Starts, then cuts out.

[backseateducation]

You might have seen in my Project YouWhyWhy thread that I broke down the other night, but a change of fuel pump relay got me going. I'm now wondering if that was a fluke, as this afternoon I went to go for a drive and the car would turn over but not start. After fiddling around with relays etc I finally managed to get the car to run, it idles smoothly and sounds great. However, as soon as you touch the throttle, it dies. After it dies, the black box I've circled here can be heard buzzing. Is this some kind of idle control valve? I would guess the other black box is the throttle position sensor.

 

[backseateducation]

Reading around the forum it does seem as others have had problems over the years with similar things. I'll strip the sensors out and give everything a clean first, if that's no better I'll see about getting the codes read.

 

[colb]

Yes that’s the idle control valve, known to get gunked up over time. Just take it off and spray carb cleaner in it and wash it out. The flapper valve should move freely once it’s cleaned. They can make a humming noise shouldn’t be anything to worry about.

 

[backseateducation]

Got home from work early so decided to try the Z again to see if there had been some kind of miracle.
Now when you turn it over the fuel pump relay clicks constantly, I'm not sure it's supposed to do that?
Hopefully now the storm has died down I'll be able to fit the new unit that I have on the way, plus my adaptor cable to try and read some codes off.

 

[backseateducation]

Hmm.

New fuel pump relay arrived today, so just popped out and fitted. Unfortunately no change, engine turns enthusiastically but still won't run. I'm almost beginning to wish the AA hadn't got it going, then it would at least have been trucked to a garage rather than being immobile on my drive. Hopefully the code reader will turn up something, if not then I'll have to get it towed.

 

[t-tony]

I suspect its the fuel pump itself. How much fuel is in the tank? Is it low enough to remove the pump/sender unit?

Tony.

 

[Andyboy]

When that ICV fails, the car just will not drive. Quite common for them to fail and I always kept a spare when I had an E36 318i with one fitted. Loads for sale on ebay I'd imagine. I've got a few in a box somewhere.

 

[backseateducation]

Thanks guys. Tank shows about a third full, the AA guy put 5 litres in just to rule out low fuel and I guess I could have used that up driving home if the gauge is faulty.
Would the faulty ICV prevent it from starting in the first place?
The title of the thread is now slightly misleading as it won't start at all!

It reminds me very much of collecting my mate's Fabia some years ago, it had been out of use for 8 or 9 months and ran perfectly for about 100 miles before cutting out and refusing to start, that turned out to be the pump. My Z has seen very limited use over the last few years, and has had several long motorway runs since I bought it - maybe it's been too much of a shock to the system!

 

[t-tony]

The fact that it won't now start at all points me to the pump. I think at 1/3 full you should be able to remove the pump but please don't take that as read.
Andy @spurs fan in a coupe might have a pump?

Tony.

 

[backseateducation]

Thanks Tony. I'll ask him - I've bought several items from him already in my time here!
This won't be a job for me, it'll be going to the garage. It's probably a bit outside my ability, at least on my own.

 

[backseateducation]

Car being picked up by my usual garage on Wednesday - hopefully they can get it properly diagnosed quickly, I could do with it on the road now the Mondeo has been crunched.

 

[backseateducation]

Well that was quicker (and cheaper) than I expected. Turns out it was all down to previous wiring issues, it looks like at some point the alarm unit and airbag system has been bypassed, and the wiring down under the steering column was in a poor state.
Fortunately I have a friendly MOT tester who will look past the lack of airbag warning light - good excuse to find a nice sports steering wheel!
Went for a blast after work and it drives as well as ever, so hopefully now I can concentrate on cosmetics, rather than fundamentals!

 

[backseateducation]

Hmm - maybe my confidence was slightly misplaced.
Took car out today, as usual it didn't start first crank, but got going ok. After five minutes or so I started climbing a hill, and it cut out just the same as before. Managed to get it restarted, it was then fine for another mile but cut out again a couple of times, but both times seemed to restart itself. After that absolutely fine, back to its best. Stopped and restarted fine, pulled no trouble with plenty of power (well for a 1.9!)
When I got home I connected my adaptor cable and read the codes. They are shown as 'generic', and are the same with the ignition on or the engine running.
PO340 - camshaft position sensor
PO135 - O2 sensor heater circuit
PO130 - O2 sensor circuit

I tried clearing the codes, but they didn't want to go away!

When I got the car, the little vac pipe going from the front of the engine into the fuel rail was blanked off, so I refitted it. Something I hadn't noticed before, I don't know if it's relevant, is that whether the ignition is just on or the engine running, there is a noise of air rushing from somewhere down by the fuel rail. The car also seems to have an extra kick of power over 4200 rpm, I don't know if this is relevant.

I'm going to have a look around the forum to see what others have found, but it's certainly not dimming my enthusiasm for the car - when its going its so much fun.

