Hello,

 

I was wondering whether any of you could help me with a little problem I seem to be having:

 

I had a problem with my ZX TT stalling at low revs. I took it to the monkeys at Nissan, who after doing a Consult said they could find no problems. After a tip from this site, I suggested that it may be the TPS. They then said that it was and that they had repaired a bit of wiring.

 

The revs weren't perfect afterwards, but it had actually stopped stalling. That was about 4 months ago and now it's started up again.

 

These are the symptoms:

 

- It only ever stalls when the engine is warmed up and seems to be especially affected after hard acceleration.

- When selecting reverse (car ias an auto) the revs drop right down, sometimes leading to a stall.

- It does not stall at speed. It's usually when slowing down to a standstill or accelearting from rest.

- The revs drop significantly on hard braking.

 

Any information would be greatly appreciated.

 

Cheers,

 

Alex.

Hello,

 

I was wondering whether any of you could help me with a little problem I seem to be having:

 

I had a problem with my ZX TT stalling at low revs. I took it to the monkeys at Nissan, who after doing a Consult said they could find no problems. After a tip from this site, I suggested that it may be the TPS. They then said that it was and that they had repaired a bit of wiring.

 

The revs weren't perfect afterwards, but it had actually stopped stalling. That was about 4 months ago and now it's started up again.

 

These are the symptoms:

 

- It only ever stalls when the engine is warmed up and seems to be especially affected after hard acceleration.

- When selecting reverse (car ias an auto) the revs drop right down, sometimes leading to a stall.

- It does not stall at speed. It's usually when slowing down to a standstill or accelearting from rest.

- The revs drop significantly on hard braking.

 

Any information would be greatly appreciated.

 

Cheers,

 

Alex.

 

I've got this too (great description!). Mine's been a heck of a lot better since swapping fuel hoses and filter, but still does this if you pootle round town and then drive hard later.

 

I saw another thread that suggested it might be PCV related, anyone who understands the scary stuff under the plenum care to comment?

 

It doesn't seem to be drinking oil or coolant at all - is yours?

 

I might be imagining it but I think I get petrochemical smells drifting into the cabin when it's being particularly bad.

 

(Mine's a manwell by the way, so I don't think it's your auto box given I have the same trouble.)

 

Several people have suggested PTU problems but I'm not sure about that, it doesn't seem to misfire, just mis-rev, if that makes sense.

Hi Alex,

 

Hmmm ... I'm not going to be able to give any difinitive answers to this particular set of problems but I can shed some light on one or two involved issues.

 

Stalling under heavy braking: This is indeed "most likely" due to clogged PCV valves. Best thing to do here is to order a complete set of 2 valves and associated hoses (I think there are 5) and replace the lot - try MJP Eastern Autos in the trader section for a good price and excellent service.

 

You've already indicated that Nissan has "fixed" the wiring to the TPS. My suggestion is to buy a new TPS (only about £40-ish from Nissan) and fit it - making sure it is set up correctly.

 

Other than that I can suggest you do the following:

 

Clean the throttle bodies, then clean the idle valve at the back of the engine, reset/adjust the base idle, replace the fuel filter, fuel pressure regulator, fuel pressure dampner and associated hoses (if your budget can stretch to it order Smithy's braded hoses), replace air filters (I sell the cracking A'PEXi Powerflow induction kits). After you've done each bit reset/clear the ECU by leaving the -ive terminal to the battery disconnected for an hour or so.

 

I must sound like I'm drumming up business for all our traders but I'm not on commission or anything ... ;) If there is someone in your area with a ConZult that will also help diagnose any error codes and set up the various bits correctly (if you want a ConZult then contact me as I sell those too!)

 

I think I have addressed most of the "simple" things you can do to try and get to the bottom of this stalling problem. Let us know how you get on.

 

Regards,

Chaps,

 

Many thanks for your replies - much appreciated.

 

OK - some additional info. It may just be a coincidence, but these problems seemed to coincide with some work I had done recently, which included an oil change with a non-Nissan filter. The oil pressure guage is all over the shop as well, sometimes dropping to zero. No warning light comes on for this though and the mechanic believes this is due to a faulty guage rather than a problem with oil pressure. I can't actually remember whether this happened before or after the oil was changed...

 

Also, before taking the car to Nissan, I did replace the TPS. However, the part I was provided from Nissan was only the bottom part. The top part is the original bit which was a bit manky. I did however, clean the connectors. Other than screwing the bottom bit in, how do I ensure it's set up correctly?

 

Cheers,

 

Alex.

Cheers Danny...

 

Does PCVs involve taking the plenum off, and does that mean you have to order other bits which you will necessarily break when doing that? And does this mean it's an all-weekend job?

