intermitant detonation!
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Junior Member
Joined: May 2012
Posts: 18
Likes: 0
From: Minnesota
Car: 86 z28
Engine: 305 l
Transmission: 700r4
Axle/Gears: 383
intermitant detonation!
so i got an 86 z28 that has a few probs, #1 the detionation it sprraticialy does. #2 the somtimes shifting out of overdrive for a few seconds and then enguages back into. #3 engine briefly cutting out during sharp cornering and some times at WoT. #4 after the car has been running in hot weather for a while, the fuel pump starts to whine pretty loud eventually stalling the camaro for hours! it has a rebulit 305 she gets up n hauls azz when she wants to but that detonation is freaky. i have found codes 23, 43, 44 looked them up just dont know where to start, just looking for advice before i swap out everything, ?does the TPS have influence on the TH700R4?
Junior Member
Joined: Sep 2010
Posts: 20
Likes: 0
From: Port Charlotte FL.
Car: 1987 GTA.
Engine: 5.7L TPI
Transmission: 700R4
Axle/Gears: 3.27
Re: intermitant detonation!
well lets see here, the shift problem, im not a trans guy but i would double check the adjustment on the TV cable, and your code 23 is for an air temp sensor fault.
OK easy stuff out of the way, the rest of your problems are related, lets break this down.
code 43 is for the knock sensor, that detonation of yours is probably setting it off. code 44 is an o2 sensor reading constantly lean. when the engine runs lean you can get some detonation.
but why are you running lean i wonder. lets look at your other problem,
going around corners and wot the engine sputters. sounds like your running around with a nearly empty tank of gas and the pump is sucking air.
and now the final piece of the puzzle. the pump,
like all electronics, generates heat as it runs. to cool it, it was designed to be submerged in the tank. as you reach somewhere around 1/4 of a tank, it is no longer completely submerged, and thus loosing cooling. driving for extended periods of time with a nearly empty tank can cause damage to the pump. the symptoms of a damaged pump include excessive noise, and lack of proper flow.
now we have already established that you pump is making noise. so what you should do next is hook up a fuel pressure gauge and check your pressure with and without the vacuum supply to the regulator disconnected to determine if the regulator is at fault. although you pressure might look good at idle, you need to do a flow test. to do this, (if your fuel pressure gauge is equipped) with the engine running, open the tap and see how long it takes to fill your average water bottle, about 15 to 20 sec, during this time the engine should not mis a beat. a properly flowing pump should be able to supply the engine and the water bottle with plenty of fuel at idle.
wow this post is longer than i thought it would be. long story short, this is what i would do,
1. replace air temp sensor
2. replace fuel pump, even if it flows ok, its noisy, meaning its on its way out
3. the regulator is probably factory so i would replace it anyway, there known for failing
4. replace the o2 sensor, running lean like that has probably fouled it out
5. check you timing, this can also set off the knock sensor
hope this helps
OK easy stuff out of the way, the rest of your problems are related, lets break this down.
code 43 is for the knock sensor, that detonation of yours is probably setting it off. code 44 is an o2 sensor reading constantly lean. when the engine runs lean you can get some detonation.
but why are you running lean i wonder. lets look at your other problem,
going around corners and wot the engine sputters. sounds like your running around with a nearly empty tank of gas and the pump is sucking air.
and now the final piece of the puzzle. the pump,
like all electronics, generates heat as it runs. to cool it, it was designed to be submerged in the tank. as you reach somewhere around 1/4 of a tank, it is no longer completely submerged, and thus loosing cooling. driving for extended periods of time with a nearly empty tank can cause damage to the pump. the symptoms of a damaged pump include excessive noise, and lack of proper flow.
now we have already established that you pump is making noise. so what you should do next is hook up a fuel pressure gauge and check your pressure with and without the vacuum supply to the regulator disconnected to determine if the regulator is at fault. although you pressure might look good at idle, you need to do a flow test. to do this, (if your fuel pressure gauge is equipped) with the engine running, open the tap and see how long it takes to fill your average water bottle, about 15 to 20 sec, during this time the engine should not mis a beat. a properly flowing pump should be able to supply the engine and the water bottle with plenty of fuel at idle.
wow this post is longer than i thought it would be. long story short, this is what i would do,
1. replace air temp sensor
2. replace fuel pump, even if it flows ok, its noisy, meaning its on its way out
3. the regulator is probably factory so i would replace it anyway, there known for failing
4. replace the o2 sensor, running lean like that has probably fouled it out
5. check you timing, this can also set off the knock sensor
hope this helps
Thread Starter
Junior Member
Joined: May 2012
Posts: 18
Likes: 0
From: Minnesota
Car: 86 z28
Engine: 305 l
Transmission: 700r4
Axle/Gears: 383
Re: intermitant detonation!
ok i checked fuel pressure running at 47 psi, even at idle...book says at idle psi should be like 4-10 psi, theres a screw on top of the regulatio it might be and adjust ment idk yet. rumor has it the previos owner was running No2 hence the new engine hehe, so maybe the injectors arnt stock, gonna check the TPS sensor today, i also think the ECM is causing tranny shift problems when the car funning about 200 degF, is this possible? the timing is spot on but seems like the ESC has troble, just got a code for that the other day during the detionation aprox 3/4 throttle, man TPI is finickey
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