Hey everyone,

My car is significantly down on power currently, and I guess I am looking for some input.

The car was running great after just getting the new 9" put in, and I was going to take it on a road trip to a SAE Mini-Baja Competition, and stop in IL for Ion to dyno tune the thing. On the road the car just started running worse and worse. Now the whole car shakes badly under high throttle, low rpm, in a high gear (5th or 6th). I have since pulled the passenger header and replaced the gasket because there was a noticeable leak, and while I was in there I replaced all of the plugs. The engine was throwing a low MAP code before, but it hasnt come back since I cleared it. Please throw some ideas out there, as I am pretty stumped at this point. I am leaning away from a vaccum leak because it still pulls alot of vaccum under decel.

 

This may not be the answer, but my car was running real bad for 2 days from bad gas. I coudlnt figure what it was, I thought it was ignition, then I ran it dry and bought new gas and its running actually better than usual.

-Dustin-

 

My car had the same symptoms and it turned out to be a burnt plug wire. Check them all thoroughly. At first I couldn't find the burnt wire, I had to actually take them off one at a time to find the bad one. Sounds like that could be the problem.

 

How old are the O2 sensors? Was this log before or after the header gasket was replaced?

 

Log was after the header gasket was replaced. I just had the passenger O2 out and it was covered in carbon so I cleaned it off. To my knowledge, they are both stock with 82k miles on them.

 

I can't view the log till I get home but feel free to email it to me at DesiZ28@hotmail.com

Does the car surge at idle? How is the oil pressure?

 

Wow, I only wish I could understand what all those numbers meant ! Is there any place I can learn this stuff or is it all pretty much hands on ?

Anyway, I too had a burned plug wire with my 1st 95 Z and that is pretty much how it acted. Good luck !

 

Injuneer has a good site that has an explanation about alot of it that is a very good read.

 

Cool, thanks for the info. I'll have to check it out !
Sorry about the thread jacking..........

 

http://members.aol.com/InjuneerZZ/ScanMast.htm

I'll take a look at the file.

 

A lill ttt for ya but i still am thinking it may be the fuel pump...

 

I will try the plug wires tonight and go from there.

 

I will email you them, but they are download ready at the links provided.

The car doesn't surge any more than it did when it was running perfect.

Oil pressure is excellent, 40psi hot idle, 60-70 psi upto about 4500rpm, and 75-80 above there. Stock replacement pump, 10w-40 valvoline.

I just replaced the plug wires and the problem is maybe slightly better, but definitely not cured. The car still shakes badly under heavy throttle in low rpm, high gears.

 

It looks like you have good potential to make power judging by the air flow... though it does jump around a lot in the upper rpm for some reason. The shaking(misfire) problem is more likely plugs or wires. Same thing happened to me when I burnt a couple plug wires installing my headers.

ok in the last run i think in first gear youll see the O2s on the left side read in teh 100s while the right is in the 900s.. thats telling me you were down on a cylinder so definitely check the plugs and wires.

 

I had a issue similar to that when I swaped my heads. It turned out to be a plug that was arcing.