Problems at WOT.

[Cerwin Vega Fan]

I drive a 1995 Z28 A4 Vert. When I go to WOT from a stop or low speed (under 25MPH) my car seems to lug in the low RPM ranges. When the car reaches around 3500 to 4000 RPMs it seems to pull better and rev quicker. When I first rev the engine and when it lugs down a type of hazey blackish/ grayish smoke comes out of my exhaust. The car seems to have no problems if I take off from a roll at a decent speed. The guy who owned the car before me upgraded the injectors in a basically stock car. Also I noticed my coil looks a little dirty as well.

I'm gussing the engine is loading up with to much fuel and cannot burn it off when I go to WOT and is lugging the engine down and is blowing the smoke the out the pipes. I was wondering if I could get some opinions on what might be wrong, thanks for the help.

[Z Ya Later]

Well, I'd definitely replace the coil regardless. That post looks horrible. Check your wires too. Assuming everything else is ok, its highly possible that you're not getting enough spark because of the bad connection. Hope this helps.

[94 formula]

Like steve said replace the coil to start with. How many miles do you have on the car? You may need to start replacing ignition parts. If you have over 100k or close to do your plugs and wires if they haven't been done yet. The smoke you mention sounds just like what you said about not burning up the gas. http://shbox.com/1/how_tos.html has some great tech advice on diagnosing your ignition system also.

[Joe 1320]

Upgraded injectors? You could have a multitude of problems. First thing is get the ignition sorted out. Next might be the fuel system. Not only could the spark be weak, there may be a fuel metering problem. I would advise one of the first things you invest in is a scan tool of some sort. Being able to read what the sensors are "seeing" is invaluable.

[Injuneer]

If the coil tower is that corroded, I'd recommend you check every critical electrical connection, starting with the ignition.... focus first on the Opti, including the terminals for the coil wire and the plug wires. Check both ends of the plug wires. Check the harness connector at the Opti housing.... that connector alone can cause a brand new Opti to exhibit the problems of one that is failing. There is also a gray Opti harness connector up on the passenger side of the intake manifold, on the same bracket as the EEC canister purge solenoid. Check the ground straps and wires, paricularly the ones to the engine, and near the IC Module.

As Joe mentioned, a scan log of the engine/PCM under varying driving conditions, including those that produce the misfire, might go a long way toward identifying the problems. There are several of us here who could look at the scan log and help identify possible problems.

[Cerwin Vega Fan]

What kind of scanning tool? Can anyone recommend a few?

Thanks

[Injuneer]

The best scan tools for diagnosing problems are the software systems that allow you to log an extended period of driving, dump the data out, then have someone who knows what they are looking at go over it. You have two options for your 1995.

First, with either system below, you need a cable. AKM Electronics can provide it. Because your 95 has the screwed up ALDL connector (16-pin OBD-II connector, on an OBD-I PDM) you need to make sure that you get the interface cable from a knowledgable source.

TTS DataMaster - You can download this for free from the TTS website, and use it for 20 times before you have to pay the licensing fee. It is excellent sowtware, althoug I have a problem with the way they calculate injector duty cycle.

FreeScan - Another free download, with unlimited use.

I'm on a computer that doesn't have all my "links" on it.... if no one else provides them, I'll add them later.

[Z Ya Later]

Here's the Datamaster link...

http://www.ttspowersystems.com/diagnostic.htm

and the Freescan link...

http://www.andywhittaker.com/ecu/ecu_software.htm