'92 Safari 4.3 'Z' engine knock (ping)
Question:
i have a 92 s-10 with the same engine and i had the same problem. i ended up replacing the electronic spark controll unit and that fixed all my problems. the engine runs nice and smothe now. let me know if you have any more questions adam
Response:
Hi all…. I need some quick advice here from a GM Technician. As mentioned, a ‘92 GMC Safari Van 4.3l TBI ‘Z’ engine. 145,000km. My nieghbours van. I work on Volvos and am not too familiar with GM stuff. Moderate to heavy knock (ping) cruise and accel. No codes. Initially thought it was the EGR and sure enough the ECM was not groung the EGR circut. Replaced the ECM and it is much better but still unacceptable. Confirmed EGR with a vac gauge. He has a GM shop manual for the truck. I’ve been through it, checking all the items that GM might suggest for ping. the only thing I can’t check is the fuel pressure becasue I don’t have the correct adapter for my gauges. I did notice on changing the plugs that one (#2) was substantially more fouled than the other 5. I also noticed that the high tension wire for the #2 plug had some arcing evidence on it. Two questions – 1) Are these engines prone to carbonning? and 2) Is it possible for just one cylinder to be so bad to could cause all the difficulties? I seem to recall reading in Motor or something that the intake manifolds were prone to carbonning and as the carbon layered, it absorbed more and more fuel, causing a lean knock. I doubt it’s a lean knock though because even at cruise, the O2 toggles from rich to lean and back sharply. I don’t recall the cross counts but it didn’t seem out to lunch. As I recall the block learn was fairly consistant around 128 but I’d have to redo it to be accurate in my statements. He also tells me that his mileage is off about 4-5 MPG. Fairly obviously due to the knock condition. If you put the super dooper hightest stuff in it, he says it doesn’t knock. Won’t pay the extra 12cents a litre. And really why should he – it’s supposed to run fine on 87 octane, not 94. Anyway, any thoughts or experiences would be appreciated. Although we’re good friends, I’m not doin’ the heads on that one for nothing – looks like a major pain getting the exhaust manifolds off. Chris Lungstrass Kanata ON
Response:
> Hi all…. > I need some quick advice here from a GM Technician. As mentioned, a > ‘92 GMC Safari Van 4.3l TBI ‘Z’ engine. Moderate to > heavy knock (ping) cruise and accel.
Chris I am not a GM technician, but I do have a 95 Astro. There could be some simple fixes or it could get complicated. Have you tried a carbon and deposit removal fluid in the gas? Redline or the Chevron brand work very well. If for some reason there was a build up on the valve stems, you might have some ping until it is cleared up. The spark plug wires might be a cause. Beyond that would be the old computer analyzer at the dealer’s shop or some similar shop. — Jim Walker Northern Virginia
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