 

I've done my fuel lines and filter (ta Smithy) and it did improve things as I said, so I'd definitely go for that, kowalski. It's fiddly but not too difficult. There's at least one vacuum line you have to replace as well, because the original comes out with the fuel lines you're replacing, like it or not. You'll have to disconnect the battery to sort the fuel lines anyway, so that'll sort your ECU reset. (In retrospect it would have been better if I'd taken the battery totally out to give a bit more working room anyway.)

 

Got an air filter coming...

It is unusual for any error codes to be evident when this happens, athough monitoring the output of some of the sensors can be very revealling !

 

Take a look at the tech articles on this site :- http://www.z-car.net

Chaps,

 

....The oil pressure guage is all over the shop as well, sometimes dropping to zero. No warning light comes on for this though and the mechanic believes this is due to a faulty guage rather than a problem with oil pressure. I can't actually remember whether this happened before or after the oil was changed...

 

Cheers,

 

Alex.

 

Hi Alex

 

This symptom will be the oil pressure sender unit, not the guage. Although it's reckoned the stock guage is not always accurate.

 

I had the same problem and replaced the sender (fekking expensive - £80+vat from Nissan for the unit) now my oil pressure is exactly per the handbook :D

 

Richard :)

Hi Alex

 

This symptom will be the oil pressure sender unit, not the guage. Although it's reckoned the stock guage is not always accurate.

 

I had the same problem and replaced the sender (fekking expensive - £80+vat from Nissan for the unit) now my oil pressure is exactly per the handbook :D

 

Richard :)

 

Thanks for the info, Richard.

 

Alex.

PCV valves should be done as part of the 60k maintanance IMO - in fact I'd do them every 30k but thats just me :D Failure to allow the engine to breathe properly will more than likely end up with engine damage due to oil contamination...

 

Do you have an aftermarket air filter on the car? This will cause the airflow meter to read incorrectly while coasting and will cause the engine to stall. There are ways round this problem though.

 

It sounds more like the idle valve at the rear of the plenum, passenger side. This clogs up over time with the vapours from the breather system and causes poor idle AND the base idle to change. The base idle must be correct or else the ecu has too hard a job to keep the idle at 750rpm... Check the connectors to that area too - especially the two on the IACV assembly - one is the idle valve and the other is the fast idle control valve (explaining the drop in revs when you select reverse).

 

Hope this gives you some pointers ;)

 

CheerZ,

 

Andy

PCV valves should be done as part of the 60k maintanance IMO - in fact I'd do them every 30k but thats just me :D Failure to allow the engine to breathe properly will more than likely end up with engine damage due to oil contamination...

 

Do you have an aftermarket air filter on the car? This will cause the airflow meter to read incorrectly while coasting and will cause the engine to stall. There are ways round this problem though.

 

It sounds more like the idle valve at the rear of the plenum, passenger side. This clogs up over time with the vapours from the breather system and causes poor idle AND the base idle to change. The base idle must be correct or else the ecu has too hard a job to keep the idle at 750rpm... Check the connectors to that area too - especially the two on the IACV assembly - one is the idle valve and the other is the fast idle control valve (explaining the drop in revs when you select reverse).

 

Hope this gives you some pointers ;)

 

CheerZ,

 

Andy

 

Thanks for the pointers. It seems I have a few things to investigate.

 

Air filter I believe is standard Nissan, but I'm not sure. Where is it located?

 

Whilst the car had a reasonably recent major service at 60k, I'm not sure if the PCV valves were done - I was not the owner at the time.

 

Does clogged idle valve explain the symptoms when the engine is warmed up? This is why I thought it may be a TPS problem since it only seems to happen when warmed and after hard accel. Can't hurt to check though - just a shame I am completley inept when it comes to Z mechanics!

 

Also, and I know this may sound stupid, but could an oil change have anything to do with it?!! Makes no sense to me, but these problems started up at EXACTLY the same time when I had some work done which included an oil change.

 

Any thoughts would be much appreciated!

 

Cheers,

 

Alex.

Clogged idle valve could well be the case yes - sometimes as the gunge inside the valve warms up it gets more sticky, other times as the engine warms up the connection to the idle valve gets worse and the valve stops responding...

If you have a Consult/ConZult the you can monitor the value of the idle valve, it should be summat like 15% open on idle. If the valve is stuck then that is unlikley to be the case. If the electrical connections to the vale are knackered then it will likely read a different value, I have discovered that when it's disconnected it seems to default to 80% (or thereabouts), which often causes the engine to stall, if the base idle is not set correctly. Turing on the a/c usually corrects for this by raising the idle a couple of hundred rpm.