Renault Alpine GTA Turbo running issue

Afternoon all,

We're the fortunate owners of a Alpine GTA Turbo which, somewhat unfortunately, has been a little troublesome in our ownership.

The symptom is that when it gets hot, it starts to hunt - and won't build any power. Eventually it'll cut out, or just continue in its hunting cycle, down to nigh-on 0 RPM then back up to 700 or so. The engine electronics warning lamp flashes during this, and occasionally will glimmer while driving.

You can cycle the ignition, and the same fault will persist.

I've not looked at the car closely myself, but I can tell you the following has been changed:

- Plugs
- Coil & module
- Leads
- Crank position sensor
- Oxygen sensor (I think)

It's also had some restorative work done to the wiring harness and ECU (dry joints).

It appears to do the same thing with the TPS unplugged, and I'm told it still does the same with other sensors unplugged - but I was wondering if anyone could give me a bit of a steer as to where to start.

Another thing that's just popped into my mind - it has an adjustment for idle fuel mixture which has been messed around with no end, and I believe done so when it's on open loop. That won't help, will it...

It's a shame, because otherwise it runs fine when cold and drives very sweetly indeed (again, when cold). That, in my mind, voids any problems with the fuel side of things. Might be wrong, though.

Half inclined to see if I can get it to run in open loop all the time, which might negate whatever's causing the issue - or prove the fault really does lie elsewhere. Is this possible?

Any pointers, so I can jump in better armed? Cheers! Thanks for any advice in advance.

(And apologies for the first post being a gripe - the car's lovely, otherwise, for its age! Few shots below.)



(Centre caps since replaced)

Fuel pump relays can be problematic , they sit on the harness next to the ecu between the back seats. Might be worth a check.

.
First off, where are you? As there may be people I can direct you too.

Fact the ecu has been messed with worries me, these ecu's never suffer dry joints, I spend a great deal of time working on them, and that is never an issue. Blown tracks yes, and component failures yes, but always reasons why. In the hands of the unwashed worries me...

Make sure the dizzy cap and rotor arm are Bosch parts only, do not run the cheap copies... mentioned this loads of times.. put cheap in, get crappie results out - period... If you search you will find what I have written up about this before. I know what I am talking about as I have a 2.5 turbo running original ecu, coil driver, and dizzy... makes 387hp, and it was not been easy getting those parts to support it...

TDC sensor is important, and they do degrade, how are you sure it has been replaced by an original part, and also check the wire colours swap either side of the connector in the engine bay: red to white and white to red. Can you post a picture of the tdc sensor cable up to the connector, if it is the right one it will have additional heat protection over braid. The sensor body should also have a heat shield over the top where it mounts.

The ecu runs open loop, and there is no lambda sensor on a D501 GTA on a Renix 1 ecu. You can run with lots of the sensors disconnected, and again I have gone into this before, and have a thread on it (Renix ecus) in the projects section. Critical inputs are the tdc sensor, water temp sensor, and the map sensor... they must be good. You can test the water temp sensor, it screws into the water thermostat housing. I think JohnC has published the sensor table - resistance against temp before, I have it obviously, but you should find it on here as well with Google as your friend.

Make sure your fuel filter is new / good, and the front and rear fuel pumps.. when they get hot they can die off...

Relays as Tony mentioned.

You say the coil pack / driver has been replaced, what with OE or an alternative, as they are NLA as far as I know?

Now, meat and two veg... is the idle bypass valve sticking when it is getting hot, what happens when you disconnect it (connector on the bottom of it, lives on the left side of the engine looking in the back) at idle, does the engine pickup / slow / stay thd same? It may be sticking. If you crack the throttle plate by hand a small touch when at idle stationary, does thd problem go away? If so, likely the idle air bypass...

The fuel regulators are getting old and these can give all sorts of trouble. Best if you can measure the fuel line pressure, but my bet is you are likely to be running rich... does the engine smell rich at idle, and black exhaust? If you disconnect the vacuum line to the reg, does it kill the engine?

Pull the plugs after it has been running rough, and post a picture up here... can then see the mixture...

If the idle / CO pot situated up by the coil pack has been played with then you will be in a mess... again, the uneducated let loose on some of these things is disastrous, unfortunately we live in a digital age, and if it isn't on an OE fault diagnostic reader, or laptop screen they are stuffed... probably best bet is get a good replacement, but again prove what is good with the secondhand parts these days, it's all old, and those pots go noisey...

That should be enough to keep you busy
Pull the plugs, and let's have a look.

Cheers,
Martin

[BIG_MVS]

Check your front fuel pump (the GTA Turbo has two) is running all the time.

Nice GTA, welcome to the forum.

Thank you for all the guidance so far. Really appreciated.

I got a brief chance to look at it myself today; unplugged the water temperature sensor and it seemed a lot happier - but after a while (after some heat soak) the initial problem reappeared.

