Rough Start

[Popeye775 16]

Hey all,

I’ve tried finding other forums - to which I only found some but unresolved - on rough start issues. So my 1990 G60 is having a rough start issue. I just fixed the timing - after it had jumped a tooth - and have looked this car up and down. Here’s a list of things replaced so far:

Distributor
Ignition coil
Plug wires
Plugs
Fuel pump (and relay)
Fuel filter
Fuel lines
Starter
All ground checked
All wire harnesses checked

The car takes a couple tries to turn on. It’ll turn on for a split second and then die the first couple times. It’ll try to keep itself on but can’t usually until the third try. I have new fuel injectors also on the way as for they have never been replaced and the seals have never been replaced either by the PO. Any advice on this rough start issue?

Timing has also been triple checked. 
 

[Dox 22]

On the 3rd try it runs smoothly?

[Popeye775 16]

On the 3rd try it runs smoothly?

Not smoothly. Will bog a tiny bit but then will start idling pretty smooth. It still has its little misfire under 2k rpm, but if I hold throttle at ~2k rpm the misfire smooths out.


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[Dox 22]

I had similar with an 8v golf, the head gasket was blown between water jacket and cylinder number 1, no fault when hot, when the engine cooled and the coolant was still pressurised the coolant would leak into the cylinder and sit there until the next cold start.

 

remove the plugs and using a torch look at the top of the pistons, if one is much cleaner than the other 3 suspect the head gasket - the coolant steam cleans the piston crown.

[Popeye775 16]

I had similar with an 8v golf, the head gasket was blown between water jacket and cylinder number 1, no fault when hot, when the engine cooled and the coolant was still pressurised the coolant would leak into the cylinder and sit there until the next cold start.
 
remove the plugs and using a torch look at the top of the pistons, if one is much cleaner than the other 3 suspect the head gasket - the coolant steam cleans the piston crown.

Will do sir!


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[Popeye775 16]

I had similar with an 8v golf, the head gasket was blown between water jacket and cylinder number 1, no fault when hot, when the engine cooled and the coolant was still pressurised the coolant would leak into the cylinder and sit there until the next cold start.
 
remove the plugs and using a torch look at the top of the pistons, if one is much cleaner than the other 3 suspect the head gasket - the coolant steam cleans the piston crown.

Just checked, seems that cylinder one and two look cleaner than three and four. One also had some sort of liquid on the piston head that looked like a rusty color?


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[Popeye775 16]

Tried different tests. Checked oil cap - there’s no milky oil - and checked for bubbling coolant in the reservoir - no bubbling in the coolant either. So could it possibly be leaking fuel injectors also cleaning the piston heads? I also have no white smoke continuously coming from the exhaust


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[Dox 22]

8 hours ago, Popeye775 said:

Tried different tests. Checked oil cap - there’s no milky oil - and checked for bubbling coolant in the reservoir - no bubbling in the coolant either. So could it possibly be leaking fuel injectors also cleaning the piston heads? I also have no white smoke continuously coming from the exhaust


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Get a cotton bud and smell the liquid - if its still there several hours later its not likely to be fuel?

If the gasket is only breached between the coolant circuit and cylinder you wont get oil / coolant mixing.

You've found something to investigate further that's probably causing the rough running on start up.

[Popeye775 16]

Get a cotton bud and smell the liquid - if its still there several hours later its not likely to be fuel?
If the gasket is only breached between the coolant circuit and cylinder you wont get oil / coolant mixing.
You've found something to investigate further that's probably causing the rough running on start up.

Hi sir, stuck cotton down there and smelt it. It only smells like exhaust/fuel. Doesn’t smell like coolant or oil


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[Bennitoapplebum 2]

Hello! By any chance you have the Bosch Digifant-1 Fuel Injection?  It *may* be as simple as changing a coolant sensor(blue)

[Popeye775 16]

Hello! By any chance you have the Bosch Digifant-1 Fuel Injection?  It *may* be as simple as changing a coolant sensor(blue)

Hi! I did think about that, but I also just changed the coolant sensor less than a year ago. Although they are relatively cheap and easy to replace so might be worth trying


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[Bennitoapplebum 2]

15 minutes ago, Popeye775 said:

Hi! I did think about that, but I also just changed the coolant sensor less than a year ago. Although they are relatively cheap and easy to replace so might be worth trying


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Hmm, maybe the sensor is still good.  Any leaks in the vacuum line to the ECU?

