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Cressa

What is Santa bringing your Corrado for Xmas 🎄

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1 hour ago, seanl82 said:

I don't think this is as much an issue when starting from cold though, so a drop in pressure seems unlikely to be the cause. It's more often seen when warm. Mine fires within 2 seconds from cold, but takes probably 6 - 8 seconds when warm and tends to be between 5 - 30 minutes after switching off. It's fine in that first 5 minutes or so then again when its had chance to cool down.

Mine is exactly the same issue. 😊

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Hmm - the last starting from warm issue I had was resolved by replacing the distributor (which has the cam sensor attached), will be separate on a coil pack car - this could be heat soakage causing intermittent failure in a a sensor or electronics solder joint due to expansion. In my case the casing around the cam sensor had cracked and the wiring was damaged. These cars drive you nuts......

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10 hours ago, fendervg said:

Hmm - the last starting from warm issue I had was resolved by replacing the distributor (which has the cam sensor attached), will be separate on a coil pack car - this could be heat soakage causing intermittent failure in a a sensor or electronics solder joint due to expansion. In my case the casing around the cam sensor had cracked and the wiring was damaged. These cars drive you nuts......

Mine has exactly the same problem and I wondered if it was a fuel pressure / evaporation issue, but if the pump doesn’t actually prime at ignition on then that’s unlikely?

Cam or crank sensor is a good call, are these ignored if engine is cold?

I don’t remember having this problem back in the old days (year 22 with this car so a reasonable amount of experience) although I have had questionable starting for a long time, both before and after going to OBD2.

Agreed, drive you nuts!

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Crank (position) sensor, cam (position) sensors are used all the time whatever temp, without them the ecu doesn't know where the engine is in order to inject fuel / spark.

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On 1/4/2022 at 9:01 PM, Cressa said:

Mine is exactly the same issue. 😊

This is exactly the same as mine, and wasn't solved with the non-return valve. I can only relay what Vince said to me on the issue as I'm no expert, which is that he's never been able to solve it, but suspects it's the ECU. If someone as experienced with the VR as Vince doesn't know, then not sure what hope we have!

The workaround he told me to do, is to momentarily blip the ignition so it just starts to turn over, literally a second or less. Then turn the ignition off and start normally - it then should start instantly. It's an odd one, but it does work.

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1 hour ago, oneohtwo said:

This is exactly the same as mine, and wasn't solved with the non-return valve. I can only relay what Vince said to me on the issue as I'm no expert, which is that he's never been able to solve it, but suspects it's the ECU. If someone as experienced with the VR as Vince doesn't know, then not sure what hope we have!

The workaround he told me to do, is to momentarily blip the ignition so it just starts to turn over, literally a second or less. Then turn the ignition off and start normally - it then should start instantly. It's an odd one, but it does work.

Because the pump runs and pressurises the fuel line?

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I couldn't really say, but doesn't the pump run on the first ignition stage before you turn over?  Vince did mention that they've tested the pressure in the system when trying to get to the bottom of it, and the fuel line has never lost pressure - he was pretty convinced it was not a fuel issue. 

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I'm happy to try the starting method when I get to drive the car. Wont be for months yet as it is blocked in. I am also happy to try the one way valve as it is a cheap attempt to solve the problem. 

Be nice to hear what even more people have done about this. All great info folks 👍🤩

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5 hours ago, oneohtwo said:

I couldn't really say, but doesn't the pump run on the first ignition stage before you turn over?  Vince did mention that they've tested the pressure in the system when trying to get to the bottom of it, and the fuel line has never lost pressure - he was pretty convinced it was not a fuel issue. 

That's the thing - I was never able to confirm that the pump runs and primes with just the ignition on (which is the way most Mk2s etc. work) - on my car at least I suspected that the pump was only triggered by the ECU relay and started running when the engine was turning and fuel pressure built up during cranking period. But that could be something specific to my car or the result of bad troubleshooting - but it might explain why the "blip" works. This is where we need someone of much missed RW1's calibre, anyone remember him? He knew the car inside out, down to practically every pin in the loom.