I then disconnected the IAC and the surging problem became smaller but still present. To a point, at least - I swear at some points it was oscillating between about 100 and 2000rpm, haha. Not a happy bunny.

Out of curiosity, I disconnected the MAP sensor - and it wouldn't run at all. I had it in my mind that it would go into a limp mode and still run - am I wrong in that respect?

Fuel pumps I can hear clearly and the pitch doesn't appear to change, but I'll double-check the front one's running in due course.

As an aside, I believe my dad's actually a member of the club - but he doesn't use the forum (yet). I'll have to get him on here!

MFaulks, duly noted RE the parts - I'll have a look at what's on there. Appreciate that these kind of cars are far more sensitive to bits that wander from the OEM specs....

When did you last change the fuel filters? There are two - front and rear.

If they're gunked up you're going to struggle. Pumps rely on getting cooled by the fuel and if they're working too hard then they are going to get hot and start surging.

Few things to check there.

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Ok, disconnect the MAP sensor and the engine will die, the fuel injection is cut.

Disconnect the water temp sensor and the running improves, tends to indicate you are running rich at idle most likely. Fuel reg crapped out, sticking open injectors i.e. need a clean, common.. left with old fuel in them, and possible but lesser than first two blocked / restrictive air filter...

Regards,
Martin

I had a similar issue when the rear fuel pump was on the way out.
Car started but after a period of time it would start to hunt, cough a bit and then just die.
This happened whilst out and about, so I called the AA but by the time they arrived it fired up again and I
managed to get home.
As mentioned above, the rear pump uses the fuel as a lubricant and I guess after twenty or so years it it simply wore out. There wasn’t any noise or other signs of it failing.

Replaced with a Walbro (not the up-rated version) with new fittings.

Apart from checking all the above the fule pressure regulators do this. The internal diaphragm gets perforated, then the fuel is sucked in to the inlet manifold so the engine starts when cold but when it is hot it will run rich the engine normally hunts up and down and is hard to start when hot.
This engine has 2 unfortunately bought one last year £49 but dart board price increases have taken place and they are now £110 each

Evening all. Thanks for the pointers.

I've ordered new fuel filters, and an air filter (just while I'm there) - and I'm mulling getting a pair of new pumps from ART, too. Just seems if I go through the fuel system, at least that's out of the way.

More I think about it, the more it does feel like a fuel-related issue - because whenever it does it, the CEL doesn't come on immediately. The engine surges, then the CEL comes on, then goes out, etc.

RE the fuel pressure regulators; is there an OEM option still or is aftermarket the best solution?

Can't wait to hear it sing again...

Apart from filters what you are planning is an expensive way of fault diagnostics. Borrow or buy a pressure gauge, this will tell you what your pumps are up to, the pressure regulators take the fuel pipes of and the small vacuum pipes remove them and put a length of clear plastic pipe on the vacuum connection turn it upside down and suck on the pipe if fuel is seen in the pipe it has had it as it should be sealed, not aware of any other manufacturer.

an expensive way of fault diagnostics

Very true Custard; have no fear, it is in the back of my mind - but I'm also thinking that this probably still has its original (or very old) pumps, filters, etc. While I'd definitely like to work out what the issue is, I'm also not adverse to making sure the rest of it is 100%.

Hi there,
just read through your symptons , sounds like fuel starvation.
Check feeder pump is working and filter is not blocked.
Its at the front of the car just behind fuel tank assesable from underneath.

Just thought I'd drop by with an update!

I had another chance to look at this on my own today. Started up from cold without an issue. After a few minutes, the symptoms developed again.

I shut it off at this point, primed it three times (just cycling the ignition), turned the key and - lo and behold - it ran just fine.

Didn't have a huge amount of time, so got underneath and doused the main pump's contacts with cleaner and gave the pump and filter a thwack.Then went round the engine bay, cleaning the ground points and every plug - including those in the rear offside arch, which didn't appear to have been looked at. Did find a few that were filled with oil/grime.

Turned the key again and it proceeded to run like a top. Let a bit of heat get into it and it seems happy enough. 14.4v at the battery, too, so at least it's charging properly.

Video: https://youtu.be/s7J9a1BJTI0

Probably could do with the tappets doing but not urgent. Been laid up for ages/started for short runs repeatedly, plus it's dead cold today, hence the condensation and water.

Front pump is quite audible so might be that which is struggling (or was just a ground/plug issue all along). Will hopefully get it up on some ramps this week so I can have a look at the front pump/filter assembly and its wiring. Do have new pumps and filters to hand so will likely install them anyway, as the ones on the car look very old.

Only annoyance is that it appears to have developed a new oil leak from the nearside rear cam cover/timing chain cover. Mind you, think it's got quite a thin oil in it - probably doesn't help a huge amount. Has done 134-odd thousand miles, mind...

Onwards!