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Showing results for tags 'timing'.
Found 7 results
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1994 Chevy Suburban K2500 454TBI Mileage=155,000 Factory setting: 4BTC Everything is stock. Searched on internet, looks like some people set it at 8BTC or even 12BTC to get more torque and better MPG. But seems like different year have different program, same setting on some year it runs good, some not. I only use #91 gas from Shell or Chevron. #91 gas allow more BTC, right? Anyone have recommend about BTC setting? Most time running light, only me in it with some tools weight no more than 100lbs. On a test run from San Jose (CA) via I680N, I580N, CA120E, CA99S, CA140E, to Mariposa(CA), cruse at speed limit, most 65MPH, CA140 is 55MPH, most flat, get 13MPG in average. Plan to tow an utility trailer with a fully loaded truck camper on it (I live in the camper). -
IVE ALMOST COMPLETED AFM DELETE FROM CAM TO ROCKERS WENT OK UNTIL NOW. I TORQUED ROCKER BOLTS NOW IT WONT TURN FULL CYCLE WITHOUT HANGING UP ON CYLINDER 3 (FIRING ORDER). WHAT COULD CAUSE THIS ABRUPT STOP IN THE CYCLE AND PUT THE PUSHROD IN THE WAY. PLZ HELP!!!!
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When traffic light turns green, I kicked the throttle pedal, finally, this time, I got the power that a 454 supposed to give me, I almost cried. ======= 1994 Chevy Suburban Silverado K2500 454 L19 TBI 4L80E 153K miles ======= Months ago, I posted several topic (2 or 3) about it stall and knock sound under the floor, while cruising on highway. Well, the "highway" include GGB (Golden Gate Bridge).? 94' 454 stall while driving and knock sound under the cab 94'454 stall again, after change fuel pump Take note that I am actually completely a newbie, new driver (2 years), new vehicle owner, and new to America. So maybe some thing in my topic is wrong, but I don't tend to misleading. Shattered catalyst After the GGB stall, I found its power is weaker than before, and sounds like the exhaust is blocked, and when drive next to a vehicle or wall, I can hear air bleeding sound. Then got MIL code 32, EGR, however I can't find any problem on EGR system. This 454 engine use Linear EGR system, the valve is controlled by ECM directly, no vacuum pipe. I tried to remove air filter, to make it performs better, then find the blocked-exhaust sound become louder. Then one day the stall happened again, I found the knock sound sounds more like opening a soda can. So I visited a muffler stop, turns out the catalyst is shattered, quite big loss. ? Since I don't have enough money for a catalyst, and it may be shattered again, so I asked them to put a steel pipe instead as a temporary manner. After that, the compressed air sound is disappeared, the blocked-exhaust sound is lighter but still there, and the performance is better but still weak. So shattered catalyst blocked exhaust, caused air bleeding sound. And caused extremely high pressure in EGR system, too much exhaust injected into intake manifold when EGR is open, caused ECM think EGR have problem, light MIL and sending code 32. Fired chip in ICM (ignition control module ) The last time it stalls, at a quiet place, I finally figured it out that it feels and sounds like wrong timing, and when press throttle pedal, it back fires, and the harder press the pedal, the louder the sound is, very loud. And when it back fires, I can feel shock on throttle pedal. I told this to my mechanic, he told me to replace the ICM. He said back to old days, he replaced many of it. He suggested me to purchase new one, because it's cheap, even from ACDelco, and this thing usually break down for years parked vehicles, vehicles in junk yard usually parked for years. I opened the metal cover of old ICM, find one of chips is black, oil or something around it is dark brown, the metal cover supposed to be glued to the plastic shell, but the gap near the black chip is open, so it's clear that the chip was exploded. After I changed the module, 3K+ miles so far, including 2 round trip from San Jose to Yosemite, stall never happened, I think the stall problem is officially solved. So the broken ICM caused wrong timing, and stall. "Knock sound" is actually backfire, the exhaust is under floor, so I felt it's knock sound under floor. Back fire caused huge pressure burst in exhaust, then transferred to intake manifold and throttle body via EGR system, caused shock on throttle pedal. Thank god this didn't ignite the gas-air mixture, or my trouble gonna be bigger.? Wrong base timing That's NOT all folks! I found it still very weak, on I680, the climb at east of Fremont, it even can't maintain 60MPH! WTF?? At this time, what I have done on it: Fueling system: New Delphi fuel pump, capable of over 60PSI; New fuel filter, ACDelco; Fuel injector, tested and cleaned; Fuel pressure regulator, changed new spring, 30PSI; Air intake system: New air filter, ACDelco; Ignition system: Distributor cleaned; New ICM, ACdelco; Full assembly of distributor and ICM from junk yard as spare part. New spark plugs, wires and ignition coil, ACDelco. Cylinder pressure: I forgot reading, but within normal range. I pulled out the distributor for cleaning and ICM change reason, but when I put it back, I tried to find the timing mark. However, only engine block have the mark, the distributor don't have mark from factory, only a mark made by the ex-owner's mechanic, and it turns out it's wrong. So I tried to do base timing. I borrowed ignition timing light from my mechanic. But I can't find the "timing connector". At that time, I thought cold start and idle is running at base timing. So you guess it, runs over 20 degree ******. Then one day, I read my shop manual carefully, find out cold idle is NOT base timing, and only when the "timing connector" disconnected, the engine runs at base timing. However I can't find the connector, then after some dig on internet, I finally find it: inside the cab, passenger side, by the side of the blower motor, a single pin connector, tan with single black stripe lead, that's it. It's a bit far from "adjacent to the distributor".? Then I borrowed the timing light again, do the base timing, hit the road again, the result, on I680, maintain 70MPH easily, like I write at beginning of this topic, I almost cried! Just recently days, it even reached over 90MPH when climbing! Yeah it's speeding too much, but you know the traffic flow on highway is a bit crazy after reopen, probably due to people lock in their home for too many days. ======================================================= So That's all folks, I currently focus on renew my truck camper, including solar panel, painting, bathroom convention, jack system rebuilt, then maintenance on the 1996 Ford F250xl, 350 engine, and convert to dually, create a "FAKE F350". ? Then come back, I found the A/C compressor is dead, my mechanic suggested me to get one from junk yard, because most of them from car part shop are rebuild in China, you know what, even I am Chinese, I always avoid "China".?