 

Well, the Bentley seem definitive for the AAA in that it should run for 1 second with ignition on - but not sure if that applies to the ABV. If you look at the wirin diagrams they are different between UK and US (probably to do with fuel pump safety cut off regulations) and the fuel pump relay only switches current to the pump when it has a signal from ignition live and the ECU.

bentley_fuel_test.JPG

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17 minutes ago, fendervg said:

That's the thing - I was never able to confirm that the pump runs and primes with just the ignition on (which is the way most Mk2s etc. work) - on my car at least I suspected that the pump was only triggered by the ECU relay and started running when the engine was turning and fuel pressure built up during cranking period. But that could be something specific to my car or the result of bad troubleshooting - but it might explain why the "blip" works. This is where we need someone of much missed RW1's calibre, anyone remember him? He knew the car inside out, down to practically every pin in the loom.

 

Well, the Bentley seem definitive for the AAA in that it should run for 1 second with ignition on - but not sure if that applies to the ABV. If you look at the wirin diagrams they are different between UK and US (probably to do with fuel pump safety cut off regulations) and the fuel pump relay only switches current to the pump when it has a signal from ignition live and the ECU.

bentley_fuel_test.JPG

I might get the GF to put the ignition on whilst I have a listen and post up what I find

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20 minutes ago, Cressa said:

I might get the GF to put the ignition on whilst I have a listen and post up what I find

Good call - because the pump is in-tank only, it's difficult to hear it priming if it does (the aux water pump will be running as well) - with an underbody pump it's a bit easier. You could also put a tester across the plug terminal in the boot and see if you get current when ignition is switched on. Needs two people really - if you look at the VAG test instructions, they mention using a "remote control unit"!

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It's also worth noting that I do have a non-return valve installed on my fuel line, so in theory whether the pump is priming or not there should always be pressure in the fuel line - and I still get the issue. Based on that evidence I am inclined to agree with Vince that it is not an issue with fuel supply, or at least pressure.

But either way, if it is a fault with the fuel pump not priming or not, or pressure dropping in the line, installing a non-return valve doesn't resolve it. It's extra work for not a lot of gain, and compromises the fuel line slightly, which is what happened to me when fuel started leaking out and down the road...!

 

 

 

Edited by oneohtwo

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2 hours ago, oneohtwo said:

It's also worth noting that I do have a non-return valve installed on my fuel line, so in theory whether the pump is priming or not there should always be pressure in the fuel line - and I still get the issue. Based on that evidence I am inclined to agree with Vince that it is not an issue with fuel supply, or at least pressure.

But either way, if it is a fault with the fuel pump not priming or not, or pressure dropping in the line, installing a non-return valve doesn't resolve it. It's extra work for not a lot of gain, and compromises the fuel line slightly, which is what happened to me when fuel started leaking out and down the road...!

 

 

 

Fair enough - could be something else then. Where did you install the valve? The usual way would be at the tank lid, on the "out" hose to the engine, and using a circular piece of additional fuel hose to join up with the outlet on the tank lid - the only issues I've seen with it is if that extra hose is not decent enough quality or cracks.

I think part of the issue troubleshooting this kind of thing is that there a re quite a few sensors and components that all need to be working 100%, and all the earth points need to be good as well.

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Prior to my engine work - just chains, head refuribishment and refreshed injectors - I was having an issue with warm starts. It would crank and crank and when it did it would cough slowly into life. I changed loads of sensors - coolant, cam and crank, the relays, I installed a 1 way valve on the fuel line, changed the FPR, new coil pack, new HT lines. Nothing solved the problem. Yet when I got back from Stealth (they did the engine work) it has been perfect ever since. 

