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Car Forum / Chevrolet / Chevrolet Trucks / October 200688 Chevy Ignition problems
88 Chevy 1500 Ext cab Long Bed. 350 CID TBI 205,000 miles About a week ago I did a tune-up, changed wires, plugs, cap & rotor. It ran great after that. My son was driving it to school and while on the highway it started to slow down and finally stopped on him. On the side of the road he tried to restart but it would crank but would not start. Had it towed to the house and I started to troubleshoot. It seems that its not getting any spark. I tried pulling the #1 plug out and holding it against the block and didn't see spark. (It was in the daytime so it could have been there but I just didn't see it). I had a coil from another vehicle (it currently isn't running but had no ignition problems the last time it did run) and nothing changed. Since the #1 was out, I bumped it to TDC. At TDC the rotor was pointed to #8 on the distributor cap instead of #1. Assuming that the distributor can be either 180° out or right on, I moved the spark plug wires instead of the distributor. I put the #1 wire on the #8, #8 to #4, #4 to #3, and so on, following the firing order. That didn't help so I put the plug wires back in their original places. I had a mechanic tell me that it sounds like the timing chain had jumped. That shouldn't be a major problem to change after getting the accessories out of the way. Before I start on a project like that I want to know if anyone out there has any ideas or suggestions that I can check before I try to tackle the timing chain & gears. If the timing chain and gears are defective, what other indications are there. What else in the ignition system could I have missed? I know it could be something else simple. I double checked all the wires and everything else electrical I think, but I may have missed something. The truck was running fine until this problem. I would check the high energy distributer for a bad module or transformer or pickup coil and related wiring old john > 88 Chevy 1500 Ext cab Long Bed. 350 CID TBI 205,000 miles > [quoted text clipped - 22 lines] > double checked all the wires and everything else electrical I think, but I > may have missed something. The truck was running fine until this problem. > 88 Chevy 1500 Ext cab Long Bed. 350 CID TBI 205,000 miles > > About a week ago I did a tune-up, changed wires, plugs, cap & rotor. It ran great after that. My son was driving it to school > and while on the highway it started to slow down and finally stopped on him. Snip Frank, there is a black module inside the distrib that all the wires (not the spark plug wires) connect to at the base. Replace it... buy two, and keep one in the truck. http://www.lmctruck.com/icatalog/cd/0141.html > Number 6 on the left side of the page. run the spark plug wires the right way. The firing order is stamped on the top of the intake manifold. 205,000 is really great for that module... they normally don't last that long Enjoy. Hawk. PS: LMC truck carries everything for your truck.. get one of their catalogs. This was it. The ignition module. I replaced it and it fired right up. Thanks to all who gave me advice >> 88 Chevy 1500 Ext cab Long Bed. 350 CID TBI 205,000 miles >> [quoted text clipped - 24 lines] > PS: LMC truck carries everything for your truck.. get one of their > catalogs. > This was it. The ignition module. I replaced it and it fired right up. Thanks to all who gave me advice ----- Glad I could help Frank. You ever need help with that truck, give me a holler here.. I know those things inside and out. Chevy made some great classic trucks.. the fifties, 67-73 years, and without a doubt, the 88 to 96 years will be sought after classics down the road. Hold onto it.. its one of their best. HDS Hi HDS, Thank you and all others that helped. I love the truck and eventually hope to restore it as much as financially & mechanically possible. (88 Silverado, 350cid, Ext. Cab, Long Bed TH700 tranny) Here's an intermittent problem I've had since I bought it. After driving for a while (engine nice & hot), it'll drive great. Once I slow down, (parking lot speeds) it wants to die out. I hear the RPM drop, the only indication besides the "feel" & sound of it is oil pressure, which drops towards zero as it dies. Oil pressure was checked with direct reading gauge and it's pretty close to what the dashboard gauge is reading. It only happens in drive and reverse (especially reverse). It will idle forever in park or neutral with no problems. It doesn't seem to happen when it's cold. It may drive normally for several days, then it'll happen a couple of times and disappear for several more days. I see it as more of an annoyance than a