I have a question about my '97 Suburban with a 5.7 Vortec, yeah, I know, but it could work for an older car too... I can't run less than 89 octane in it without pinging like a bastard. It says in the manual that they should be running 87 octane. I want to do a tune up anyway since I have put 10K on it since I bought it in September. Do I retard the timing a tad and run colder plugs?
I'm pretty sure the timing is set by the ECM in a '97. Nothing to adjust. Perhaps there is a replacement chip to run on regular. Usually people desire just the oposite.
sure is, sounds like you've got other problems. check engine light on? move the distributor and it will be for sure..... they use that as a cam position sensor. has a crank sensor down at the balancer but there ain't much you can do with either one but fuck things up if you change anything. OBDII takes a scanner, no way(that i'm aware of) to "jump pins) and pull codes,either
seriously, I traded off my 97 full size truck because it clattered on anything under 91 octane. I took it in twice under warranty and once after warranty for the problem and they could not figure out how to fix it. I traded it in on a Dodge diesel truck because of that fucking clattering. At least the diesel has a reason to be noisy.
My friendly G.M. store sells a product they call "top end cleaner" that did wonders for a pair of '83 Ford Ranger 2.3 litre dogs in my little fleet of 123 pieces of equiptment. I know, I know, they're all supposed to have a knock sensor to retard timing when they get carboned up and begin to ping. After they get a lotta miles on 'em, the computer reaches it parameter on timing retardation and the carbon buildup will cause it to ping until the carbon is cleaned out. That's where this product comes in. Ya follow the directions on the can and it works. Sometimes I'd leave it in the chambers overnight to really clean out that carbon. I never had any chevys that ever required this poeration but that GM stuff works great on high-mileage fords. Side note: It had been a couple months since I'd treated the Rangers to a carbon bustin party and I went on a 3 week long vacation from work... When I got back, there was only one ranger parked outside. The other one had gotten carboned up and the crew kept driving it until they packed so much carbon up into #1 combustion chamber it knocked out the rod bearing........
Not sure of your application, but GM did use knock sensors on various motors.A bad one would make your engine ping really bad.
tomslik, you are right about the check engine light. It pops on after being driven at highway speeds for extended periods of time and turns off after a couple of days. Tranny will shift hard from first to second as well, next day, no problem. Will colder plugs fuck with the computer?
El, don't try to screw with the factory timing, it won't work. The computer controls it. As weldemup said, if the engine knocks, the knock sensor should retard the timing to stop it. If it is not working, it will knock. If it IS working ( a scanner will tell you!), then the computer may be retarding the timing as far as it can, but the knock is still there. So look at why it is knocking (not timing issues) Could be running too hot, non functioning EGR, lean condition (vacuum leak, bad O2 sensor, other sensor problems), mechanical knock (carbbon build-up on pistons). In any case, you need a scanner to check most of these, if you're not an expert. A shop manual is also needed. You can't just go in and start moving distributors, and turning screws without knowing what to do, like an old engine. It just DON'T work.
I agree, ain't gonna touch the timing. I'll see who can pull codes and go from there. I promise, I will not touch the distributor.
Take it to get repaired. The service engine soon lamp is on for a reason. Hence the title of the lamp: "SERVIE ENGINE SOON". Let me give you a little of my background: I've been a GM Master Tech for 16 years. ASE Master Tech, blah blah blah... I still can't understand why people think they can just drive on and on with the SES lamp lit, and expect the vehicle to opperate normally. Something is wrong with the system.... that is why it is not acting normally. YOU WILL NOT BE ABLE TO FIX IT YOURSELF. DO NOT MOVE THE DISTRIBUTOR. Spark plugs are not the problem. DO NOT TRY TO MODIFY OR ADJUST ANYTHING. Save yourself some money (and some brain damage, trying in vain to repair it yourself) and take it in. Your wallet will thank you in the long run. (just my professional advice) LP P.S. A slight pinging is normal opperation. I can show you where it states that in the service manual and the owner's manual. The PCM will retard the timing durring a Heavy pinging situation... also if the PCM cannot retard the timing far enough to lessen the ping, the SES lamp will come on. However, I suspect the noise you hear is normal and the lamp is on for something else because you say it shifts abnormally. My bet is you have a faulty ignition switch... Thats right... ignition switch.
LP, that is the most interesting theory yet. Ignition switch? How? As for not touching the distributor, I already promised I wouldn't. The SES goes away, as noted, could it be the carbon that Rocky was talking about? I appreciate your insights. PS, I voted for your car on Egorama...
These trucks are famous for ignition switch failures. They sometimes will not send power to the transmission, which causes the PCM to comand the transmission to default mode and light the SES lamp. That sounds like what is happening. IF NO CODES ARE STORED for the knock sensor system, the pinging you are hearing is normal. LP THANKS FOR THE VOTE MY FRIEND! Remember to vote for 5 (five) HAMBERS!!!!
I agree with LP, I've replaced several switches also and can also tell you they do ping (and that's normal......but sad)...........I also voted for LP's car.
I think I'd just want to get a scan tool on that before I did anything the MIL light system comming on after some driving seems to me that you could be having an 02 senser that is lazy and could be driving the injectors rich causing the carbon build up and the pinging...could also be plugging the cat and cuasing the tranny to shift erractily...I would not spend a knickel till I got it scanned for codes and then post what the codes are...I am also a master tech and work with this stuff all day....Another thing real common with this engine is intake manifold leaks coolant leaking into the engine shitty gaskets that dex cool eats intake gaskets and that can also cause pinging and affect the 02 also There is a PCM Re-flash that is designed to remedy a complaint of 'Ping/Detonation At High Altitude, Moderate to Heavy Throttle Application'. .and any drivability problem could cause the tranny to shift erractily..I recommend cleaning the upper cylinders. Common problem. Add a couple cans of X66 or some upper cyl decarbonizer down the intake while running, shut it off to soak in.I would also make sure the egr is working....I doubt very much that your ignition switch is the problem although they do fail alot but I have yet to experience one that cuased the symtoms you described...fatchuk
I'll find out if anyone around here at the parts houses can do that. I am not hopeful, this is a dismal place for getting anyone who is squared away. Schuck's sucks. No AutoZone. The Boy's pissed me off long ago, ain't here either.
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