Difficult to conclude what it was. I had my chains done becuase there was a noticeable vibration at idle every 2 or 3 seconds and I was worried. My chains were stretched and my tensioner battererd. I have considered the warm start issue might have related to tolerences in the engine due to the chain stretch but I don't know really.

 

 

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19 hours ago, MJA said:

Prior to my engine work - just chains, head refuribishment and refreshed injectors - I was having an issue with warm starts. It would crank and crank and when it did it would cough slowly into life. I changed loads of sensors - coolant, cam and crank, the relays, I installed a 1 way valve on the fuel line, changed the FPR, new coil pack, new HT lines. Nothing solved the problem. Yet when I got back from Stealth (they did the engine work) it has been perfect ever since. 

Difficult to conclude what it was. I had my chains done becuase there was a noticeable vibration at idle every 2 or 3 seconds and I was worried. My chains were stretched and my tensioner battererd. I have considered the warm start issue might have related to tolerences in the engine due to the chain stretch but I don't know really.

 

 

Did you have a new MAF or clean the old one maybe

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No but the MAF did later fail 2 or so years later after the bodyshop. They had the airbox off and I assume ran it with the dust etc and destroyed it.

Sent from my SM-G960F using Tapatalk

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On 1/14/2022 at 4:50 PM, MJA said:

Prior to my engine work - just chains, head refuribishment and refreshed injectors - I was having an issue with warm starts. It would crank and crank and when it did it would cough slowly into life. I changed loads of sensors - coolant, cam and crank, the relays, I installed a 1 way valve on the fuel line, changed the FPR, new coil pack, new HT lines. Nothing solved the problem. Yet when I got back from Stealth (they did the engine work) it has been perfect ever since. 

Difficult to conclude what it was. I had my chains done becuase there was a noticeable vibration at idle every 2 or 3 seconds and I was worried. My chains were stretched and my tensioner battererd. I have considered the warm start issue might have related to tolerences in the engine due to the chain stretch but I don't know really.

 

 

That's interesting. I too changed the chains and tensioners, and had the head and injectors refurbished. Prior to doing the work, I had hoped it would fix that the warm start issue (among other things), assuming the same as you did that it was down to worn parts and tolerance. But, alas for some reason it hasn't.

On 1/15/2022 at 1:00 PM, 1xshaunx1 said:

Interesting read, I couldn't work out what this was referring to  

"look at the back center of the engine compartment for a missing part. There is a damper for the idle control system that often is blown apart by a backfire when enough fumes collect in the intake/breather system (see photo 2)." 

 

 

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Just to add i also had a new fuel pump installed when it was at Stealth with the other work so it could even have been that? The car was also remapped to suit cams. Lots done so very difficult to narrow it down now.

 

Sent from my SM-G960F using Tapatalk

 

 

 

 

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20 hours ago, oneohtwo said:

That's interesting. I too changed the chains and tensioners, and had the head and injectors refurbished. Prior to doing the work, I had hoped it would fix that the warm start issue (among other things), assuming the same as you did that it was down to worn parts and tolerance. But, alas for some reason it hasn't.

Interesting read, I couldn't work out what this was referring to  

"look at the back center of the engine compartment for a missing part. There is a damper for the idle control system that often is blown apart by a backfire when enough fumes collect in the intake/breather system (see photo 2)." 

 

 

Looks like a little black suitcase, and is attached to the ISV - back and right of engine when standing in front of the car, but may be hidden by the trim pieces that hold the plug leads. They often leak and can lead to poor idling and stalling. A lot of people delete them.

isv-damper.jpg

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Yes my one of those exploaded when the car was in the Bodyshop and gave them all a shock - they were too scared to even turn the engine on fearing some mechanical failure. I chatted to Vince at the time and he said it can be a sign of the crank sensor failing - no joke that actually happened 2 weeks later when i got the car home - no crank signal on VCDS on cranking and the car would not start. 

I replaced it with a used part and bought another as a spare rather than delete. 

 

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