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Car Forum / Chevrolet / Chevrolet Trucks / July 2006Chevy 454 Timing problems
I have a 97 Chevy 3500HD w/454 vortec I bought the truck not running and after checking it out found the pick up was bad replaced that and it started up but ran very rich After checking it out now I found the cylinder 1 fuel injector was running like a fuel pump all the time I replaced that and it seemed to be clearing up so I drove it around the block to clear it out only to get worse It coded p1435 so I pulled the distributor cap and found the rotor button mount was loose from the distributor so I replaced that now and no more code and it seemed to be running ok but after 2 minutes or so it started again to load up very bad and backfire I think the timing chain is ok but is there anyway to check witout pulling it apart? If it had a bad injector, replace them all. Do a COMPLETE ignition tune-up. When the plugs are out, do a compression check. >I have a 97 Chevy 3500HD w/454 vortec I bought the truck not running > and after checking it out found the pick up was bad replaced that and [quoted text clipped - 7 lines] > bad and backfire I think the timing chain is ok but is there anyway to > check witout pulling it apart? I didn't want to pay for all the injectors yet if I don't have to I did do the tune up and same thing I was just working on it and found it was out of gas so now it starts but still runs very rich misses and stalls at idle.One thing I noticed when I had the plentum off #1 and #8 injectors when you turn the switch on ran as long as the fuel pump are they supoposed to?If not any ideas why? > If it had a bad injector, replace them all. Do a COMPLETE ignition tune-up. > When the plugs are out, do a compression check. [quoted text clipped - 10 lines] > > bad and backfire I think the timing chain is ok but is there anyway to > > check witout pulling it apart? >I have a 97 Chevy 3500HD w/454 vortec I bought the truck not running >and after checking it out found the pick up was bad replaced that and [quoted text clipped - 7 lines] >bad and backfire I think the timing chain is ok but is there anyway to >check witout pulling it apart? I would check engine coolant temp sensor for starter as it could be bad and not code and cause it to go real rich and get worse as it warms up. ----------------- The SnoMan www.thesnoman.com I checked that because thats what I was thinking but it's okay too > >I have a 97 Chevy 3500HD w/454 vortec I bought the truck not running > >and after checking it out found the pick up was bad replaced that and [quoted text clipped - 14 lines] > The SnoMan > www.thesnoman.com >I checked that because thats what I was thinking but it's okay too Did you do a resistance check of it and of MAP sensor too? 454's are pretty sturdy internally and not know to have internal weaknesses of the than valve guide seals (oil consumption) ----------------- The SnoMan www.thesnoman.com What should it be on both of those sensors?I unhooked them because I thought the obd2 would override and use a default sense of them but it ran the same.Do you know what the map would read at like 2k rpms on a obd2 trouble shooter computer? > >I checked that because thats what I was thinking but it's okay too > [quoted text clipped - 4 lines] > The SnoMan > www.thesnoman.com >What should it be on both of those sensors?I unhooked them because I >thought the obd2 would override and use a default sense of them but it >ran the same.Do you know what the map would read at like 2k rpms on a >obd2 trouble shooter computer? What is the static ohm reading of them with engine off and cool. Check TPS ready too as to what idle resistance is and if the change is smooth throughout range. ----------------- The SnoMan www.thesnoman.com I don't think it is but would this thing run if the distributor was 180 out? > >What should it be on both of those sensors?I unhooked them because I > >thought the obd2 would override and use a default sense of them but it [quoted text clipped - 7 lines] > The SnoMan > www.thesnoman.com >I don't think it is but would this thing run if the distributor was 180 >out? Yes is the cap was wired to that firing order relative to distibutor position. No if not. Did I confuse you? ----------------- The SnoMan www.thesnoman.com About what?I just checked the maf and map sensors on my computer and the maf is 0.32 and the map 29.5 and the temp before startup 80 > >I don't think it is but would this thing run if the distributor was 180 > >out? [quoted text clipped - 4 