Topic: trouble codes

[BLACKDOG]

I was messing with my truck tonight, and I replaced the distributor cap and rotor. 

I checked the codes, and then I tried to clear them and they still came up.

12
 RPM SIGNAL-NO SIGNAL TO ECU FROM DISTRIBUTOR ("Ne" OR "G") AFTER ENGINE HAS BEEN CRANKED
--DISTRIBUTOR/CIRCUIT

--STARTERSIGNAL CIRCUIT

--IGNITER/IGNITER CIRCUIT

--ECU

71
 EGR VALVE MALFUNCTION--EXHAUST GAS TEMPEATURE BELOW SPEC. FOR EGR CONTROL
--EGR SYSTEM

--EGR GAS TEMPERATURE SENSOR/CIRCUIT
 
In laymans terms, does the first one basically mean that the distributor is bad? 
and the 2nd one mean that the EGR valve is bad?  any suggestions on how to fix and or test?  My truck is running, and it runs fine under power, it just has a screwy idle at about 500rpm, and then in fluxuates and idles fine at about 1000

 

[reklund5]

blackdog-

The code 71 means something is goofy with either the EGR modulator valve or the EGR temp sensor.  The actual EGR valve should be checked by applying vacuum directly to the port on the EGR while the engine is running.  If the EGR valve is working, the engine will stumble badly or even stall when vacuum is applied.  Sometimes the EGR modulator gets plugged up- its on the left side of the engine as you face it, on the front near where the intake meets the upper passenger side of the timing belt cover.  It's a plastic thing about the diameter of a soda can with 3 hoses hooked to it.  Pull it off, carefully pop the cap off of it and throw away the little sponge inside, then reassemble and reinstall.  Thirdly, the EGR temp sensor could be faulty- ohm it out and check its reading against the service manual.  I've seen those go out from time to time...

The code 12 sounds like it was push started...I'd clear it by pulling the EFI fuse for like 5 minutes and then try again.  It can't be that big of a deal, as the engine wouldn't run right if the ECU wasn't really getting signal from the distributor...

Ryan

[brainlessfool]

used to be on GM stuff you'd get a code 12 all the time if the motor was not running. just means the dist is not sending a seg. to the puter. 

[BLACKDOG [OP]]

cool, thanks.  I havent push started my truck, so that is kinda weird, but I'll clear it again.  My check engine light doesnt stay on, I was messing with the timing, trying to get the computer to take control off with the jumper wire in, and I turned the truck on, and I was getting codes   I wasnt too worried about it, but the 12 code didnt make sense to me

[lucky7]

Curious too what the fix was i nhave same issue wondering where to start egr or igniter.

[BLACKDOG [OP]]

Curious too what the fix was i nhave same issue wondering where to start egr or igniter.

If I remember right, I went back through, checked and cleaned all the electrical connections for the AFM, EGR stuff, rechecked all the vaccum lines (might have replaced some of them).  After I did all that, I disconnected the battery, and pulled the EFI relay overnight.  I put the jumper wire in before I hooked everything back up, and let it run, set the timing, let it run like that for a while, then pulled the jumper wire.  I *think* that solved to problem, but I'm really not sure, its been a while.