1987 Vette, Runs Too Rich

[Grumpy]

Hi, I have a 1987 Vette. It is running very rich, blows black smoke rich, and when it begins to warm up it starts to run rough and acts like its loading up. When you give it some Rpm's it gets a miss and when returned to idle it dies. Now after letting it sit and coming back to mess with it, it smells of raw gas and is hard to crank, when it eventually does it sputters badly and dies. Almost like a car that has flooded. I replaced the coil, cap and rotor with a kit from DUI. It also has a new egr valve and IAC, and temp sensors aside from the MAT, along with new injectors. The throttle body and intake have all been taken apart and cleaned and had new gaskets installed. The TPS and fuel pressure checks out good and there is no fuel in the vacuum line to the fuel regulator. It is now giving code 45, witch suggests the next thing on the list to check is the o2 sensor. The only things that aren't new is the MAF, MAT, ECM, o2 sensor and TPS, plugs are new-ish, I've cleaned them, but they probably have been through the ringer now.... Thats all I can think of off hand. Any suggestions on what could be going on? Thanks.

Id adjust the TPS and IAC as a quick check, as its easily done and costs nothing,
your running rich is obviously something related to a defective control sensor or defective part, check carefully for loose or cracked vacuum hose, test for intake manifold vacuum leaks, vacuum leaks cause oxygen sensor reading to richen the injector pulse duration.
code 45 is a rich exhaust, you already know your running rich, fuel enters the cylinders from the injectors or due to,a defective fuel pressure regulator and the maf is the major control on fuel flow rates, test heat sensor.
Id start by verifying the injectors are not leaking, they may be new, but that does not mean they are functioning correctly,
Id test and if required replace the MAF and the relays behind the battery on the engine compartment firewall ,and the oxygen sensors as they are most likely trash at this point, you also did not mention the fuel pressure, if you turn on the key but not start the engine, the fuel pump should pressurize the fuel rail, to about 40 psi, it should remain pressurized for at least 6=7 minutes before slowly losing pressure, if it loses pressure the fuel is leaking at the injectors or fuel pressure regulator or the fuel pump, if its the fuel pump, it would not cause your issue, if you block off the fuel pressure return line and it still loses pressure you know its the injectors
I built that whole web site to help the guys with less experience wade through the all too typical, delays, B.S. most repair shops provide,
and allow guys to learn, how to think logically, isolate and test,
and in the process learn how to do their own correct diagnoses and repair work without having to spend 50 plus years gaining personal experience the hard way.
I got really tired of being lied to, stalled, and having crappy machine work passed off as "NORMAL" and having guys try to B.S. you so the billing could be pushed higher as I slowly gained experience and knowledge.

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ttp://garage.grumpysperformance.com/index.php?threads/curing-that-problem-with-how-your-c4-corvette-runs-badly.15212/

http://garage.grumpysperformance.co...-system-trouble-shooting-flow-chart-info.596/

http://garage.grumpysperformance.co...too-common-questions-can-be-found-here.12892/


http://garage.grumpysperformance.co...lay-switch-locations-and-info.728/#post-93196

http://garage.grumpysperformance.co...g-tpi-crossfire-or-lt1-vette.1401/#post-39419

http://garage.grumpysperformance.co...asic-trouble-shooting-on-the-c4.302/#post-367

should help if you read through the links and sub links
and yes it still sounds like a couple leaking injectors, or defective sensors (OXYGEN, MAF, OR TEMP SENSORS)

 

[Mark Bradley]

Make sure you don’t have an exhaust leak anywhere between the cyl head and 18” after the O2 sensor.
Any additional atmosphere added in this area will contribute to the sensor reporting a lean condition thus it will dump more fuel in to compensate...
This will give you the rich readings at the plugs and correct at the sensor.