Curveball question of the day: Renault Alpine GTA Turbo running fault!

Lashout_UK

Lashout_UK

Lashout_UK

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Afternoon all,

My dad's at his wits end with a Renault Alpine GTA Turbo that he's got. I believe it uses a Renix ECU, a la Jeeps of the '80s.

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.

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.

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

Any pointers, so I can jump in better armed? Appreciate it's not exactly a common car, but it's not entirely different from a lot of modern kit - nothing ventured, nothing gained!

Half wondering whether I can get it to run in open loop all the time, like it's cold - might stop it doing it...

Cheers! Any guidance appreciated.
 
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...
 
IACV? Sounds very much like the behaviour I was getting when closed loop idle wasnt setup to react fast enough to changes in load

Edit: I wouldn't have thought it would have a means adjust fuel mixture of its injected? Are you sure it's not an idle speed adjustment screw instead?
 
Frozennova said:
IACV? Sounds very much like the behaviour I was getting when closed loop idle wasnt setup to react fast enough to changes in load

Edit: I wouldn't have thought it would have a means adjust fuel mixture of its injected? Are you sure it's not an idle speed adjustment screw instead?
Click to expand...

My thoughts. Just as it cuts, you hear it suck noisily (fnaar) - then it idles up. Not sure if the IACV is actually working.

Alas, no - it's archaic enough that it has various points (at least one, anyway) where you can tweak the mixture for emissions purposes. There's a pot on the RHS of the engine bay that's for adjusting this idle mix, to bring the emissions down to a specific range. Tweaks just the idle mix, nothing else, I think - and doesn't effect running mix.
 
IACV would the first thing that jumps out to me, I assume it still drives ok as long as you drive around the hunting idle?

A long shot but do you have any sort of what Lambda/AFR are like at idle, could be a lean stumble as well?

I know early MX5s were batch fire injected and don't idle particularly well unless they are quite a bit richer than stoich
 
A few pictures, too, as consolation for the ongoing griping about French wiring and electrics :D

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

IMAG0100.jpg


(Centre caps since replaced)

IMAG0588.jpg
 
Frozennova said:
IACV would the first thing that jumps out to me, I assume it still drives ok as long as you drive around the hunting idle?

A long shot but do you have any sort of what Lambda/AFR are like at idle, could be a lean stumble as well?

I know early MX5s were batch fire injected and don't idle particularly well unless they are quite a bit richer than stoich
Click to expand...

No, it runs like absolute garbage unfortunately - once it starts hunting you're flat out of luck. It won't build any power and you can't drive through the erratic revs. You can get the revs up briefly, but it cycles around.

I did wonder if it's going lean, and the ignition's being cut by the ECU as a safety measure, then the fuel comes back and it settles down again...
 
Diddums said:
If you can't get it going again just put it somewhere where loads of people can enjoy the looks. Such a cool car :)
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Haha! Really is a great car - problems aren't uncommon to any neglected '80s turbo car, but it's just getting annoying at the moment. It's very quick - had to drive the wheels off my TT to keep anywhere near to it. Feels very modern on the road and makes a very odd, but very entertaining noise!


 
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My mates Dad had one of these, took me out in it when I was like 17, such a quick car for the time and very unique.
 
Id be looking at what voltage the coolant temp sensor gives when the engine is cold, unplug it and give the ecu the same voltage, see how it runs.
 
That sounds like a damned good idea, Firestar. From what I recall, there's always been a question about the coolant temperature sensor. I'll have a look in the manual, just to make sure there's not more than one - it's very much one of those kinds of cars, constant curveballs...
 
As it's plastic and it's had bits done to it's wiring I'd be looking at earthing issues. It's a common problem on TVR's.
 
Dogbreath said:
Possibly a failing fuel pump. If possible putting a pressure gauge on the fuel rail would be useful if only to rule it out.
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I don't think it will be pump if it is okay when cold. My guess is it has some sort of cold start sensor then when up to temperature switches (which explains why o2 sensor was first port of call). Have you been able to get another ECU to test just to rule it out?

What you need to find out is what switches on when it switches from cold start to normal operating temperature and go from there.
 
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Firestar_3x said:
Id be looking at what voltage the coolant temp sensor gives when the engine is cold, unplug it and give the ecu the same voltage, see how it runs.
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Surely the sensor just needs its resistance measuring? If it's an NTC one the resistance will be high when cold, and drops as the coolant warms up, and if a PTC it will be the other way around.
 
Finally got to have a look at it today:

- Starts just fine when cold, revs fine
- Runs better with coolant temperature sensor unplugged

Problem still exhibited itself later, but was less annoying with IAC unplugged and the water temperature sensor off.

What was odd, however, was that with the MAP sensor unplugged the Renault refused to run at all. I thought it should be okay without that? Wondering if that's an indication of a problem in that area...

I don't think it actually has an O2 sensor; I'm told that's the later ones - not sure where I got the idea it'd been replaced from.
 
Lashout_UK said:
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..
Click to expand...
When you say it gets hot ,Does the engine also over heat ?

Have you checked for any air leaks /vacuum leaks

Is this hunting cycle just at idle rpm's or at all rpm's ?


Checked for water in the fuel tank ?
 
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chaparral said:
When you say it gets hot ,Does the engine also over heat ?

Have you checked for any air leaks /vacuum leaks
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No, the cooling system does its job just fine - just hot, as in there's heat in the bay and everything's up to temperature. Does seem to be thermally related, somehow.

Definitely going to take some unpicking, this... Bah! :D
 
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