I have a 93 z28 6 speed and am having some issues. The car has a low (rough idle) and the high speed fan kicks on right after the car starts. It's not throwing any codes (that i can see). i still get no service engine soon light. I used the jumper wire and it seems to be reporting normal. It was running somewhat fine for the longest time and then when i tested a couple sensors (because it was randomly bogging) with a voltmeter it started this. I'm really kind of stumped on this one. please if you guys have any ideas as to what i can check, please let me know. Thank you soo much.

Brian

 

Do you have anything to scan the car with? IE Datamaster?

 

If the car began to run bad *immediately* after your voltmeter testing,
then it has to be one of two things: (1) it's one of the connections that
you tested, (2) it's an extreme case of coincidence that something else
went bad at the same time you did the testing.

Re-check every connection you tested. You might even want to run up
to the auto parts store and pick up a can of electrical spray and spray
all connections under the hood - and check all fuses. And be sure to
check all ground straps.

BTW: "desperate" subject lines arent very effective and dont reflect
the true subject matter.

 

No, i don't have a datamaster or any other diagnostic tools. All i have been able to do is test check engine light codes with a jumper wire. I've checked all of the sensors i tested (map, iat, tps) and applied electronic cleanser to the terminals and still no luck! Would a datamaster be able to diagnose a problem that the self diagnostic couldn't? I apologize for my subject being vague, but i really am desperate here guys. This is my daily driver and i need it to get me to work! I've also checked all of my ground straps and all seem ok. Anyone else ever have this problem? Thank you guys for your responses.

 

Your check engine light may just be burned out and it may indeed have codes. I had the same problem.

 

Are you following the correct procedure for flashing the codes on the SES light (courtesy of Shoebox):

http://shbox.com/1/dlc2.jpg

Did you attempt to measure the O2 sensors with a volt meter? Is it a high impedance meter?

A scan would allow you to track the readings of all the sensors continuously, along with critcal ECM parameters like injector pulse width, IAC position, commanded ignition timing, etc.. Its way better than whatever you may be calling a "self diagnostic".

 

your towo symptoms, the low rough idle and the fans turning on sound like they both could be related to the coolant temp sensor. if it is unpluged or shorted it can cause the fans to turn on. not shure what else would cause this.

 

A lot of things cause the fans to come on when there is a code.

 

Might disconnect the negative part of the battery for a couple of hours,and see if that helps.I think your chip is removable,pull it out,then,put it back in.(I may be crazy,but it keeps me from going insane).Hope this helps.My02

 

Thank you guys for your replies. I had left it for a day, went out to start it and i can't say i've ever been that shocked in my life. It ran beautiful! I have no idea what could have happened in 24hrs to make all of that go away. Anyway i did follow the procedure Injuneer had posted about and it reported normal. I did not test the o2's though. I have a buddy that has a much nicer meter than mine, so i think i'll borrow his to test the o2's. I'm still not sure as to why the car sporatically bogs down on cold and hot starts, but it seems to be directly related to weather conditions outside. Hotter it is, the more bogging i get. hmm... I'm just glad it's not dying and the high speed fans aren't running now. Thank you guys for all of your help. You're the best