Alfa Romeo Giulia Forum banner

2017 Giulia Ti stuttering at high RPM

4K views 24 replies 8 participants last post by  Alfissimo 
#1 ·
So it's likely not a major issue with the vehicle, but I can't pinpoint exactly whats going on.

Over the past week and a half, I have gotten an oil change at the dealership, changed my spark plugs from the OEM, to the Champion (9407) RER8ZWYCB4 (I had a hard time finding the OEM), replaced the stock air filter with a K&N filter, and refilled the cars gas as a smaller scale local station. So I figured it has to be one of these 4 things, and I'm leaning towards the plugs.

Whenever I drive the car mostly conservatively it's completely fine, I can go 10mph or 100mph and feel nothing wrong with car, as long as I don't really put my foot down and crank up the RPMs beyond like 4k-5k. Never has the issue before.

What do you guys think is likely the culprit here? I'm thinking maybe taking the plugs out and checking the gap? Idk, I just got any to figure it out ASAP.
 
#2 ·
So it's likely not a major issue with the vehicle, but I can't pinpoint exactly whats going on.

Over the past week and a half, I have gotten an oil change at the dealership, changed my spark plugs from the OEM, to the Champion (9407) RER8ZWYCB4 (I had a hard time finding the OEM), replaced the stock air filter with a K&N filter, and refilled the cars gas as a smaller scale local station. So I figured it has to be one of these 4 things, and I'm leaning towards the plugs.

Whenever I drive the car mostly conservatively it's completely fine, I can go 10mph or 100mph and feel nothing wrong with car, as long as I don't really put my foot down and crank up the RPMs beyond like 4k-5k. Never has the issue before.

What do you guys think is likely the culprit here? I'm thinking maybe taking the plugs out and checking the gap? Idk, I just got any to figure it out ASAP.
I think as @Beta Romeo said it’s most likely the champion spark plugS. Switch to OEM.
 
#3 ·
Definitely the spark plugs. The Champions are garbage.... not to say all Champions are garbage, just these don't work with the car. A lot of high RPM stumbles, maybe some misfire codes if you're lucky. If you still have the old ones, put them in until you can get the OEM NGK units.
 
#11 ·
I'm starting to actually think it might be the K&N filter feeding too much air and causing the engine to run lean. It could make just enough of a difference to throw off the air to fuel ratio, I have noticed much Turbo is much louder after the switch.

I've removed all the spark plugs and checked all the gaps and they seem to be correct. When I took the car back out, there was still significant stuttering, no CEL though.

It seems to only happen when I'm building boost. You can't even tell there's an issue otherwise. I may try a regular filter.

I'm probably going to still get the OEM plugs to be safe. Thoughts?
 
#12 ·
I'm starting to actually think it might be the K&N filter feeding too much air and causing the engine to run lean. It could make just enough of a difference to throw off the air to fuel ratio, I have noticed much Turbo is much louder after the switch.

I've removed all the spark plugs and checked all the gaps and they seem to be correct. When I took the car back out, there was still significant stuttering, no CEL though.

It seems to only happen when I'm building boost. You can't even tell there's an issue otherwise. I may try a regular filter.

I'm probably going to still get the OEM plugs to be safe. Thoughts?
These cars seem to dislike anything “foreign” and unless it really makes a difference for performance, I would generally keep to stock. I wouldn’t be surprised if you got an aftermarket light bulb and it would give a CEL.
 
#14 ·
Did they use the correct spec oil ?

I have been told by a dealership that they actually experimented with a different brand (Caltex) but same spec, and it threw up CEL warnings - they flushed it and replaced it with Selenia and it cleared that particular CEL
that could mean it rejected the Caltex version or the sensors didnt like something added in the Caltex, or whatever, but nevertheless, it happened ... which oil did they use
 
#15 ·
Some more weird updates. Last night when I turned off the car the highest the fuel range went up to was 400. I turned it on this morning and now it defaults to 500. Is this normal?

I'd like to add they (supposedly) did that W05 recall when I took it in the other day.

104365
 
#16 ·
It's not the filter. Higher/lower flowing filter does not affect fuel ratio, it only affects the volume of air the engine is capable of pulling in. Turbulence caused by an improper installation could cause wonky readings by the MAF sensor though. Make sure all of the intake piping and filter box are properly secured.
 
#17 ·
Just an update.

It's was the spark plugs. I cleaned out the spark plug well, the coils, and the plugs themselves and The Champions had to be set to 0.40. which is neither how they came nor what is recommended by Alfa.

I would say it's still only at 90-95%. So the OEM plugs are on their way from @Alfissimo

Don't ever touch the Champions, they suck.
 
#18 ·
Just an update.

It's was the spark plugs. I cleaned out the spark plug well, the coils, and the plugs themselves and The Champions had to be set to 0.40. which is neither how they came nor what is recommended by Alfa.

I would say it's still only at 90-95%. So the OEM plugs are on their way from @Alfissimo

Don't ever touch the Champions, they suck.
.60 - .65mm is OEM gap.
 
#21 ·
@Alfissimo

I just received your spark plugs today and would like to install them ASAP. Do they come gapped. If not, do you know what to gap them to? As I've gotten mixed answers.
.60 - .65mm is OEM gap.
 
#25 ·
So it's likely not a major issue with the vehicle, but I can't pinpoint exactly whats going on.

Over the past week and a half, I have gotten an oil change at the dealership, changed my spark plugs from the OEM, to the Champion (9407) RER8ZWYCB4 (I had a hard time finding the OEM), replaced the stock air filter with a K&N filter, and refilled the cars gas as a smaller scale local station. So I figured it has to be one of these 4 things, and I'm leaning towards the plugs.

Whenever I drive the car mostly conservatively it's completely fine, I can go 10mph or 100mph and feel nothing wrong with car, as long as I don't really put my foot down and crank up the RPMs beyond like 4k-5k. Never has the issue before.

What do you guys think is likely the culprit here? I'm thinking maybe taking the plugs out and checking the gap? Idk, I just got any to figure it out ASAP.
Check the gaps first.
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top