Stumbling around 2000-3000 RPM
04-29-04, 03:24 PM
#1
Lawn Ornament
Thread Starter
Stumbling around 2000-3000 RPM
Ok I drove my car to an exhaust shop today to get an IC pipe made and exhaust aligned.... Well this is the first trip that car has made in over a year... closer to two 
It idles great, but when i get near 2K RPM it begins to stutter, and miss pretty bad, after i get passed about 2.5-3K it stops and is smooth again.
Now I do have 1680cc secondaries with stock "cleaned" primaries. The PFC is set to 1500cc for the time being, is this just something I should expect until i get the thing tuned and injectors set to the right amount?
I'm not going to be driving it around, I just wanted to know if there was anyway to fix this before I have to drive her home tomorrow night...
Im guessing this has to do with the secondary injector transition...
It idles great, but when i get near 2K RPM it begins to stutter, and miss pretty bad, after i get passed about 2.5-3K it stops and is smooth again.
Now I do have 1680cc secondaries with stock "cleaned" primaries. The PFC is set to 1500cc for the time being, is this just something I should expect until i get the thing tuned and injectors set to the right amount?
I'm not going to be driving it around, I just wanted to know if there was anyway to fix this before I have to drive her home tomorrow night...
Im guessing this has to do with the secondary injector transition...
04-29-04, 07:17 PM
#5
Senior Member
Join Date: Nov 2003
Location: Irvine, California
Posts: 599
Likes: 0
Received 0 Likes
on
0 Posts
There is the 3k hesitation, I have it and have studied it for months. I have come to the conclusion its much like Osoma Bin Laden, there but hard to find. There seems to be little rationality to it or when it will appear.
04-29-04, 07:40 PM
#6
Vagina Junction
Join Date: Mar 2001
Location: Seattle, WA
Posts: 1,838
Likes: 0
Received 0 Likes
on
0 Posts
There's no 3k hesitation on a standalone ECU 
You weren't boosting, obviously, with no intercooler piping, so your secondaries shouldn't have even come on. It's probably due to the new exhaust and tuning. With different amounts of backpressure/flow you inherantly run a little different. Probably just bounching between lean and rich fuel cells.
You weren't boosting, obviously, with no intercooler piping, so your secondaries shouldn't have even come on. It's probably due to the new exhaust and tuning. With different amounts of backpressure/flow you inherantly run a little different. Probably just bounching between lean and rich fuel cells.
Trending Topics
04-29-04, 08:25 PM
#8
Lawn Ornament
Thread Starter
lol 3K hesitation... nope long gone....
Its a T04S single, straight pipe to a Greddy Exhaust.. and all the normal mods... Its running on a base map on the PFC, like I said it was just a ~15 mile drive to his shop...
Its a T04S single, straight pipe to a Greddy Exhaust.. and all the normal mods... Its running on a base map on the PFC, like I said it was just a ~15 mile drive to his shop...
04-29-04, 08:26 PM
#9
built my own engine
perhaps you are running the old style ignition coil harness, i have seen people eliminate issues with this by updating it with the newer (non grounded) one
04-29-04, 08:59 PM
#11
Rotary Enthusiast
Join Date: Jan 2004
Location: New Zealand
Posts: 1,003
Likes: 0
Received 0 Likes
on
0 Posts
ignition , check ******s and coils, also ignition pickups ( although missing with this will only happen at low RPM, )check all groundings.
Could be a wastgate problem check vacume hosing,
have you just sat in neutral and WOT past 3000k to see if you still get missing while stationary?
Could be a wastgate problem check vacume hosing,
have you just sat in neutral and WOT past 3000k to see if you still get missing while stationary?
04-29-04, 09:14 PM
#13
No it's not Turbo'd
Did you have the 1600's before !? And if not they need to be attenuated with Power FC (Add Resitors) or else they won't act right, also if you've gotten things adjusted in your intake path, you're likely to have to adjust the injetor duty cycle to be able to transition smoothly... this might be a good question to post in the PFC section under EMS, since it seems like a fuel or ignition map issue...
