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khizersozay 11-02-2017 05:24 PM

Please help!!
I have a 97 six speed Z28. Ruffly 97k miles. Ive had it for a few years. The guy i got it off of did some bolt on mod's " long tube headers, cheap cold air intake, larger throttle body". Aside from that and a dual cat into single 3 pipe its pretty stock. It developed a ruff idle and extreme sputter/miss at around 2500 rpms. I replaced ... The opti spark, coil, wires, plugs, ICM, fuel pump, fuel regulator, fuel filter, MAP, MAF, throttle position sensor, and thermostat. The idle smoothed up a bit. It still smells extremely rich and will burp black smoke a little. And after driving it for about 15 min starts to act like its loading up. And at times, the idle will drop back down and turn ruff. I bought an egr valve and solenoid only to find out the guy apparently deleted it. Theres just a plate on the back of the intake. It shows no code "if the check engine light has to be on to show a code". And for some unknown reason it shows the fluid level light on half the time. Even though it has plenty of coolant. So, in short ... wtf is making this thing run so rich and idle ruff?? Any ideas before i drop money at a shop?

Injuneer 11-02-2017 06:28 PM

Re: Please help!!
There are codes that don't turn on the SES light. Always a good idea to scan it. Write down the exact 4-digit codes if there are any. Does the SES light come on for a few seconds, with all the other dash lights when you first turn the key to “run”?

The low coolant light is often a problem due to corrosion of the printed circuit board, when coolant penetrates the case. Cleaning might work, if not, replace it. Or just unplug it and make it a habit to check level regularly. The switch is wired to the dash light through a latching relay in the body control module (BCM). Has nothing to do with the PCM, or how the engine runs.

Sounds like it may possibly be a coolant temp sensor in the water pump housing, that feeds the PCM. Code scan may turn up a problem, or check circuit/sensor per this:

4th Gen LT1 F-body Tech Articles

At any time, before replacing all those parts, did you scan for codes, run a PCM data log, or check the fuel pressure? There is free scanning software for OBD-2:

Free OBD2 scanner software - ECM/PCM - Firebird Nation

The person who wrote the software is a member here, to help with any problems, and I can review the data log it for you if necessary.

David94TA 11-12-2017 07:00 PM

Re: Please help!!
I didn't see O2 sensors on your replacement list. Did you replace them?

Injuneer 11-12-2017 11:05 PM

Re: Please help!!
The "thread starter" signed off one minute after reading my response, and has not returned and signed into the site since.... 11 days and counting. 😴

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