadsa times on there.

 

Tim

Raz,

 

To clean your throttle bodies use carberetor cleaner (I got mine from Halfords and works very well). The hoses can be a bugger to get off but if you do it while the engine is still hot it should be easier. Brute force does it, don't worry about them breaking. Make sure you undo the bottom clamp on the intake hose because that will make it easier to move the top bit off. Cleaning the throttle bodies did a world of good for my engine although I'm not sure it will cure your mid-boost hessitation. I used to have hessitation from standstill and it was mainly due to a fuel leak over the plenum and low idle (adjusted that manually and all is fine now.)

Good luck.

 

CHeers!

 

Danny

Hi all,

Revived this oldie for a bit of an update and, yep, some more Q's =)

 

Finally managed to get the car checked out - at a main dealer I'm afraid... I know I know, but I was depsperate and didn't know anywhere else locally!

 

They've listed three parts that need changing: transistor ignition unit (assuming they mean the PTU), coolant temp sensor and the camshaft position sensor.

 

Does this sound plausible to you guys? Sounds okay to me, other than the coolant temp sensor... I can't see that being related. Is it the same sensor that provides the temp gauge on the dash? I've had no probs with that.

 

Last question, does anyone have ballpark figures for what these three little bits might cost? They should be calling me this afternoon with prices so I'd like to know how far they want me to bend over.... =)

 

Thanks,

Raz

 

PTU is $178 (less 20% discount) from Courtesy Nissan. Carriage, VAT, duty etc will bump it up a bit tho ...

The coolant temp sensor is a seperate sensor than the one used for the dash. look on the top radiator (metal) hose - the left hand sensor (has two connectors) is the ECU sensor, the right hand (has one connector) is the dash sensor. And that can cause all manner of idle/hesitation problems.

 

The CAS is pricy BTW..

 

23731-45V10 for cars up to 09/93 $265.34 at nissanparts.cc

Cant' seem to find a price on the 93> part.

 

Az

 

------------------

Yes.. I know my back wheels *were* on backwards.. They're not now, 'k? ;)

Funny you should mention that, was only on about the price of PTU's yesterday.

 

Right, 271 incl. VAT, that's what's on my invoice from Middlehurst althought that could be plus VAT...confusing...but anyway. No-way should you get a figure like 394+VAT which is what somebody has been quoted in the last few days.

 

My invoice was from last December, can't tell me the price of that part has rocketed that much in 9 months for christs sake!!!???!!!

 

Have you checked the coil pack connectors? Make sure that they are on firmly, mine was doing the same thing...chugging and when the Nelson tech. guy pulled one of the coil pack connectors off one of the cyls. no change in the engine RPM. Connector? Coil pack? Injector? Spark Plug? All are possible failures.

 

Later

 

Tim

;-)

 

 

 

I can not imagine all those parts fail at the same time.

It shows how incompetent those bastards are.

They are incapable of a correct diagnosis and you are going to

pay for it.

Soon they'll suggest a rebuild...

 

Your problem can be caused by many things.

The easiest ones are corrosion on contacts to the CAS, PTU, injectors, coils and the coolant temp sensor.

The problem can also be related to a vacuum leak.

 

Get your car to a mechanic that is capable of doing

some diagnosis work.

Don't let them charge you for their ignorance!

 

Maciej (DIYourselfer)

 

------------------

www.z-car.net

I thoroughly recommend the Maciej approach - DIY

 

Even with all the problems I have.. I just don't trust garages as far as I can throw them!

 

Az

Thanks for the advice and info everyone.

 

Tim, I did do a novice's visual check on the coil packs but couldn't see anything obviously wrong (ie, no broken wires). I wouldn't know what else to look for though =(

To their credit, perhaps, I did see the Nissan mech check them over too.

 

Times like this I wish I'd more machanical or engineering stuff as a nipper, instead of pissing all my time away with with pointless computers

 

The only reason I haven't gone back to my 'usual' garage (a performance car dealer where I bought it) is that its a fair distance away in west London. I'm a bit nervous of driving the car for any length of time, as any real use of the accelerator starts to cook the exhausts...

 

Don't suppose there's anyone close to J4 of the M3 who fancies making a housecall to a sick Z, or having one limp up to their place, is there? =)

 

Raz, sobbing quietly

 

Put the ecu in test mode..report errors

 

Clean the water temp sensor

Clean the throttle position sensor

Clean your throttle bodies

 

Your CAS and PTU are EXTREMELY LIKELY to be fine (unless they swapped with known bad parts)

 

 

Report the results

 

Zee you

 

 

Raz,

 

I had this exact problem which started intermitently last Friday and on Tuesday it just carried on. Darren diagnosed it as a problem coil pack and he was absolutley correct. One of the coil packs that is under the balance tube was off by about 5mm. I cleaned up all the connectors and now it's fine. I know you said the Nissan mechanic checked them out, but mine looked ok untill I took them all out.

 

If there's anything I can do to help like help you clean all the contacts and the throttle bodies, I'm in NW London and can help anyday of the week (apart from Sundays cos I'm usually hung over).

 

Vijay

RESULT!

 

This forum is the terminator Z forum!!! Excellent!

Raz mate,

NEVER TAKE IT TO A MAIN DEALER,

MOST OF THEM KNOW TWAT ABOUT 300ZX'S

Best that you speak to DARREN and he'll put it right.If any one knows he does!

Best of luck.

Tony

 

BOLLOX to nissan main dealers They REALLY piss me off

Hesitation (and possibly erratic idle) is lack of spark - thats why the exhaust temp warning light is coming on - unburnt fuel to the cats..... Hicas light is simple too - top up the reservoir for the power steering pump.

For the spark, check the connectors on the coil packs etc etc etc....

 

CheerZ,

 

Andy

Big thanks to everyone for all the help so far!

 

Right, I've done an ECU test. It looks to be giving me code 21 - two long flashes followed by a short one. There's not a hell of a lot of difference between long flashes and short though is there?? It looked like code 12 for a while!

 

Something puzzles me though - according to the ttnet instructions I followed, code 21 should be reported by the Check Engine light under normal conditions, but my light only comes on with all the others before the engine is fired up.

 

I think a lot of you have got it right in pointing to the coil packs. Idle is quite lumpy now; the left exhaust has a pronounced chugging that shakes the whole car =)

 

Haven't been able to do any cleaning proceedures yet - hopefully Vijay will be able to help me out with that (get my email mate?). Is that still the next logical step?

 

Raz