Engine light coming on for awhile and then going off for awhile.

[robertbassin5]

No I have not change the KS wire yet. But I noticed that the wire is not even close to the spark plug wires. I use 87 octane. All these problem started after I had the motor rebuilt.

[silicon212]

Originally Posted by robertbassin5

No I have not change the KS wire yet. But I noticed that the wire is not even close to the spark plug wires. I use 87 octane. All these problem started after I had the motor rebuilt.

It helps to know this stuff! If that's the case, your engine may now have slightly higher compression, considering it was probably bored, decked and the heads milled. All 3 of these things can raise compression.

Try running 89 octane in it and see if that helps.

[robertbassin5]

Well I changed the KS wire and I noticed that the existing wire was slightly greenish and copper looking. Looks like the wire might have been bad. After changing the wire connector and driving around for about 5 mins. the light turned itself off.

[j cAT]

Originally Posted by robertbassin5

Well I changed the KS wire and I noticed that the existing wire was slightly greenish and copper looking. Looks like the wire might have been bad. After changing the wire connector and driving around for about 5 mins. the light turned itself off.

you most likely fixed it... the KS output is a very low a/c volt...if you have a corroded connection this will happen and this is very common...

good luck

[robertbassin5]

Man I really hope so.

[robertbassin5]

Well guys guess what? You'll know I changed my KS connector. I put about a half tank of unleaded plus in it and drove about 95 miles, then the light came back on. Now what do I do?

[j cAT]

Originally Posted by robertbassin5

Well guys guess what? You'll know I changed my KS connector. I put about a half tank of unleaded plus in it and drove about 95 miles, then the light came back on. Now what do I do?

it is possible that the computer has to relearn the Ks voltage output...the KS produces a/c voltage when shocked as in engine detonation..


can you hear engine noises...maybe the engine has mechanical noise thats creating the KS output to be incorrect...95mi then it comes on is strange unless something else occured..

if your engine is running too hot this can cause detonation..what temp does it run at ???

[robertbassin5]

I don't hear anything that is knocking or pinging anywhere. My engine temp is about 195 F. Which I believe to be normal. When the light comes on I dont hear anything different.

[j cAT]

Originally Posted by robertbassin5

I don't hear anything that is knocking or pinging anywhere. My engine temp is about 195 F. Which I believe to be normal. When the light comes on I dont hear anything different.

this I feel is a bad connection then as the engine appears to be running at normal temp and does not make any noises...

are you very sure you checked all the grounds ???? this will also cause all kinds of problems such as yours...battery , frame rails, engine etc...there are many and with the job they did it is very common for the rebuilders to forget to secure and clean surface before securing the grounds...

[robertbassin5]

I checked everything that I can see. I am about ready to go buy some C4.

[briand069]

I'm not 100% positive on this, but I recall reading somewhere that knock sensors use a special sealant (silicone?) or no sealant at all on the threads. This might be worth a shot checking into since the engine has been replaced and maybe the shop put the wrong stuff on it. Other than that, I suppose it's possible during the install that a wire got pinched somewhere in the harness and it is causing your trouble. Good luck, and I'm sure you'll figure it out soon.

[robertbassin5]

Took the knock sensor out and there was no sealant of any kind on it.

[j cAT]

Originally Posted by robertbassin5

Took the knock sensor out and there was no sealant of any kind on it.

replace the KS sensor they probably dropped it.....

[briand069]

Is it possible the engine block was painted and the threads for the knock sensor have paint in them? Also, you really need a manual for your truck to follow the troubleshooting steps for checking the circuit as well as the sensor. It's possible the new sensor you bought was dropped and it's bad as well. Do you have a scanner that you can watch the knock sensor with?


Brian

[robertbassin5]

I have already ran all the checks for the knock sensor and they were ok.