Hi to all,My check engine light came on yesterday on a short highway run 20 mi. stop at the Dr. for about 1 hour got back in and it was not on anymore drove home without it coming on.I have not pulled codes yet any guesses?once the check engine comes on should it stay on till reset?I may have a loose bulb.The car runs fine.

 

Must be an intermitant code. Hard to catch unless your running a scan when it comes on.

 

You'll have to pull the codes before we can help you. Sometimes the SES light will stay on when a code is registered, sometimes not.

Get the code yourself or if you don't know how, AutoZone will read them for you at no charge.

 

My guess is that one of the sensors sent information that didn't match (fit the parameters of) what the ECM is programmed to see, base on the input from all the other sensors. Generally, THAT is what causes the "Check Engine" light to illuminate.

The light stays on while the ECM is receiving the out of parameter information. When the "Check Engine" light comes on a code is supposed to be set in the ECM. Whereas the light goes out when the conditions no longer exist, the code stays set until you clear it. Is there any reason, "I have not pulled codes yet"?

Remember...Don't shoot the messenger!

RACE ON!!!

 

Yep, you gotta pull the codes on my 87 I had the same type of situation, when I pulled the codes it was an EGR code, on mine it turned out to be the EGR switch. But, I'm not guessing at yours.

 

No reason,going to check codes today.

 

Ok I checked the codes it thru a code 32 egr system,now what? I have a slight leak where the Ex. pipe meets the manifold on the passenger side,could this cause it to throw a code 32?

 

You will now have to center your repair efforts on the EGR system. It will be a tremendous help to you to purchase the Helms FSM since it details what to look for and explains the various parts of the L98 EGR system.

Typically, what happens is there are leaks in the system or a failed component. For instance, when I fixed Code 32 on my LT1, I found two leaks in the EGR system: one was a tear in the rubber connector at the EGR solenoid, and the other was the EGR valve itself leaking.

 

Don't shoot the messenger. Chances are that the EGR valve, itself, is not defective. Follow the trouble shooting chart(s) in your FSM to avoid throwing money at the problem by replacing parts, needlessly.

RACE ON!!!

 

I agree with CFI-EFI, the best bet is to follow the Diagnostic Chart in the FSM for a code 32. Since the problem appeared as an intermittant that did not return on another trip, one problem that occurs quite often is corrosion of the EGR temp switch wire. The wire runs from the EGR temp switch screwed into the EGR pipe bung to a single wire connector under the distributor. The wire/connector is subject to high heat and the under hood environment, so it often corrodes at the wire/crimp points. Vibration causes the intermittant condition in the wire.

The switch screws into a bung on the EGR pipe and the switch wire is screwed in and internally sealed with ceramic. The heat and engine vibration often cause the ceramic to crack around the point where the switch wire screws into the switch ceramic housing. Sometimes the switch wire can loosen inside the ceramic housing. Where the wire enters the ceramic housing, it can be retightened by hand, but will eventually require the entire switch to be replaced.

If a quick eyeballing of the above doesn't reveal the problem, open that FSM and use the chart.

 

Thanks for the help.I'll let you all know what I find out.

 

listen to him,......... he helped me fix mine, the Helms book was right on the money.....

 

If it were me, I'd leave it alone till the light came on more than that. Hard enough to find the exact problem that has no symptom other than the check engine light coming on. Even harder if it's intermittant or a one time event. jmo

 

The code means that the EGR diagnostic switch was closed during start-up or that the switch was not detected closed under these conditions

1. Coolant temp > 176
2. EGR duty cycle commanded by the ECM is > 48%
3. TPS < WOT but not at idle
4. Codes 21,22,33,34 not present
5. All these conditions must be meet for about 4 min.

Try this NR NICE, Take a look at the vacuums on the EGR and switch. With ignition off disconnect battery for about 30 sec. Coolant temp below 82* or first thing in the morning (cold engine). Start engine and watch for SES light to come on. Stop engine and ground the ALDL pins . Turn ignition on but don't crank. If the code still exist, we'll go from there. It will be hard to catch this code if it is intermittant.