SERVICE ENGINE SOON

[GOFAST]

I have a '95 with about 9k miles. After a short burst at WOT (wide open throttle), the service engine soon comes on but then goes out after a few seconds. Any idea on the cause or how I can capture the code?

Thanks

[scottfab]

I have a '95 with about 9k miles. After a short burst at WOT (wide open throttle), the service engine soon comes on but then goes out after a few seconds. Any idea on the cause or how I can capture the code?

Thanks

Do you have the power key on? Try with it off.
If it does not happen with the key off that is a data point
for going forward.

Easiest way to get codes out is with a scanner ($80 or so).
It's a good investment. Most parts stores will have them.
There is a way to read them out on the dash that involves
shorting two pins on the diag connector the turning the ign key on.
This is tedious but
if you want to one of us can post the procedure.

[VetteMed]

Not so tedious:

bend paperclip into U shape.
insert ends into the far right terminals on the upper row of the diagnostic connector (under the LH hush panel, near driver's right knee)
Key On, Engine Off.
Service Engine Soon light will start to flash. Each code is repeated three times, then on to the next code.
By default, a properly functioning ECM will relay Code 12 - this shows up as one flash - pause - two flashes - pause. That is repeated 3 times, then on to the next code.
Have a pen/paper handy to record the codes, then report back!

Andrew

[rhipsher]

Here's a vid of me doing the procedure.
http://static.photobucket.com/player.swf?file=http://vid301.photobucket.com/albums/nn63/keeno1970/codes001.mp4

[Blue Flame Restorations]

Scanner is nice but if you don't have one, paperclip will work easily. Counting the codes is very easy.

[tomtom72]

Just as a point of reference, you said the light blinked at ya under WOT conditions and then went out. If you were in Full Power mode, then it could be signaling running out of vacuum reserve for the secondary port throttle system. The MAP under the plenum is what monitors vacuum supplied to keep the port throttle actuators open during WOT conditions. That could be the issue or there could be a leak at either actuator or some place else in the secondary vacuum system.

Do what Scott said and try the WOT blast with the key in "Normal" and see if the SES light does blink at you again. If no SES light, just try the WOT again with the power key set to "Full Power" and if it binks at ya then you for sure have something a miss with the secondary port throttle system.

:cheers:
Tom

[tpr60]

Interesting Tom!!!

[GOFAST]

Thanks for the input. I'll buy a code reader this weekend and check the stored code. The "service engine soon" light comes on with and without the power key on so that most likely eliminates an issue with the secondary system.

[scottfab]

Thanks for the input. I'll buy a code reader this weekend and check the stored code. The "service engine soon" light comes on with and without the power key on so that most likely eliminates an issue with the secondary system.

Just thinking out loud here. You may want to pick up a fuel pressure gauge too. If you have an Harbor Freight near you that's the place to get a reasonably priced one.
I'm thinking you maybe going lean. But all guessing aside getting the codes out is first.
The normal procedure is to write them down then clear them using the scanner. Then run the car until the failure then get the codes out again.

[ZZZZZR1]

Question

What has been done to the car recently? Any maintenance?

How long have you owned the car?

:cheers:

David

[QB93Z]

I haver deleted several posts from this thread. The discussion got way off the original poster's question and the sarcasm and personal slams have no place on our Forum.

This thread is locked. GOFAST, please start a new thread if you need any assistance troubleshooting your Z.

Jim Voter