 

[colb]

You need to look for where that air noise is comming from as its causing an air leak in the engines vaccum system, look for a split pipe and fix any leaks you find. Replace the camshaft position sensor with an oem brand, do not buy cheap sensors stick to Bosch or Seimens brands.
Then turn your attention to the exhaust sensors pre cat and post cat. The code you have dosn't say which sensor is at fault so it would be worth looking at their live data with diagnostics to see which is not performing correctly. Pre cat should show up as a regular wave form in graph diagnostics as its voltage ranges up and down the scale. Your code shows as a heater circuit fault in the sensor which would be an indication that the heater element in the sensor has burnt out. The post cat sensor when viewed in live data usually remains pretty static if the car is being fueled correctly, it would react to excess air or high unburnt fuel being present in the exhaust gas.
Viewing fuel trims in diagnostics will also be an aid to diagnosing whats wrong. If you have high fuel trims its probably going to be due to a vaccum air leak, the exhaust sensors if they are working will see unmetered air (air that hasn't been measured when it flowed through the Maf sensor) and believe the car is running lean. It will try and compensate by adding more fuel at the injectors to richen the mixture. It will add up to 20% more fuel as it tries to compensate, finally giving up and setting the EML on the dash. Overfueling will play havoc with your running and empty your pockets as you end up visting the garage for fuel more often. If you sort outn all these points and it still has problems it would be time to suspect the Maf sensor being bad.

 

[backseateducation]

Thank you!
The air noise is immediatley above the injectors and fuel rail so I'll start doing some investigation. I'll order up a new cam sensor now.

 

[colb]

Have a good look around the entire engine when you look for air leaks, check all the rubber hoses and the plastic hoses, also check out the rear of the inlet manifold some models have rubber blanking plugs on unused stubs, these rot and fall off introducing vaccum leaks. If you cant find any visually then a smoke test will find any problem areas. If you were closer I would smoke it for you.

 

[backseateducation]

Well the running faults continue. On my trip up to Castle Combe a couple of weeks ago, the car was great, but seems to have started to gradually run rougher and rougher. Leaving work on Friday it took four bouts of cranking to start it, and three today. It also briefly cut out again across a junction, but restarted straight away. As ever, it drives and performs fine, but idle rough. Hot starting also fine.
Got home from a very enjoyable drive and read the codes off - Misfire on cylinder 1, cylinder 3 and cylinder 4, also 'General misfire'
Possible coil pack on way out? I might to treat it to new plugs and leads as well as I have no history at all.

As for that funny rushing noise, it's never returned, so goodness knows what caused that, unless the garage managed to cure it when it was in the other week.

 

[NZ00Z3]

Misfires are caused by Electrical and Mixture problems:

Electrical

• Plugs and coils. Swap with another cylinder to see if fault follows
• Harness. Dirty connectors, damaged wires, faulty coil earthing resistor
• DME. Inspect the 2 sets of 6 MOSFETS (Black boxes) around the outside of the DME PC Board for damage. Inspect for PC Board track damage. Any damage will be obvious.

Mixture

• Too rich. Too much fuel, not enough air. Faulty MAF or Pre-Cat sensor fooling the DME into thinking 1 or the 2 prior causes is happening, blocked Cats, if the problem is bank specific, a leaking injector.
• Too lean. Too much air, not enough fuel. Faulty MAF or Pre-Cat sensor fooling the DME into thinking 1 or the 2 prior causes is happening. Vacuum leaks (see first tip)
• The DME has a performance tune. The DME tables may not match the MAF or injectors fitted. The Air/Fuel tables have been incorrectly altered. Put the DME back to its original tune and see if the problem is fixed.

First step is to check you fuel trims with a hot engine at idle. If any are > +/- 8% then you have problems to find.

• Greater than +8% is likely a vacuum leak. Smoke test the engine to find them. https://www.e46fanatics.com/threads/how-to-smoke-test.1261077/ A quick test is with a hot engine at idle check and record your fuel trims. Rev the engine to 3,000 rpm for 30 seconds and watch the short term fuel trim. If it reduces significantly, might even go negative, then it's confirmed that you have vacuum leaks to find.
• More negative than -8% and you have rich conditions.

If after smoke testing the engine and you still have problems or if you have rich fuel trims, then data logging is the way to find the problem.
Read this thread and set up OBD Fusion to do the logging. https://www.e46fanatics.com/threads/obd-fusion.1240733/

To read the logs, either post a link to the CSV file here so I can download them, or look in the Resources section of this forum for the "How To" on reading engine OBD2 logs.

 

[backseateducation]

Cheers guys. Im going to replace the ignition side of things as I have no history for the car at all. However, I had a thought today (I know, it's a rarity....) - as this has only started just after I had the cam sensor replaced, would they have had to remove the intake manifold to get at where the sensor plugs into the loom? If so I guess I could now have a leak on the manifold gaskets. I've earmarked Saturday to try and get this sorted, so I'll have a really good try to find any kind of air leaks.

 

[backseateducation]

If you were closer I would smoke it for you.

I might have to have a drive up to the ZedShed one of these days!