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420A Stuttering problems

Inkdlyfe

Proven Member
438
7
Feb 23, 2016
Summer feild, Florida
Alright so I been having this problem for quite some time now and it's really starting to drive me up a wall for real so it's a fully built turbo 420a with all the works done to it I have done countless tube ups even tried to use 89 still does it spark plugs are tapped at .28 bout to go change it to .32 and see if that helps any but I doubt it I have no boost leaks that I know of or vacc leaks... Can someone tell me why this is doing this please.... But here is the problem when I'm driving it and it under load while crusing I can like tell exactly when it's about to do it it does it exactly at 4000 EVERY TIME and it's like it hits red line and I lean out and it's like the car just looses power but if I shift at 3900 it don't act up at all BUT if I'm at a stand still and drop it from 7000 rpms and keep my rpms high it don't act up at all... Why is this please help me
 

Vegas Smith

Proven Member
4,850
2,723
Dec 2, 2002
Houston, Texas
Unfortunately we know nothing about your car but it sounds like it could be a fuel pump/filter problem. Maybe it's fuel cut you are referring to when you hit boost and the car stutters because the car doesn't have enough fuel.
 

ThunderChild

Supporting VIP
3,760
1,124
Jan 5, 2012
Rathdrum, Idaho
Did you ever get a proper tune or a way to data log anything? You keep throwing parts and cheap fixes at this thing, when what you need to do is have a way to log the events.
Your issue could be multiple things: fuel, ignition, sensors gone bad etc. Without a way to show us a data log, we can't help.

Also, if you mean you're gapping your plugs out to .32", I wouldnt recommend that. Also, I highly doubt 89 octane (again I'm assuming this is what you're referring to) is enough for your turbo'd 420a. You should be running premium at the minimum, 91-93 octane.
 

Inkdlyfe

Proven Member
438
7
Feb 23, 2016
Summer feild, Florida
Did you ever get a proper tune or a way to data log anything? You keep throwing parts and cheap fixes at this thing, when what you need to do is have a way to log the events.
Your issue could be multiple things: fuel, ignition, sensors gone bad etc. Without a way to show us a data log, we can't help.

Also, if you mean you're gapping your plugs out to .32", I wouldnt recommend that. Also, I highly doubt 89 octane (again I'm assuming this is what you're referring to) is enough for your turbo'd 420a. You should be running premium at the minimum, 91-93 octane.
The car has been tuned at kings profoamce in Orlando fl about a year ago and no cheap parts or fixes have been done I gapped them to .32 and made no difference so Imma put them back to .28 and I only run 93 oct in my car all the time. And for the most part every sensor in the engine is new and I have a missing link nap sensor too new wire and coil pack and the fuel pump is fairly new.... And the not getting enough fuel question how would that be if I can drop it at 7k and it not act up at all it's only when building up to 4k from a stop
 

ThunderChild

Supporting VIP
3,760
1,124
Jan 5, 2012
Rathdrum, Idaho
like i said, without a log, we wont really be able to help much. being tuned somewhere with no way to data-log isnt helpful, as any number of cars can be tuned, but that doesnt mean the tune is worth a darn.

if you cant accelerate through the rpm range, but can dump the clutch from a stand still, i suspect you might have a fuel issue based on load and boost. best guess right now, but we really need to see a log with showing the event youre describing to give you the best advice.
 

dsmcrzy

Proven Member
1,628
333
Dec 20, 2009
Trenton, Ohio
The fact that you say you have a missing link tells me the car is not tuned. Your running a FMU or SFMU. That's not tuning... That's throwing more fuel and hoping for the best.

Do you have a wideband AFR gauge? Whats it reading when this happens? YOu have literally given no info besides the fact that the car is turbo, has some new sensors, wires and coil pack. Start a profile for your car and fill it out so we can properly help you.
 

Inkdlyfe

Proven Member
438
7
Feb 23, 2016
Summer feild, Florida
When I got the car it didn't have a missing link but I kept getting a code for the map sensor so maybe running a missing link could be the problem for this ??? I never thought of that ... It don't say my map is bad nor is acting up just says it has a high out put but yes it is tuned and car ran perfectly fine no problems what do ever just ran into this problem a few weeks ago . had the car for about 7 months now maybe a clogged fuel filter ?? This happened outta no where one day
 

dsmcrzy

Proven Member
1,628
333
Dec 20, 2009
Trenton, Ohio
ok. So that missing link is doing absolutely nothing! The MS unit has its own on board MAP sensor. Plug in your laptop open up tunerstudio and take a log. Post it here and I'll take a look at it.

What is MS controlling? just fuel or fuel and spark?
 

Inkdlyfe

Proven Member
438
7
Feb 23, 2016
Summer feild, Florida
Not even sure tbh I have a aem fms that's piggy backing my computers
 
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