lines] > The SnoMan > www.thesnoman.com >About what?I just checked the maf and map sensors on my computer and >the maf is 0.32 and the map 29.5 and the temp before startup 80 I meant about my answer to your distributor question The map sounds good but not to sure about MAF. How is it reporting timing and TPS data. ----------------- The SnoMan www.thesnoman.com No I knew what you meant I'll have to check on those Whats the best way to check the tps?It shows up good on the computer 0 at no throttle and smooth to 100% And for the timing thing I did turn the distributor 180 and it was right before for sure > >About what?I just checked the maf and map sensors on my computer and > >the maf is 0.32 and the map 29.5 and the temp before startup 80 [quoted text clipped - 6 lines] > The SnoMan > www.thesnoman.com When I have the obd2 system tester hooked up it reads that the ignition adv (deg) is 28.0 and bounces around a little I have two other chevy trucks here both w/vortec but ones 4.3 and the others 5.0 and they both read -18 or so and the more throttle you give them the less they read Does that sound like a problem?Also how about lobes on the cam being wiped?Thanks alot for the help so far by the way > >About what?I just checked the maf and map sensors on my computer and > >the maf is 0.32 and the map 29.5 and the temp before startup 80 [quoted text clipped - 6 lines] > The SnoMan > www.thesnoman.com >When I have the obd2 system tester hooked up it reads that the ignition >adv (deg) is 28.0 and bounces around a little I have two other chevy >trucks here both w/vortec but ones 4.3 and the others 5.0 and they both >read -18 or so and the more throttle you give them the less they read >Does that sound like a problem?Also how about lobes on the cam being >wiped?Thanks alot for the help so far by the way Timing is not the same from engine to engine as it varies with engine load and size. Typical it should be atound 20 degrees at a idle (plus or minus 5 degrees) and it will vary a lotwhen you drive. Crusiing at 60 or so light throtle it may be 30 to 35 degrees or more at times. You are not looking for it to be constant but you are looking for it to be predictable. WOT it should be around 25 to 28 degress or a bit more at 4000 RPM. It would help if you could graph it while driving and watch the see if the spark is erratic. I had a problem with my 2000K3500 that drove me a bit nutz. It would develop a funny idle at time and then steady out. It never thru a code and dealer under extended warranty said all was well. I finally found the problem. It had a flakey crank pos sensor because at times it would through erraticing timing data but not enough to code. Never likely would have found it without a live data graph. ----------------- The SnoMan www.thesnoman.com I found out the #1 and #8 injectors are running all the time I checked and it has a full time ground to both of them rather then the pulsating.I think it's the ecm but I'm not positive but thats what it seems They're not grounding when it's unhooked so it almost has to be inside that > >When I have the obd2 system tester hooked up it reads that the ignition > >adv (deg) is 28.0 and bounces around a little I have two other chevy [quoted text clipped - 20 lines] > The SnoMan > www.thesnoman.com >I found out the #1 and #8 injectors are running all the time I checked >and it has a full time ground to both of them rather then the >pulsating.I think it's the ecm but I'm not positive but thats what it >seems They're not grounding when it's unhooked so it almost has to be >inside that Are you saying that the short appears to be ib ECM? I can dig up a schematic for the injector wiring. (it would be a 98 but it should be the same.) ----------------- The SnoMan www.thesnoman.com I'm thinkin it has to be I don't know where else it would be it's not grounded when I unhook the harnesses > >I found out the #1 and #8 injectors are running all the time I checked > >and it has a full time ground to both of them rather then the [quoted text clipped - 8 lines] > The SnoMan > www.thesnoman.com >I'm thinkin it has to be I don't know where else it would be it's not >grounded when I unhook the harnesses Okay, I just pulled up the schematic on that engine in and all of the the injectors are tied together on the power side to a 20 amp fuse called ECM 1. They are fired by the ECM grounding them. I uploaded a schematic to the members only tech referance area of my forum. ----------------- The SnoMan www.thesnoman.com |
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