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#1
06-20-2009, 08:59 AM
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94 sonoma knock under load
Hi I have a 94 sonoma 4.3L V6 TBI engine code Z. Recently had the distributor shaft bearing replaced as it was seizing and causing the truck to run rough and die out. During this heavy carbon was built up. I replaced the plugs (bosch) wires (champion) cap and rotor. My problem is the truck now has a knock/deiseling sound whenever you have the truck under acceleration. I replaced the Map sensor as a local mech had the truck diagnoised as a bad Map sensor. I then replaced the EGR valve however it doesn't seem to move as it should. When you are just cruising with your foot off the gas the noise isn't present. Any thoughts would be appreciated.
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#2
06-20-2009, 06:10 PM
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Re: 94 sonoma knock under load
Check and set your base ign timing.
Also a egr valve not working will give a spark knock
__________________
Remember proper testing gives us the answer to many problems. MT
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#3
06-21-2009, 12:03 AM
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Re: 94 sonoma knock under load
ok so I now see how the egr works once the truck is hot. It is working ok. Never set the base ign timing, how would I go about doing this. I'm also going to do a oil change and change the plugs back to Delco plugs. Would you suggest I pull the valve covers and check to ensure all rockers are tight. I was monkeying around tonite and noticed if I gave steady slow acceleration, I did not hear the diesling sound, however if I punched it, the diesling knock sound could be heard momentarily until the RPM's steadied out. Thanks for the reply MT!
Last edited by perplexed783836; 06-21-2009 at 12:46 AM.
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#4
06-21-2009, 10:09 AM
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Re: 94 sonoma knock under load
You need to get some good repair info and go threw the base time procedure for your truck.
Most of them there is a EST single tan /black wire with a black plastic disconect on it. Most are under heater core housing inside cab and some time under carpet there or behind glove box. You have to discnnect the EST wire and set truck base time. by moving dist to TDC specs for your truck. Good Luck
__________________
Remember proper testing gives us the answer to many problems. MT
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#5
08-25-2009, 06:59 PM
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Re: 94 sonoma knock under load
Thanks for the advice MT. The truck is now running fine, the timing mark was advanced about a half inch past 0. The only issue I have now is occasionally the truck will run at a very high idle and the check engine light comes on. I have looked for codes with my code reader but none are registered either before the truck is turned off or after. It usually happens when coming to a stop the truck kicks up high and remains at a high idle with the light on. If I pull over shut the truck off for 10-15 secs and restart it, it is usually ok. Any thoughts?
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