Hi everyone! I have a 95 Z28 with a six speed tranny. I bought it almost a year ago and havent had so much of a problem until now. Sometimes the service engine soon light will come on for awhile the shut right back off. I went and had it tested and no codes came up since it wasnt on. When it comes on its a lil sluggish and acts kinda like its running on fouled plugs. And it seems to happen the most when I have a good load on the engine like going on a over pass on the highway going 70. Anybody have any clue what could be causing this? Thanks for any input or ideas. I dont wanna just throw cash into things that might not be bad like sensors and stuff.

 

could be a knock sensor, knock sensors can do pretty weird things when they go bad.
Does the idiot light only come on at higher speeds? or when it becomes sluggish? When was your last tune up completed

 

ok thanks for the fast reply! I just did a tune up thinking that was the problem. And yeah it only does it a higher speeds. Or atleast thats when the service engine soon light kicks on. Some times I can get the ses light to kick on if I bog the motor down like keeping it in a higher gear when driving. But it goes right back off?!?!

 

first of all the ses light does not have to be on for a code to show on a scanner. the codes are stored in the computer so you may have some codes that didnt show for some reason. cnc may be right and a knock sensor is failing or the wire to the sensor is. unplug the knock sensor and see if the car acts like it does when the light comes on. if so then thats most likely your problem.

 

reason I say knock sensor is because, you said it happens under load, the knock sensor monitors spark knock/pre-detonation, and at higher speeds vibrations increase and if your knock sensor is failing it may just give the ECU a bad reading, then the ECU will try to correct the timing (VVT/variable valve timing) or display a DTC code.

 

Thanks again for the reply guys. I'm going to unplug the knock sensor and try that route. Hopefully I will have time this weekend to try it. I'll post back up and let ya"ll know if that help narrow it down or anything. Thanks!

 

did you do the "tune up" and please elaborate on what was done as a "tune up"

with the lack of access under the hood, it's easy to not tightern a spark plug, not have the boot on securely or worse, did you drop a plug and perhaps crack it?

a cracked insulator can do strange things when under load.

last question, please tell me that you are running premium fuel??????????????

 

Sorry I haven't got back to this topic. It seems like the fuel pressure regulator is the problem. Or atleast that's what some mechanics seem to think. So I'm going to replace that and see what happens. I'll keep y'all posted.

 

I would check to see what the stored codes are. Some handheld code readers only look at the active codes in the computer. Others have the ability to look at the stored codes as well.

 

Every place and I even tried to get any codes and couldn't. Just get linking error message.