09 Suzuki Super Stalker with a pre-ignition condition. K6A engine. Truck sat for a year. Just had the valves done and got the head back on. Runs good, but has a pinging under load. Filled the tank with higher octane gas, drove it about 10 miles, and no difference. I've ruled out the chance of it being high combustion temp because it does it parked under a load when cold. Shouldn't be timing or fuel pressure because it seems to have plenty of power and run smooth. Only thing I can figure is maybe contaminated injectors, but from previous experiences, contaminated injectors cause misfires, which this doesn't have. Looking for some suggestions here. Timing advance is computer controlled. No distributor. Spark plugs were done just a couple months before the truck was parked.
Should there be a comma in there? Parked AND under load maybe? I ask as I don't know how you can "load" it when parked. Does it ping at idle then?
That being said...ignition timing would be MY first concern as to the cause of the problem. You mentioned that you are distributor-less, but do you not have a Cam Position Sensor (or alike item) that is adjustable and dictates the INITIAL ignition timing setting, after which the computer takes over with fine tuning control?
Another possible problem could be in the incorrect setting of VALVE (camshaft) timing upon engine reassembly.
Also, might the re-worked head have been machined down in excess, thus altering the compression ratio higher (even causing piston to valve interference) to the point of causing the sound that you hear?
Lastly, are you able to scan the computer for errors / codes?
I can hold the brake and put it in drive, apply the gas a little while holding the brake, and get the noise. No noise at idle, and no noise cruising down the highway at 45. But you start up a hill and pull the engine down a little, and there it goes. It does have a cam sensor, but looks to be non-adjustable. Cam timing is the last on my list of things to check. The engine runs out fine, and has plenty of power. The starter turns over fine, with no "kicking back," like you would normally see when the timing is too far advanced. The head was not surfaced, so no change in compression. There's absolutely no way there is valve to piston interference. I tried to get one scan tool to link up to view live data with no luck. Plan on trying a second this evening. Ran out of time yesterday. If this were something I had service information on, this wouldn't be a problem, whether it was domestic or import. If I can get my second scanner to link up, I'll find the problem, but I'm doubtful it is going to work.
Cam Sensor was removed prior to timing cover removal. No adjustment on it. It fits into a round hole, and has an ear on it to bolt to the cover. I spoke with a tech yesterday evening at a place that specializes in these, and he agreed he didn't think it was a timing issue, but maybe a fuel injector issue. I don't know if he was being honest with me, or maybe like a lot of guys that do this for a living, and didn't want to give out any info. I always try to help other shops in town when they call me, but after a while I do get short with them because they need to figure stuff out on their own if they're doing this for a living, the same as I am. At the same time, I try to help guys trying to do stuff themselves to save a few bucks because I understand money can get tight. I've got to get back at it. Only been able to reply this morning because I've been in the office doing paperwork. I've got to get out on the floor and start getting some cars out of here. I'll check back on this either this evening or in the morning, and if I can get one of my scanners to link to this thing, I'll bite it in the butt and let you know what I figured out. I appreciate your help.
Well I'm eating crow. It appears the exhaust cam has jumped one tooth forward. I know it was on when I put the chain on because I spun it over by hand and re-checked to make sure my marks were all on the money. Any time I put an engine together, when it comes time to start it, I disable the fuel and ignition and turn it over with the starter to build oil pressure. Then I enable and start it up. I'm betting when I was doing this, the exhaust cam jumped before the hydraulic tensioner had a chance to build full pressure. I did manage to get my scanner to link up, but it did no good. There was no data stream, but it would read codes, which there were none. This goes to show that a guy should be certain of nothing because it can cause him to overlook the obvious.
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