86gt rough idle and missfire
10-18-2009, 03:44 AM
#1
Thread Starter
Join Date: May 2009
Location: New Zealand
Posts: 22
86gt rough idle and missfire
ive got an 86gt with edelbrock heads and 2.02 valves. its had the cats removed but still has the O2 sensors in place. the EGR valve is gone and the hole has been sealed.
i;ve had a couple of problems with it though:
first problem is the idle, it surges a bit between about 800-1500rpm. sometimes it will keep doing this till it stalls and sometimes it won't do it at all. i'm planning to pull the manifold apart and replacing the gaskets. any ideas what else i can do to help it?
second problem is that driving at low rpm say below about 2500rpm it sometimes missfires slightly but not bad. and often feels like it gets restricted, like the power is held back. then you put your foot down a little bit more and after a couple of seconds it feels like someone flicks a switch and all the power comes back. could this be the plugs and leads? how about dirty injectors?
cheers
i;ve had a couple of problems with it though:
first problem is the idle, it surges a bit between about 800-1500rpm. sometimes it will keep doing this till it stalls and sometimes it won't do it at all. i'm planning to pull the manifold apart and replacing the gaskets. any ideas what else i can do to help it?
second problem is that driving at low rpm say below about 2500rpm it sometimes missfires slightly but not bad. and often feels like it gets restricted, like the power is held back. then you put your foot down a little bit more and after a couple of seconds it feels like someone flicks a switch and all the power comes back. could this be the plugs and leads? how about dirty injectors?
cheers
10-18-2009, 06:38 AM
#5
The Rogue Mod
Join Date: Feb 2006
Location: Maryland Sucka's!!
Posts: 21,918
Well, for the idle issue, it could be the IAC, try removing it and cleaning it or just a simple vacuum leak. For the flat spot, it could be the tps. There may be a dead spot in it. You'll need some type of graphing meter to be able to watch it's range of movement.
10-18-2009, 06:49 AM
#6
Thread Starter
Join Date: May 2009
Location: New Zealand
Posts: 22
how does the TPS sensor work? is it just like a variable resistor type thingy?
before i cleaned the manifold for pictures, dust was sitting noticeably more around the joint i have highlighted. would this suggest a vacuum leak at that point?
before i cleaned the manifold for pictures, dust was sitting noticeably more around the joint i have highlighted. would this suggest a vacuum leak at that point?
10-18-2009, 12:44 PM
#7
6th Gear Member
Join Date: Jul 2006
Location: San Diego, CA
Posts: 6,882
not really, take a can of carb cleaner, turn on the car and spray around on lines and any areas you think there are leaks, if the rpms shoot up then you found a leak, also heres how you pull codes from the ecu
http://sbftech.com/index.php/topic,2471.0.html
http://sbftech.com/index.php/topic,2471.0.html
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