okay, so my van [before you ****, listen} is a 91 gmc 2500 with the 5.7 in it! now then, i am putting it and the brand new 700r4 in my 53 this winter! [so thats why its not so OT dammit!] here go's! so a couple weeks ago, the minor spark knock seemed to have gotten a lil worse! was bad when cold in the morn, but came out of it after a few mins warmup in the driveway! now, its bad all the time! not sure if its related but it did actually overheat while this was goin on a couple weeks ago! ***umed it was the thermy and changed it! so! ive changed the knock sensor timed it perfect module in dizzy plenty of compression spark plugs are new cap, wires are also new still knocks! only on the RIGHT BANK! never on the left side! was told to plug off the egr valve line to see if that was it! nothing! also, when we timed it, plugged the electronic advance back in, it didnt advance! imma gonna burn this sum***** if i cant come up with something, but like me, most the guys i know dont work on this **** much! k, time for a beer......
Todd does it do it with good gas too ( last time I was over there in my truck I got gas and my truck pinged until I got gas again, it never pings with my gas from here) try putting some 92 or 93 in it and see if that helps any and BTW the gas I got over there that was **** was Vpower Shell
mike, i have tried that..nothing...and i wouldnt put shell gas in it at all! ill push it first! but why would it only be on the one BANK if it was the gas anyway? ****, im lost~
check the plugs! if they are burning fine it could be wrist pin. see if some premium fuel changes the sound. pull the valve cover and listen.
Plugging off the egr line is not the way to test it. Hook a vacuum pump to it and with the engine running apply vacuum. Should be able to hear a noticable difference. If not then it's probably stuck in the open position and causing a lean condition. Might even be carbon build up from bad valve seals. Use a squirt bottle with water down the throttle body a few times the give it a good run. Could be a vacuum leak from the intake as well. Spark advance won't kick in until it's up to operating temp so check the temp control on the intake or thermostat housing. Sounds like its a real ***** to diagnose.
Actually on that unit it is more likely to knock or ping if the EGR didn't operate than vise versa! EGR cools the combustion temp down to get rid of oxides of nitrogen and ping! EGR isn't all bad!
Don't expect it to advance the timing if it's really spark knock. The ECU is busy trying to retard it until the knock quits.
Ground out one plug wire at a time. If you can isolate it to one or two cylinders then maybe you can get somewhere. I'd start looking for something other than spark knock. Lifters, rockers, exhaust manifold leak or heat riser if equipped, head gasket, etc,etc.. Just shootin in the dark
those distributors were bad for getting a crack in the pickup. it could also be that one of the injectors is restricted or has a weird spray pattern that could cause this concern.
If it's one or two cylenders it could be a carbon depisoit causing a hot spot. run a combustion chamber conditioner through it.
Todd, my OT shop truck (95 TBI motor) did that, but was worse than what you're saying--mine pinged all the time, and ran rich. It was the coolant temp sensor---the engine thought it was cold all the time--messed with timing and fuel delivery. Turned out my radiator was all gummed up with rusty **** and fouled the sensor.
okay! been to busy farmin till today! [another ****load of rain] so i decided to just drive it up our road a mile or so and try tweekin the timing by ear! it pegged out the temp gauge FAST! then on the way back, it went back to normal! ANYONE"?
I wouldn't be so sure it's a "spark" knock..... A knock at first start up "could" be piston slap or........a main... If it's knocking when just idling, start pullin' plug wires off that side of engine. If it's a bearing, the knock will get quieter or go away, as there won't be a "load" on it.
only does it under a load! was doin it when it is cold outside in the morn, but doesnt seem to be now...im sure the timing is a lil off seeins how im tryin it by ear, but no shop and downpours make it hard to stand out there and time it!!!LOL
breeder, you won't be able to time an efi motor by ear. It has to be put into a static mode to set base timing, then the ECU takes over. If you have played with the distributor without using the base timing process, it will be out of it's little transistorized mind. Find the timing interupt connector on the firwall harness, single wire, big connector. Unplug it and start the engine, set base timing to about 10*, turn off engine, reconnect wire.
Is it knocking or popping? It could be related to exhaust valves not seating if it seems like a popping. I had a similar problem, it would miss or pop (I had zoomies at the time so it was easy to isolate which cylinder), sometimes it would go away when it warmed up but got considerably worse until I put on new heads. I looked at the old ones after pulling them off and could definitly tell they were in bad shape.
i had the base timing set before! didnt help...im just tryin to get it to a buddys shop without it overheating and blowing up! its for sure spark knock! just cant figure out the damn reason! never thought id miss heat and comfy seats!!!!
pull the vacuum advance hose off and plug it. then go for a ride. my '88 350 was pinging and that fixed it. i used a earlier delco 60s style distributor though. too much advance too soon. runs fine without the vacuum. others may not run fine. try it and see.
Check your throttle body base gasket under the throttlebody. I have seen them crack and cause a lean condition on one bank of cylinders before. It happened on a truck a customer brought in and drove me NUTS for a week before I found it.
you can decarbon the cylinders the old fashioned way. Run a high idle and dribble water in as fast as you can w/o stslling the motor. It will knock all the deposits loose and send them out the tail pipe. If you have an old converter, it may not like it so much, but a honeycomb should be ok. Follow that with a mist of atf to put a little oil back in the top end for a short time while the soot clears out. (ssshhh, the EPA is listening)
The knock sensor also has a matching knock sensor module/electronic spark control (ESC) mounted near the throttle body if you did not clear fault codes after fitting the new knock sensors the ESC can set a new code and stop the timing functioning correctly. It could it have gone into limp home mode ? Full rich---- full advance? Is the truck black smoking and using heaps of gas? You can read the trouble codes by shorting out the diagnostic terminal in the ALDL plug under the dash on the left. You will need a list of codes and instructions.........in most manuals, or an OBD-1 code reader.
WOW! im thinkin ill just burn the ****er at this point!!! lol! thx for all the tips guys! once i get the new water heater in my house tomm...imma print this and take it to my buddys shop!
The Jalopy Journal
