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Discussion Starter · #1 ·
I have a 1993 Chevy K1500 4x4 with a 350 TBI engine and a 4L60E auto transmission. Truck runs and drives but is currently overheating if driven for very long. I put in a new fail safe thermostat and replaced the clutch fan. When I take out the thermostat it doesn't overheat but it never gets up to operating temperature. I have had to buy 3 or 4 Fial safes before I get a good one so I think that's whats happening. Truck CURRENTLY WON'T PASS SMOG because it has the check engine light on. It it throwing code 43 and 83. It seems to shift fine but it's still throwing that code. Odometer reads 250,XXX miles but I did an engine swap with a 350 motor with 180,XXX miles. When I did the engine swap I replaced the exhaust manifold gaskets, knock sensor, 02 sensor, transmission wiring harness and all sensors and solenoids, changed tranny fluid and filter, and brand new Magnaflo catalytic converter. I looked up code 43 and replaced the knock sensor but I've still got that code. I looked up 83 and replaced all the tranny solenoids but I still have that code. Does anybody have any insight? Do you think my ECM and/or PROM are bad? Is there any way I can test them?
 

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Discussion Starter · #3 ·
No the truck I pulled the engine out of did not have the check engine light on. My dad was wondering if the knock sensor could be hearing mechanical noise because the engines old or could it be picking up road noises because we live on a rough dirt road? He has already set the base timing at 0. He will be doing a compression test later today
 

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Ok, you have just done the engine swap. When I read your post, I thought the engine swap was awhile ago. I wasn't asking if the codes were there with the old engine, or the donor truk, just trying to figure out when the codes showed.

So, it appears that the codes started when the new engine was started.

The 43 is knock sensor, the 83 is low collant temps, probably because you removed the t-stat

Guessing you have a sensor/ECM in-compatibility (due to different years) problem.
 

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Discussion Starter · #5 ·
The donor truck was a 1992 and my truck is a 1993. I have already replaced the knock sensor. I looked up code 83 and found it to be a transmission code, the TCC solenoid but I have already replaced every sensor, solenoid, and the wiring harness in the transmission.
 

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Discussion Starter · #6 ·
I just did a compression test and we have good compression in all but the #3 cylinder. It only has about 140. I don't know that this engine didn't have low compression before I did that swap. I just bought my compression tester.
 

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Discussion Starter · #7 ·
The wire goes from the knock sensor under the hood into the firewall. I'm wondering if I essentially have two ESC hooked up, one under the hood and the one that's in the PCM because the engines from a 91 with an under hood ESC and the truck and computer are 93 with a built in ESC? The wiring harness is brand new and for the 93 tranny. I don't have the tools to test the fuel pressure. I don't believe it has a vacuum leak because it idles fines and runs good. I did a compression test last night and I have good compression in all but the #3 cylinder its only 140.
 

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If you are in CA, the AQMD changed SMOG specifications for older vehicles a couple of years ago. My 1993 which had passed every year failed then. After spending almost $1K at the mechanic it barely passed. I told him that it was running cool because I had put in a 180 degree thermostat, but he said that did not matter (BS). I just had it smogged again after installing a 195 degree thermostat, and it passed with no problem. The SMOG technician even remarked how few emissions it generated for a big block. Bottom line, the high temp thermostat is a must to reliably pass under the revised regulations.
 
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