problem, so I haven't really worried about it. Once it dies, it'll start back up without any problems. About the only maintenance done is tune-up & oil change. The worst part is that when it happens, it's at the most unfeasible time to troubleshoot. When I try to duplicate the problem, it runs great. Sometimes I think it may be something on the transmission since it only happens when it's in gear. Any advice/tips would be appreciated. Frank >> This was it. The ignition module. I replaced it and it fired right up. >> Thanks to all who gave me advice [quoted text clipped - 11 lines] > > HDS > Hi HDS, > [quoted text clipped - 14 lines] > > Frank -------- Well it sounds like the IAC (Idle Air Control Valve) might be getting stuck (http://www.lmctruck.com/icatalog/cd/0112.html > #4 on bottom of page). It has 4 wires that come out of the back, and is on the left corner of the throttle body. With 200,000 + miles on it, I would bet that the throttle body (and it components) need a good cleaning. I would remove the throttle body, unscrew the IAC, and really clean out everything, and replace all the gaskets with a kit you can buy from LMC, or your favorite parts store. There are little veins on the bottom side of the throttle body that can get gummed up pretty easy. Also, if you have an EGR valve, I would replace that as well. Clean out all the vac lines that feed into the throttle body also. If you end up changing the IAC valve, you'll have to get the truck warmed up, and on the road over 30 MPH for a few miles. The computer will "learn" the new valve, and your idle problems should go away. This kind of job is really easy to do. There are only three bolts that hold the throttle body onto the intake manifold. You'll need a set of star/hex screw driver/bits to take the throttle body apart for the gasket replacement. You might want to go ahead and replace the fuel pressure regulator parts as well (its part of the throttle body), and have the two fuel injectors pressure cleaned. The low oil pressure in your case is just slow engine idle. With the auto trans, it should idle 750 to 900 rpms, and dip slightly when you turn the wheel hard, or the AC comes on, etc... but shouldn't drop below 700. In fact, you should hear the truck speed up the idle speed when these things happen. HDS Thanks HDS. That makes a lot of sense to me. I think in the beginning someone told me it may be a fuel problem and I ran just about every fuel conditioner/cleaner with fill-ups. I think it may have helped a little but not too much. That's a problem I'll get to in a couple of weeks or so, unless it gets worse. I just don't have the time right now. When you say to get the injectors pressure cleaned, does that involve taking them out and to a shop or can that be done at home (I have an air compressor) I've seen the injectors in work and they look like they put out a pretty good pattern, a decent spray. I do want to do it all at once as far as the TBI is concerned so when I get a free weekend I'll take care of it. Can I get to the IAC valve without taking the throttle body apart, and use a carb cleaner for now until I can tear it apart, or would that be a waste of time? Frank >> Hi HDS, >> [quoted text clipped - 57 lines] > > HDS > Thanks HDS. > That makes a lot of sense to me. I think in the beginning someone told me it may be a fuel problem and I ran just about every [quoted text clipped - 6 lines] > > Frank ------ Hi Frank... Yea, you can take the IAC out without taking the throttle body off. It simply screws in. You can clean out allot with the old carb spray. There is a large vac pipe on the back that you can pull off and get to more of the "inners". It's such a simple throttle body. Almost no moving parts to speak of. GM realized their mistake, and no longer make the 220 throttle body (IFAIK that is). It's a great little gem. The IAC controls the idle, so if your having idle problems, that's where its at. Pressure cleaning is something the shop has to do. They will hook them up to a do-dad and run cleaner through em under pressure. Jiffy lube can do it with em still installed in the truck. Not sure of the price though. But check with a couple auto parts stores, they may offer the service... and you'll have to take them out. With over 200,000 miles, I can guarantee they need it bad. It'll be like a new truck after you do. HDS Try removing the #1 plug turn over engine till you feel air comming out of hole then with a scockt wrench turn over engine till piston is all the way to the top[stick a pencel in the hole] then it should read Top dead center or 0 at crankshaft then check where the rotor is pointing if it not at # 1 the timing chain has jumped |
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