Rough Start

[Popeye775 16]

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

I will do more investigating on my grounds! I might just end up replacing them because I doubt they have ever been replaced.


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[Popeye775 16]

UPDATE:

Started second try today. Ran pretty well. I took it out for a test drive and the only place it felt weird was in boost shifting to third. It felt like right off the shift for a split second, it started to misfire. Out of boost - going into third or any gear - there wasn't much of any misfire if any at all. But in boost, it felt like it was misfiring/burbling going into third. I am going to get it vacuum tested, but I have a feeling there could be a vacuum leak in the boost hoses maybe?? Possible ground issues as mentioned above?? 

Ideas???

[Bennitoapplebum 2]

1 hour ago, Popeye775 said:

UPDATE:

Started second try today. Ran pretty well. I took it out for a test drive and the only place it felt weird was in boost shifting to third. It felt like right off the shift for a split second, it started to misfire. Out of boost - going into third or any gear - there wasn't much of any misfire if any at all. But in boost, it felt like it was misfiring/burbling going into third. I am going to get it vacuum tested, but I have a feeling there could be a vacuum leak in the boost hoses maybe?? Possible ground issues as mentioned above?? 

Ideas???

It’s definitely worth checking for vacuum leaks and voltage drops.  That way you’ll be playing with a full deck of cards.  But if she runs fine with no misfires or hiccups while cruising out of boost, then I’d say it’s more of a tuning issue.  The worst case scenario is if you’re running out of fuel in boost, causing misfires and ECU timing pull.  The ‘not so bad’ scenario is your boost is blowing out your spark.

After your next test drive(after the vacuum leak check) it’ll be helpful to pull your plugs and do two things:

1.  Take a picture. Compare them to online pictures of what’s healthy for boost. Or send pics here

2.  Close the spark plug gap a little smaller than factory specs(~.023”)

If your plugs show dangerous signs then you gotta address the fueling first before going for another drive.

[Popeye775 16]

It’s definitely worth checking for vacuum leaks and voltage drops.  That way you’ll be playing with a full deck of cards.  But if she runs fine with no misfires or hiccups while cruising out of boost, then I’d say it’s more of a tuning issue.  The worst case scenario is if you’re running out of fuel in boost, causing misfires and ECU timing pull.  The ‘not so bad’ scenario is your boost is blowing out your spark.
After your next test drive(after the vacuum leak check) it’ll be helpful to pull your plugs and do two things:
1.  Take a picture. Compare them to online pictures of what’s healthy for boost. Or send pics here
2.  Close the spark plug gap a little smaller than factory specs(~.023”)
If your plugs show dangerous signs then you gotta address the fueling first before going for another drive.

Sounds good! Tomorrow I am also going to check for weak spark.


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[Popeye775 16]

It’s definitely worth checking for vacuum leaks and voltage drops.  That way you’ll be playing with a full deck of cards.  But if she runs fine with no misfires or hiccups while cruising out of boost, then I’d say it’s more of a tuning issue.  The worst case scenario is if you’re running out of fuel in boost, causing misfires and ECU timing pull.  The ‘not so bad’ scenario is your boost is blowing out your spark.
After your next test drive(after the vacuum leak check) it’ll be helpful to pull your plugs and do two things:
1.  Take a picture. Compare them to online pictures of what’s healthy for boost. Or send pics here
2.  Close the spark plug gap a little smaller than factory specs(~.023”)
If your plugs show dangerous signs then you gotta address the fueling first before going for another drive.

Now this may also be a dumb question but when adjusting the fuel pressure up for the chip - since it needs 3.5 bar - , is it 3.5 bar with the vacuum line plugged in or unplugged because I saw someone say with it unplugged but want to double check this


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[Bennitoapplebum 2]

12 hours ago, Popeye775 said:

Now this may also be a dumb question but when adjusting the fuel pressure up for the chip - since it needs 3.5 bar - , is it 3.5 bar with the vacuum line plugged in or unplugged because I saw someone say with it unplugged but want to double check this


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Yes that is correct.  Unplugged.  

[Popeye775 16]

Yes that is correct.  Unplugged.  

Ok I just wanted to be sure o had the fuel pressure set correctly.


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[Popeye775 16]

It’s definitely worth checking for vacuum leaks and voltage drops.  That way you’ll be playing with a full deck of cards.  But if she runs fine with no misfires or hiccups while cruising out of boost, then I’d say it’s more of a tuning issue.  The worst case scenario is if you’re running out of fuel in boost, causing misfires and ECU timing pull.  The ‘not so bad’ scenario is your boost is blowing out your spark.
After your next test drive(after the vacuum leak check) it’ll be helpful to pull your plugs and do two things:
1.  Take a picture. Compare them to online pictures of what’s healthy for boost. Or send pics here
2.  Close the spark plug gap a little smaller than factory specs(~.023”)
If your plugs show dangerous signs then you gotta address the fueling first before going for another drive.

It sounds like I won’t have access to a smoke tester until next weekend. So in the meantime, would it help to go ahead and pull the plugs and I will post them up?