[Popeye775 16]

Hmm, maybe the sensor is still good.  Any leaks in the vacuum line to the ECU?

All vacuum lines have been replaced


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[Popeye775 16]

And are at proper length


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[Bennitoapplebum 2]

On 7/17/2020 at 12:38 PM, Popeye775 said:

Hey all,

I’ve tried finding other forums - to which I only found some but unresolved - on rough start issues. So my 1990 G60 is having a rough start issue. I just fixed the timing - after it had jumped a tooth - and have looked this car up and down. Here’s a list of things replaced so far:

Distributor
Ignition coil
Plug wires
Plugs
Fuel pump (and relay)
Fuel filter
Fuel lines
Starter
All ground checked
All wire harnesses checked

The car takes a couple tries to turn on. It’ll turn on for a split second and then die the first couple times. It’ll try to keep itself on but can’t usually until the third try. I have new fuel injectors also on the way as for they have never been replaced and the seals have never been replaced either by the PO. Any advice on this rough start issue?

Timing has also been triple checked. 
 

Other than the rough start, it runs and drives fine? I don’t know where else to check besides fuel pressure regulation, and compression. Sorry if I’m too persistent, I just LOVE these cars

[Popeye775 16]

Other than the rough start, it runs and drives fine? I don’t know where else to check besides fuel pressure regulation, and compression. Sorry if I’m too persistent, I just LOVE these cars

No no you’re good! I had a compression issue but it was that the timing skipped a tooth when the belt became loose a while back. That has since been fixed. At this point everything else has been checked over. The only other thing it does is misfire under 2k rpm. But it throttle is blurped or held at anywhere under 2k the misfire will clear up. As if - what I’m assuming - the injectors are dirty or something to that effect. The injectors and seals have never been replaced on the car so they are 30 years old at this point. PO never replaced them to my knowledge


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[Bennitoapplebum 2]

I just read your other post.  Just a thing to point out is your crankshaft pulley bolt.  If there is loose red iron dust around the head of the bolt, it may be coming loose and slipping. That may be the cause of your timing coming undone.  

[Popeye775 16]

I just read your other post.  Just a thing to point out is your crankshaft pulley bolt.  If there is loose red iron dust around the head of the bolt, it may be coming loose and slipping. That may be the cause of your timing coming undone.  

I will look into this thank you!


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[Popeye775 16]

Hey guys, here’s a video of the rough start. This is with new injectors.

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[Bennitoapplebum 2]

Other than the rough start, did it clear up your low rpm misfires?  From the video it seemed to be running okay?  

[Dox 22]

On 7/18/2020 at 11:19 PM, Popeye775 said:

Hi sir, stuck cotton down there and smelt it. It only smells like exhaust/fuel. Doesn’t smell like coolant or oil


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Time to investigate more?

[Popeye775 16]

Other than the rough start, did it clear up your low rpm misfires?  From the video it seemed to be running okay?  

It did clear that up!


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[Popeye775 16]

Time to investigate more?

Still chances of being a blown head gasket you think?


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[Popeye775 16]

Weird development:

I put on an old ISV I had to see if the ISV could be the cause. As soon as that one went on, the car started it’s misfiring again. Put the new one that I had bought for it back on, and the misfire continued.


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[Bennitoapplebum 2]

20 hours ago, Popeye775 said:

Weird development:

I put on an old ISV I had to see if the ISV could be the cause. As soon as that one went on, the car started it’s misfiring again. Put the new one that I had bought for it back on, and the misfire continued.


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Intermittent problems are usually caused by bad power/ground connections. 

I know you said you’ve checked all grounds and harnesses.  How was that tested? Resistance testing? Or voltage drop testing?  Or just a visual inspection?

Resistance testing is not really accurate as older wires may show good continuity, but cannot carry current when the load is present.

A visual inspection is even worse with these older cars.

Voltage drop testing is key to finding these electrical gremlins.

I was forced to learn a LOT just for owning a Corrado😂