Knocking, sensors, idling,....

[RoyEdwards]

Hi, new to 3geez.

So i have a 1988 lxi and bought it with a bad head gasket. replaced it and fired right up. Engine light was on and didn't know about the ECU under my seat. It was on for a TW sensor. On my way to get the part, it died and had started making some noises. i got jumped and of course it takes forever to start(like 20 cranks) and it dies again a mile down the road. this time I got a bit down the road and BAM, it quit at 3000 rpm and wouldn't even crank. got it home and charged the dead battery and it had trouble cranking but finally did(at this point i had the new TW sensor) it started today right off, but started revving high like my fast idle worked, but was fluctuating. It knocked pretty bad and at first my ECU told me that the Throttle Angle sensor was out of whack, reset it and fiddled trying to get the damn TA sensor off. Then it told me my MAP sensor is out. Now after another reset it still blinks 5 times for MAP, but the mil is not on....

What could possibly be going on, i don't want to run money and money into parts that don't need to be fixed. Oh and the first guy to jump me put his still connected positive jump on my Negative post to keep it on there as he removed his negative(it was loose die to working on it constantly.)

Thank you so much for all effort and time,

[Dr_Snooz]

Sounds to me like your ECU might be bad. You need to sit down and diagnose properly the CEL's you're getting. They indicate a problem in the circuit controlling a sensor, NOT that you should run out and replace that sensor. The shop manual is here. A chart explaining the codes is on p. 12-10. Troubleshooting procedures are on the pages following. When you get a code, move through the troubleshooting procedure until you find the problem. If the ECU is bad, the procedure should help you determine that.

When the car doesn't start, diagnose it like any no-start situation. Find out if it's lacking fuel or spark and keep testing parts until you find out what's going on.

[RoyEdwards]

Thanks for the reply, what about my knocking got going on though? I don't want to take time to rebuild this engine as I'm leaving for basic(Air Force) at the end of this summer and want as much time as I can possibly get. I wouldn't mind parting this car out, and the ECU is good(i think) it runs pretty much perfect now except the knocking causing rpm surges. And the serpentine belt squeals, but other than that.

[Dr_Snooz]

I might not be sure what you're asking. In your first post, you describe an intermittent no-start condition, knocking and a lot of weirdness surrounding the ECU. In that context, I would say the knocking is the result of pre-ignition, detonation, etc. In your latest post, you say everything is great, except for the knock. In that situation, I would lean toward a different diagnosis. So do you have an intermittent no-start condition and sensor problems, CEL lights, etc. or not?

It's possible you also have a rod knocking but it's not sounding like that from what you describe. A rod knock would happen under changing load conditions. Your knock sounds like it's just randomly happening and is causing idle surges too. As far as I'm concerned, that still sounds like pre-ignition. I haven't heard the knock, of course. If you want to post a video of it, then we can make a better diagnosis.

[RoyEdwards]

it doesnt sound like preignition or detonationcould , its more of a metal on metal sound and sounds like it could blow at any second. I dont have a check engine light or blinks on the ECU it fires right up and idles a little randomly

I am getting something new and want to part this.car out, everything is good in it except the head or block, not sure which because I havent thorn it apart

[RoyEdwards]

taking the valve cover off, i realized that there somehow came to be gas inside the head, mixed in with the oil. causing something to spin.

Thank you for your time and effort.

[Dr_Snooz]

Oh dear.