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454 Vortec Tapping and Knocking
RW22 posted a topic in 1988-1999 Chevrolet & GMC C/K GMT400 Platform
I have a 1997 k2500 Suburban with the 7.4 vortec. It is a 290,000 mile engine and I was recently doing some work to it. I put new injectors, valve cover and upper intake gaskets, distributor, plugs, wires, and a fuel presssure regulator. This engine was fine before and the only reason I had done this work was because it was cranking for about 5-8 seconds before it would start. When I put everything back together, I got the timing as best as I could (I do not know how to properly time these newer engines) and started it. Immediately, the engine was shuttering and I could hear what sounded like a lifter tap. It was idling very rough and after about 4-5 min a louder knocking sound started up. I immediately cut the engine and checked the oil for metal, and there was none. I am simply baffled at this as I didn’t touch anything when I had the valve covers off. My only two ideas are this. 1) it is not timed right, and I need to figure out how, or 2) the old distributor had some wear on the gear, and possibly the cam has the same wear and isn’t working right with the new distributor. Any help on this would be greatly appreciated. Thanks. -
I just put a new 6.0 long block in my 2002 chevy Silverado and it won't start. All new sensors, plugs and wires. When I go to start it it back fires through the intake. Plugs are soaked in fuel as well. I've checked to make sure nothing is unplugged....any suggestions?
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I dropped a 1988 big block in my 1986 Blazer and went thru the timing chain. Put all back together as always. Tried to fire it up and backfire thru carb. So figured 180 out. Pulled the dot towards each other and re dropped the distributor in and set all up. Still getting same.... I am a seasoned mechanic getting my butt kicked. Help. Thanks.
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Hey guys, I'm new to this forum and new to owning my first chevy truck (with a small problem - hopefully!) and I wanted to post this here for some help/advice/guidance. I have done some research on this problem and only found one other post on the internet with this problem so it seems like a rare one! Unfortunately, the post I found died once the OP stopped responding. So here is the story and the problem:. As of yesterday, I am the new owner of my first Chevy truck! It's a: 1989 GMC Sierra 2500 with a TBI 350 It's completely stock and runs great! (while the EST Bypass wire is connected) No check engine light Got it for $500 There is a problem... The truck does not pass CA smog testing Smog Visual: Passed Smog Emissions/sniffer: Passed Smog Functional test: Failed The reason it failed (as printed on the smog failure report) is: Ignition timing is not readable. Also vehicle will not run when single wire tan/black connector is disconnected which is procedure for checking timing. This was my first attempt at resolving the problem: Started the engine and warmed it up Disconnected the tan/black EST bypass connector WHILE the engine was running and the engine went from idling smoothly to a idling rough. Using a timing light: I set the timing to 0 degrees. The engine then began to run smoothly! I reconnected the EST bypass connector. (This was done while the engine was still running - The engine continued to run smoothly.) I shut the engine off I started the engine and it ran perfectly fine. (I thought I had resolved the issue!) Just to double check: I shut the engine off then I disconnected the EST bypass connector again. I tried to start the engine Results: Engine cranks over but does not start After realizing the engine was not going to start: I reconnected the EST bypass connector. The engine took quite a bit of cranking before it started. Once started, it ran fine. Basically I am able to replicate the exact same same problem that the smog shop came across. Based on my research, the correct procedure to check the timing is: Warm up engine Shut off engine Disconnect EST bypass wire Start engine (Cannot get past this step...) Set timing to 0 Shut off engine Reconnect EST bypass wire I'm guessing this is the procedure the smog shop is trying to follow so seems I need to get this to work for them so the smog test passes. I hope this is enough details for everyone. Please let me know if you have any ideas guys. Thanks for the help in advance!