04-29-04, 09:45 PM
#14
Lawn Ornament
Thread Starter
Originally posted by DCrosby
Did you have the 1600's before !? And if not they need to be attenuated with Power FC (Add Resitors) or else they won't act right, also if you've gotten things adjusted in your intake path, you're likely to have to adjust the injetor duty cycle to be able to transition smoothly... this might be a good question to post in the PFC section under EMS, since it seems like a fuel or ignition map issue...
Did you have the 1600's before !? And if not they need to be attenuated with Power FC (Add Resitors) or else they won't act right, also if you've gotten things adjusted in your intake path, you're likely to have to adjust the injetor duty cycle to be able to transition smoothly... this might be a good question to post in the PFC section under EMS, since it seems like a fuel or ignition map issue...
04-29-04, 10:03 PM
#16
Lawn Ornament
Thread Starter
Originally posted by DCrosby
That might be your issue, since that area is where the secondaries come online...
That might be your issue, since that area is where the secondaries come online...
04-29-04, 10:14 PM
#17
Dont make me Laugh
iTrader: (8)
Join Date: Feb 2002
Location: All Hope is Lost
Posts: 1,238
Likes: 0
Received 0 Likes
on
0 Posts
Might be the fuel? How old is it and did you add anything to it to stablize it?
Secondaries come on when there is a need. I really doubt there is one at that RPM.
Secondaries come on when there is a need. I really doubt there is one at that RPM.
04-29-04, 10:19 PM
#18
No it's not Turbo'd
So I stand corrected, but I'm pretty certain it's not waiting for you to have 7-8 psi for the secondaries to come online, but the fact the Power FC has improper information isn't going to help...
As soon, as the seconday runners get air, the secondaries come online, but in an FD, you'd have to keep a feather on the pedal not to go to 0 Manifold pressure, and anything above is boost...
As soon, as the seconday runners get air, the secondaries come online, but in an FD, you'd have to keep a feather on the pedal not to go to 0 Manifold pressure, and anything above is boost...
04-29-04, 10:30 PM
#19
I find it helpful to know if the car is going lean or rich.
Sounds like it could be an injector overlap issue. Many of us had to play with the inj settings to get transition to be smooth. Put an AFR meter on it and try adjusting your inj overlap, sec transition, etc settings. Search the PFC forum and read up, there are many tips on this. If you have trouble just search for my name on the PFC forum and you should uncover some threads on this topic.
Sounds like it could be an injector overlap issue. Many of us had to play with the inj settings to get transition to be smooth. Put an AFR meter on it and try adjusting your inj overlap, sec transition, etc settings. Search the PFC forum and read up, there are many tips on this. If you have trouble just search for my name on the PFC forum and you should uncover some threads on this topic.
04-29-04, 10:54 PM
#20
Lawn Ornament
Thread Starter
Fuel is new.... injector overlap is what I have htought from the beginning was the cause of it... I guess Ill search the PFC forum to find info on tuning it....
04-29-04, 11:29 PM
#21
Vagina Junction
Join Date: Mar 2001
Location: Seattle, WA
Posts: 1,838
Likes: 0
Received 0 Likes
on
0 Posts
no, you're supposed to be
100% primary in vacuum
75% primary 25% secondary at 0
50% primary 50% secondary in boost
approximately. if you're not getting out of vacuum at that RPM, you're not getting secondaries.
100% primary in vacuum
75% primary 25% secondary at 0
50% primary 50% secondary in boost
approximately. if you're not getting out of vacuum at that RPM, you're not getting secondaries.
04-29-04, 11:47 PM
#22
Full Member
Join Date: Oct 2003
Location: Tucson
Posts: 241
Likes: 0
Received 0 Likes
on
0 Posts
04-29-04, 11:48 PM
#23
Lawn Ornament
Thread Starter
read the damn thread, its seemingly more apparent that it is due to fuel maps than anything, but I still dont see how that is...
Last edited by ejmack1; 04-29-04 at 11:51 PM.
04-30-04, 12:16 AM
#24
John
Join Date: Mar 2001
Location: Oregon
Posts: 1,393
Likes: 0
Received 0 Likes
on
0 Posts
Same thing happened to my brother's FD. He had a single TO4S with PFC, 1600cc, 850cc inj. It stubled at 4K really bad. Took it to the dyno and found it running lean as hell!! Fuel pressure for some reason dropped to like 30psi. After it was tuned with correct afr's it ran fine. I'd say find out what your afr's are
