Did plugs and wires about 3 months ago, along with the new opti. New TPS, and MAP. Cleaned the MAF (using approved MAF cleaner), I am running a K&N CAI. I have a new IAC as welll, just have not installed it yet because it looks like I have to remove the t-stat housing to get to the screws. I figured with 180k, it can't hurt to go ahead and replace the 17 year old sensors. Then from there I go to wiring and vacuum lines. at least then I have 99% chance of knowing all the sensors are good (theres always that 1% chance that an ots sensor will be bad). SES light came on again today. It is consistant. Comes on at the same time and same distance into the drive every day. When it does, the cooling fans come on high speed and the car picks up a barely noticable hickup/miss at very light throtte/low RPM (like just crusing).

Funny dealer story, when I took it to the chevy dealer yesterday, explained my problem, stated I could not get the codes, etc. Service advisor said, give us about an hour....about 20 mins later he comes into the waiting room and says, "this car is OBD1, it does not store codes when the SES light comes on and goes off on its own, we can only get the codes if the light was still on when I took it to them, the only thing we can do is check the ABS codes, since the light is on". I just said, hmm..OK whatever, you guys are the experts here... he comes back a little while later and says "we did get codes and here they are, we had to go to the internet and alldata to find out what they mean" and then shows me the flow charts for troubleshooting the codes, saying that the intake is clogged and it would require pulling the intake to fix it. Seems like finding competent folks to work on OBDI cars is like years ago when you could not find anyone to work on carburators or points (showing my age here). I just thought the whole experience was funny...needless to say, the search for a scanner continues, I will not be taking it back to the dealer.

 

i wouldnt trust the maf, if you have anther vehicle with a maf the same try switching. when the ses light comes on the computer is going into open loop which causes a rich condition. i would not be surprised if your plugs are fouled already, 02 sensors may be as well. the miss should go away once the code is fixed

 

Good Lord I hope not! I DO NOT want to go through that again! lol

 

I have a 94 Z28 with an LT1 and I went through this for years with my car. It didn't cause any drive-ability issues but the SES light drove me nuts when it would turn on and off. It would normally turn on when going around 60mph with cruise control on in 6th in 3 to 4 minutes then turn off in 15 to 30 minutes. Every time I turned the car off the light was off so I couldn't pull the codes. Finally I was driving home and the light turned on so I kept the car running and plugged in the diagnostic device and pulled an EGR code. I even took it with me for a few months but never had a chance to plug it in when the light was on.

I eventually built the circuit that interfaces the car with TunerPro and I have been monitoring the car and reprogramming the computer. I no longer have the SES light turning on and off and the car drives closer to the way I want it to drive after adjusting the different tables. It took several months but I adjust the IAC and several other tables to get the car to drop the RPM's at the same speed that I like to shift. I know that sounds a little crazy but it feels like the car was build for me and how I like to drive.

Basically TunerPro is going to give you a ton of data that you can't get any other way. You will see what's going on with each sensor and you can dump all of that data into Excel to find out which sensor isn't sending the correct data and when it whatever happens.

 

Just a follow up. Purchased an Actron CP9185 off ebay and an OBDI cable off amazon, total @$150 invested. Got the unit today. Bam, hooked up right away. P032. EGR circuit failure. This unit also lets you see and log a bunch of info. Best purchase I have made so far. There are a few of these units on ebay if anyone that has a 94 is interested. Well worth the money. Now I gotta go change my EGR valve if I can get to the flippin thing...

 

Sweet

 

Changed the EGR and solenoid last night. No code on the way to work today! I did some logging for the EGR (there are readings for EGR Duty% and EGR valve position). The EGR valve position is a 1 or 0 and it is never 1 for much of the time, even when the EGR duty is 100%, the valve position just sits there switching from 0 to 1 constantly. I know there is no feedback from the valve on if it is actually open or not, the scanner only sees the command to open from the PCM (I am assuming, this is OBDI after all) so the question is does the EGR valve supposed to ever open and stay there, especially if the duty is 100% (assuming that means it should be open 100%). I know what the EGR system does (introducing exhaust gasses into the combustion chamber to lower combustion temperatures). Just wondering, now that I can see what it's doing. Maybe it knows it's open by the O2 sensors or something.