Car runs good, and has 25-30 oil psi in gear when engine is at 180 degrees. Once it's warmed up it run just a little rougher and won't start when I shut it off. If I wait 5 mins it will start right up. Anyone else ever had this problem? Thanks for any help given.

 

Year of car, and any other specifics, like major engine mods will help us help you.

Do you have a way to scan the coolant temp sensor reading (the one in the water pump housing for the PCM)?

 

It's a 1995 Z28. The only mod I know of is a cold air intake. I bought the car and that is all that is done. Is the factory temp gauge not good to go off of? I know the oil pressure gauge is not accurate, so I instal a mechanical gauge. When the car is reading 180 degrees it is around 27lbs of oil pressure at idle, in gear. Any other info that can help figure out my problem?

 

Temperature gauge uses a different sensor then the one the PCM uses. So no.

Your gona play hell finding a scanner that can use the OBDII connector but read OBDI.

Need to look into getting some cabling and a laptop program.

http://www.aldlcable.com/sc/details.asp?item=aldlobd2u

If you're gona keep this vehicle, you're gona need to be able to scan it real time.

 

So you are saying it could be the computer is getting a false reading that the car is hot?

 

Yes, that is one possibility.When the pcm thinks the engine is cold, via data from the coolant sensor in the water pump, it richens the mixture to make starting and cold running better. Then as the engine warms, it leans the mixture to what is required for warm engine operation. If the pcm thinks the engine is warm when starting, it doesn't enrich the mixture and you have starting problems cold. If it thinks the engine is cold when it's actually warmed up, it enriches the mixture and the car runs poorly. An over-rich mixture cause the engine to run 'flat' and not rev cleanly.

Unfortunately, there are few more situations where the car will run like this, that's why most people will tell you to get it scanned and to look at all the sensor outputs.

That said, you can measure the output of the sensor with a ohmmeter. Use this link: http://shbox.com/1/4th_gen_tech2.html#ect from ShoeBox and look at the table ECT Temperature Vs Resistance Values. I know it's cold outside and this isn't easy to do...it is one way of getting the data.

Good luck!

 

What is a scanner I can get that works with these cars that can tell me what the problem is? Sorry for these questions, last time I built a car I eliminated all the computer stuff.

 

The problem here is that you have a '95. They have teh OBD2 compute link under the dash but are actually OBD1. This will confuse most scanners. What you can do is find an OBD1 scanner and use jumpers to get the readings....like this: http://shbox.com/1/xraycable.jpg or you can buy the correct cable from someone like akmcables.com and get some freescan software to use with your laptop....

 

Oh ok. So that cable you sent me the link for just plugs into a laptop and the software that comes with it will read what is going on with the car, again sorry trying to learn something new to me.

 

Sorry, no, I wasn't clear. You'll need a sftware program to use it with. Here is a free one: http://andywhittaker.com/ECU/FreeSca...0/Default.aspx

You can also download TTS powersystems Datamaster. It's very good and allows 20 free uses before you have to buy it. http://www.ttspowersystems.com/DataMaster.html

I don't use either of these. I have a Snap-On MT-2500 scanner I got from a guy on another forum. They have them on ebay all the time.

If I were you, I'd go with the cable and Datamaster....

 

Great, thank you very much for the help.

 

The ScanMaster LT1 was the best invention ever....... real time data, codes, etc. in an easy-to-read format. I've had mine for about 13 years, and its been extremely useful in helping to figure out how the PCM controls the engine.

 

Is the Scanmaster available anymore?

 

http://www.thunderracing.com/shop-by...gnostic-Tools/

 

I would love a scanmaster, but kind of pricey when I can buy a cable and hook it to my computer.