LT1/LT4 Tech 1993-1997

'94 Z issues....help!

Thread Tools
 
Search this Thread
 
  #1  
Old 01-16-2012 | 09:26 PM
htownZ's Avatar
Thread Starter
|
Newbie
Joined: Dec 2008
Posts: 10
From:
Default '94 Z issues....help!

Greetings! I've been digging through here for a couple of days and not finding what I'm looking for, so if the answer is in another thread or sticky, please forgive.

OK. 94Z, 6 speed, 155K. In the last 8 months, I have replaced: optispark (with vacuum hose upgrade), plugs, wires, coil, ignition module, EGR valve, vacuum line kit (quadruple checked), air pump, all coolant temperature sensors, and all O2 sensors are within 2 years old. The problem I'm having is at low RPM above 59 degrees, the car stumbles and loses power until around 2,000 RPM. The car runs fine with lots of power when below 59 degrees. Am going to be trying to pull the data stream when I get a silly battery for my scanner, but am at a loss as to what could be causing the problem. Does anybody know of any sensor outside of the air pump that activates after 59 degrees? I am also curious if I could be having computer problems since I've had to install a fan override switch because the computer will not turn on the fans for some reason. Any help would be GREATLY appreciated!
 
  #2  
Old 01-17-2012 | 12:09 AM
Catmaigne's Avatar
2nd Gear member
Joined: Apr 2011
Posts: 499
From: Philadelphia, Pennsylvania
Default

I'm assuming the car runs like crap when it goes into closed loop? Unplug the MAF sensor and try driving it around in open loop. It sounds like an EFI problem from faulty sensors. Is it throwing any codes?
 
  #3  
Old 01-17-2012 | 05:01 AM
craby's Avatar
April 2011 ROTM
Joined: Mar 2009
Posts: 21,770
From: Tokeland, Washington
ROTM Winner's Club
Default

test your coolant temp sensor and intake air temp sensor. number 20 on the list here 4th Gen LT1 F-Body Tech Aids
 
  #4  
Old 01-17-2012 | 07:07 AM
htownZ's Avatar
Thread Starter
|
Newbie
Joined: Dec 2008
Posts: 10
From:
Default

Haven't tried running the car in open loop... and no, no codes activated or were found with the scanner. Will try unpluging a sensor and see if the stumble goes away...
 
  #5  
Old 01-17-2012 | 06:45 PM
htownZ's Avatar
Thread Starter
|
Newbie
Joined: Dec 2008
Posts: 10
From:
Default

Well, unplugged the MAF sensor as per your suggestion, and started the car from cold. the MIL lit up, fans came on, and was stumbling from the first second, and stayed that way till it reached thermostat temp. I let the car cool, plugged the MAF back in and started the car, and again from cold, ran great till aprox. 60deg. where the misfire began.
I watched the data stream while it warmed up, and didn't see anything change radically when the temp came up, but, honestly, I really don't know what to monitor, or what the values should be to begin with. I'm stumped...
 
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
WIspartan1026
LT1/LT4 Tech
13
06-19-2012 05:28 PM
mick.mcgirr
General Tech
10
01-03-2011 12:23 PM
camarophil22
93-02 V6 Tech
2
02-18-2010 10:42 PM
red star
93-02 General
3
08-21-2009 02:46 PM
laxloser18
New Members Area
4
04-28-2007 10:06 AM




All times are GMT -5. The time now is 12:41 PM.