Re: I'm stumped, please help

I have the same problem with my 94 Z28 (110,000 miles also). I have replaced the MAF sensor as well. It did not help. Please let me know if you ever fix it.
Skynard
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
I cant find the original message. What are the symptoms?

replaced the MAF sensor as well. It did not help. Please let me know if you ever fix it.

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
There are two issues. I think they are related but Im not sure. Both problems are intermittent but seem more common when the engine is hot. First, when I push on the gas from low RPM the engine stumbles and then goes great. It feels like a fuel filter problem but replacing the fuel filter did not help. Second when at an idle the engine idles fast then slow. I have an automatic transmission and I have to push hard on the brake to hold the car in place.
I have replaced the distributor cap, rotor, spark plugs, and even the MAF sensor at the suggestion of a good mechanic. Nothing has helped. I dont know what to do next. I would just have Chevrolet fix it but they cant find anything
Thanks, Skynard
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Skynard,
The problem has not been solved. It has been minimized, but it's still there.
Since my original post, I have once again replaced the OptiSpark. I have also replaced the muffler, all 8 injectors and the fuel pressure regulator.
I still have a stumble/miss condition under load below 2000rpm. I'll be going after the CAT, an exhaust leak on the left bank and the oxygen sensors next.
-Kevin

replaced the MAF sensor as well. It did not help. Please let me know if you ever fix it.

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Kevin,
Im very disappointed to hear that. I was going after the fuel injectors next. I guess Ill hold off for now. I dont know what to do.
Just to let you know. I already checked with Chevrolet to see if there were any service messages but they found nothing on it. My problem is intermittent. It seems more prominent when the engine is hot.
Good Luck, Skynard
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Have you cleaned out your Idle Air Control valve? Basically, just pull out two bolts, remove it and blast it down with carb cleaner. Doing this could help with your unstable idle. Also check the seal on the top "plate" of your throttle body. It's the small rectangular cover on top and has a rubber seal that can go bad and cause an intake vacuum leak.
The OptiSpark is weak and can get worse when hot due to moisture and such. It's quite a job to replace though.
Good luck,
-Kevin

next. I guess I'll hold off for now. I don't know what to do.

were any service messages but they found nothing on it. My problem is intermittent. It seems more prominent when the engine is hot.

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Kevin,
Thanks for the suggestions. I'll give it a try. I have the car in storage for the winter. But I may get it out to try this. I'll let you know what happens.
Skynard
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Motorsforum.com is a website by car enthusiasts for car enthusiasts. It is not affiliated with any of the car or spare part manufacturers or car dealers discussed here. All logos and trade names are the property of their respective owners.