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[Popeye775 16]

Here are the plugs. I dropped the gap on them because they were at .029. I also did a voltage test on the harness connector going to the distributor as well as a voltage test on the grounds. I am going to do a voltage drop test later to make double check the grounds as well.


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[Popeye775 16]

New development as well. Took her back out again after regapping plugs. Car started right up, and this time if I eased into boost going into third, there wasn’t any misfire action. But if I shifted into third and immediately went foot down, then it misfired.


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[Bennitoapplebum 2]

19 minutes ago, Popeye775 said:

New development as well. Took her back out again after regapping plugs. Car started right up, and this time if I eased into boost going into third, there wasn’t any misfire action. But if I shifted into third and immediately went foot down, then it misfired.


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Make sure those plugs are resistor type.  You seem to be running lean, most definitely causing the misfires.  The porcelain is white, lighter than tan.  The color for these motors should be more sooty, darker grey.  You’re almost there, after you sort out the fueling issue I’ll bet she’ll pull like a freight train.  It would help to have a wideband 02 meter to squeeze the most out of your motor, but pulling the plugs for a reading isn’t bad on the 8 valve motors.  

You can address the fueling with one of three ways:

1. CO potentiometer adjustment

2. Higher fuel pressure regulator (4 bar)

3. Stand alone fuel management.

[Popeye775 16]

Make sure those plugs are resistor type.  You seem to be running lean, most definitely causing the misfires.  The porcelain is white, lighter than tan.  The color for these motors should be more sooty, darker grey.  You’re almost there, after you sort out the fueling issue I’ll bet she’ll pull like a freight train.  It would help to have a wideband 02 meter to squeeze the most out of your motor, but pulling the plugs for a reading isn’t bad on the 8 valve motors.  

You can address the fueling with one of three ways:
1. CO potentiometer adjustment
2. Higher fuel pressure regulator (4 bar)
3. Stand alone fuel management.

So I am running a 3-5 bar fuel pressure regulator so I could turn up the fuel pressure. My CO pot is set to a resistance of 550 ohms, what would you say this should be turned up to? Or should I turn the fuel pressure to 4bar and leave the CO pot where it’s at?


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[Bennitoapplebum 2]

52 minutes ago, Popeye775 said:

So I am running a 3-5 bar fuel pressure regulator so I could turn up the fuel pressure. My CO pot is set to a resistance of 550 ohms, what would you say this should be turned up to? Or should I turn the fuel pressure to 4bar and leave the CO pot where it’s at?


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I’d say leave the CO pot where its at, and just turn up the fuel pressure for now.  Then go for a drive and pull the plugs again to have another look.

It sounds bothersome, but it’s tuning😂

Edited August 14, 2020 by Bennitoapplebum
Spell check

[Popeye775 16]

I’d say leave the CO pot where its at, and just turn up the fuel pressure for now.  Then go for a drive and pull the plugs again to have another look.
It sounds bothersome, but it’s tuning

Perfect! I will turn it up to 4bar with the vacuum unplugged and see what it does. Thank you sir!


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[Popeye775 16]

Here’s a drive on 4bar fuel pressure and .024 gap. Felt good shifting in boost but felt a little misfire-ish cruising. So I might increase gap to .025. Am I going about that the right way?


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[Bennitoapplebum 2]

2 hours ago, Popeye775 said:

Here’s a drive on 4bar fuel pressure and .024 gap. Felt good shifting in boost but felt a little misfire-ish cruising. So I might increase gap to .025. Am I going about that the right way?


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Looking a little better now, still a little on the lean side for these motors.  But the 4th plug looks a little whiter than the rest. I’d look into that.  Increasing the gap will be harder to ignite under boost, but may help with the cruising loads.

The current plug conditions you show are safe for about 8-10 lbs of boost. If you’re running any higher boost you need more fuel.  

Are you comfortable with adjusting your timing?  If you’re running low boost ~8 lbs I feel that advancing the timing slightly will help with the cruising misfire.

[Popeye775 16]

13 hours ago, Bennitoapplebum said:

Looking a little better now, still a little on the lean side for these motors.  But the 4th plug looks a little whiter than the rest. I’d look into that.  Increasing the gap will be harder to ignite under boost, but may help with the cruising loads.

The current plug conditions you show are safe for about 8-10 lbs of boost. If you’re running any higher boost you need more fuel.  

Are you comfortable with adjusting your timing?  If you’re running low boost ~8 lbs I feel that advancing the timing slightly will help with the cruising misfire.

The timing is set for 6 degrees BTDC currently. I only increased the plug gap by .001 (.024 - .025) so I didn't compromise the fuel igniting under boost. Advancing the timing maybe like one degree? Maybe two?

[Bennitoapplebum 2]

5 hours ago, Popeye775 said:

The timing is set for 6 degrees BTDC currently. I only increased the plug gap by .001 (.024 - .025) so I didn't compromise the fuel igniting under boost. Advancing the timing maybe like one degree? Maybe two?

