hello ,
I have a 95 camaro z28 6spd.my mods are a small cam ,bbk headers,flowmaster 80 series, air intake,removed the screen on the maf sensor,ford 9" rear,msd 6al ignition box,blaster coil, and msd pro billet distributor, 1.5 gold series roller rockers. My problem is that when i first start my car it runs good has excellent acceleration and does great until the check engine light comes on. then it seems to be sluggish .After i stop the car and turn it off for a while and then turn it back on the light will go away but after about 1 min it comes back on. here are my ideas im thinking that because it has roller rockers on it the knock sensor is picking them up and retarding my timing. i am going to have it put on a computer this week sometime and see if it stored any codes. what do you guys think is wrong!

 

Knock retard does not turn on the SES light. Why guess.... when a simple scan will tell you exactly why the SES light is coming on?

 

Check the code, and go from there.

 

thanks guys having it checked tomarrow!!!!!

 

hello,
today i didnt get to put the car on a comp. but i did advance the timming on the MSD dist. 5 degrees the car runs really good . threw me back in the seat like it has never before, but as soon as the SES light came on the car ran like ****. i pulled over turned the car off and waited a minute turned it back on and the light was off. run it down the road and it ran very well again. Any idea why the light goes off after i let it set . ithought the ses light was suppose to stay on! thanks

 

The SES light only stays on while the code is "active". Some PCM diagnostic routines can only be run under very specific operating conditions, and the light doesn't come on until you operate the engine under those conditions and the diagnostic is run and failed. You need to get it scanned. Even if the SES light turns off, the code stays stored in the PCM for quite a while.

 

ok . i will try to have that done today. thanks

 

ok.
here are the codes
(1) #18 Injector circuit
(2) #23 IAT sensor circuit Temp low
(3) #29 AIR circuit
(4) #84 Skip shift circuit

ok i understand the #29 because i done away with the air pump and the EGR system.

also #84 i understand i guess its unplugged i havent checked but i dont think that is causing my problem.
can you guys explain # 18 and #23? and what i can do to fix them or help me trouble shoot them. on #18 i understand it has something to do with the injectors but what all do i check on them? and i know that the IAT is my intake air temp but how do i check it . Thank you guys for helping me with this i greatly apperciate it.

 

DTC 18 indicates there is an electrical fault in the injector circuit. You need to check to make sure you have +12V at the pink wire in each injector harness connctor. With the connector off, you need to measure the resistance across the pins on each injector. Should measure in the range of 12-15ohms. If all that checks out right, you need a "noid" light to plug into the injector to insure it is getting the ground signal from the PCM to fire. Sometimes you can identify a non-working injector by listening to the injector with a mechanic's stethescope, or by pulling the connector off the injectors one at a time. If the injector is working, pulling the connector off will cause an apparent misfire. If the injector was not working, it won't produce a noticeable difference.

DTC 23 indicates an open circuit on the IAT sensor. With key on, check across the two wires in the IAT harness connector for +5V. If you have that, measure the resistance of the IAT sensor, and compare the resistance to the table on Shoebox's site:

http://shbox.com/1/4th_gen_tech2.html#ect

DTC 29 is only for the electrical circuit for the AIR pump. It has nothing to do with EGR. Check the fuse for the AIR pump. As long as the fuse is good, you will not get a code in OBD-I when you disconnect and remove the pump.

DTC 84 means you are lucky enough to have disabled the skip shift solenoid, that prevents you from shifting from 1st to 2nd gear under some operating conditions. If you look at the driver's side of the tranny, you will find the skip shift solenoid harness connector hanging loose. If you want to eliminate the code, put a 2000 ohm resistor in the pins of the harness connector.

 

thank you very much for the info . bryan from pcm4less said i need a new iat and to check the wires and injectors and if everything was good then it was something in the pcm. iwiil get back to you on the outcome. again thanks

 

Ok
I got a meter and checked all the pink wires to the injectors.all of them were 11.81v(need to get a better connection on my neg of my battery cable so ithink thats why i got 11.81v). also i checked the resistance on each injector they were all 12.2ohms,and i checked the IAT sensor harness and got 4.99v. Waiting to borrow a "noid" light off of a friend so i can check to see if the injectors are getting a ground from the pcm.

 

i also checked the resistance on the IAT sensor got nothing. i think the sensor is bad!!!

 

ok pulled iat sensor out and cleaned it for the hell of it with carb cleaner and a cleaning brush (man was it dirty) put it back in . also the AIR fuse was blowed so i put a new one in it . and i got the noid light from a friend and checked all the injector plug in's. all were fine except #3 the clips in the harness were loose so i fixed them and put everything back together started it and let it run for about 45 mins havent seen the check engine light yet . hopefully i wont. also i put new plugs and plug wires in and at night i notice that when the engine fires threw its cycle i can see a ring flash around between the nut head and the porcielin of the plugs(not on all) i mentioned it to advance autos but the guy there said that it wasnt the plugs it was the connection between the plug boot and plug itself i redone all of them making sure they were connected and it still does it . any suggestions. also i need to know next month i have a race planned against a srt4 neon. i have a NX 150 kit on my car now plus a msd digital windowswitch and everything else you can get for an lt1 from msd including the billet distributor .I can advance or retard the timming +or - 5 how much should a retard it . everyone around here said to retard it the full -5 . Thanks for the help some of you have given me i greatly appreciate it alot.

 

I have a code 29 on my 95 z and it does the same thing you have described. I need to get rid of the AIR system.

 

check the fuse under the hood . i unplugged my air system . if the fuse is blown the light will come on .