mid range studder and flashing ses
Thread Starter
Teching In
Joined: Feb 2006
Posts: 5
Likes: 0
mid range studder and flashing ses i have a 2001 z28 with heads and cam. i recently put new heads on and now have all sorts of problems. between 3 and 5 thousand rpms the cars pops and studders like it is only running on 4 and then the ses light starts flashing. it does this at all throttle positions just a lot worse at full. it also wants to idle high while driving it wants to stay between 2 and 25 hundred rpms until i stop and let it idle down for 20 to 30 sec. i mean the car used to run great and now it wont out run a volkswagen. it has new plugs and wires and front 02 sensors. help please before i set it on fire.
TECH Senior Member
Joined: Nov 2001
Posts: 7,036
Likes: 1
From: Lake Zurich, IL
If you can get access to a scanner software, scan the cylinder misfire counts while it's happening... see if any are way higher than others.. a flashing SES means multiple misfires are detected.
Check the plugs as suggested above, also check the wires (I've had problems in the past where when it was really cold I cracked the boot to a few wires... if you start the car when it's dark out, pop the hood, you can see if there's any sparking/arching)
Check the plugs as suggested above, also check the wires (I've had problems in the past where when it was really cold I cracked the boot to a few wires... if you start the car when it's dark out, pop the hood, you can see if there's any sparking/arching)
Thread Starter
Teching In
Joined: Feb 2006
Posts: 5
Likes: 0
i just put new plugs and wires and i did what you said and check them. i also pull the injectors and the o-rings on the bottom are dried and cracked could that cause the problem. none of them were leaking. i test drove it today and it won't even make it past 3 thousand rpm's and the ses didnt flach till i let off. and it idles at 3 thousand till i let it set. 
TECH Senior Member
Joined: Nov 2001
Posts: 7,036
Likes: 1
From: Lake Zurich, IL
the idle hanging like that sounds like it may be a vacuum leak somewhere...
if it's a big one, you may be maxing your fuel trims (they try to add fuel if it detects a lean condition) at 25% and then still being lean you may be having detonation ...
Really need to scan it, see what the fuel trims are at and see which cylinder(s) are misfiring the most
when you put the heads on... were they milled alot? are you sure everything's sealed at the intake manifold?
you can check for a vacuum leak by taking a flammable spray and spraying around the intake (anything after the MAF basically), if the engine reacts (RPMs go up) then there's a leak
post up your location, maybe someone is local that could lend a hand
if it's a big one, you may be maxing your fuel trims (they try to add fuel if it detects a lean condition) at 25% and then still being lean you may be having detonation ...
Really need to scan it, see what the fuel trims are at and see which cylinder(s) are misfiring the most
when you put the heads on... were they milled alot? are you sure everything's sealed at the intake manifold?
you can check for a vacuum leak by taking a flammable spray and spraying around the intake (anything after the MAF basically), if the engine reacts (RPMs go up) then there's a leak
post up your location, maybe someone is local that could lend a hand