Yes, about two degrees should be good.  Be careful, with the power addition from the increased timing, you’ll want to keep advancing timing till the engine blows up😂it gets addicting. 
 

 Try 2 degrees.  See how she drives.

[Popeye775 16]

1 hour ago, Bennitoapplebum said:

Yes, about two degrees should be good.  Be careful, with the power addition from the increased timing, you’ll want to keep advancing timing till the engine blows up😂it gets addicting. 
 

 Try 2 degrees.  See how she drives.

Awesome sounds good sir! Thank you so much for all of your constant help

[Popeye775 16]

Update: 

I just took it out after the gap being at .025 and increasing the timing by about one degree. It felt really good. It misfired a little full throttle at first but then stopped doing it after a couple pulls. It also didn't feel like it was missing while cruising. At least if it was, then I didn't feel it. Under 2k it was a little missy or burbly taking off unless I blurped the throttle. I am assuming there is a boost leak or vacuum leak somewhere causing it to do that because it wasn't consistent. But that is the best it has felt in a long time. Do you think I should decrease the gap back down to .024 and try it that way or take a look at the plugs first and figure out where to go from there?

 

 PS: I will post a photo of the plugs here in a little once the car cools off a little bit.

[Bennitoapplebum 2]

5 hours ago, Popeye775 said:

Update: 

I just took it out after the gap being at .025 and increasing the timing by about one degree. It felt really good. It misfired a little full throttle at first but then stopped doing it after a couple pulls. It also didn't feel like it was missing while cruising. At least if it was, then I didn't feel it. Under 2k it was a little missy or burbly taking off unless I blurped the throttle. I am assuming there is a boost leak or vacuum leak somewhere causing it to do that because it wasn't consistent. But that is the best it has felt in a long time. Do you think I should decrease the gap back down to .024 and try it that way or take a look at the plugs first and figure out where to go from there?

 

 PS: I will post a photo of the plugs here in a little once the car cools off a little bit.

Sounds like she’s almost there!  There could be a vacuum leak somewhere, but it’s sounding more like a tuning issue.  

When you say ‘missy’ or ‘burbly’ do you feel a hesitation? Or just slightly jerky with a steady throttle?  From what I remember with the 268 cams there was always a light load/cruising misfire under 2000rpm that immediately went away upon throttle addition.  If there’s hesitation upon any acceleration, then I’d worry.  I’m not sure if that’s what you mean though.
 

You can leave that spark plug gap for now. It should be good, but if you wanna add more boost then you should close the gap.

Im assuming you just need a tad more fuel, but we’ll see after looking at those plugs.

 

[Popeye775 16]

10 hours ago, Bennitoapplebum said:

Sounds like she’s almost there!  There could be a vacuum leak somewhere, but it’s sounding more like a tuning issue.  

When you say ‘missy’ or ‘burbly’ do you feel a hesitation? Or just slightly jerky with a steady throttle?  From what I remember with the 268 cams there was always a light load/cruising misfire under 2000rpm that immediately went away upon throttle addition.  If there’s hesitation upon any acceleration, then I’d worry.  I’m not sure if that’s what you mean though.
 

You can leave that spark plug gap for now. It should be good, but if you wanna add more boost then you should close the gap.

Im assuming you just need a tad more fuel, but we’ll see after looking at those plugs.

 

The 268 cam is not yet in there. I am waiting on a valve cover gasket to get here before I can put it in. So when I say burbly or missy I mean it sounds like it is stuttering and it lacks acceleration. Basically like it is hesitating. Here is an old video that has the sound captured pretty well. You can hear as soon as I go to rev the car, there is a burble like sound.

 

https://www.youtube.com/watch?v=4AOgdg1Hsps

[Bennitoapplebum 2]

3 hours ago, Popeye775 said:

The 268 cam is not yet in there. I am waiting on a valve cover gasket to get here before I can put it in. So when I say burbly or missy I mean it sounds like it is stuttering and it lacks acceleration. Basically like it is hesitating. Here is an old video that has the sound captured pretty well. You can hear as soon as I go to rev the car, there is a burble like sound.

 

https://www.youtube.com/watch?v=4AOgdg1Hsps

Ah, I’ve assumed you had the cams in there already. Yeah that’s definitely a misfire.  With that understood I’m thinking it’s still a fuel issue.  Next step would be to try the CO pot adjustment.  You want those plugs looking a little more sooty.

[Popeye775 16]

Ah, I’ve assumed you had the cams in there already. Yeah that’s definitely a misfire.  With that understood I’m thinking it’s still a fuel issue.  Next step would be to try the CO pot adjustment.  You want those plugs looking a little more sooty.

When it comes to adjusting the CO pot, do you do it while the car is on or off? Also I’m assuming in 1/4 turn increments clockwise?


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[Popeye775 16]

So I did some research and from what it seems the CO pot should be set to 500ohm. That way it isn’t pulling or adding fuel. So what I did was set mine to 500ohm and I will see how it feels from that adjustment


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