Nathan Boron

Ok I have a 1997 Z28 that set for a period of time. Had problems with starts so checked fuel pressure and it was low. Replaced fuel pump and would start but had a very bad miss. I replaced the Opti Cap and rotor, Coil, Ignition Module, MAF sensor. Now the car runs fine when you get it started but the hard start is back in a different way. i checked fuel pressure again just to make sure the new pump was still working and no leaks in the system. i have 45lbs with key on and will hold that pressure when I turn the key off so not fuel pressure issue.

It attempts to fire when just bump the starter but will not start unless cranking for several second usually around 8 sec before it start. If you shut it off and immediately restart it will fire right up. If I leave it set for 30 sec or longer I have to crank again for 8 sec to get to start up. this morning I came out from work and it was around 32 degree outside and it would not start at all till the outside temp warmed up. It has a engine light on had it read and its saying mass air flow intake. Is it possible that MAF sensor went bad in a week and if so would it cause these problems?

I just have bolt on mods. Borla exhaust and cold air intake and under drive pulleys everything else is stock. It has about 75000 miles on the car? ANY ideas cause I am completely lost.

mrmint69

Did you reset the codes after replacing the parts and what was the code number? If not the code gets stored for a period of time. You just need to pull the pcm fuse for 30 seconds to reset it. Then wait to see if it come back. A common problem is a broken power supply wire. Pull the harness connector off, & check for +12V on the pink wire or for being dirty. Have you replaced plugs and wires recently? Your temperature sensor in the water pump could be bad as well as a leaky injector or something completely different. Are you doing the work yourself and if so, do you have much experience? Welcome to the best site for our cars!

Nathan Boron

Did you reset the codes after replacing the parts and what was the code number? If not the code gets stored for a period of time. You just need to pull the pcm fuse for 30 seconds to reset it. Then wait to see if it come back. A common problem is a broken power supply wire. Pull the harness connector off, & check for +12V on the pink wire or for being dirty. Have you replaced plugs and wires recently? Your temperature sensor in the water pump could be bad as well as a leaky injector or something completely different. Are you doing the work yourself and if so, do you have much experience? Welcome to the best site for our cars![/QUOTE]


I have general knowledge of the LT1. I had our Vocation School do the Opti Cap project only cause I have no lift and it much easy on a lift. The supply wire is on the plug that goes to the Opti? Yes I replaced plugs and wires less then 3000 miles on them. Would the temp sensor cause no/hard start? I did take the fuel rail off today and tested and not getting a pulse to the rail when turning over. No security light on so not sure if the VATS could be a issue without it throwing a light?

Injuneer

The reference to the broken power supply wire referred to the MAF sensor. The pink 12V wire breaking inside the harness is a somewhat frequent problem on the 97's. As noted, what was the code for the MAF sensor? There are several, and which of the codes it is may guide you to the solution.

Coolant temp sensor affects hard starting. When the engine is cold, the PCM enriches the A/F mixture for cold start.... just like a choke on a carb. If the PCM doesn't know the correct engine temp, it may not be setting the correct A/F ratio.

Scan it for codes again. A problem with the optical cam position sensor in the Opti will set a code that causes the PCM to shut down the fuel system. And that code doesn't turn on the SES light. When you had the fuel rail up, and pressurized the system, was there any sign of dripping injectors?

If there is no injector pulsing when you crank the engine are you indicating that the engine no longer starts at all?

mrmint69

Check both the maf sensor wire and the opti connection. The test i stated earlier is for the maf. The opti is to be checked for corrosion and bent pins. The fuel rail test is with the rail removed and raised but key on, no start. Looking for an injector leaking. Don't attempt to start while up of course. Temp sensor can cause all sorts of issues but don't know if it is what you have.

Nathan Boron

Yes sorry I didn't update that. I now can not get the car to start at all. Im thinking the cam position sensor at I just did a cap and rotor. I will check the MAF wire and since inexpensive will prob just replace the coolant temp sensor and will update.

mrmint69

When did the no start happen in relation to the new cap and rotor? Has the car ran good since the replacement?

Injuneer

Address the no start condition first. If the injectors are not pulsing when you try to start it there are limited possibilities - injector fuses blown (will set code), VATS problem (SECURITY light will be flashing), code for cam position sensor, PCM injector driver problem. Neither the MAF problem nor the CTS problem will shut down the injectors.

Nathan Boron

The problem started the approximately the 3rd start after installing new cap and rotor. For about 10 starts it started really hard cranking it for around 8 sec each time before it would start and now it does not start at all. Again I didn't replace the whole destributor of the harness going from Opti to PCM. I got a muti meter and checked for voltage to the pink wire on MAF as well as Ignition Coil Module, and Optispark. All had 12 volts going to them. I then checked via a video I found on youtube for volts going to Ignition coil module while cranking it and I got nothing coming to the Ignition Coil Module while cranking. Could it be the PCM going out of would the Cam Position Sensor inside the Opti cause this? Not VATS or atleast the security light is not on but thats the next check I found a link to bypass the VATS. I am posting the youtube video I used for the testing with multi meter below.

[autostream]http://autostream.com/camaroz28/?page_type=firebirdplayerthumbnail&framepage=200&t ransactionid=1350414650-17381544&posted_by=Nathan_autoblankauto_Boron_www. camaroz28.com&youtube_video_id=lFCjaz6zHfc[/autostream]

Injuneer

If the cam position sensor sets the code for loss of low resolution pulse, the PCM shuts down the fuel, and the PCM can not send the signal to the ICM that tells it to fire the coil. That's the white wire from the PCM to the ICM. There is a "sticky" at the top of the LT1 Based Engine forum telling you how to test the Opti. Shoebox also has a guide:

4th Gen LT1 F-body Tech Articles

Nathan Boron

Fixed it today. It was the cam position sensor inside the Opti. Lesson learned if replacing the Opti replace it all. I said before I had the Vocation School change the Opti Cap and rotor cause it was hard to get to. Well I talked to the teach today and he didn't prevent the coolant draining from the water pump removal from getting onto the opti so im guessing that it drowned the Cam Sensor. Anyways yes it shuts off fuel rail to prevent flooding and will not send signal to coil to fire the Opti. thanks for all the help everyone glad I have my ride back forgot how much fun they was to drive